Efflux transporters- and cytochrome P-450-mediated interactions between drugs of abuse and antiretrovirals

Beyond the Syndemic of Opioid Use Disorders and HIV: The Impact of Opioids on Viral Reservoirs

People with HIV are more likely to have opioid use disorder and to be prescribed opioids for chronic pain than the general population; however, the effects of opioids on the immune system and HIV persistence have not been fully elucidated. Opioids may affect HIV reservoirs during their establishment, maintenance, and reactivation by enhancing HIV infectivity and replication due to upregulation of co-receptors and impairment of innate antiviral responses. Opioids may also modulate immune cell functioning and microbial translocation and can reverse viral latency. In this review, we summarize the current findings for and against the modulating effects of opioids on HIV cellular and anatomical reservoirs, highlighting the current limitations that affect in vitro, ex vivo, and in vivo studies in the field. We propose further research targets and potential strategies to approach this topic.

The Impact of P-Glycoprotein on Opioid Analgesics: What's the Real Meaning in Pain Management and Palliative Care?

Opioids are widely used in cancer and non-cancer pain management. However, many transporters at the blood-brain barrier (BBB), such as P-glycoprotein (P-gp, ABCB1/MDR1), may impair their delivery to the brain, thus leading to opioid tolerance. Nonetheless, opioids may regulate P-gp expression, thus altering the transport of other compounds, namely chemotherapeutic agents, resulting in pharmacoresistance. Other kinds of painkillers (e.g., acetaminophen, dexamethasone) and adjuvant drugs used for neuropathic pain may act as P-gp substrates and modulate its expression, thus making pain management challenging. Inflammatory conditions are also believed to upregulate P-gp. The role of P-gp in drug-drug interactions is currently under investigation, since many P-gp substrates may also act as substrates for the cytochrome P450 enzymes, which metabolize a wide range of xenobiotics and endobiotics. Genetic variability of the ABCB1/MDR1 gene may be accountable for inter-individual variation in opioid-induced analgesia. P-gp also plays a role in the management of opioid-induced adverse effects, such as constipation. Peripherally acting mu-opioid receptors antagonists (PAMORAs), such as naloxegol and naldemedine, are substrates of P-gp, which prevent their penetration in the central nervous system. In our review, we explore the interactions between P-gp and opioidergic drugs, with their implications in clinical practice.

Emerging nanotechnology-based therapeutics to combat multidrug-resistant cancer

Cancer often develops multidrug resistance (MDR) when cancer cells become resistant to numerous structurally and functionally different chemotherapeutic agents. MDR is considered one of the principal reasons for the failure of many forms of clinical chemotherapy. Several factors are involved in the development of MDR including increased expression of efflux transporters, the tumor microenvironment, changes in molecular targets and the activity of cancer stem cells. Recently, researchers have designed and developed a number of small molecule inhibitors and derivatives of natural compounds to overcome various mechanisms of clinical MDR. Unfortunately, most of the chemosensitizing approaches have failed in clinical trials due to non-specific interactions and adverse side effects at pharmacologically effective concentrations. Nanomedicine approaches provide an efficient drug delivery platform to overcome the limitations of conventional chemotherapy and improve therapeutic effectiveness. Multifunctional nanomaterials have been found to facilitate drug delivery by improving bioavailability and pharmacokinetics, enhancing the therapeutic efficacy of chemotherapeutic drugs to overcome MDR. In this review article, we discuss the major factors contributing to MDR and the limitations of existing chemotherapy- and nanocarrier-based drug delivery systems to overcome clinical MDR mechanisms. We critically review recent nanotechnology-based approaches to combat tumor heterogeneity, drug efflux mechanisms, DNA repair and apoptotic machineries to overcome clinical MDR. Recent successful therapies of this nature include liposomal nanoformulations, cRGDY-PEG-Cy5.5-Carbon dots and Cds/ZnS core–shell quantum dots that have been employed for the effective treatment of various cancer sub-types including small cell lung, head and neck and breast cancers.

EVALUATING THE IATROGENIC EFFECTS OF POLYPHARMACY AND DRUG INTERACTIONS IN HIV-POSITIVE PATIENTS ADMITTED TO THE INTENSIVE CARE UNIT: A SINGLE-CENTER RETROSPECTIVE STUDY

Background. Polypharmacy and drug interactions are of particular concern in people living with HIV/AIDS, especially those who receive antiretroviral therapy (ARVs). Polypharmacy and drug-drug interactions (DDIs) can impact the efficacy and toxicity of HIV treatment. ARVs used in HIV treatment are often prone to drug interactions if administered with other non-ARV drugs because many of them are metabolized through the cytochrome P450 system. The pharmacological management of HIV patients in the intensive care unit (ICU) is usually complex and typically involves the administration of several classes of drugs. This patient group may be at higher risk for potential DDIs due to polypharmacy in the ICU. Objectives. The main objective of this study was to assess the iatrogenic effects of polypharmacy in HIV patients treated in the ICU and to describe the DDI profile between ARVs and other non-ARV medications prescribed in the ICU. Methods and materials. Between 2018 and 2020, we conducted a single-center, retrospective study evaluating the medical records of 59 HIV patients admitted to the ICU for more than 24 hours at the Infectious Disease Clinical Hospital № 2, Moscow, Russia. We evaluated the impact of polypharmacy on renal, hepatic and haemopoietic function. The Liverpool HIV Drug Interaction database was used to identify DDIs in ART-treated HIV patients. Results. All patients received more than 5 different medications matching the definition of polypharmacy. The average number of concurrent medications prescribed was 15 6.713 (maximum 40, minimum 6). All drug interactions recorded were between ARVs and antibiotics: 30 cases of potential interactions in 65.5% patients who received ARV. Of such patients, 94% were exposed to at least two potential interactions. Tenofovir (TDF) and the antibiotic vancomycin underlaid the most common potential interaction (49.2%), followed by lopinavir ritonavir (LPV/RTV) and ciprofloxacin (30.3%). A significant difference in average creatinine levels was found in patients with TDF/vancomycin potential interactions (p 0.05). Conclusion. This study demonstrated that potential DDIs frequently occur in ICU patients in line with previous investigations. It is necessary to implement collaborations among clinical pharmacologists and infectious disease/HIV specialists, as well as frequent clinical and laboratory monitoring, aimed at developing effective and actionable strategies that could reduce potential DDIs in HIV patients in the ICU.

Assessment of Herb-Drug Interaction Potential of Five Common Species of Licorice and Their Phytochemical Constituents

The dried roots and rhizomes of Glycyrrhiza species (G. glabra, G. uralensis and G. inflata), commonly known as licorice, have long been used in traditional medicine. In addition, two other species, G. echinata and G. lepidota are also considered "licorice" in select markets. Currently, licorice is an integral part of several botanical drugs and dietary supplements. To probe the botanicals' safety, herb-drug interaction potential of the hydroethanolic extracts of five Glycyrrhiza species and their key constituents was investigated by determining their effects on pregnane X receptor, aryl hydrocarbon receptor, two major cytochrome P450 isoforms (CYP3A4 and CYP1A2), and the metabolic clearance of antiviral drugs. All extracts enhanced transcriptional activity of PXR and AhR (>2-fold) and increased the enzyme activity of CYP3A4 and CYP1A2. The highest increase in CYP3A4 was seen with G. echinata (4-fold), and the highest increase in CYP1A2 was seen with G. uralensis (18-fold) and G. inflata (16-fold). Among the constituents, glabridin, licoisoflavone A, glyasperin C, and glycycoumarin activated PXR and AhR, glabridin being the most effective (6- and 27-fold increase, respectively). Licoisoflavone A, glyasperin C, and glycycoumarin increased CYP3A4 activity while glabridin, glyasperin C, glycycoumarin, and formononetin increased CYP1A2 activity (>2-fold). The metabolism of antiretroviral drugs (rilpivirine and dolutegravir) was increased by G. uralensis (2.0 and 2.5-fold) and its marker compound glycycoumarin (2.3 and 1.6-fold). The metabolism of dolutegravir was also increased by G. glabra (2.8-fold) but not by its marker compound, glabridin. These results suggest that licorice and its phytochemicals could affect the metabolism and clearance of certain drugs that are substrates of CYP3A4 and CYP1A2.Supplemental data for this article is available online at https://doi.org/10.1080/19390211.2022.2050875 .

Crossroads of Drug Abuse and HIV Infection: Neurotoxicity and CNS Reservoir

Drug abuse is a common comorbidity in people infected with HIV. HIV-infected individuals who abuse drugs are a key population who frequently experience suboptimal outcomes along the HIV continuum of care. A modest proportion of HIV-infected individuals develop HIV-associated neurocognitive issues, the severity of which further increases with drug abuse. Moreover, the tendency of the virus to go into latency in certain cellular reservoirs again complicates the elimination of HIV and HIV-associated illnesses. Antiretroviral therapy (ART) successfully decreased the overall viral load in infected people, yet it does not effectively eliminate the virus from all latent reservoirs. Although ART increased the life expectancy of infected individuals, it showed inconsistent improvement in CNS functioning, thus decreasing the quality of life. Research efforts have been dedicated to identifying common mechanisms through which HIV and drug abuse lead to neurotoxicity and CNS dysfunction. Therefore, in order to develop an effective treatment regimen to treat neurocognitive and related symptoms in HIV-infected patients, it is crucial to understand the involved mechanisms of neurotoxicity. Eventually, those mechanisms could lead the way to design and develop novel therapeutic strategies addressing both CNS HIV reservoir and illicit drug use by HIV patients.

Comprehensive pharmacogenomics characterization of temozolomide response in gliomas

Recent developments in pharmacogenomics have created opportunities for predicting temozolomide response in gliomas. Temozolomide is the main first-line alkylating chemotherapeutic drug together with radiotherapy as standard treatments of high-risk gliomas after surgery. However, there are great individual differences in temozolomide response. Besides the heterogeneity of gliomas, pharmacogenomics relevant genetic polymorphisms can not only affect pharmacokinetics of temozolomide but also change anti-tumor effects of temozolomide. This review will summarize pharmacogenomic studies of temozolomide in gliomas which can lay the foundation to personalized chemotherapy.

No implication of HIV coinfection on the plasma exposure to rifampicin, pyrazinamide, and ethambutol in tuberculosis patients

There are contrasting findings regarding the effect of HIV on the pharmacokinetics of first‐line anti‐tubercular drugs (FLATDs) due to a lack of prospective controlled clinical studies, including patients with tuberculosis (TB) and patients with TB living with HIV. This study aims to assess the effect of HIV coinfection and antiviral therapy on the plasma exposure to FLATDs in patients with TB. HIV negative (TB‐HIV− group; n = 15) and HIV positive (TB‐HIV+ group; n = 18) adult patients with TB were enrolled during the second month of FLATDs treatment. All TB‐HIV+ patients were on treatment with lamivudine, tenofovir (or zidovudine), and raltegravir (or efavirenz). Serial blood sampling was collected over 24 h and FLATDs pharmacokinetic parameters were evaluated using noncompartmental methods. In the TB‐HIV+ patients, dose‐normalized plasma exposure area under the curve from zero to 24 h (nAUC_0–24; geometric mean and 95% confidence interval [CI]) values at steady‐state to rifampicin, pyrazinamide, and ethambutol were 18.38 (95% CI 13.74–24.59), 238.21 (95% CI 191.09–296.95), and 18.33 (95% CI 14.56–23.09) µg∙h/ml, respectively. Similar plasma exposure was found in the TB‐HIV− patients. The geometric mean and 90% CI of the ratios between TB‐HIV− and TB‐HIV+ groups suggest no significant pharmacokinetic interaction between the selected antivirals and FLATDs. Likewise, HIV coinfection itself does not appear to have any effect on the plasma exposure to FLATDs.

Effects of Genetic Polymorphisms of Drug Transporter ABCB1 (MDR1) and Cytochrome P450 Enzymes CYP2A6, CYP2B6 on Nicotine Addiction and Smoking Cessation

Objectives

To determine the effects of genetic polymorphisms of ABCB1 (MDR1), CYP2A6, CYP2B6 on smoking status, and clinical outcomes of smoking cessation therapies in a Turkish population.

Methods

130 smokers and 130 non-smokers were recruited. Individuals who never smoked were described as non-smokers. 130 smokers were treated with nicotine replacement therapy (NRT) (n = 40), bupropion (n = 47), bupropion + NRT (n = 15), and varenicline (n = 28). Smokers were checked by phone after 12 weeks of treatment whether they were able to quit smoking or not. Genotyping and phenotyping were performed.

Results

Cessation rates were as follows; 20.0% for NRT, 29.8% for bupropion, 40.0% for bupropion + NRT, 57.1% for varenicline (p = 0.013). The frequency of ABCB1 1236TT-2677TT-3435TT haplotype was significantly higher in non-smokers as compared to smokers (21.5% vs. 10.8, respectively; p = 0.018). Neither smoking status nor smoking cessation rates were associated with genetic variants of CYP2A6 (p = 0.652, p = 0.328, respectively), or variants of CYP2B6 (p = 0.514, p = 0.779, respectively).

Conclusion

Genetic variants of the drug transporter ABCB1 and the 1236TT-2677TT-3435TT haplotype was significantly associated with non-smoking status. Neither ABCB1 nor CYP2A6, CYP2B6 genetic variants were associated with smoking cessation rates at the 12th week of drug treatment.

Molecular dynamic mechanism(s) of inhibition of bioactive antiviral phytochemical compounds targeting cytochrome P450 3A4 and P-glycoprotein

P-glycoprotein (ABCB1) and cytochrome P450 3A4 (CYP3A4) metabolize almost all known human immunodeficiency virus' protease inhibitor drugs (PIs). Over induction of these proteins' activities has been linked to rapid metabolism of PIs which are then pumped out of the circulatory system, eventually leading to drug-resistance in HIV-positive patients. This study aims to determine, with the use of computational tools, the inhibitory potential of four phytochemical compounds (PCs) (epigallocatechin gallate (EGCG), kaempferol-7-glucoside (K7G), luteolin (LUT) and ellagic acid (EGA)) in inhibiting the activities of these drug-metabolizing proteins. The comparative analysis of the MM/GBSA results revealed that the binding affinity (ΔG_bind) of EGCG and K7G for CYP3A4 and ABCB1 are higher than LUT and EGA and fall between the ΔG_bind of the inhibitors of CYP3A4 and ABCB1 (Ritonavir (strong inhibitor) and Lopinavir (moderate inhibitor)). The structural analysis (RMSD, RMSF, RoG and protein-ligand interaction plots) also confirmed that EGCG and K7G showed similar inhibitory activities with the inhibitors. The study has shown that EGCG and K7G have inhibitory activities against the two proteins and assumes they could decrease intracellular efflux of PIs, consequently increasing the optimal concentration of PIs in the systemic circulation.Communicated by Ramaswamy H. Sarma.

P-glycoprotein associated with diabetes mellitus and survival of patients with pancreatic cancer: 8-year follow-up

Diabetes mellitus (DM) has a high prevalence in patients with pancreatic cancer (PaC), but the prognostic value of DM in PaC remains controversial. Alterations of P-glycoprotein (P-gp) and cytochrome P450 3A4 (CYP3A4) contribute to multidrug resistance and intestinal metabolism in a variety of cancer types, which may be implicated in DM development. This study aimed to explore the potential prognostic value of P-gp and CYP3A4 in PaC patients in the context of DM through long-term follow-up. We retrospectively reviewed the medical records of patients with PaC admitted at The First People's Hospital of Changzhou, Jiangsu, China, from January 2011 to November 2019 and identified two cohorts of adult patients with PaC, including 24 with DM and 24 without DM (non-DM). The baseline clinical characteristics and outcomes were compared. Immunohistochemistry showed that protein expression of P-gp, but not CYP3A, in duodenum tissues was significantly upregulated in PaC patients with DM compared with those without DM. Kaplan-Meier analysis and log-rank test showed that the survival of patients with PaC and DM/high expression of P-gp was not significantly reduced compared with that of patients without DM/low expression of P-gp. These findings suggested that P-gp expression levels were different in the DM and non-DM groups of patients with PaC, but DM and duodenal P-gp levels were not associated with the long-term survival of patients with PaC. It appears that the presence of DM or P-gp expression levels may not serve as effective prognostic markers for PaC.

Antiretroviral Penetration and Drug Transporter Concentrations in the Spleens of Three Preclinical Animal Models and Humans

Adequate antiretroviral (ARV) concentrations in lymphoid tissues are critical for optimal antiretroviral therapy (ART). While the spleen contains 25% of the body's lymphocytes, there are minimal data on ARV penetration in this organ. This study quantified total and protein-unbound splenic ARV concentrations and determined whether drug transporters, sex, or infection status were modifiers of these concentrations in animal models and humans. Two humanized mice models (hu-HSC-Rag [n = 36; 18 HIV-positive (HIV⁺) and 18 HIV-negative (HIV^-)] and bone marrow-liver-thymus [n = 13; 7 HIV⁺ and 6 HIV^-]) and one nonhuman primate (NHP) model (rhesus macaque [n = 18; 10 SHIV⁺ and 8 SHIV^-]) were dosed to steady state with ARV combinations. HIV⁺ human spleens (n = 14) from the National NeuroAIDS Tissue Consortium were analyzed postmortem (up to 24 h postdose). ARV concentrations were measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS), drug transporter concentrations were measured with LC-MS proteomics, and protein binding in NHP spleens was determined by rapid equilibrium dialysis. Mice generally had the lowest splenic concentrations of the three species. Protein binding in splenic tissue was 6 to 96%, compared to 76 to 99% in blood plasma. NHPs had quantifiable Mrp4, Bcrp, and Ent1 concentrations, and humans had quantifiable ENT1 concentrations. None significantly correlated with tissue ARV concentrations. There was also no observable influence of infection status or sex. With these dosing strategies, NHP splenic penetration most closely resembled that of humans. These data can inform tissue pharmacokinetic scaling to humans to target HIV reservoirs by identifying important species-related differences.

An update on drug-drug interactions between antiretroviral therapies and drugs of abuse in HIV systems

INTRODUCTION

While considerable progress has been made in the fight against HIV/AIDS, to date there has not been a cure, and millions of people around the world are currently living with HIV/AIDS. People living with HIV/AIDS have substance abuse disorders at higher rates than non-infected individuals, which puts them at an increased risk of drug-drug interactions.

AREAS COVERED

Potential drug-drug interactions are reviewed for a variety of potential drugs of abuse, both licit and illicit. These drugs include alcohol, cigarettes or other nicotine delivery systems, methamphetamine, cocaine, opioids, and marijuana. Potential interactions include decreased adherence, modulation of drug transporters, or modulation of metabolic enzymes. We also review the relative incidence of the use of these drugs of abuse in People living with HIV/AIDS.

EXPERT OPINION

Despite considerable improvements in outcomes, disparities in outcomes between PLWHA who use drugs of abuse, vs those who do not still exist. It is of critical necessity to improve outcomes in these patients and to work with them to stop abusing drugs of abuse.

Profile of drug-drug interactions and impact on the effectiveness of antiretroviral therapy among patients living with HIV followed at an Infectious Diseases Referral Center in Belo Horizonte, Brazil

HIV infection may be considered a chronic condition for people living with HIV with access to antiretrovirals and this has effectively increased survival. Moreover, this has also facilitated the emergence of other comorbidities increasing the risk for drug–drug interactions and polypharmacy. The profile of these interactions as well as their consequences for people living with HIV are still not completely elucidated. The objectives of this study were to describe the profile of these interactions, their prevalence and their classification according to the potential for significant or non-significant drug–drug interactions. From June 2015 to July 2016, people living with HIV on follow-up at an Infectious Diseases Referral Center in Belo Horizonte, Brazil have been investigated for the presence of drug–drug interactions. A total of 304 patients were included and the majority (75%) had less than 50 years of age, male (66.4%), and 37.8% self-defined as brown skinned. Approximately 24% were on five or more medications and half of them presented with drug–drug interactions. Patients older than 50 years had a higher frequency of antiretrovirals drug–drug interactions with other drugs compared to younger patients (p = 0.002). No relationship was found between the number of drug–drug interactions and the effectiveness of antiretrovirals. As expected, the higher the number of non-HIV medications used (OR = 1.129; 95%CI 1.004–1.209; p = 0.04) was associated with an increase in drug–drug interactions. The high prevalence of drug–drug interactions found and the data collected should be useful to establish measures of quaternary prevention and to increase the medication security for people living with HIV.

Bidirectional Associations among Nicotine and Tobacco Smoke, NeuroHIV, and Antiretroviral Therapy

People living with HIV (PLWH) in the antiretroviral therapy (ART) era may lose more life-years to tobacco use than to HIV. Yet, smoking rates are more than twice as high among PLWH than the general population, contributing not just to mortality but to other adverse health outcomes, including neurocognitive deficits (neuroHIV). There is growing evidence that synergy with chronic inflammation and immune dysregulation that persists despite ART may be one mechanism by which tobacco smoking contributes to neuroHIV. This review will summarize the differential effects of nicotine vs tobacco smoking on inflammation in addition to the effects of tobacco smoke components on HIV disease progression. We will also discuss biomarkers of inflammation via neuroimaging as well as biomarkers of nicotine dependence (e.g., nicotine metabolite ratio). Tobacco smoking and nicotine may impact ART drug metabolism and conversely, certain ARTs may impact nicotine metabolism. Thus, we will review these bidirectional relationships and how they may contribute to neuroHIV and other adverse outcomes. We will also discuss the effects of tobacco use on the interaction between peripheral organs (lungs, heart, kidney) and subsequent CNS function in the context of HIV. Lastly, given the dramatic rise in the use of electronic nicotine delivery systems, we will discuss the implications of vaping on these processes. Despite the growing recognition of the importance of addressing tobacco use among PLWH, more research is necessary at both the preclinical and clinical level to disentangle the potentially synergistic effects of tobacco use, nicotine, HIV, cognition and immune dysregulation, as well as identify optimal approaches to reduce tobacco use. Graphical Abstract Proposed model of the relationships among HIV, ART, smoking, inflammation, and neurocognition. Solid lines represent relationships supported by evidence. Dashed lines represent relationships for which there is not enough evidence to make a conclusion. (a) HIV infection produces elevated levels of inflammation even among virally suppressed individuals. (b) HIV is associated with deficits in cognition function. (c) Smoking rates are higher among PLWH, compared to the general population. (d) The nicotine metabolite ratio (NMR) is associated with smoking behavior. (e) HIV and tobacco use are both associated with higher rates of psychiatric comorbidities, such as depression, and elevated levels of chronic stress. These factors may represent other mechanisms linking HIV and tobacco use. (f) The relationship between nicotine, tobacco smoking, and inflammation is complex, but it is well-established that smoking induces inflammation; the evidence for nicotine as anti-inflammatory is supported in some studies, but not others. (g) The relationship between tobacco use and neurocognition may differ for the effects of nicotine (acute nicotine use may have beneficial effects) vs. tobacco smoking (chronic use may impair cognition). (h) Elevated levels of inflammation may be associated with deficits in cognition. (i) PLWH may metabolize nicotine faster than those without HIV; the mechanism is not yet known and the finding needs validation in larger samples. We also hypothesize that if HIV-infection increases nicotine metabolism, then we should observe an attenuation effect once ART is initiated. (j) It is possible that the increase in NMR is due to ART effects on CYP2A6. (k) We hypothesize that faster nicotine metabolism may result in higher levels of inflammation since nicotine has anti-inflammatory properties.

Adverse pharmacokinetic interactions between illicit substances and clinical drugs

Adverse pharmacokinetic interactions between illicit substances and clinical drugs are of a significant health concern. Illicit substances are taken by healthy individuals as well as by patients with medical conditions such as mental illnesses, acquired immunodeficiency syndrome, diabetes mellitus and cancer. Many individuals that use illicit substances simultaneously take clinical drugs meant for targeted treatment. This concomitant usage can lead to life-threatening pharmacokinetic interactions between illicit substances and clinical drugs. Optimal levels and activity of drug-metabolizing enzymes and drug-transporters are crucial for metabolism and disposition of illicit substances as well as clinical drugs. However, both illicit substances and clinical drugs can induce changes in the expression and/or activity of drug-metabolizing enzymes and drug-transporters. Consequently, with concomitant usage, illicit substances can adversely influence the therapeutic outcome of coadministered clinical drugs. Likewise, clinical drugs can adversely affect the response of coadministered illicit substances. While the interactions between illicit substances and clinical drugs pose a tremendous health and financial burden, they lack a similar level of attention as drug-drug, food-drug, supplement-drug, herb-drug, disease-drug, or other substance-drug interactions such as alcohol-drug and tobacco-drug interactions. This review highlights the clinical pharmacokinetic interactions between clinical drugs and commonly used illicit substances such as cannabis, cocaine and 3, 4-Methylenedioxymethamphetamine (MDMA). Rigorous efforts are warranted to further understand the underlying mechanisms responsible for these clinical pharmacokinetic interactions. It is also critical to extend the awareness of the life-threatening adverse interactions to both health care professionals and patients.

Effects of CYP3A4 Polymorphisms on Drug Addiction Risk Among the Chinese Han Population

Background:Cytochrome P450 3A4 (CYP3A4) regulates pharmacokinetic and pharmacodynamic interactions during the process of drug absorption and metabolism, suggesting CYP3A4 plays an important role in drug addiction. However, the association between CYP3A4 polymorphisms and drug addiction risk is still not clear.

Methods: This case-control study included 504 drug addicts and 501 healthy controls from Xi'an, China. Four single nucleotide polymorphisms (SNP) in CYP3A4 (rs3735451, rs4646440, rs35564277, and rs4646437) were genotyped by Agena MassARRAY platform. After adjusting by age and gender, we calculated odd ratios (OR) and 95% confidence intervals (CI) by logistic regression to estimate the association between CYP3A4 polymorphisms and drug addiction risk.

Results: We found rs4646440 and rs4646437 were associated with decreased risk of drug addiction in codominant (rs4646440: OR = 0.41, 95%CI = 0.19–0.92, p = 0.030; rs4646437: OR = 0.19, 95%CI = 0.04–0.87, p = 0.032) and recessive (rs4646440: OR = 0.41, 95%CI = 0.19–0.91, p = 0.028; rs4646437: OR = 0.20, 95%CI = 0.04–0.90, p = 0.036) models. Rs3735451 and rs4646437 were associated with drug addiction risk in the subgroup of middle-aged people (44 < age ≤ 59) and elderly people (age ≥ 60), individually. For men, rs3735451, rs4646440, and rs4646437 had strong relationship with decreased risk of drug addiction (p < 0.05). The effects of rs3735451 on drug addiction risk were related to drug-using time (p < 0.05). We also observed one block (rs4646440 and rs35564277) in haplotype analysis.

Conclusion:CYP3A4 polymorphisms were associated with drug addiction risk among the Chinese Han population.

Pharmacokinetics and Placental Transfer of Bupivacaine Enantiomers in HIV-Infected Parturient Women on Antiretroviral Therapy

Bupivacaine, a local anesthetic, is commercialized as a racemic mixture of R-bupivacaine and S-bupivacaine enantiomers. HIV infection increases the expression of placental P-glycoprotein (P-gp), and antiretroviral (ARV) therapy inhibits cytochrome P450 3A and P-gp. The present study evaluates the kinetic disposition of bupivacaine enantiomers in HIV-infected parturient women on ARV therapy. In this study, HIV-infected parturient women (n = 10) treated with zidovudine, lamivudine, lopinavir, and ritonavir were investigated. Anesthesia and/or analgesia was achieved by the administration of 0.5% racemic bupivacaine hydrochloride with 1:200000 epinephrine in the epidural space at doses of 2.5 to 22.5 mg. Maternal serial blood samples were obtained at the time immediately before and 5, 15, 30, 45, and 60 minutes and 2, 4, 6, 8, 10, 12, and 14 hours after administration of the bupivacaine. At the time of delivery, samples of maternal and umbilical cord vein blood were also collected. The results suggest that bupivacaine pharmacokinetics are enantioselective, revealing higher maternal plasma concentrations of the R-bupivacaine enantiomer (area under the total plasma concentration-time curve was calculated by the trapezoid method with extrapolation to infinity/dose_(S)/(R) = 0.91; P < .05). The plasma unbound fraction of the drug (0.09 vs 0.06) and the umbilical cord vein/maternal plasma ratio (0.47 vs 0.39) were higher for the R-bupivacaine enantiomer than the S-bupivacaine enantiomer (P < .05). ARV therapy with ritonavir confers an enantioselective interaction between the enantiomers of bupivacaine and placental P-gp, producing greater inhibition of efflux transport of the R-bupivacaine enantiomer. Possible changes in the well-being of the fetuses of mothers under analgesia may be a consequence of the increased placental transfer of bupivacaine enantiomers to the fetal circulation.

Methadone and buprenorphine pharmacokinetics and pharmacodynamics when coadministered with fostemsavir to opioid-dependent, human immunodeficiency virus seronegative participants

AIMS

Regional human immunodeficiency virus (HIV) prevalence rates are high in people with history of injection drug use, including those managed with maintenance opioids. Fostemsavir (FTR) is an oral prodrug of temsavir, a first-in-class attachment inhibitor that binds HIV-1 gp120, preventing initial HIV attachment and entry into host immune cells. Here we determine the impact of FTR on the pharmacokinetics of opioids methadone (MET: R-, S- and total) or buprenorphine and norbuprenorphine (BUP and norBUP) when coadministered.

METHODS

Study 206216 (NCT02666001) was a Phase I, open-label study, assessing the effect of FTR 600 mg (extended-release formulation) twice daily on pharmacokinetics of MET or BUP and norBUP, in non-HIV-infected participants on stable maintenance therapy with MET (40-120 mg; n = 16) or BUP plus naloxone (8-24 mg plus 2-6 mg; n = 16); pharmacodynamic response was assessed using standard opioid rating scales.

RESULTS

Following coadministration with FTR, dose-normalized MET (R-, S- and total) exposures (maximum concentration in plasma, area under the plasma concentration-time curve over the dosing interval and concentration in plasma at 24 hours) increased 9-15% and BUP and norBUP exposures increased 24-39%. The 90% confidence interval ranges for MET (1.01-1.21) and BUP and norBUP (1.03-1.69) were within respective no-effect ranges (0.7-1.43 and 0.5-2.0). Opioid pharmacodynamic scores were similar with and without MET/BUP with no symptoms of withdrawal/overdose; no new safety signal for FTR when combined with a stable opioid regimen.

CONCLUSIONS

FTR did not impact MET and had no clinically significant impact on BUP pharmacokinetics. Standardized assessments of opioid pharmacodynamics were unchanged throughout FTR administration with MET or BUP. FTR can be administered with MET or BUP without dose adjustment.

Potential effects of nicotine on glioblastoma and chemoradiotherapy: a review

Introduction: Glioblastoma multiforme (GBM) has a poor prognosis despite maximal surgical resection with subsequent multi-modal radiation and chemotherapy. Use of tobacco products following diagnosis and during the period of treatment for non-neural tumors detrimentally affects treatment and prognosis. Approximately, 16-28% of patients with glioblastoma continue to smoke after diagnosis and during treatment. The literature is sparse for information-pertaining effects of smoking and nicotine on GBM treatment and prognosis. Areas covered: This review discusses cellular pathways involved in GBM progression that might be affected by nicotine, as well as how nicotine may contribute to resistance to treatment. Similarities of GBM pathways to those in non-neural tumors are investigated for potential effects by nicotine. English language papers were identified using PubMed, Medline and Scopus databases using a combination of keywords including but not limited to the following: nicotine, vaping, tobacco, e-cigarettes, smoking, vaping AND glioblastoma or brain cancer OR/AND temozolomide, carmustine, methotrexate, procarbazine, lomustine, vincristine, and neural tumor cell lines. Expert opinion: Understanding the impact of nicotine on treatment and resistance to chemotherapeutics should allow physicians to educate their patients with GBM with evidence-based recommendations about the effects of continuing to use nicotine-containing products after diagnosis and during treatment.

Impact of Tobacco Smoke in HIV Progression: a Major Risk Factor for the Development of NeuroAIDS and Associated of CNS Disorders

Aim

With the advent of highly active and combination antiretroviral therapy have substantially increased the life expectancy of patients infected with human immunodeficiency virus (HIV). However, this has brought into sharp contrast the incidence of several 'Non-acquired immunodeficiency syndrome (AIDS) diseases such as NeuroAIDS which identifies a group of neurological disorders caused primarily by HIV-mediated damage to the central and peripheral nervous systems. Given the patients depleted immune condition, the use and abuse of drug and addictive substances such as tobacco smoking can further deteriorates their overall health and accelerate the progression and severity of the disease. In this review we detail the pathogenesis, progression and characteristics of HIV and the impact of tobacco smoking as a risk factor for the progression of the disease to NeuroAIDS. This is a poorly understood aspect of HIV-related complications that needs to be addressed.

Subjects and methods

Review of theoretical approaches and knowledge synthesis.

Results

Tobacco smoking is highly prevalent in HIV patients when compared to the general population. The oxidative damage and inflammatory stress caused by chronic smoking on the cerebrovascular system have been well established. Considering that HIV patients have an impaired immune system and smokers per se are more susceptible to viral and bacterial inflammatory neuropathologies than non-smokers, it is conceivable that tobacco smoking as a risk factor for the progression of HIV into NeuroAIDS and related neurological impairments.

Conclusion

Tobacco smoke (TS) may bring about a synergistic effect in the context of persistent inflammatory state and cerebrovascular damage which facilitate HIV infection and progression to NeuroAIDS when compared to non-smokers.

Effects of simvastatin on the PXR signaling pathway and the liver histology in Mugilogobius abei

Simvastatin is one of the most commonly cholesterol-lowering prescribed drugs all over the world. With the increase of consumption of these pharmaceuticals and subsequent their discharge into the aquatic environment in recent years, they are present at detectable levels in most sewage effluents. Unfortunately, limited information is provided about their potential impacts on aquatic organisms, especially on the detoxification-related metabolism in fish. In the present study, one local native benthic fish (Mugilogobius abei) in southern China was employed as test species and exposed to SV (0.5 μg L^-1, 5 μg L^-1, 50 μg L^-1 and 500 μg L^-1) for 72 h. The transcriptional expression of nucleus transcriptional factor pregnane X receptor (PXR) and its downstream targeted genes including multixenobiotics resistance protein or permeability glycoprotein (P-gp), cytochrome 1A (CYP1A), cytochrome P450 3A (CYP3A), glutathione-S-transferase (GST) and the expression of associated microRNA such as miR-27, miR-34 and miR-148 in Mugilogobius abei were investigated. Result showed that the expressions of P-gp, CYP 1A, CYP 3A, GST and PXR were induced to some extend under simvastatin exposure for 72 h. A positive correlation was observed between PXR and CYP1A, CYP3A and P-gp. While for microRNA, a negative relationship was found between miR-34a and CYP3A, CYP1A. The expression of miR-148a was significantly induced under the exposure of SV (50 μg L^-1), which was positive related to the transcriptional expression of PXR. For enzyme activity, erythromycin N-demethylase (ERND) significantly increased at 24 h and the activity of catalase (CAT) and superoxide dismutase (SOD) exhibited different trends. CAT was slightly inhibited at 24 h exposure but SOD was significantly induced in high concentration. Glutathione-S-transferase (GST) activity was significant inhibited after 72 h exposure. The reductive small molecule glutathione (GSH) content showed obvious decrease, while the quantity of malondialdehyde (MDA) increased significantly in high concentrations of SV exposure. GSH and MDA showed a typical negative correlation to some degree. Moreover, simvastatin caused histological changes in the liver tissues of M. abei, especially the size of adipocyte significantly decreased. The present study indicated that environmentally relevant concentration SV may affect the PXR signaling pathway in M. abei and pose potential ecological risks to non-target organisms like fish.

Gut microbiota: a new angle for traditional herbal medicine research

Traditional Herbal Medicine (THM) has been used for thousands of years, and is popular worldwide due to its effectiveness in a variety of diseases.

Effects of Tobacco Usage and Antiretroviral Therapy on Biomarkers of Systemic Immune Activation in HIV-Infected Participants

Like HIV infection, smoking, which is common among HIV-infected persons, is associated with chronic, systemic inflammation. However, the possible augmentative effects of HIV infection and smoking and other types of tobacco usage on indices of systemic inflammation and the impact of combination antiretroviral therapy (cART) thereon remain largely unexplored and represent the focus of the current study. Of the total number of HIV-infected persons recruited to the study (n = 199), 100 were categorised as pre-cART and 99 as virally suppressed (HIV viral load < 40 copies/mL). According to serum cotinine levels, 144 and 55 participants were categorised as nonusers and users of tobacco, respectively. In addition to cytokines (IL-6, IL-8, and TNF-α) and chemokines (IP-10, MIG, IL-8, MCP-1, and RANTES), other biomarkers of systemic inflammation included C-reactive protein (CRP), β2-microglobulin, and those of neutrophil activation [ICAM-1, L-selectin, matrix metalloproteinase-9 (MMP-9)], microbial translocation (soluble CD14, LPS-binding protein), and oxidative stress (cyclophilin A, surfactant D). These were measured using multiplex bead array, ELISA, and immunonephelometric procedures. Viral suppression was associated with significant decreases in the levels of most of the biomarkers tested (P < 0.0037-0.0008), with the exceptions of CRP, cyclophilin A, and MMP-9. With respect to tobacco usage, irrespective of cART status, circulating levels of β2-microglobulin, cyclophilin A, and RANTES were significantly elevated (P < 0.042-0.012) in users vs nonusers. Additional analysis of the groups of tobacco users and nonusers according to cART status revealed high levels of RANTES in pre-cART/tobacco users relative to the three other subgroups (P < 0.004-0.0001), while more modest increases in cyclophilin A and MMP-9 (P < 0.019-0.027) were observed in comparison with the cART/tobacco user subgroup. Notwithstanding the efficacy of cART in attenuating HIV-associated, chronic systemic inflammation, the current study has identified RANTES as being significantly and seemingly selectively increased in those with active HIV infection who use tobacco, a mechanism which may underpin augmentative proinflammatory activity.

MDR1 not CYP3A4 gene expression is the predominant mechanism of innate drug resistance in pediatric soft tissue sarcoma patients

BACKGROUND

Intratumoral up-regulation of genes coding for drug transporters and metabolizing enzymes, such as MDR1 and CYP3A4, after chemotherapy are linked to cancer drug resistance. However their expression in primary soft tissue sarcomas (STS) prior to drug treatment and their role in innate resistance remain unclear.

OBJECTIVE

The aim of this study was characterize MDR1 and CYP3A4 expression pattern before to chemotherapy and its clinical implication in pediatric STS.

METHODS

In this prospective study we analyzed MDR1 and CYP3A4 mRNA expression in both normal and tumor tissues from 28 newly diagnosed STS pediatric and then compared with patients' clinical-pathological data, including chemotherapy response.

RESULTS

Our data showed that the expression of the MDR1 gene was significantly higher in malignant tissue than in the normal tissues of patients with STS. In addition, high MDR1 expression was significantly associated with local advances, as well as poor response to treatment. In contrast, CYP3A4 expression level was negligible in both tumoral and non-tumoral tissues.

CONCLUSIONS

These results suggest that a significant mRNA level of MDR1 gene was intrinsically present in STS before exposure to chemotherapeutic drugs, suggesting that MDR1 may be important contributors of innate chemoresistance of this tumor type.

The dawn of precision medicine in HIV: state of the art of pharmacotherapy

INTRODUCTION

Combination antiretroviral therapy (ART) reduces viral load to under the limit of detection, successfully decreasing HIV-related morbidity and mortality. Due to viral mutations, complex drug combinations and different patient response, there is an increasing demand for individualized treatment options for patients.

AREAS COVERED

This review first summarizes the pharmacokinetic and pharmacodynamic profile of clinical first-line drugs, which serves as guidance for antiretroviral precision medicine. Factors which have influential effects on drug efficacy and thus precision medicine are discussed: patients' pharmacogenetic information, virus mutations, comorbidities, and immune recovery. Furthermore, strategies to improve the application of precision medicine are discussed.

EXPERT OPINION

Precision medicine for ART requires comprehensive information on the drug, virus, and clinical data from the patients. The clinically available genetic tests are a good starting point. To better apply precision medicine, deeper knowledge of drug concentrations, HIV reservoirs, and efficacy associated genes, such as polymorphisms of drug transporters and metabolizing enzymes, are required. With advanced computer-based prediction systems which integrate more comprehensive information on pharmacokinetics, pharmacodynamics, pharmacogenomics, and the clinically relevant information of the patients, precision medicine will lead to better treatment choices and improved disease outcomes.

Chrysosplenetin inhibits artemisinin efflux in P-gp-over-expressing Caco-2 cells and reverses P-gp/MDR1 mRNA up-regulated expression induced by artemisinin in mouse small intestine

CONTEXT

CYP3A4 and P-gp together form a highly efficient barrier for orally absorbed drugs and always share the same substrates. Our previous work revealed that chrysosplenetin (CHR) significantly augmented the rat plasma level and anti-malarial efficacy of artemisinin (ART), partially due to the uncompetitive inhibition effect of CHR on rat CYP3A. But the impact of CHR on P-gp is still unknown.

OBJECTIVE

The present study investigates whether CHR interferes with P-gp-mediated efflux of ART and elucidates the underlying mechanism.

MATERIALS AND METHODS

P-gp-over-expressing Caco-2 cells were treated with ART (10 μM) or ART-CHR (1:2, 10:20 μM) in ART bidirectional transport experiment. ART concentration was determined by UHPLC-MS/MS method. Healthy male ICR mice were randomly divided into nine groups (n = 6) including negative control (0.5% CMC-Na solution, 13 mL/kg), ART alone (40 mg/kg), verapamil (positive control, 40 mg/kg), ART-verapamil (1:1, 40:40 mg/kg), CHR alone (80 mg/kg), ART-CHR (1:0.1, 40:4 mg/kg), ART-CHR (1:1, 40:40 mg/kg), ART-CHR (1:2, 40:80 mg/kg) and ART-CHR (1:4, 40:160 mg/kg). The drugs were administrated intragastrically for seven consecutive days. MDR1 and P-gp expression levels in mice small intestine were examined by performing RT-PCR and western blot analysis. ABC coupling ATPase activity was also determined.

RESULTS

After combined with CHR (1:2), Papp (AP-BL) and Papp (BL-AP) of ART changed to 4.29 × 10 - 8 (increased 1.79-fold) and 2.85 × 10 - 8 cm/s (decreased 1.24-fold) from 2.40 × 10 - 8 and 3.54 × 10 - 8 cm/s, respectively. Efflux ratio (PBA/PAB) declined 2.21-fold (p < 0.01) versus to ART alone. ART significantly up-regulated both MDR1 mRNA and P-gp levels compared with vehicle, while CHR in combination ratio of 0:1, 0.1:1, 1:1, 2:1 and 4:1 with ART, reversed them to normal levels as well as negative control (p < 0.05). The ATPase activities in ART-CHR 1:4 and CHR alone groups achieved a slight increase (p < 0.05) when compared with ART alone.

DISCUSSION AND CONCLUSION

These results confirm that CHR inhibited P-gp activity and reverse the up-regulated P-gp and MDR1 levels induced by ART. It suggested that CHR potentially can be used as a P-gp reversal agent to obstruct ART multidrug resistance.

Hepatotoxicity of Herbal Supplements Mediated by Modulation of Cytochrome P450

Herbal supplements are a significant source of drug-drug interactions (DDIs), herb-drug interactions, and hepatotoxicity. Cytochrome P450 (CYP450) enzymes metabolize a large number of FDA-approved pharmaceuticals and herbal supplements. This metabolism of pharmaceuticals and supplements can be augmented by concomitant use of either pharmaceuticals or supplements. The xenobiotic receptors constitutive androstane receptor (CAR) and the pregnane X receptor (PXR) can respond to xenobiotics by increasing the expression of a large number of genes that are involved in the metabolism of xenobiotics, including CYP450s. Conversely, but not exclusively, many xenobiotics can inhibit the activity of CYP450s. Induction of the expression or inhibition of the activity of CYP450s can result in DDIs and toxicity. Currently, the United States (US) Food and Drug Administration does not require the investigation of the interactions of herbal supplements and CYP450s. This review provides a summary of herbal supplements that inhibit CYP450s, induce the expression of CYP450s, and/or whose toxicity is mediated by CYP450s.

Drug-transporter mediated interactions between anthelminthic and antiretroviral drugs across the Caco-2 cell monolayers

BACKGROUND

Drug interactions between antiretroviral drugs (ARVs) and anthelminthic drugs, ivermectin (IVM) and praziquantel (PZQ) were assessed by investigating their permeation through the Caco-2 cell monolayers in a transwell. The impact of anthelminthics on the transport of ARVs was determined by assessing the apical to basolateral (AP → BL) [passive] and basolateral to apical (BL → AP) [efflux] directions alone, and in presence of an anthelminthic. The reverse was conducted for the assessment of the influence of ARVs on anthelminthics.

METHODS

Samples from the AP and BL compartments were taken at 60, 120, 180 and 240 min and quantified either by HPLC or radiolabeled assay using a liquid scintillating counter for the respective drugs. Transepithelial resistance (TEER) was used to assess the integrity of the monolayers. The amount of compound transported per second (apparent permeability, Papp) was calculated for both AP to BL (PappAtoB), and BL to AP (PappBtoA) movements. Samples collected after 60 min were used to determine the efflux ratio (ER), quotient of secretory permeability and absorptive permeability (PappBL-AP/PappAP-BL). The reverse, (PappAP-BL/PappBL-AP) constituted the uptake ratio. The impact of SQV, EFV and NVP on the transport of both IVM and PZQ were investigated. The effect of LPV on the transport of IVM was also determined. The influence of IVM on the transport of SQV, NVP, LPV and EFV; as well as the effect PZQ on the transport of SQV of was also investigated, and a two-tailed p value of <0.05 was considered significant.

RESULTS

IVM significantly inhibited the efflux transport (BL → AP movement) of LPV (ER; 6.7 vs. 0.8, p = 0.0038) and SQV (ER; 3.1 vs. 1.2 p = 0.00328); and increased the efflux transport of EFV (ER; 0.7 vs. 0.9, p = 0.031) suggesting the possibility of drug transporter mediated interactions between the two drugs. NVP increased the efflux transport of IVM (ER; 0.8 vs. 1.8, p = 0.0094).

CONCLUSIONS

The study provides in vitro evidence of potential interactions between IVM, an anthelminthic drug with antiretroviral drugs; LPV, SQV, NVP and EFV. Further investigations should be conducted to investigate the possibility of in vivo interactions.

Alterations in cellular pharmacokinetics and pharmacodynamics of elvitegravir in response to ethanol exposure in HIV-1 infected monocytic (U1) cells

Ethanol consumption is negatively associated with antiretroviral therapy (ART) adherence and general health in HIV positive individuals. Previously, we demonstrated ethanol-mediated alterations to metabolism of elvitegravir (EVG) in human liver microsomes. In the current study, we investigated ethanol influence on the pharmacokinetic and pharmacodynamic interactions of EVG in HIV infected monocytic (U1) cells. U1 cells were treated with 5 μM EVG, 2 μM Cobicistat (COBI), a booster drug, and 20 mM ethanol for up to 24 hours. EVG, HIV p24 levels, alterations in cytochrome P450 (CYP) 3A4, MRP1, and MDR1 protein expressions were measured. Presence of ethanol demonstrated a significant effect on the total exposures of both EVG and EVG in combination with COBI. Ethanol also increased the HIV replication despite the presence of drugs and this elevated HIV replication was reduced in the presence of MRP1 and MDR1 inhibitors. Consequently, a slight increase in EVG concentration was observed in the presence of MRP1 inhibitor but not with MDR1 inhibitor. Furthermore, CYP3A4, MRP1 and MDR1 protein levels were significantly induced in treatment groups which included ethanol compared to those with no treatment. In summary, these findings suggest that Ethanol reduces intra cellular EVG exposure by modifying drug metabolism and transporter protein expression. This study provides valuable evidence for further investigation of ethanol effects on the intracellular concentration of EVG in ex vivo or in vivo studies.

Prevalence and clinical impact of recreational drug consumption in people living with HIV on treatment: a cross-sectional study

OBJECTIVES

Drug interactions, poor adherence to medication and high-risk sexual behaviour may occur in individuals with HIV using recreational drugs. Thus, we aimed to assess the prevalence of recreational drugs use and to explore its clinical impact in HIV patients on treatment.

METHODS

Observational, cross sectional, study conducted in a 700 bed university hospital, Barcelona, Spain. A total of 208 adults living with HIV on treatment were included. A questionnaire was administered by clinical pharmacists, including evaluation of sociodemographic variables, past 12-month drug consumption, adherence to antiretrovirals (Simplified Medication Adherence Questionnaire) and high-risk sexual behaviour (condomless sex/multiple partners). Additional data were obtained from clinical records. Recreational drug-antiretroviral interactions were checked in reference databases. Prevalence was calculated for 5% precision and 95% CI. Crude and adjusted binary logistic regressions were performed to identify associations between recreational drug use and adherence problems, and between recreational drug use and high-risk sexual behaviour.

RESULTS

From the overall sample, 92 participants (44.2%) consumed recreational drugs over the past 1 year. Of these, 44 (48.8%) had used different types of recreational drugs in this period. We detected 11 recreational substances, including sildenafil and nitrites. The most consumed drugs were: cannabis (68.5%), cocaine (45.5%), nitrites (31.5%), sildenafil (28.3) and ecstasy (19.6%). Relevant interactions occurred in 46 (50%) of the individuals consuming drugs. Recreational drug consumption was found to be related to adherence problems with antiretrovirals (OR: 2.51 (95% CI 1.32 to 4.77) p=0.005) and high-risk sexual behaviour (OR: 2.81 (95% CI 1.47 to 5.39) p=0.002).

CONCLUSIONS

Recreational drugs are frequently used by HIV patients on treatment. Classical drugs and new substances consumed in sexual context are usual. Recreational drug consumption interferes with several clinical outcomes, including potentially relevant interactions between drugs and antiretrovirals, adherence problems and high-risk sexual behaviour. Thus, there is the urgent need of implementing patient-centred care involving recreational drug consumption.

Transporter effects on cell permeability in drug delivery

INTRODUCTION

The role of drug transporters as one of the determinants of cellular drug permeability has become increasingly evident. Despite the lipophilicity of a drug molecule as rate-limiting factor for passive diffusion across biological membranes, carrier-mediated and active transport have gained attention over the years. A better understanding of the effects and roles of these influx transporters towards transmembrane permeability of a drug molecule need to be delineated for drug development and delivery. Areas covered: This review focuses on findings relative to role of transporters in drug absorption and bioavailability. Particularly the areas demanding further research have been emphasized. This review will also highlight various transporters expressed on vital organs and their effects on drug pharmacokinetics. Expert opinion: Significant efforts have been devoted to understand the role of transporters, their iterative interplay with metabolizing enzymes through molecular enzymology, binding and structure-activity relationship studies. A few assays such as parallel artificial membrane permeation assay (PAMPA) have been developed to analyze drug transport across phospholipid membranes. Although large web-accessible databases on tissue selective expression profiles at transcriptomic as well as proteomic are available, there is a need to collocate the scattered literature on the role of transporters in drug development and delivery.

Dosing Recommendations for Concomitant Medications During 3D Anti-HCV Therapy

The development of direct-acting antiviral (DAA) agents has reinvigorated the treatment of hepatitis C virus infection. The availability of multiple DAA agents and drug combinations has enabled the transition to interferon-free therapy that is applicable to a broad range of patients. However, these DAA combinations are not without drug-drug interactions (DDIs). As every possible DDI permutation cannot be evaluated in a clinical study, guidance is needed for healthcare providers to avoid or minimize drug interaction risk. In this review, we evaluated the DDI potential of the novel three-DAA combination of ombitasvir, paritaprevir, ritonavir, and dasabuvir (the 3D regimen) with more than 200 drugs representing 19 therapeutic drug classes. Outcomes of these DDI studies were compared with the metabolism and elimination routes of prospective concomitant medications to develop mechanism-based and drug-specific guidance on interaction potential. This analysis revealed that the 3D regimen is compatible with many of the drugs that are commonly prescribed to patients with hepatitis C virus infection. Where interaction is possible, risk can be mitigated by paying careful attention to concomitant medications, adjusting drug dosage as needed, and monitoring patient response and/or clinical parameters.

Effect of Methamphetamine on Spectral Binding, Ligand Docking and Metabolism of Anti-HIV Drugs with CYP3A4

Cytochrome P450 3A4 (CYP3A4) is the major drug metabolic enzyme, and is involved in the metabolism of antiretroviral drugs, especially protease inhibitors (PIs). This study was undertaken to examine the effect of methamphetamine on the binding and metabolism of PIs with CYP3A4. We showed that methamphetamine exhibits a type I spectral change upon binding to CYP3A4 with δA_max and K_D of 0.016±0.001 and 204±18 μM, respectively. Methamphetamine-CYP3A4 docking showed that methamphetamine binds to the heme of CYP3A4 in two modes, both leading to N-demethylation. We then studied the effect of methamphetamine binding on PIs with CYP3A4. Our results showed that methamphetamine alters spectral binding of nelfinavir but not the other type I PIs (lopinavir, atazanavir, tipranavir). The change in spectral binding for nelfinavir was observed at both δA_max (0.004±0.0003 vs. 0.0068±0.0001) and K_D (1.42±0.36 vs.2.93±0.08 μM) levels. We further tested effect of methamphetamine on binding of 2 type II PIs; ritonavir and indinavir. Our results showed that methamphetamine alters the ritonavir binding to CYP3A4 by decreasing both the δA_max (0.0038±0.0003 vs. 0.0055±0.0003) and K_D (0.043±0.0001 vs. 0.065±0.001 nM), while indinavir showed only reduced K_D in presence of methamphetamine (0.086±0.01 vs. 0.174±0.03 nM). Furthermore, LC-MS/MS studies in high CYP3A4 human liver microsomes showed a decrease in the formation of hydroxy ritonavir in the presence of methamphetamine. Finally, CYP3A4 docking with lopinavir and ritonavir in the absence and presence of methamphetamine showed that methamphetamine alters the docking of ritonavir, which is consistent with the results obtained from spectral binding and metabolism studies. Overall, our results demonstrated differential effects of methamphetamine on the binding and metabolism of PIs with CYP3A4. These findings have clinical implication in terms of drug dose adjustment of antiretroviral medication, especially with ritonavir-boosted antiretroviral therapy, in HIV-1-infected individuals who abuse methamphetamine.

Increasing use of 'party drugs' in people living with HIV on antiretrovirals: a concern for patient safety

Use of 'party drugs', a particular set of recreational drugs used in the context of 'ChemSex', is frequent among MSM living with HIV. A recently published observational study showed that more than half of HIV-infected MSM interviewed reported use of illicit substances in the previous 3 months, with frequent concomitant use of three or more drugs. These substances are a combination of 'club drugs' (methylenedioxymethamphetamine, gamma-hydroxybutyrate, ketamine, benzodiazepine) and drugs that are more specifically used in a sexualized context (methamphetamine, mephedrone, poppers and erectile dysfunction agents). Although formal data on pharmacokinetic or pharmacodynamic interactions between recreational drugs and antiretroviral agents are lacking, information regarding potentially toxic interactions can be theorized or sometimes conclusions may be drawn from case studies and cohort observational studies. However, the risk of coadministering party drugs and antiretrovirals should not be overestimated. The major risk for a drug-drug interaction is when using ritonavir-boosting or cobicistat-boosting agents, and maybe some nonnucleoside reverse transcriptase inhibitors. Knowledge of the metabolic pathways of 'party drugs' may help in advising patients on which illicit substances have a high potential for drug-drug interactions, as this is not the case for all.

Interaction Studies of Resolvin E1 Analog (RX-10045) with Efflux Transporters

PURPOSE

Screening interactions of a resolvin E1 analog (RX-10045) with efflux transporters (P-glycoprotein [P-gp], multidrug resistance-associated protein [MRP2], and breast cancer-resistant protein [BCRP]).

METHODS

Madin-Darby canine kidney cells transfected with P-gp, MRP2, and BCRP genes were selected for this study. [3H]-Digoxin, [3H]-vinblastine and [3H]-abacavir were selected as model substrates for P-gp, MRP2, and BCRP. Uptake and permeability studies across cell monolayer in both apical to basal (AP-BL) and BL-AP of these substrates were conducted in the presence of specific efflux pump inhibitors and RX-10045. Cell viability studies were conducted with increasing concentrations of RX-10045.

RESULTS

Uptake studies showed a higher accumulation in the presence of inhibitors (GF120918 and ketoconazole for P-gp; MK571 for MRP2; and β-estradiol for BCRP) as well as RX-10045. Similarly, dose-dependent inhibition studies demonstrated higher accumulation of various substrates ([3H]-digoxin, [3H]-vinblastine, and [3H]-abacavir) in the presence of RX-10045. IC50 values of dose-dependent inhibition of RX-10045 for P-gp, MRP2, and BCRP were 239±11.2, 291±79.2, and 300±42 μM, respectively. Cell viability assay indicated no apparent toxicity up to 350 μM concentration. Enhanced permeability for model substrates was observed in the presence of RX-10045. Uptake studies in human corneal epithelial cells suggest that RX-10045 is a strong inhibitor of organic cation transporter-1 (OCT-1).

CONCLUSIONS

In summary, the resolvin analog (RX-10045) was identified as a substrate/inhibitor for efflux transporters (MRP2 and BCRP). Also, RX-10045 appears to be a strong inhibitor/substrate of OCT-1. Novel formulation strategies such as nanoparticles, nanomicelles, and liposomes for circumventing efflux barriers and delivering higher drug concentrations leading to a higher therapeutic efficacy may be employed.

Drug-drug interactions between anti-retroviral therapies and drugs of abuse in HIV systems

INTRODUCTION

Substance abuse is a common problem among HIV-infected individuals. Importantly, addictions as well as moderate use of alcohol, smoking, or other illicit drugs have been identified as major reasons for non-adherence to antiretroviral therapy (ART) among HIV patients. The literature also suggests a decrease in the response to ART among HIV patients who use these substances, leading to failure to achieve optimal virological response and increased disease progression.

AREAS COVERED

This review discusses the challenges with adherence to ART as well as observed drug interactions and known toxicities with major drugs of abuse, such as alcohol, smoking, methamphetamine, cocaine, marijuana, and opioids. The lack of adherence and drug interactions potentially lead to decreased efficacy of ART drugs and increased ART, and drugs of abuse-mediated toxicity. As CYP is the common pathway in metabolizing both ART and drugs of abuse, we discuss the possible involvement of CYP pathways in such drug interactions.

EXPERT OPINION

We acknowledge that further studies focusing on common metabolic pathways involving CYP and advance research in this area would help to potentially develop novel/alternate interventions and drug dose/regimen adjustments to improve medication outcomes in HIV patients who consume drugs of abuse.

Clinical chemistry profiles in injection heroin users from Coastal Region, Kenya

Background

Although the co-burden of injection drug use and HIV is increasing in Africa, little is known about the laboratory markers of injection drug use and anti-retroviral treatment (ART) in Kenyan injection drug users. This study, therefore, aimed at determining the clinical chemistry profiles and identifying the key laboratory markers of HIV infection during ART in injection heroin users (IHUs).

Methods

Clinical chemistry measurements were performed on serum samples collected from HIV-1 infected ART-experienced (n = 22), naive (n = 16) and HIV-1 negative (n = 23) IHUs, and healthy controls (n = 15) from Mombasa, coastal Kenya.

Results

HIV uninfected IHUs had lower alanine aminotransferase (ALT) levels (P = 0.023) as ART-exposed IHUs exhibited lower albumin (P = 0.014) and higher AST to platelet index (APRI) (P < 0.0001). All IHUs presented with lower aspartate aminotransferase to ALT values (P = 0.001) and higher C-reactive protein (CRP) levels (P = 0.002). ART-naive IHUs had higher globulin levels (P = 0.013) while ART-experienced and naive IHUs had higher albumin to total protein (P < 0.0001) and albumin to globulin (P < 0.0001) values. In addition, CD4+ T cells correlated with ALT (ρ = −0.522, P = 0.011) and CRP (rho, ρ = 0.529, P = 0.011) in HIV negative and ART-experienced IHUs, respectively. HIV-1 viral load correlated with albumin to globulin index in ART-experienced (ρ = −0.468, P = 0.037) and naive (ρ = −0.554, P = 0.040) IHUs; and with albumin to total protein index (ρ = −0.554, P = 0.040) and globulin (ρ = 0.570, P = 0.033) in ART-naive IHUs.

Conclusion

Absolute ALT, albumin, globulin, and CRP measurements in combination with APRI, AST to ALT, albumin to total protein and albumin to globulin indices may be useful laboratory markers for screening IHUs for initiating and monitoring treatment.

Clinically relevant drug-drug interactions between antiretrovirals and antifungals

INTRODUCTION

Complete delineation of the HIV-1 life cycle has resulted in the development of several antiretroviral drugs. Twenty-five therapeutic agents belonging to five different classes are currently available for the treatment of HIV-1 infections. Advent of triple combination antiretroviral therapy has significantly lowered the mortality rate in HIV patients. However, fungal infections still represent major opportunistic diseases in immunocompromised patients worldwide.

AREAS COVERED

Antiretroviral drugs that target enzymes and/or proteins indispensable for viral replication are discussed in this article. Fungal infections, causative organisms, epidemiology and preferred treatment modalities are also outlined. Finally, observed/predicted drug-drug interactions between antiretrovirals and antifungals are summarized along with clinical recommendations.

EXPERT OPINION

Concomitant use of amphotericin B and tenofovir must be closely monitored for renal functioning. Due to relatively weak interactive potential with the CYP450 system, fluconazole is the preferred antifungal drug. High itraconazole doses (> 200 mg/day) are not advised in patients receiving booster protease inhibitor (PI) regimen. Posaconazole is contraindicated in combination with either efavirenz or fosamprenavir. Moreover, voriconazole is contraindicated with high-dose ritonavir-boosted PI. Echinocandins may aid in overcoming the limitations of existing antifungal therapy. An increasing number of documented or predicted drug-drug interactions and therapeutic drug monitoring may aid in the management of HIV-associated opportunistic fungal infections.