Mechanisms of respiratory depression induced by the combination of buprenorphine and diazepam in rats

BACKGROUND

The safety profile of buprenorphine has encouraged its widespread use. However, fatalities have been attributed to benzodiazepine/buprenorphine combinations, by poorly understood mechanisms of toxicity. Mechanistic hypotheses include (i) benzodiazepine-mediated increase in brain buprenorphine (pharmacokinetic hypothesis); (ii) benzodiazepine-mediated potentiation of buprenorphine interaction with opioid receptors (receptor hypothesis); and (iii) combined effects of buprenorphine and benzodiazepine on respiratory parameters (pharmacodynamic hypothesis).

METHODS

We studied the neuro-respiratory effects of buprenorphine (30 mg kg-1, i.p.), diazepam (20 mg kg-1, s.c.), and diazepam/buprenorphine combination in rats using arterial blood gas analysis, plethysmography, and diaphragm electromyography. Pretreatments with various opioid and gamma-aminobutyric acid receptor antagonists were tested. Diazepam impact on brain 11C-buprenorphine kinetics and binding to opioid receptors was studied using positron emission tomography imaging.

RESULTS

In contrast to diazepam and buprenorphine alone, diazepam/buprenorphine induced early-onset sedation (P<0.05) and respiratory depression (P<0.001). Diazepam did not alter 11C-buprenorphine brain kinetics or binding to opioid receptors. Diazepam/buprenorphine-induced effects on inspiratory time were additive, driven by buprenorphine (P<0.0001) and were blocked by naloxonazine (P<0.01). Diazepam/buprenorphine-induced effects on expiratory time were non-additive (P<0.001), different from buprenorphine-induced effects (P<0.05) and were blocked by flumazenil (P<0.01). Diazepam/buprenorphine-induced effects on tidal volume were non-additive (P<0.01), different from diazepam- (P<0.05) and buprenorphine-induced effects (P<0.0001) and were blocked by naloxonazine (P<0.05) and flumazenil (P<0.05). Compared with buprenorphine, diazepam/buprenorphine decreased diaphragm contraction amplitude (P<0.01).

CONCLUSIONS

Pharmacodynamic parameters and antagonist pretreatments indicate that diazepam/buprenorphine-induced respiratory depression results from a pharmacodynamic interaction between both drugs on ventilatory parameters.

Pharmacokinetics of gallic acid and protocatechuic acid in humans after dosing with Relinqing (RLQ) and the potential for RLQ-perpetrated drug-drug interactions on organic anion transporter (OAT) 1/3

CONTEXT

Relinqing granules (RLQ) are being used alone or in combination with antibacterial drugs to treat urological disorders.

OBJECTIVE

This study investigates the pharmacokinetics of RLQ in humans and the potential for RLQ-perpetrated interactions on transporters.

MATERIALS AND METHODS

Twelve healthy subjects (six women and six men) participated to compare single- and multiple-dose pharmacokinetics of RLQ. In the single-dose study, all 12 subjects received 8 g of RLQ orally. After a 7-d washout period, the subjects received 8 g of RLQ for seven consecutive days (t.i.d.) and then a single dose. Gallic acid (GA) and protocatechuic acid (PCA) in plasma and urine samples were analysed using LC-MS/MS. The transfected cells were used to study the inhibitory effect of GA (50-5000 μg/L) and PCA (10-1000 μg/L) on transporters OAT1, OAT3, OCT2, OATP1B1, P-gp and BCRP.

RESULTS

GA and PCA were absorbed into the blood within 1 h after administration and rapidly eliminated with a half-life of less than 2 h. The mean peak concentrations of GA (102 and 176 μg/L) and PCA (4.54 and 7.58 μg/L) were lower in males than females, respectively. The 24 h urine recovery rates of GA and PCA were about 10% and 5%, respectively. The steady-state was reached in 7 d without accumulation. GA was a potent inhibitor of OAT1 (IC₅₀ = 3.73 μM) and OAT3 (IC₅₀ = 29.41 μM), but not OCT2, OATP1B1, P-gp or BCRP.

DISCUSSION AND CONCLUSIONS

GA and PCA are recommended as PK-markers in RLQ-related pharmacokinetic and drug interaction studies. We should pay more attention to the potential for RLQ-perpetrated interactions on transporters.

Cannabinoid Metabolites as Inhibitors of Major Hepatic CYP450 Enzymes, with Implications for Cannabis-Drug Interactions

The legalization of cannabis in many parts of the United States and other countries has led to a need for a more comprehensive understanding of cannabis constituents and their potential for drug-drug interactions. Although (-)-trans-Δ9-tetrahydrocannabinol (THC), cannabidiol (CBD), and cannabinol (CBN) are the most abundant cannabinoids present in cannabis, THC metabolites are found in plasma at higher concentrations and for a longer duration than that of the parent cannabinoids. To understand the potential for drug-drug interactions, the inhibition potential of major cannabinoids and their metabolites on major hepatic cytochrome P450 (P450) enzymes was examined. In vitro assays with P450-overexpressing cell microsomes demonstrated that the major THC metabolites 11-hydroxy-Δ9-tetra-hydrocannabinol and 11-nor-9-carboxy-Δ9-THC-glucuronide competitively inhibited several major P450 enzymes, including CYP2B6, CYP2C9, and CYP2D6 (apparent Ki,u values = 0.086 ± 0.066 µM and 0.90 ± 0.54 µM, 0.057 ± 0.044 µM and 2.1 ± 0.81 µM, 0.15 ± 0.067 µM and 2.3 ± 0.54 µM, respectively). 11-Nor-9-carboxy-Δ9- tetrahydrocannabinol exhibited no inhibitory activity against any CYP450 tested. THC competitively inhibited CYP1A2, CYP2B6, CYP2C9, and CYP2D6; CBD competitively inhibited CYP3A4, CYP2B6, CYP2C9, CYP2D6, and CYP2E1; and CBN competitively inhibited CYP2B6, CYP2C9, and CYP2E1. THC and CBD showed mixed-type inhibition for CYP2C19 and CYP1A2, respectively. These data suggest that cannabinoids and major THC metabolites are able to inhibit the activities of multiple P450 enzymes, and basic static modeling of these data suggest the possibility of pharmacokinetic interactions between these cannabinoids and xenobiotics extensively metabolized by CYP2B6, CYP2C9, and CYP2D6. SIGNIFICANCE STATEMENT: Major cannabinoids and their metabolites found in the plasma of cannabis users inhibit several P450 enzymes, including CYP2B6, CYP2C9, and CYP2D6. This study is the first to show the inhibition potential of the most abundant plasma cannabinoid metabolite, THC-COO-Gluc, and suggests that circulating metabolites of cannabinoids play an essential role in CYP450 enzyme inhibition as well as drug-drug interactions.

Prevalence, beliefs and impact of drug-drug interactions between antiretroviral therapy and illicit drugs among people living with HIV in Spain

Drug use implies important challenges related to HIV management, particularly due to an increased risk of potential interactions between antiretroviral therapy (ART) and illicit drugs (pDDIs). This study analyses the prevalence and severity of pDDIs among people living with HIV (PLHIV). It also explores their awareness of pDDIs and their beliefs about the toxicity that they may cause, as well as the impact of pDDIs on selected health variables. We conducted an on-line cross-sectional survey across 33 Spanish hospitals and NGOs to collect demographics and clinical data. pDDIs were checked against the Interaction Checker developed by Liverpool University. The sample of the present study was composed of 694 PLHIV who used illicit drugs. They represented 49.5% of the 1,401 PLHIV that participated in the survey. After excluding 38 participants due to lack of information on their ART or illicit drug use, 335 (51.1%) participants consuming drugs presented with some potentially significant pDDIs between their ART and illicit drugs, with a mean of 2.1±1.7 (1–10) pDDIs per patient. The drugs most frequently involved in pDDIs were cocaine, cannabis, MDMA and nitrates ("poppers"). The prevalence of pDDIs across ART regimens was: protease inhibitors (41.7%); integrase inhibitor-boosted regimens (32.1%), and non-nucleoside reverse transcriptase inhibitors (26.3%). An awareness of pDDIs and beliefs about their potential toxicity correlated positively with intentional non-adherence (p<0.0001). Participants with pDDIs exhibited a higher prevalence of intentional non-adherence (2.19±1.04 vs. 1.93±0.94; p = 0.001). The presence of pDDIs was not associated with poorer results in the clinical variables analysed. A significant proportion of PLHIV who use drugs experience pDDIs, thereby requiring close monitoring. pDDIs should be considered in the clinical management of HIV patients. Adequate information about pDDIs and indicators about how to manage ART when PLHIV use drugs could improve ART non-adherence.

Cytochrome P450-Catalyzed Metabolism of Cannabidiol to the Active Metabolite 7-Hydroxy-Cannabidiol

Cannabidiol (CBD) is a naturally occurring nonpsychotoxic phytocannabinoid that has gained increasing attention as a popular consumer product and for its use in Food and Drug Administration-approved Epidiolex (CBD oral solution) for the treatment of Lennox-Gastaut syndrome and Dravet syndrome. CBD was previously reported to be metabolized primarily by CYP2C19 and CYP3A4, with minor contributions from UDP-glucuronosyltransferases. 7-Hydroxy-CBD (7-OH-CBD) is the primary active metabolite with equipotent activity compared with CBD. Given the polymorphic nature of CYP2C19, we hypothesized that variable CYP2C19 expression may lead to interindividual differences in CBD metabolism to 7-OH-CBD. The objectives of this study were to further characterize the roles of cytochrome P450 enzymes in CBD metabolism, specifically to the active metabolite 7-OH-CBD, and to investigate the impact of CYP2C19 polymorphism on CBD metabolism in genotyped human liver microsomes. The results from reaction phenotyping experiments with recombinant cytochrome P450 enzymes and cytochrome P450-selective chemical inhibitors indicated that both CYP2C19 and CYP2C9 are capable of CBD metabolism to 7-OH-CBD. CYP3A played a major role in CBD metabolic clearance via oxidation at sites other than the 7-position. In genotyped human liver microsomes, 7-OH-CBD formation was positively correlated with CYP2C19 activity but was not associated with CYP2C19 genotype. In a subset of single-donor human liver microsomes with moderate to low CYP2C19 activity, CYP2C9 inhibition significantly reduced 7-OH-CBD formation, suggesting that CYP2C9 may play a greater role in CBD 7-hydroxylation than previously thought. Collectively, these data indicate that both CYP2C19 and CYP2C9 are important contributors in CBD metabolism to the active metabolite 7-OH-CBD. SIGNIFICANCE STATEMENT: This study demonstrates that both CYP2C19 and CYP2C9 are involved in CBD metabolism to the active metabolite 7-OH-CBD and that CYP3A4 is a major contributor to CBD metabolism through pathways other than 7-hydroxylation. 7-OH-CBD formation was associated with human liver microsomal CYP2C19 activity, but not CYP2C19 genotype, and CYP2C9 was found to contribute significantly to 7-OH-CBD generation. These findings have implications for patients taking CBD who may be at risk for clinically important cytochrome P450-mediated drug interactions.

18F-FDG PET/CT imaging in the diagnosis of drug-induced lung disease and pulmonary infection in lymphoma

OBJECTIVE

Lymphoma is a hematological disease with high prevalence. Multi-cycle chemotherapy (CHT) or local radiotherapy is applied usually; however, adverse events have been reported, such as drug-induced lung disease (DILD). Positron emission tomography/computed tomography (PET/CT) is often used to evaluate the lesion, treatment effect, and prognosis of lymphoma. We investigated DILD and pulmonary infection (PI) after multi-cycle CHT in lymphoma patients, to identify DILD and PI, provide guidance for later treatment for them.

METHODS

In all, 677 patients diagnosed with lymphoma and who underwent CHT were included. These patients underwent 18fluorodeoxyglucose (18F-FDG) PET/CT before and after CHT at Shandong Cancer Hospital (affiliated with Shandong University) between April 2015 and November 2019. Fifty patients developed DILD, 41 patients had lung infections; lesion characteristics were analyzed based on clinical characteristics, laboratory examinations, and PET/CT imaging.

RESULTS

Among the 677 lymphoma patients, there were 50 cases of DILD, with an incidence rate of 7.4%. PET/CT showed an elevated 18fluorodeoxyglucose uptake lung background, septal thickening and reticulation, multiple ground glass-like shadows, and grid-shaped blur shadows, which were more common in the lung periphery and under the pleura. The maximum standardized uptake value in the lung was 2.45 ± 0.52. Pulmonary infections occurred in 41 patients, and the maximum standardized uptake value was 4.05 ± 1.42. Age, sex, CHT cycle, Ann-Arbor stage, and lymphocyte levels were not significantly different between DILD and PI patients. Leukocyte and neutrophils showed significant differences; the PI patients had increased laboratory indexes of leukocyte and neutrophils. The mean number of CHT cycles was 4 cycles for DILD and PI.

CONCLUSIONS

PET/CT imaging has high sensitivity and detection rates for primary and metastatic lymphoma lesions. DILD mostly occurs in the middle and late stages of CHT. Laboratory tests and PET/CT can evaluate the lesions and treatment effects, and provide guidance for subsequent treatment plans for patients.

Severe Inflammation, Acute Kidney Injury, and Drug-Drug Interaction: Triple Penalty for Prolonged Elimination of Apixaban in Patients With Coronavirus Disease 2019: A Grand Round

ABSTRACT

In this article, we present a case of apixaban elimination prolonged by 450% in a patient with coronavirus disease 2019 because of multiple conditions, including drug-drug interaction, severe inflammation, and acute kidney injury. Therapeutic drug monitoring was used to explain unusual routine coagulation assays. This grand round highlights the importance of dialog between the clinician and a therapeutic drug monitoring consultant for optimal patient care.

What Can Electrochemical Methods Offer in Determining DNA-Drug Interactions?

The interactions of compounds with DNA have been studied since the recognition of the role of nucleic acid in organisms. The design of molecules which specifically interact with DNA sequences allows for the control of the gene expression. Determining the type and strength of such interaction is an indispensable element of pharmaceutical studies. Cognition of the therapeutic action mechanisms is particularly important for designing new drugs. Owing to their sensitivity, simplicity, and low costs, electrochemical methods are increasingly used for this type of research. Compared to other techniques, they require a small number of samples and are characterized by a high reliability. These methods can provide information about the type of interaction and the binding strength, as well as the damage caused by biologically active molecules targeting the cellular DNA. This review paper summarizes the various electrochemical approaches used for the study of the interactions between pharmaceuticals and DNA. The main focus is on the papers from the last decade, with particular attention on the voltammetric techniques. The most preferred experimental approaches, the electrode materials and the new methods of modification are presented. The data on the detection ranges, the binding modes and the binding constant values of pharmaceuticals are summarized. Both the importance of the presented research and the importance of future prospects are discussed.

Enantioselectivity in Drug Pharmacokinetics and Toxicity: Pharmacological Relevance and Analytical Methods

Enzymes, receptors, and other binding molecules in biological processes can recognize enantiomers as different molecular entities, due to their different dissociation constants, leading to diverse responses in biological processes. Enantioselectivity can be observed in drugs pharmacodynamics and in pharmacokinetic (absorption, distribution, metabolism, and excretion), especially in metabolic profile and in toxicity mechanisms. The stereoisomers of a drug can undergo to different metabolic pathways due to different enzyme systems, resulting in different types and/or number of metabolites. The configuration of enantiomers can cause unexpected effects, related to changes as unidirectional or bidirectional inversion that can occur during pharmacokinetic processes. The choice of models for pharmacokinetic studies as well as the subsequent data interpretation must also be aware of genetic factors (such as polymorphic metabolic enzymes), sex, patient age, hepatic diseases, and drug interactions. Therefore, the pharmacokinetics and toxicity of a racemate or an enantiomerically pure drug are not equal and need to be studied. Enantioselective analytical methods are crucial to monitor pharmacokinetic events and for acquisition of accurate data to better understand the role of the stereochemistry in pharmacokinetics and toxicity. The complexity of merging the best enantioseparation conditions with the selected sample matrix and the intended goal of the analysis is a challenge task. The data gathered in this review intend to reinforce the importance of the enantioselectivity in pharmacokinetic processes and reunite innovative enantioselective analytical methods applied in pharmacokinetic studies. An assorted variety of methods are herein briefly discussed.

The pharmacokinetics and drug-drug interactions of ivermectin in Aedes aegypti mosquitoes

Mosquitoes are vectors of major diseases such as dengue fever and malaria. Mass drug administration of endectocides to humans and livestock is a promising complementary approach to current insecticide-based vector control measures. The aim of this study was to establish an insect model for pharmacokinetic and drug-drug interaction studies to develop sustainable endectocides for vector control. Female Aedes aegypti mosquitoes were fed with human blood containing either ivermectin alone or ivermectin in combination with ketoconazole, rifampicin, ritonavir, or piperonyl butoxide. Drug concentrations were quantified by LC-MS/MS at selected time points post-feeding. Primary pharmacokinetic parameters and extent of drug-drug interactions were calculated by pharmacometric modelling. Lastly, the drug effect of the treatments was examined. The mosquitoes could be dosed with a high precision (%CV: ≤13.4%) over a range of 0.01–1 μg/ml ivermectin without showing saturation (R²: 0.99). The kinetics of ivermectin were characterised by an initial lag phase of 18.5 h (CI_90%: 17.0–19.8 h) followed by a slow zero-order elimination rate of 5.5 pg/h (CI_90%: 5.1–5.9 pg/h). By contrast, ketoconazole, ritonavir, and piperonyl butoxide were immediately excreted following first order elimination, whereas rifampicin accumulated over days in the mosquitoes. Ritonavir increased the lag phase of ivermectin by 11.4 h (CI_90%: 8.7–14.2 h) resulting in an increased exposure (+29%) and an enhanced mosquitocidal effect. In summary, this study shows that the pharmacokinetics of drugs can be investigated and modulated in an Ae. aegypti animal model. This may help in the development of novel vector-control interventions and further our understanding of toxicology in arthropods.

Mosquitoes are responsible for the transmission of pathogens, which cause diseases that are of major health significance such as dengue fever and malaria. Preventive strategies involving the use of insecticides, however, have led to the emergence of resistant mosquitoes. Consequently, development of complementary approaches is urgently needed to stop the spread of these pathogens. Our study reports on a pioneering approach to investigate how well drugs are taken up by the mosquitoes and how long they reside in their body. We focused on ivermectin, which is toxic for mosquitoes, and several drugs that interfere with drug metabolising enzymes. We demonstrated that the exposure of drugs can be precisely determined in individual mosquitoes and that drugs interact with each other in the same way as observed in vertebrates. In this regard, we were able to increase the exposure and mosquito toxicity of ivermectin by co-administering ritonavir, a broad-spectrum inhibitor of drug metabolising enzymes. This study establishes Aedes mosquitoes as a new model organism for pharmacokinetic studies. It opens the door for the investigation of novel insecticide strategies and optimisation of lead compounds against mosquitoes.

Interaction of silymarin components and their sulfate metabolites with human serum albumin and cytochrome P450 (2C9, 2C19, 2D6, and 3A4) enzymes

Silymarin is a mixture of flavonolignans isolated from the fruit of milk thistle (Silybum marianum (L.) Gaertner). Milk thistle extract is the active ingredient of several medications and dietary supplements to treat liver injury/diseases. After the oral administration, flavonolignans are extensively biotransformed, resulting in the formation of sulfate and/or glucuronide metabolites. Previous studies demonstrated that silymarin components form stable complexes with serum albumin and can inhibit certain cytochrome P450 (CYP) enzymes. Nevertheless, in most of these investigations, silybin was tested; while no or only limited information is available regarding other silymarin components and metabolites. In this study, the interactions of five silymarin components (silybin A, silybin B, isosilybin A, silychristin, and 2,3-dehydrosilychristin) and their sulfate metabolites were examined with human serum albumin and CYP (2C9, 2C19, 2D6, and 3A4) enzymes. Our results demonstrate that each compound tested forms stable complexes with albumin, and certain silymarin components/metabolites can inhibit CYP enzymes. Most of the sulfate conjugates were less potent inhibitors of CYP enzymes, but 2,3-dehydrosilychristin-19-O-sulfate showed the strongest inhibitory effect on CYP3A4. Based on these observations, the simultaneous administration of high dose silymarin with medications should be carefully considered, because milk thistle flavonolignans and/or their sulfate metabolites may interfere with drug therapy.

Investigational Treatments for COVID-19 may Increase Ventricular Arrhythmia Risk Through Drug Interactions

Many drugs that have been proposed for treatment of coronavirus disease 2019 (COVID-19) are reported to cause cardiac adverse events, including ventricular arrhythmias. In order to properly weigh risks against potential benefits, particularly when decisions must be made quickly, mathematical modeling of both drug disposition and drug action can be useful for predicting patient response and making informed decisions. Here, we explored the potential effects on cardiac electrophysiology of four drugs proposed to treat COVID-19: lopinavir, ritonavir, chloroquine, and azithromycin, as well as combination therapy involving these drugs. Our study combined simulations of pharmacokinetics (PKs) with quantitative systems pharmacology (QSP) modeling of ventricular myocytes to predict potential cardiac adverse events caused by these treatments. Simulation results predicted that drug combinations can lead to greater cellular action potential prolongation, analogous to QT prolongation, compared with drugs given in isolation. The combination effect can result from both PK and pharmacodynamic drug interactions. Importantly, simulations of different patient groups predicted that women with pre-existing heart disease are especially susceptible to drug-induced arrhythmias, compared with diseased men or healthy individuals of either sex. Statistical analysis of population simulations revealed the molecular factors that make certain women with heart failure especially susceptible to arrhythmias. Overall, the results illustrate how PK and QSP modeling may be combined to more precisely predict cardiac risks of COVID-19 therapies.

Improvement Initiative to Develop and Implement a Tool for Detecting Drug-Drug Interactions During Oncology Clinical Trial Enrollment Eligibility Screening

OBJECTIVES

Screening subjects for drug-drug interactions (DDIs) before enrollment in oncology clinical trials is integral to ensuring safety, but standard procedures or tools are not readily available to screen DDI in this setting. Our objectives were to develop a DDI screening tool for use during oncology clinical trial enrollment and to test usability in single-center and multicenter pilot studies.

METHODS

A multistage approach was used for this quality improvement intervention. Semistructured interviews with individuals responsible for DDI screening were conducted to develop a prototype tool. The tool was used for screening DDI in subjects enrolling in National Clinical Trials Network trials of commercially available agents during a single-center 3-month pilot. Improvements were made, and a 3-month multicenter pilot was conducted at volunteer SWOG Cancer Research Network sites. Participants were surveyed to determine tool usability and efficiency.

RESULTS

A tool was developed from semistructured interviews. A critical feature was reporting which medications had specific pharmacokinetic and pharmacodynamic characteristics including transporter and cytochrome P450 substrates, inhibitors, or inducers and QT prolongation. In the 12-site study, average (SD) DDI screening time for each patient decreased by 15.7 (10.2) minutes (range, 3-35 minutes; P < 0.001). Users reported the tool highly usable, with >90% agreeing with all positive usability characterizations and disagreeing with all negative complexity characterizations.

CONCLUSIONS

A DDI screening tool for oncology clinical trial enrollment was created and its usability confirmed. Further testing with more diverse investigator sites and study drugs during eligibility screening is warranted to improve safety and data accuracy within clinical trials.

Minimal biophysical model of combined antibiotic action

Phenomenological relations such as Ohm's or Fourier's law have a venerable history in physics but are still scarce in biology. This situation restrains predictive theory. Here, we build on bacterial "growth laws," which capture physiological feedback between translation and cell growth, to construct a minimal biophysical model for the combined action of ribosome-targeting antibiotics. Our model predicts drug interactions like antagonism or synergy solely from responses to individual drugs. We provide analytical results for limiting cases, which agree well with numerical results. We systematically refine the model by including direct physical interactions of different antibiotics on the ribosome. In a limiting case, our model provides a mechanistic underpinning for recent predictions of higher-order interactions that were derived using entropy maximization. We further refine the model to include the effects of antibiotics that mimic starvation and the presence of resistance genes. We describe the impact of a starvation-mimicking antibiotic on drug interactions analytically and verify it experimentally. Our extended model suggests a change in the type of drug interaction that depends on the strength of resistance, which challenges established rescaling paradigms. We experimentally show that the presence of unregulated resistance genes can lead to altered drug interaction, which agrees with the prediction of the model. While minimal, the model is readily adaptable and opens the door to predicting interactions of second and higher-order in a broad range of biological systems.

Physiologically-Based Pharmacokinetic Modeling Characterizes the CYP3A-Mediated Drug-Drug Interaction Between Fluconazole and Sildenafil in Infants

Physiologically-based pharmacokinetic (PBPK) modeling can potentially predict pediatric drug-drug interactions (DDIs) when clinical DDI data are limited. In infants for whom treatment of pulmonary hypertension and prevention or treatment of invasive candidiasis are indicated, sildenafil with fluconazole may be given concurrently. To account for developmental changes in cytochrome P450 (CYP) 3A, we determined and incorporated fluconazole inhibition constants (KI ) for CYP3A4, CYP3A5, and CYP3A7 into a PBPK model developed for sildenafil and its active metabolite, N-desmethylsildenafil. Pharmacokinetic (PK) data in preterm infants receiving sildenafil with and without fluconazole were used for model development and evaluation. The simulated PK parameters were comparable to observed values. Following fluconazole co-administration, differences in the fold change for simulated steady-state area under the plasma concentration vs. time curve from 0 to 24 hours (AUCss,0-24 ) were observed between virtual adults and infants (2.11-fold vs. 2.82-fold change). When given in combination with treatment doses of fluconazole (12 mg/kg i.v. daily), reducing the sildenafil dose by ~ 60% resulted in a geometric mean ratio of 1.01 for simulated AUCss,0-24 relative to virtual infants receiving sildenafil alone. This study highlights the feasibility of PBPK modeling to predict DDIs in infants and the need to include CYP3A7 parameters.

Recognition of a disulfiram ethanol reaction in the emergency department is not always straightforward

OBJECTIVES

Disulfiram is an adjunct in the treatment of alcohol use disorders, but case reports indicate that disulfiram ethanol reactions are not always recognized in the emergency department. Our first aim is to remind of this risk with two case reports of life-threatening reactions not immediately considered by the emergency physician. The second aim is to estimate the probability that a disulfiram reaction goes unrecognized with the use of a retrospective study of patients admitted to the emergency department.

METHODS

Clinical files of patients admitted between October 1, 2010 and September 30, 2014 to the emergency department were retrospectively screened for the key words "ethanol use" and "disulfiram". Their diagnoses were then scored by a panel regarding the probability of an interaction.

RESULTS

Seventy-nine patients were included, and a disulfiram-ethanol reaction was scored as either 'highly likely', 'likely' or 'possible' in 54.4% and as 'doubtful' or 'certainly not present' in 45.6% of the patients. The interrater agreement was 0.71 (95% CI: 0.64-0.79). The diagnosis was not considered or only after a delay in 44.2% of the patients with a 'possible' to 'highly likely' disulfiram interaction. One patient with a disulfiram overdose died and was considered as a 'possible' interaction.

DISCUSSION AND CONCLUSIONS

A disulfiram ethanol interaction can be life threatening and failure to consider the diagnosis in the emergency department seems frequent. Prospective studies with documentation of the intake of disulfiram and evaluation of the value of acetaldehyde as a biomarker are needed to determine the precise incidence. Improving knowledge of disulfiram interactions and adequate history taking of disulfiram intake may improve the care for patients.

Effects of curcumin on the pharmacokinetics of amlodipine in rats and its potential mechanism

Context: Hyperlipidaemia and hypertension are often treated together with curcumin and amlodipine. It is necessary to investigate the drug-drug interaction between curcumin and amlodipine.Objective: The interaction between curcumin and amlodipine was investigated in rats and with rat liver microsomes.Methods: The pharmacokinetics of amlodipine (1 mg/kg) was investigated in rats with or without curcumin pre-treatment (2 mg/kg), six rats in each group. The metabolic stability of amlodipine was investigated with rat liver microsomes.Results: Curcumin significantly increased the C_max (26.19 ± 2.21 versus 17.80 ± 1.56 μg/L), AUC_(0-t) (507.27 ± 60.23 versus 238.68 ± 45.59 μg·h/L), and t_1/2 (14.69 ± 1.64 versus 11.43 ± 1.20 h) of amlodipine (p < 0.05). The metabolic stability of amlodipine was significantly increased with the half-life time in rat liver microsomes increased from 34.23 ± 3.33 to 44.15 ± 4.12 min, and the intrinsic rate decreased from 40.49 ± 3.26 to 31.39 ± 2.78 μL/min/mg protein.Discussion and conclusions: These results indicated that drug-drug interaction might appear during the co-administration of curcumin and amlodipine. The potential mechanism may be due to the inhibition of CYP3A4 by curcumin. Thus, this interaction should be given special attention in the clinic and needs further experiments to characterize the effect in humans.

Effects of puerarin on the pharmacokinetics of astragaloside IV in rats and its potential mechanism

Context: Puerarin and astragaloside IV (AS-IV) are sometimes used together for the treatment of disease in Chinese clinics, however, the drug-drug interaction between puerarin and AS-IV is still unknown.Objective: This study investigates the effects of puerarin on the pharmacokinetics of astragaloside IV in rats and clarifies its main mechanism.Materials and methods: The pharmacokinetic profiles of oral administration of astragaloside IV (20 mg/kg) in Sprague-Dawley rats, with or without pre-treatment of puerarin (100 mg/kg/day for 7 days) were investigated. The effects of puerarin on the transport and metabolic stability of AS-IV were also investigated using Caco-2 cell transwell model and rat liver microsomes.Results: The results showed that puerarin could significantly increase the peak plasma concentration (from 48.58 ± 7.26 to 72.71 ± 0.62 ng/mL), and decrease the oral clearance (from 47.5 ± 8.91 to 27.15 ± 9.27 L/h/kg) of AS-IV. The Caco-2 cell transwell experiments indicated that puerarin could decrease the efflux ratio of astragaloside IV from 1.89 to 1.26, and the intrinsic clearance rate of astragaloside IV was decreased by the pre-treatment with puerarin (34.8 ± 2.9 vs. 41.5 ± 3.8 μL/min/mg protein).Discussion and conclusions: These results indicated that puerarin could significantly change the pharmacokinetic profiles of astragaloside IV, via increasing the absorption of astragaloside IV or inhibiting the metabolism of astragaloside IV in rats.

Effects of ticagrelor on the pharmacokinetics of rivaroxaban in rats

CONTEXT

Rivaroxaban and ticagrelor are two common drugs for the treatment of atrial fibrillation and acute coronary syndrome. However, the drug-drug interaction between them is still unknown.

OBJECTIVE

To investigate the effects of ticagrelor on the pharmacokinetics of rivaroxaban in rats both in vivo and in vitro.

MATERIALS AND METHODS

A sensitive and reliable UPLC-MS/MS method was developed for the determination of rivaroxaban in rat plasma. Ten Sprague-Dawley rats were randomly divided into ticagrelor pre-treated group (10 mg/kg/day for 14 days) and control group. The pharmacokinetics of orally administered rivaroxaban (10 mg/kg, single dose) with or without ticagrelor pre-treatment was investigated with developed UPLC-MS/MS method. Additionally, Sprague-Dawley rat liver microsomes were also used to investigate the drug-drug interaction between these two drugs in vitro.

RESULTS

The C _max (221.34 ± 53.33 vs. 691.18 ± 238.31 ng/mL) and the AUC_(0-t) (1060.97 ± 291.21 vs. 3483.03 ± 753.83 μg·h/L) of rivaroxaban increased significantly (p < 0.05) with ticagrelor pre-treatment. The MRT_(0-∞) of rivaroxaban increased from 4.41 ± 0.79 to 5.97 ± 1.11 h, while the intrinsic clearance decreased from 9.93 ± 2.55 to 2.89 ± 0.63 L/h/kg (both p < 0.05) after pre-treated with ticagrelor. Enzyme kinetic study indicated that ticagrelor decreased rivaroxaban metabolic clearance with the IC₅₀ value of 14.04 μmol/L.

CONCLUSIONS

Our in vivo and in vitro results demonstrated that there is a drug-drug interaction between ticagrelor and rivaroxaban in rats. Further studies need to be carried out to verify whether similar interactions truly apply in humans and whether these interactions have clinical significance.

Effect of gastric acid-reducing agents on the pharmacokinetics and efficacy of lemborexant

Lemborexant is a dual orexin receptor antagonist approved for treating insomnia. As the solubility of lemborexant is pH-sensitive, the impact of the gastric acid-reducing agent (ARA), famotidine, on lemborexant pharmacokinetics was evaluated in a Phase 1 study. Additionally, post hoc analysis of data from Phase 3 studies examined the potential effect of concomitant ARAs on patient-reported/subjective sleep onset latency (sSOL) in subjects with insomnia. Coadministration of lemborexant 10 mg with famotidine decreased the maximum observed concentration by 27% and delayed time of maximum observed concentration by 0.5 hours. Famotidine did not affect overall lemborexant exposure based on comparison of area under the concentration curves. Concomitant ARA use in the Phase 3 studies did not impact the effect of lemborexant on sSOL; the change from baseline during the last 7 nights of 1 month of treatment with lemborexant 10 mg was -17.1 minutes with vs -17.9 minutes without ARAs. Collectively, these results indicate that lemborexant can be coadministered with ARAs.

Effects of acid and lactone forms of statins on S-warfarin 7-hydroxylation catalyzed by human liver microsomes and recombinant CYP2C9 variants (CYP2C9.1 and CYP2C9.3)

The inhibition of CYP2C9-mediated warfarin metabolism by acid or lactone forms of statin converted in the body and effects of CYP2C9 genetic variants on their inhibition are not fully understood. Here, the effects of acid and lactone forms of statins on S-warfarin 7-hydroxylation were investigated in vitro. S-Warfarin 7-hydroxylase activities of human liver microsomes (HLMs), recombinant CYP2C9.1 (rCYP2C9.1), and rCYP2C9.3 (Ile359Leu variant) in the presence of statins were determined by high-performance liquid chromatography. Lactone forms of atorvastatin, lovastatin, pitavastatin, pravastatin, rosuvastatin, and simvastatin inhibited the activity of HLMs more potently than the corresponding acid forms, whereas fluvastatin acid showed stronger inhibition than fluvastatin lactone. When the effects of statins on rCYP2C9 variants were examined, inhibition profiles of acid versus lactone forms of statins except for fluvastatin were similar between rCYP2C9.1 and rCYP2C9.3. However, the degrees of inhibition by atorvastatin lactone, fluvastatin acid, fluvastatin lactone, lovastatin lactone, and pitavastatin lactone (K_i values) were significantly different between these variants. These results indicated that lactone forms of statins other than fluvastatin showed more potent inhibition of CYP2C9-catalyzed S-warfarin 7-hydroxylation than the corresponding acid forms. Furthermore, our results indicated that Ile359Leu substitution in CYP2C9 affected the inhibitory potencies of statins.

Physiologically Based Pharmacokinetic Modeling Approach to Identify the Drug-Drug Interaction Mechanism of Nifedipine and a Proton Pump Inhibitor, Omeprazole

BACKGROUND AND OBJECTIVES

Proton pump inhibitors (PPIs) can affect the intragastric release of other drugs from their dosage forms by elevating the gastric pH. They may also influence drug absorption and metabolism by interacting with P-glycoprotein or with the cytochrome P450 (CYP) enzyme system. Nifedipine is a Biopharmaceutics Classification System (BCS) class II drug with low solubility across physiologic pH and high permeability. Previous studies have demonstrated that drug-drug interaction (DDI) existed between omeprazole and nifedipine with significantly increased systemic exposure of nifedipine in subjects after pre-treatment for 7 days with omeprazole compared to the subjects without omeprazole treatment. It was shown that omeprazole not only induced an increase in intragastric pH, but also inhibited the CYP3A4 activity, while CYP3A4-mediated oxidation is the main metabolic pathway of nifedipine. The purpose of this study is to apply a physiologically based pharmacokinetic (PBPK) modeling approach to investigate the DDI mechanism for an immediate release formulation of nifedipine with omeprazole.

METHODS

A previously published model for omeprazole was modified to integrate metabolites and to update CYP inhibition based on the most updated published in vitro data. We simulated the nifedipine pharmacokinetics in healthy subjects with or without the multiple-dose pretreatment of omeprazole (20 mg) following oral administrations of immediate-release (IR) (10 mg) nifedipine. Nifedipine solubility at different pHs was used to simulate the nifedipine pharmacokinetics for both clinical arms. Multiple sensitivity analyses were performed to understand the impact of gastric pH and the CYP3A4-mediated gut and liver first pass metabolism on the overall nifedipine pharmacokinetics.

RESULTS

The developed PBPK model properly described the pharmacokinetics of nifedipine and predicted the inhibitory effect of multiple-dose omeprazole on CYP3A4 activity. With the incorporation of the physiologic effect of omeprazole on both gastric pH and CYP3A4 to the PBPK model, the verified PBPK model allows evaluating the impact of the increase in gastric pH and/or CYP3A4 inhibition. The simulated results show that the nifedipine metabolic inhibition by omeprazole may play an important role in the DDI between nifedipine and omeprazole for IR nifedipine formulation.

CONCLUSION

The developed full PBPK model with the capability to simulate DDI by considering gastric pH change and metabolic inhibition provides a mechanistic understanding of the observed DDI of nifedipine with a PPI, omeprazole.

Therapeutic Monitoring of Lacosamide in Japanese Patients With Epilepsy: Clinical Response, Tolerability, and Optimal Therapeutic Range

BACKGROUND

Lacosamide is a novel anticonvulsant that acts by enhancing sodium channel slow inactivation. The aims of this study were to evaluate the influence of concomitant antiepileptic drugs (AEDs) on serum lacosamide concentration and explore the relationship between lacosamide serum concentration and both clinical response and adverse effects.

METHODS

The authors analyzed 649 serum samples from 426 Japanese patients with epilepsy. The concentration-to-dose (CD) ratio of lacosamide was compared among patients on various AED regimens. Clinical information about seizure frequency and adverse events was obtained from clinical records.

RESULTS

In patients who did not receive enzyme-inducing AEDs, the CD ratio (mean ± SD) of lacosamide was 1.84 ± 0.68. By contrast, the CD ratio in patients who received phenytoin, carbamazepine, and phenobarbital was 1.42 ± 0.66 (22.8% lower), 1.46 ± 0.40 (20.7% lower), and 1.36 ± 0.38 (26.1% lower), respectively. Seventy-four patients (17.3%) achieved >50% seizure reduction. The median lacosamide concentration in patients who received and did not receive a sodium channel blocker was 6.6 mcg/mL (26.4 μmol/L) and 8.4 mcg/mL (33.6 μmol/L), respectively. Adverse events, including dizziness, somnolence, diplopia, and anorexia, were reported by 70 patients (16.4%). The incidence rate in patients treated with sodium channel blockers was significantly higher than that in patients not treated with these drugs (21.1% vs. 10.3%; P < 0.005), and the median lacosamide concentration in these patient groups was 5.1 (20.4 μmol/L) and 7.5 mcg/mL (30 μmol/L), respectively.

CONCLUSIONS

Therapeutic drug monitoring of lacosamide is clinically useful because it allows physicians to estimate the extent of drug interactions and adjust the dose in individual AED regimens.

Reduction of Drug-Drug Interaction Risk; CDC Guidelines Influence on Opiate Benzodiazepine Prescribing

We examined the results of 1.3 million drug tests performed on patients being monitored for compliance with pain medications and substance abuse rehabilitation to determine if the 2016 CDC prescribing guidelines had any impact on opiate benzodiazepine use. We observed that the combination of the opiate drugs morphine, oxycodone, and hydrocodone with the benzodiazepine metabolites oxazepam, alphahydroxyalprazolam, and 7-aminoclonazepam showed many patients were on a combination of these drugs. This ranged from approximately 9 to 16%. There was considerable variability between opiate drug pairs, but there was a general trend to fewer patients on the combination of opiate-benzodiazepine over the 2016 to 2019 time frame.

Clinical Pharmacology of Elagolix: An Oral Gonadotropin-Releasing Hormone Receptor Antagonist for Endometriosis

The clinical pharmacology of elagolix was extensively evaluated in clinical studies in healthy subjects and in women with endometriosis. Elagolix pharmacokinetics (PK) show significant population variability, however they are minimally affected by patients' baseline characteristics and demographics, except for clinically relevant extrinsic and intrinsic factors such as coadministrated strong organic anion transporting polypeptide (OATP) 1B1 inhibitors and severe hepatic impairment, which are contraindications for the use of elagolix. These studies enabled a comprehensive understanding of elagolix mechanism of action and the downstream pharmacodynamic (PD) effects on gonadotropin and ovarian hormones, as well as full characterization of the PK/PD (PKPD) relationships of elagolix at various dosages, including the approved 150 mg once daily and 200 mg twice daily dosing regimens for the management of moderate to severe pain associated with endometriosis. Several model-based analyses have contributed to understanding of the benefit-risk profile of elagolix in patients with endometriosis, through characterization of the exposure relationship with responder rates, with changes in bone mineral density over time, as well as the interaction with coadministered drugs. Collectively, these studies and analyses served as supportive evidence for the effectiveness of the approved dosages and provided general dosing instructions of the first approved oral gonadotropin-releasing hormone receptor antagonist.

Management of the Patient With HIV/Hepatitis C Drug Interactions: A Guide for Nurses and Nurse Practitioners

Approximately one third of patients coinfected with HIV and hepatitis C virus (HCV) who initiate direct-acting antivirals (DAAs) for HCV treatment may have to switch antiretroviral therapy (ART) because of drug interactions. ART switches can negatively affect quality of life, increase HIV symptom burden, and delay HCV therapy. Approaches to identify ART/DAA drug interactions that minimize the impact of switching ART are urgently needed. Nurses can lead the way in addressing this new and major need. We provide a guide for registered nurses and nurse practitioners who care for patients coinfected with HIV and HCV to identify HIV/HCV drug interactions and manage ART/DAA coadministration when needed.

An Interactive Process for Delivering Pharmacologic Interventions for Migraine Headache to First-Year Medical Students

INTRODUCTION

This interactive didactic session is designed for first-year medical students to explore the common clinical symptom of headache and its various management strategies. The session provides an opportunity to cover a variety of drugs, mechanisms of action, drug-drug interactions, and routes of administration in a single 50-minute time frame.

METHODS

Using a modified case-based approach, we designed an interactive session for 41 first-year medical students. Students prepared for the session using basic learning objectives and a table of drugs that treat headache pain. In class, we distributed a patient scenario and a series of discussion questions to explore headache management. We assessed student performance using questions purchased from the National Board of Medical Examiners and student perceptions using both qualitative and quantitative data collected from faculty and end-of-block evaluations.

RESULTS

Student performance on purchased questions related to content was significantly increased when compared to the national average (n = 5; 90.6% ± 6.0% vs. 82.6% ± 8.5%; p = .0052). Student perceptions of the overall quality of the faculty, content presentation, and material were positive (4.4 out of 5.0). Two themes emerged in the end-of-block evaluations: Students commented positively on the prereading materials, and students commented on the need to address underlying physiology associated with the discussed pharmacology.

DISCUSSION

This flexible activity can be delivered in a short time (50 minutes) by a single faculty member in a variety of curricular structures. Our data demonstrate strong student performance and suggest that incorporating additional content would enhance delivery.

A randomized, placebo-controlled, phase 1 study to evaluate the effects of TAK-063 on ketamine-induced changes in fMRI BOLD signal in healthy subjects

RATIONALE

Phosphodiesterase 10A inhibitor TAK-063 has shown effects that suggest efficacy in schizophrenia treatment.

OBJECTIVE

This randomized, double-blind, placebo-controlled, incomplete-crossover study investigated effects of single oral administration of TAK-063 on ketamine-induced changes in blood oxygen level-dependent (BOLD) signal in healthy males.

METHODS

Healthy men aged 18 to 45 years with normal magnetic resonance imaging (MRI) scans and electroencephalogram measurements at screening were eligible. Each subject was randomized to one of nine treatment schedules: all subjects received placebo and two of three doses of TAK-063 followed by ketamine. The primary endpoint was ketamine-induced brain activity in select regions of the brain during resting state. Secondary endpoints included pharmacokinetic parameters of TAK-063, proportion of subjects with treatment-emergent adverse events (AEs), and percentage of subjects meeting criteria for abnormal safety laboratory tests and vital sign measurements.

RESULTS

The study comprised 27 subjects. Prior to ketamine infusion, TAK-063 exerted region-specific effects on resting state functional MRI (fMRI) BOLD signal. After ketamine administration, TAK-063 reduced the Cohen's effect size for resting-state fMRI BOLD signal in key brain regions examined, and exerted similar effects on BOLD signal during the working memory task across all doses. TAK-063 was safe and well tolerated.

CONCLUSIONS

Our results are consistent with non-clinical studies of ketamine and TAK-063 and clinical studies of ketamine and risperidone. It is unknown whether these data are predictive of potential antipsychotic efficacy, and further analyses are required.

Physicians' acceptance of pharmacists' interventions in daily hospital practice

Background The physicians' acceptance rate of pharmacists' interventions to improve pharmacotherapy can vary depending on the setting. The acceptance rate of interventions proposed by pharmacists located in the hospital pharmacy over the telephone and factors associated with acceptance are largely unknown. Objective To determine the physicians' acceptance rate of pharmacists' interventions proposed over the telephone in daily hospital practice and to identify factors associated with acceptance. Setting A retrospective case-control study was performed concerning adult patients admitted to a university hospital in the Netherlands. Method Pharmacists' interventions, based on alerts for drug-drug interactions and drug dosing in patients with renal impairment, recorded between January 2012 and June 2013 that were communicated over the telephone were included. Factors associated with physicians' acceptance were identified with the use of a mixed-effects logistic model. Main outcome measure The primary outcome was the proportion of accepted interventions. Results A total of 841 interventions were included. Physicians accepted 599 interventions, resulting in an acceptance rate of 71.2%. The mixed-effects logistic model showed that acceptance was significantly associated with the number of prescribed drugs (16 to ≤ 20 drugs ORadj 1.88; 95% CI 1.05-3.35, > 20 drugs ORadj 2.90; 95% CI 1.41-5.96, compared to ≤ 10 drugs) and the severity of the drug-related problem (problem without potential harm ORadj 6.36; 95% CI 1.89-21.38; problem with potential harm OR 6.78; 95% CI 2.09-21.99, compared to clinically irrelevant problems), and inversely associated with continuation of pre-admission treatment (ORadj 0.55; 95% CI 0.35-0.87). Conclusion Over the study period, the majority of pharmacists' interventions proposed over the telephone were accepted by physicians. The probability for acceptance increased for patients with an increasing number of medication orders, for clinically relevant problems and for problems related to treatment initiated during admission.

Prediction of Drug-Drug Interactions Between Opioids and Overdosed Benzodiazepines Using Physiologically Based Pharmacokinetic (PBPK) Modeling and Simulation

Background

Researchers have long been interested in the potential drug–drug interactions (DDIs) between opioids and benzodiazepines. However, much remains unknown concerning the interactions between these two drug classes. The objective of this work is to study the mechanism underlying the DDIs between opioids and benzodiazepines from the perspective of their pharmacokinetic (PK) interactions. A PK interaction occurs when two drugs are metabolized by the same cytochrome P450 enzymes and is one of the most common reasons for DDIs.

Methods

We quantitatively predicted the DDIs between three opioids (fentanyl, oxycodone and buprenorphine) and four benzodiazepines (alprazolam, diazepam, midazolam and triazolam) using a physiologically based pharmacokinetic (PBPK) modeling approach. A set of PBPK models was first constructed for these common opioids and benzodiazepines using SimCYP software, and the DDIs between them were then explored at various dosages.

Results

Our simulation results suggested there were no PK interactions between normal doses of opioids and benzodiazepines; but weak interactions can be expected with the combination of opioids and overdosed benzodiazepines. Particular attention should be given to the combination of fentanyl and overdosed alprazolam since a PK interaction can be observed between them.

Conclusion

Our results appear to indicate that pharmacodynamics may play a more important role than PKs in causing DDIs between opioids and benzodiazepines. This study also demonstrated that molecular modeling can be a very useful tool to mitigate the problem of “missing metabolic reaction parameters” in PK modeling and simulation.

Electronic supplementary material

The online version of this article (10.1007/s40268-019-00282-3) contains supplementary material, which is available to authorized users.

Effect of proton pump inhibitors on high-dose methotrexate elimination: a systematic review and meta-analysis

Background Drug interaction is one factor which may influence high-dose methotrexate (MTX) elimination. Proton pump inhibitors are commonly used as an adjuvant drugs in chemotherapy. However, the effect of proton pump inhibitors on high-dose MTX elimination is currently controversial. Objective To perform a systematic review and meta-analysis to assess the association between co-administration of proton pump inhibitors with plasma MTX concentration and delayed MTX elimination. Setting The Hospital of Kunming Medical University, China. Method We followed the PRISMA guidelines in this meta-analysis and systemic review. We searched PubMed, the Cochrane Database, Embase, the WHO International Clinical Trials Registry Platform, the Wanfang database, the Chinese National Knowledge Infrastructure, the VIP database and the Chinese BioMedical Literature Database. Main outcome measure The main outcome measures are: (1) the plasma MTX concentration at 24 h, 48 h and 72 h.; (2) the frequency of patients with delayed MTX elimination. Results Ten retrospective cohort studies were included in the meta-analysis, with a total of 2760 cycles of high-dose MTX treatment. A meta-analysis revealed that compared to patients who did not receive proton pump inhibitors, patients who received proton pump inhibitors had a significantly higher plasma MTX concentration at 24 h (mean difference 2.71 μM, 95% confidence interval 0.55 to 4.87; p = 0.01) and at 48 h (mean difference 0.14 μM, 95% confidence interval 0.06 to 0.21; p < 0.01) after the MTX infusion. Furthermore, delayed MTX elimination was more frequent in patients that received PPIs (risk ratio 0.59, 95% confidence interval 0.41 to 0.84; p = 0.004). Conclusion This systematic review and meta-analysis reveals that the co-administration of proton pump inhibitors with methotrexate is associated with delayed high-dose MTX elimination. Proton pump inhibitors should be cautiously given when co-administered with high-dose MTX treatment.

Simplified Method to Determine the Efflux Ratio on P-Glycoprotein Substrates Using Three-Compartment Model Analysis for Caco-2 Cell Assay Data

PURPOSE

Multiple time-point sampling is required in transcellular transport studies to accurately calculate the appropriate efflux ratio (ER). Our study sought to develop a simplified method to determine the ER in Caco-2 cells.

METHODS

The equation for the ER was derived from a three-compartment model of apical to basal and basal to apical transport. Transcellular transport studies were conducted with 10 non-P-glycoprotein (P-gp) and 6 P-gp substrates in Caco-2 cells, and the ER was calculated using this equation.

RESULTS

The equation for the ER used the concentration ratio in the receiver compartment at the same time-point; therefore, the ER can theoretically be calculated using only a single point. The ER of all non-P-gp substrates tested was close to 1 at all sampling times. The ERs of cyclosporine A calculated from the concentration ratio at 30, 60, 90, and 120 min incubation were 2.93, 6.43, 7.12, and 9.57, respectively, and the ER at 120 min was almost identical to the theoretical value (9.62) calculated using three-compartment model analysis. The other 5 P-gp substrates showed a similar tendency. Single-point sampling can be used to accurately calculate ER at 120 min.

CONCLUSIONS

Single-point sampling is a promising approach for calculating appropriate ERs in the drug discovery stage.

Clinically Significant Drug-Drug Interactions with Agents for Attention-Deficit/Hyperactivity Disorder

This article provides an overview of the pharmacokinetic drug-drug interactions (DDIs) for agents prescribed for attention-deficit/hyperactivity disorder (ADHD). Polypharmacy in the treatment of patients with ADHD leads to high exposures to DDIs and possibly adverse safety outcomes. We performed a systematic search of DDI reports for ADHD agents in Embase and Medline. We also searched for agents in the pharmacological pipeline, which include (1) mazindol, molindone and viloxazine, which were previously prescribed for other indications; (2) centanafadine and AR-08, never before approved; and (3) two extracts (Polygala tenuifolia extract and the French maritime pine bark extracts). The identified literature included case reports, cross-sectional, cross-over and placebo-controlled studies of patient cohorts and healthy volunteers. The DDIs were classified as follows: ADHD agents acting as perpetrators, i.e., affecting the clearance of co-prescribed agents (victim drugs), or ADHD agents being the victim drugs, being affected by other agents. Ratios for changes in pharmacokinetic parameters before and after the DDI were used as a rough estimate of the extent of the DDI. Alcohol may increase plasma dextroamphetamine concentrations by presystemic effects. Until studies are done to orient clinicians regarding dosing changes, clinicians need to be aware of the potential for cytochrome P450 (CYP) 2D6 inhibitors to increase amphetamine levels, which is equivalent to increasing dosages. Atomoxetine is a wide therapeutic window drug. The CYP2D6 poor metabolizers who do not have CYP2D6 activity had better atomoxetine response, but also an increased risk of adverse effects. CYP2D6 inhibitors have been used to increase atomoxetine response in CYP2D6 extensive metabolizers. Guanfacine is mainly metabolized by CYP3A4, which can be induced and inhibited. The package insert recommends that in guanfacine-treated patients, after adding potent CYP3A4 inducers, the guanfacine dose should be doubled; after adding potent CYP3A4 inhibitors the guanfacine dose should be halved. Based on a phenobarbital case report and our experience with CYP3A4-metabolized antipsychotics, these correction factors may be too low. According to two case reports, carbamazepine is a clinically relevant inducer of methylphenidate (MPH). A case series study suggested that MPH may be associated with important elevations in imipramine concentrations. Due to the absence of or limitations in the data, no comments for clinicians can be provided on the pharmacokinetic DDIs for clonidine, centanafadine, mazindol, molindone, AR-08, P. tenuifolia extract and the French maritime pine bark extracts. According to currently available data, clinicians should not expect that ADHD drugs modify each other's serum concentrations. A summary table for clinicians provides our current recommendations on pharmacokinetic DDIs of ADHD agents based on our literature review and the package inserts; whenever it was possible, we provide information on serum concentrations and dose correction factors. There will be a need to periodically update these recommendations and these correction factors as new knowledge becomes available.

Effectiveness of three-dimensional visualisation on undergraduate nursing and midwifery students' knowledge and achievement in pharmacology: A mixed methods study

BACKGROUND

Historically nursing and midwifery students have reported difficulty understanding the concept-based science underpinning the interactions between drugs and their targets. This knowledge is crucial for the administration and monitoring of the therapeutic and adverse effects of medications. Immersive three-dimensional technology is reported to enhance understanding of complex scientific concepts but the physical effects of motion sickness may limit its use.

OBJECTIVES

This project compared the effectiveness of three-dimensional immersive visualisation technology with two-dimensional visualisation technology as a teaching method to improve student understanding of a pharmacological concept, and to assess levels of student discomfort and satisfaction associated with the experience.

DESIGN

Traditional lecture content and presentation about drug-receptor binding was followed by exposure to either a two- or three-dimensional artifact visualising β-adrenoceptor binding. Two student groups were compared by type of exposure: Group 1 watched the artifact via a three-dimensional immersive facility and Group 2 on a wide, two-dimensional screen.

SETTINGS

School of Nursing and Midwifery in a regional university in Southeast Queensland, Australia.

PARTICIPANTS

Two hundred and two second year undergraduate nursing and midwifery students.

METHODS

The study used mixed methods methodology. Pre- and post- testing of student knowledge was collected using five multiple-choice questions. A post-intervention survey elicited students' self-assessed perceptions of discomfort and satisfaction with the learning experience.

RESULTS

The three-dimensional immersive learning experience was comparable to the two-dimensional experience in terms of satisfaction and comfort but resulted in statistically significant improvements in post-test scores.

CONCLUSIONS

The three-dimensional experience improved understanding when compared to two-dimensional viewing, satisfied students leaning needs, and caused minimal discomfort. The results are encouraging in terms of using three-dimensional technology to enhance student knowledge of pharmacological concepts necessary for competency in medication management.

Meloxicam-desmopressin drug-drug interaction producing hyponatremia

BACKGROUND

People with schizophrenia and medical comorbidities are often on multiple medications to manage their symptoms. Herein we present a case of drug-drug interaction (meloxicam and desmopressin), in a patient also on clozapine, that ultimately resulted in hyponatremia and seizure.

METHODS

The patient provided consent to have his case published. We searched PubMed and after reviewing 321 articles, 11 were chosen for relevance.

RESULTS

Meloxicam enhanced the adverse effect (hyponatremia) of desmopressin and was the likely culprit.

CONCLUSIONS

In a patient with higher ADH levels, as in our patient taking desmopressin, the addition of an NSAID could further increase water retention and worsen hyponatremia; indeed, meloxicam was the only new medication added to the patient's regimen, and a drug interaction calculator supports the desmopressin-meloxicam drug-drug interaction as the culprit. We urge clinicians to avoid the use of desmopressin in patients with schizophrenia as this can lead to water intoxication. As meloxicam may worsen desmopressin-induced hyponatremia and could result in seizure, one should avoid using NSAIDs in patients with schizophrenia whom are also prescribed vasopressin/desmopressin. Serum sodium levels should be closely monitored in patients with schizophrenia whose regimen includes desmopressin.

Drug-Target Interaction Prediction Based on Drug Fingerprint Information and Protein Sequence

The identification of drug-target interactions (DTIs) is a critical step in drug development. Experimental methods that are based on clinical trials to discover DTIs are time-consuming, expensive, and challenging. Therefore, as complementary to it, developing new computational methods for predicting novel DTI is of great significance with regards to saving cost and shortening the development period. In this paper, we present a novel computational model for predicting DTIs, which uses the sequence information of proteins and a rotation forest classifier. Specifically, all of the target protein sequences are first converted to a position-specific scoring matrix (PSSM) to retain evolutionary information. We then use local phase quantization (LPQ) descriptors to extract evolutionary information in the PSSM. On the other hand, substructure fingerprint information is utilized to extract the features of the drug. We finally combine the features of drugs and protein together to represent features of each drug-target pair and use a rotation forest classifier to calculate the scores of interaction possibility, for a global DTI prediction. The experimental results indicate that the proposed model is effective, achieving average accuracies of 89.15%, 86.01%, 82.20%, and 71.67% on four datasets (i.e., enzyme, ion channel, G protein-coupled receptors (GPCR), and nuclear receptor), respectively. In addition, we compared the prediction performance of the rotation forest classifier with another popular classifier, support vector machine, on the same dataset. Several types of methods previously proposed are also implemented on the same datasets for performance comparison. The comparison results demonstrate the superiority of the proposed method to the others. We anticipate that the proposed method can be used as an effective tool for predicting drug-target interactions on a large scale, given the information of protein sequences and drug fingerprints.

Ontogeny of Hepatic Sulfotransferases and Prediction of Age-Dependent Fractional Contribution of Sulfation in Acetaminophen Metabolism

Cytosolic sulfotransferases (SULTs), including SULT1A, SULT1B, SULT1E, and SULT2A isoforms, play noteworthy roles in xenobiotic and endobiotic metabolism. We quantified the protein abundances of SULT1A1, SULT1A3, SULT1B1, and SULT2A1 in human liver cytosol samples (n = 194) by liquid chromatography-tandem mass spectrometry proteomics. The data were analyzed for their associations by age, sex, genotype, and ethnicity of the donors. SULT1A1, SULT1B1, and SULT2A1 showed significant age-dependent protein abundance, whereas SULT1A3 was invariable across 0-70 years. The respective mean abundances of SULT1A1, SULT1B1, and SULT2A1 in neonatal samples was 24%, 19%, and 38% of the adult levels. Interestingly, unlike UDP-glucuronosyltransferases and cytochrome P450 enzymes, SULT1A1 and SULT2A1 showed the highest abundance during early childhood (1 to <6 years), which gradually decreased by approx. 40% in adolescents and adults. SULT1A3 and SULT1B1 abundances were significantly lower in African Americans compared with Caucasians. Multiple linear regression analysis further confirmed the association of SULT abundances by age, ethnicity, and genotype. To demonstrate clinical application of the characteristic SULT ontogeny profiles, we developed and validated a proteomics-informed physiologically based pharmacokinetic model of acetaminophen. The latter confirmed the higher fractional contribution of sulfation over glucuronidation in the metabolism of acetaminophen in children. The study thus highlights that the ontogeny-based age-dependent fractional contribution (fm) of individual drug-metabolizing enzymes has better potential in prediction of drug-drug interactions and the effect of genetic polymorphisms in the pediatric population.

Clinical Pharmacokinetics of Second-Generation Triazoles for the Treatment of Invasive Aspergillosis and Candidiasis

Second-generation triazoles were developed in response to the quest for more efficacious and safer therapeutic options for the treatment of severe systemic aspergillosis and candidiasis. These agents include voriconazole, posaconazole, isavuconazole, and ravuconazole. The aim of this review was to present and compare the pharmacokinetic characteristics of second-generation triazoles for the treatment of invasive aspergillosis and candidiasis, emphasizing their clinical implications. The MEDLINE, Scopus, EBSCO, Google Scholar, and SCIndeks databases were searched using advanced search options, including the names of second-generation triazoles and pharmacokinetic terms as keywords. The intravenous administration of voriconazole, posaconazole, and isavuconazole results in stable pharmacokinetics of these drugs, with mostly predictable variations influenced by common and usually known factors in routine clinical settings. The high oral bioavailability of isavuconazole and, to some extent, voriconazole makes them suitable for intravenous-to-oral switch strategies. Except for intravenous voriconazole (due to the accumulation of the toxic vehicle hydroxypropyl betadex), dose reduction of second-generation triazoles is not needed in patients with renal failure; patients with hepatic insufficiency require dose reduction only in advanced disease stages. The introduction of therapeutic drug monitoring could aid attempts to optimize the blood concentrations of triazoles and other drugs that are known to or that possibly interact, thus increasing treatment efficacy and safety. There is a need for new studies that are designed to provide useful data on second-generation triazole pharmacokinetics, particularly in special circumstances such as central nervous system and ocular infections, infections in newborns and infants, and in subjects with genetic polymorphisms of metabolizing enzymes.

Drug-Drug Interactions of Infectious Disease Treatments in Low-Income Countries: A Neglected Topic?

Despite recent advances in recognizing and reducing the risk of drug-drug interactions (DDIs) in developed countries, there are still significant challenges in managing DDIs in low-income countries (LICs) worldwide. In the treatment of major infectious diseases in these regions, multiple factors contribute to ineffective management of DDIs that lead to loss of efficacy or increased risk of adverse events to patients. Some of these difficulties, however, can be overcome. This review aims to evaluate the inherent complexities of DDI management in LICs from pharmacological standpoints and illustrate the unique barriers to effective management of DDIs, such as the challenges of co-infection and treatment settings. A better understanding of comprehensive drug-related properties, population-specific attributes, such as physiological changes associated with infectious diseases, and the use of modeling and simulation techniques are discussed, as they can facilitate the implementation of optimal treatments for infectious diseases at the individual patient level.

An Extensively Humanized Mouse Model to Predict Pathways of Drug Disposition and Drug/Drug Interactions, and to Facilitate Design of Clinical Trials

Species differences in drug metabolism and disposition can confound the extrapolation of in vivo PK data to man and also profoundly compromise drug efficacy studies owing to differences in pharmacokinetics, in metabolites produced (which are often pharmacologically active), and in differential activation of the transcription factors constitutive androstane receptor (CAR) and pregnane X receptor (PXR), which regulate the expression of such enzymes as P450s and drug transporters. These differences have gained additional importance as a consequence of the use of genetically modified mouse models for drug-efficacy testing and also patient-derived xenografts to predict individual patient responses to anticancer drugs. A number of humanized mouse models for cytochrome P450s, CAR, and PXR have been reported. However, the utility of these models has been compromised by the redundancy in P450 reactions across gene families, whereby the remaining murine P450s can metabolize the compounds being tested. To remove this confounding factor and create a mouse model that more closely reflects human pathways of drug disposition, we substituted 33 murine P450s from the major gene families involved in drug disposition, together with Car and Pxr, for human CAR, PXR, CYP1A1, CYP1A2, CYP2C9, CYP2D6, CYP3A4, and CYP3A7. We also created a mouse line in which 34 P450s were deleted from the mouse genome. Using model compounds and anticancer drugs, we demonstrated how these mouse lines can be applied to predict drug-drug interactions in patients and discuss here their potential application in the more informed design of clinical trials and the personalized treatment of cancer.

Pharmacodynamic Drug-Drug Interactions

Pharmacodynamic drug-drug interactions (DDIs) occur when the pharmacological effect of one drug is altered by that of another drug in a combination regimen. DDIs often are classified as synergistic, additive, or antagonistic in nature, albeit these terms are frequently misused. Within a complex pathophysiological system, the mechanism of interaction may occur at the same target or through alternate pathways. Quantitative evaluation of pharmacodynamic DDIs by employing modeling and simulation approaches is needed to identify and optimize safe and effective combination therapy regimens. This review investigates the opportunities and challenges in pharmacodynamic DDI studies and highlights examples of quantitative methods for evaluating pharmacodynamic DDIs, with a particular emphasis on the use of mechanism-based modeling and simulation in DDI studies. Advancements in both experimental and computational techniques will enable the application of better, model-informed assessments of pharmacodynamic DDIs in drug discovery, development, and therapeutics.

Drug-Drug Interactions in Prostate Cancer Treatment

Polypharmacy is associated with an increased risk of drug-drug interactions (DDIs), which can cause serious and debilitating drug-induced adverse events. With a steadily aging population and associated increasing multimorbidity and polypharmacy, the potential for DDIs becomes considerably important. Prostate cancer (PCa) is the most common cancer in men and occurs mostly in elderly men in the Western world. Therefore, the aim of this review is to give an overview of DDIs in PCa therapy to better understand pharmacodynamic and pharm kinetic side effects as well as their interactions with other medications. Last, we explore potential future strategies, which might help to optimize treatment and reduce adverse events patients with polypharmacy and PCa.

Preincubation With Everolimus and Sirolimus Reduces Organic Anion-Transporting Polypeptide (OATP)1B1- and 1B3-Mediated Transport Independently of mTOR Kinase Inhibition: Implication in Assessing OATP1B1- and OATP1B3-Mediated Drug-Drug Interactions

Organic anion transporting polypeptides (OATP)1B1 and OATP1B3 mediate hepatic uptake of many drugs including lipid-lowering statins. Current studies determined the OATP1B1/1B3-mediated drug-drug interaction (DDI) potential of mammalian target of rapamycin (mTOR) inhibitors, everolimus and sirolimus, using R-value and physiologically based pharmacokinetic models. Preincubation with everolimus and sirolimus significantly decreased OATP1B1/1B3-mediated transport even after washing and decreased inhibition constant values up to 8.3- and 2.9-fold for OATP1B1 and both 2.7-fold for OATP1B3, respectively. R-values of everolimus, but not sirolimus, were greater than the FDA-recommended cutoff value of 1.1. Physiologically based pharmacokinetic models predict that everolimus and sirolimus have low OATP1B1/1B3-mediated DDI potential against pravastatin. OATP1B1/1B3-mediated transport was not affected by preincubation with INK-128 (10 μM, 1 h), which does however abolish mTOR kinase activity. The preincubation effects of everolimus and sirolimus on OATP1B1/1B3-mediated transport were similar in cells before preincubation with vehicle control or INK-128, suggesting that inhibition of mTOR activity is not a prerequisite for the preincubation effects observed for everolimus and sirolimus. Nine potential phosphorylation sites of OATP1B1 were identified by phosphoproteomics; none of these are the predicted mTOR phosphorylation sites. We report the everolimus/sirolimus-preincubation-induced inhibitory effects on OATP1B1/1B3 and relatively low OATP1B1/1B3-mediated DDI potential of everolimus and sirolimus.

Optimizing Drug-Drug Interaction Alerts Using a Multidimensional Approach

OBJECTIVES

Excessive alerts are a common concern associated with clinical decision support systems that monitor drug-drug interactions (DDIs). To reduce the number of low-value interruptive DDI alerts at our hospital, we implemented an iterative, multidimensional quality improvement effort, which included an interdisciplinary advisory group, alert metrics, and measurement of perceived clinical value.

METHODS

Alert data analysis indicated that DDIs were the most common interruptive medication alert. An interdisciplinary alert advisory group was formed to provide expert advice and oversight for alert refinement and ongoing review of alert data. Alert data were categorized into drug classes and analyzed to identify DDI alerts for refinement. Refinement strategies included alert suppression and modification of alerts to be contextually aware.

RESULTS

On the basis of historical analysis of classified DDI alerts, 26 alert refinements were implemented, representing 47% of all alerts. Alert refinement efforts resulted in the following substantial decreases in the number of interruptive DDI alerts: 40% for all clinicians (22.9-14 per 100 orders) and as high as 82% for attending physicians (6.5-1.2 per 100 orders). Two patient safety events related to alert refinements were reported during the project period.

CONCLUSIONS

Our quality improvement effort refined 47% of all DDI alerts that were firing during historical analysis, significantly reduced the number of DDI alerts in a 54-week period, and established a model for sustained alert refinements.

Evaluation of a collaborative care approach between general practitioners and clinical pharmacists in primary care community settings in elderly patients on polypharmacy in Slovenia: a cohort retrospective study reveals positive evidence for implementation

BACKGROUND

The population of developed countries is aging, leading to an increase in the use of medication in daily practice, which can lead to serious treatment costs and irrational polypharmacy. A collaborative care approach, such as providing medication review service provided by a clinical pharmacist (CP), is a possible way to reduce drug-related problems and irrational polypharmacy. The aim of this study was to determinate whether a CP's medication review service can improve the quality of drug prescribing in elderly patients treated with polypharmacy in primary care.

METHODS

In a retrospective observational medical chart review study, patients aged 65 years or more in the period 2012-2014 who received 10 or more medications concomitantly and who were screened by a CP were included. Data on pharmacotherapy and CPs' interventions were obtained from the patients' medical records (non-electronic chart review). Potential drug-drug interactions (pDDIs) were determined with Lexicomp Online™ 3.0.2. Only potential X-type DDIs (pXDDIs) were included. Potentially inappropriate medications in the elderly (PIMs) were identified using the PRICUS list.

RESULTS

Ninety-one patients were included. The CPs suggested 625 interventions, of which 304 (48.6%) were accepted by the general practitioners (GPs). After adopting the CPs' interventions, the number of total medications decreased by 11.2% (p <  0.05) and the number of pXDDIs decreased by 42% (p <  0.05). The number of clinically important pXDDIs decreased by 50% (3 cases). The number of prescribed PIMs decreased by 20% (p = 0.069). The acceptance of CP's recommendations reduced the number of pXDDIs (p < 0.05) and improved the adherence to heart failure treatment guidelines.

CONCLUSIONS

A collaborative care approach offering a CP medication review service significantly improved the quality of pharmacotherapy by reducing the total number of medications and pXDDIs. The results support the implementation of this service in the Slovenian healthcare system.

Does testosterone mediate the relationship between vitamin D and prostate cancer? A systematic review and meta-analysis protocol

BACKGROUND

Evidence from studies on prostate cancer progression have identified vitamin D to be a potentially important nutrient. However, the World Cancer Research Fund and American Institute for Cancer Research have reported the quality of this evidence to be limited and warrant further investigation. We plan to use the recently developed WCRF International/University of Bristol mechanistic systematic review framework to determine whether the observed association between vitamin D and prostate cancer exists through a plausible biological pathway.

METHODS

This protocol sets out how we will perform a systematic review of the literature in human and animal studies. We will search the electronic databases MEDLINE, EMBASE, PubMed, and BIOSIS Citation Index without restrictions on year of publication or language. We will extract data from observational and experimental studies examining two inter-linked pathways in the relationship between vitamin D and prostate cancer progression: (1) vitamin D and testosterone, and (2) testosterone and prostate cancer progression. We focus on testosterone as its actions form a potentially novel intermediate mechanism that was identified via our online literature mining tools. The outcomes of interest include incidence or prevalence of prostate cancer, measures of prostate cancer progression (including biochemical recurrence, local, or distal metastases), and prostate cancer-specific mortality. We will assess study quality and the level of certainty of the evidence. We will analyse data where possible, using meta-analysis with forest plots or albatross plots; otherwise, a narrative synthesis will be performed.

DISCUSSION

To our knowledge, this will be the first systematic synthesis of the evidence underpinning the vitamin D-testosterone-prostate cancer mechanistic pathway. The results of the review may inform future research, intervention trials, and public health messages.

Pharmacist-led medication reviews for geriatric residents in German long-term care facilities

BACKGROUND

The benefit of medication reviews for long-term care (LTC) residents has been generally recognized throughout health care systems. Whereas many studies showed the impact of comprehensive medication reviews performed by specialized clinical pharmacists, little is known about the impact of medication reviews performed by community pharmacists. Involving them in the provision of medication reviews may help satisfy the increasing demand for ensuring medication safety.

METHODS

Community pharmacists supplying drugs to the LTC facilities performed a medication review for German LTC residents aged at least 65 years and taking five or more drugs per day based on the patients' medication only. Documented potential drug-related problems (DRPs) and the implementation rate of pharmaceutical interventions were evaluated descriptively. To assess the quality of the medication reviews, we developed a corresponding reference system based on the analysis of two experienced clinical pharmacists.

RESULTS

Twelve pharmacies performed medication reviews for 94 LTC residents. Overall, the pharmacists documented 154 potential DRPs (mean 1.6 per patient, SD 1.5) of which the most common were drug-drug interactions (40%) followed by potentially inappropriate medication (PIM) (16%) and inappropriate dosages (14%). 33% of the pharmacists' interventions to solve DRPs were successfully implemented, mostly dosage adjustments. The identification of potentially severe drug-drug interactions and PIM showed the highest agreement (88 and 73%) with the reference system.

CONCLUSIONS

The medication review program of community pharmacists for LTC residents led to the identification of relevant DRPs. The reference system assessing the quality of the service can contribute to its transparency and reveals the potential for its improvement. The community pharmacists' knowledge of the LTC residents and their relation to the prescribers is crucial for providing successful medication reviews.