Pharmacokinetic interaction between regorafenib and atorvastatin in rats

BACKGROUND

Regorafenib is used in the treatment of colorectal cancer and hepatocellular carcinoma. Due to the co-morbidity of hyperlipidemia in these conditions, statins, including atorvastatin, are used as potential adjuvant therapy agents. Both regorafenib and atorvastatin are metabolized by CYP3A4. In addition, atorvastatin is a P-gp and BCRP substrate, whereas regorafenib and its active metabolites M-2 and M-5 are inhibitors of these transporters. Hence, the concomitant use of both drugs may increase the risk of a clinically significant drug-drug interaction. Therefore, the present study aimed to assess the pharmacokinetic interactions of atorvastatin and regorafenib and their active metabolites.

METHODS

Male Wistar rats were assigned to three groups (eight animals in each) and were orally administered: regorafenib and atorvastatin (IREG+ATO), a carrier with regorafenib (IIREG), and atorvastatin with a carrier (IIIATO). Blood samples were collected for 72 h. UPLC-MS/MS was the method of measurement of regorafenib and atorvastatin concentrations. The pharmacokinetic parameters were calculated with a non-compartmental model.

RESULTS

A single administration of atorvastatin increased the exposure to regorafenib and its active metabolites. In the IREG+ATO group, the Cmax, AUC0-t, and AUC0-∞ of regorafenib increased 2.7, 3.2, and 3.2-fold, respectively. Atorvastatin also significantly increased the Cmax, AUC0-t, and AUC0-∞ of both regorafenib metabolites. Regorafenib, in turn, decreased the AUC0-t and AUC0-∞ of 2-OH atorvastatin by 86.9% and 67.3%, and the same parameters of 4-OH atorvastatin by 45.0% and 46.8%, respectively.

CONCLUSIONS

This animal model study showed a significant pharmacokinetic interaction between regorafenib and atorvastatin. While this interaction may be clinically significant, this needs to be confirmed in clinical trials involving cancer patients.

Bidirectional pharmacokinetic drug interactions between olaparib and metformin

OBJECTIVE

Olaparib is a PARP (poly-ADP-ribose polymerase) inhibitor used for maintenance therapy in BRCA-mutated cancers. Metformin is a first-choice drug used in the treatment of type 2 diabetes. Both drugs are commonly co-administered to oncologic patients with add-on type 2 diabetes mellitus. Olaparib is metabolized by the CYP3A4 enzyme, which may be inhibited by metformin through the Pregnane X Receptor. In vitro studies have shown that olaparib inhibits the following metformin transporters: OCT1, MATE1, and MATE2K. The aim of the study was to assess the influence of 'the perpetrator drug' on the pharmacokinetic (PK) parameters of 'the victim drug' after a single dose. To evaluate the effect, the AUC0→∞ (area under the curve) ratio was determined (the ratio between AUC0→∞ in the presence of the perpetrator and AUC0→∞ without the presence of the perpetrator).

METHODS

Male Wistar rats were assigned to three groups (eight animals in each group), which were orally administered: metformin and olaparib (IMET+OLA), vehiculum with metformin (IIMET), and vehiculum with olaparib (IIIOLA). Blood samples were collected after 24 h. HPLC was applied to measure the concentrations of olaparib and metformin. The PK parameters were calculated in a non-compartmental model.

RESULTS

Metformin did not affect the olaparib PK parameters. The AUC0→∞ IMET+OLA/IIIOLA ratio was 0.99. Olaparib significantly increased the metformin Cmax (by 177.8%), AUC0→t (by 159.8%), and AUC0→∞ (by 74.1%). The AUC0→∞ IMET+OLA/IIMET ratio was 1.74.

CONCLUSIONS

A single dose of metformin did not affect the PK parameters of olaparib, nor did it inhibit the olaparib metabolism, but olaparib significantly changed the metformin pharmacokinetics, which may be of clinical importance.

THC-Reduced Cannabis sativa L.-How Does the Solvent Determine the Bioavailability of Cannabinoids Given Orally?

The bioavailability levels of cannabidiol (CBD) and tetrahydrocannabinol (THC) determine their pharmacological effects. Therefore, for medical purposes, it is essential to obtain extracts containing the lowest possible content of the psychogenic component THC. In our extract, the CBD/THC ratio was 16:1, which is a high level compared to available medical preparations, where it is, on average, 1:1. This study assessed the bioavailability and stability of CBD and THC derived from Cannabis sativa L. with reduced THC content. The extract was orally administered (30 mg/kg) in two solvents, Rapae oleum and Cremophor, to forty-eight Wistar rats. The whole-blood and brain concentrations of CBD and THC were measured using liquid chromatography coupled with mass spectrometry detection. Much higher concentrations of CBD than THC were observed for both solvents in the whole-blood and brain after oral administration of the Cannabis sativa extract with a decreased THC content. The total bioavailability of both CBD and THC was higher for Rapae oleum compared to Cremophor. Some of the CBD was converted into THC in the body, which should be considered when using Cannabis sativa for medical purposes. The THC-reduced hemp extract in this study is a promising candidate for medical applications.

Population pharmacokinetic-pharmacodynamic model of dexmedetomidine in elderly patients undergoing sedation after abdominal aortic surgery

Background. Dexmedetomidine (DEX) is a widely used sedative agent for treating post-surgery patients. It also acts on hemodynamic parameters like heart rate or cardiac output. This study aimed to develop a pharmacokinetic-pharmacodynamic (PK/PD) model of DEX using bispectral index (BIS) and cardiac output (CO) as a response. Methodology and results. 21 mechanically ventilated elderly cardiac patients undergoing abdominal aortic surgery were enrolled in the study. DEX was given to maintain moderate or deep sedation. Genotypes of ADR2A*55 were identified using real-time PCR-HRM. Data were analyzed using nonlinear mixed-effect modelling. A two-compartment model described DEX pharmacokinetics. The sigmoid Emax and linear models were used to describe BIS and CO measurements. The typical value of EC50 for DEX effects on BIS was 3.62 ng/ml, and the slope between CO and DEX concentrations was 0.819 (L/min)/(ng/ml). We were unable to show the effects of considered covariates on DEX pharmacodynamics. Conclusions. WE proposed the PK/PD model of DEX to understand better the BIS and CO changes observed after surgery. The measured CI values were in the reference range showing that the used doses of DEX ensured stable cardiac function in the studied patients.

Population Pharmacokinetic-Pharmacodynamic Modeling and Probability of Target Attainment Analysis of Rocuronium and Sugammadex in Children Undergoing Surgery

BACKGROUND AND OBJECTIVES

Probability of target attainment (PTA) curves are commonly used to support dose recommendations of antibiotics for different patient groups. In this study we propose PTA analysis to optimize sugammadex dosing in children.

METHODS

This study involved data from an observational cohort study of 30 American Society of Anesthesiologists (ASA) Physical Status I and II children undergoing surgery requiring muscle relaxation. All patients received 0.6 mg/kg rocuronium, with sugammadex administered at the end of surgery in three different doses (0.5, 1.0, and 2.0 mg/kg) to reverse the neuromuscular blockade.

RESULTS

The data were analyzed using a population Bayesian-based approach. The developed model was used to simulate pharmacokinetic-pharmacodynamic profiles for different patient groups and dosing regimens before the PTA analysis was performed to translate these simulations into a clinically useful measure. The target was defined as neuromuscular blockade reversal measured by Train-of-Four (TOF ratio > 90%) at 1.5, 3, and 5 min post sugammadex dose. The sugammadex doses leading to 90% PTA were determined for different patients' body weights, rocuronium doses, and time gaps between rocuronium and sugammadex administration assuming the model, priors, and gathered data. For comparison, PTA curves for a range of clinical scenarios are provided to illustrate the usefulness of PTA analysis in selecting the appropriate dose for a given patient.

CONCLUSIONS

The proposed PTA analysis is useful to support the sugammadex dose selection in different clinical scenarios.

TRIAL REGISTRATION

The study was registered by ClinicalTrials.gov under number NCT04851574 on 21 April 2021.

The use of Ctrough for the therapeutic drug monitoring of olaparib in patients with ovarian cancer

OBJECTIVE

Olaparib is the poly-[Adenosine diphosphate ribose (ADP-ribose)] polymerase inhibitor (PARPI) used in maintenance therapy of patients with platinum-sensitive ovarian cancer with mutations in breast cancer genes 1/2 (BRCA1/2). Oncologists still do not have recommendations of treatment depending on efficient plasma concentrations of the PARP inhibitor. The aim of the study was the assessment of plasma trough concentrations of olaparib at steady state (Ctrough) in ovarian cancer patients. The severity of olaparib adverse effects (AEs) was noted.

PATIENTS AND METHODS

The retrospective study involved 33 patients [mean standard deviation (SD)]; age 57.0 (8.4) years; weight 68.7 (13.7) kg; and body mass index (BMI) 26.4 (4.9) kg/m2, with ovarian cancer treated with olaparib (tablets in dose 300 mg/12 h, 250 mg/12 h, 200 mg/12 h or capsules 400 mg/12 h, 200 mg/12 h, 100 mg/12 h). Plasma drug levels were measured by HPLC-UV method (λ = 254 nm; Symmetry C8 column; gradient flow). The severity of olaparib AEs was assessed by Common Terminology Criteria for Adverse Events (CTCAE) v5.0 scale. Drug interactions were analyzed.

RESULTS

In total, 130 measurements (n) of Ctrough were determined in 33 patients (median sample frequency per patient was 4). The olaparib Ctrough in patients with AEs was 87.840-7,213.262 ng/mL [coefficient of variation (CV) = 91%], in patients without AEs 48.021-7,073.350 ng/mL (CV = 88%). AEs were the following: fatigue (modest, n = 4, severe, n = 2), anemia (grade G1 n = 66, G2 n = 6, G3 n = 3), neutropenia (grade G1 n = 15, G2 n = 4), prediabetes (n = 1). There was a correlation between Ctrough and olaparib-induced fatigue (p = 0.0015). The lower values of dose-adjusted olaparib concentrations (p = 0.0121) and dose/kg-adjusted olaparib concentrations (p = 0.0389) were correlated with higher grade of neutropenia.

CONCLUSIONS

There was a correlation between Ctrough, expressed as ng/ml, ng/ml/mg or ng/ml/mg/kg, and fatigue degree, but not anemia. Patients with neutropenia had statistically significant lower plasma concentrations of olaparib.

Pharmacokinetic Drug Interaction Study of Sorafenib and Morphine in Rats

A combination of the tyrosine kinase inhibitor—sorafenib—and the opioid analgesic—morphine—can be found in the treatment of cancer patients. Since both are substrates of P-glycoprotein (P-gp), and sorafenib is also an inhibitor of P-gp, their co-administration may affect their pharmacokinetics, and thus the safety and efficacy of cancer therapy. Therefore, the aim of this study was to evaluate the potential pharmacokinetic drug–drug interactions between sorafenib and morphine using an animal model. The rats were divided into three groups that Received: sorafenib and morphine (I_SOR+MF), sorafenib (II_SOR), and morphine (III_MF). Morphine caused a significant increase in maximum plasma concentrations (C_max) and the area under the plasma concentration–time curves (AUC_0–t, and AUC_0–∞) of sorafenib by 108.3 (p = 0.003), 55.9 (p = 0.0115), and 62.7% (p = 0.0115), respectively. Also, the C_max and AUC_0–t of its active metabolite—sorafenib N-oxide—was significantly increased in the presence of morphine (p = 0.0022 and p = 0.0268, respectively). Sorafenib, in turn, caused a significant increase in the C_max of morphine (by 0.5-fold, p = 0.0018). Moreover, in the presence of sorafenib the C_max, AUC_0–t, and AUC_0–∞ of the morphine metabolite M3G increased by 112.62 (p < 0.0001), 46.82 (p = 0.0124), and 46.78% (p = 0.0121), respectively. Observed changes in sorafenib and morphine may be of clinical significance. The increased exposure to both drugs may improve the response to therapy in cancer patients, but on the other hand, increase the risk of adverse effects.

The Safety of a Vegan Diet During Pregnancy

There is an increasing number of people who go vegetarian. Some young parents also switch to this diet. The safety of vegetarian diets, especially vegan diets, is very important, especially during pregnancy. Unfortunately, reference publications do not provide coherent data on the safety of vegetarian diets during pregnancy. On the one hand, the vegan diet has advantages because it reduces the risk of heart disease and gestational diabetes. On the other hand, vegetarians/vegans should be aware of potential deficiencies of some nutrients (iron, zinc, vitamin B12, vitamin D, omega-3 fatty acids, calcium, iodine) and the clinical consequences for the fetus. For example, iron deficiency may affect cognitive abilities, behavior, intelligence and increase the risk of preterm birth and low birth weight of infants. Plant food contains non-haem iron with variable absorption. Therefore, the vegan diet should include nutrients increasing the bioavailability of iron, e.g. ascorbic acid, carotene and retinol. Due to the fact that animal food is the main source of vitamin B12, vegans are at a very high risk of vitamin B12 deficiency, which will affect the infant’s weight at birth. Low level of vitamin D, which is prevalent in animal food, is the most common deficiency among vegans and lacto-ovo vegetarians. This vitamin prevents gestational diabetes, reduces insulin resistance and guarantees normal function of the musculoskeletal system. Zinc deficiency during pregnancy may lead to preterm birth, neural tube defects or even miscarriage. In view of the clinical consequences of potential deficiencies of nutrients, the vegetarian/vegan diet should be well balanced.

The Safety of TheVegan Diet During Pregnancy

There is an increasing number of people who go vegetarian. Some young parents also switch to this diet. The safety of vegetarian diets, especially ve-gan diets, is very important, especially during pregnancy. Unfortunately, reference publications do not provide coherent data on the safety of vegetar-ian diets during pregnancy. On the one hand, the vegan diet has advantages because it reduces the risk of heart disease and gestational diabetes. On the other hand, vegetarians/vegans should be aware of potential deficiencies of some nutrients (iron, zinc, vitamin B12, vitamin D, omega-3 fatty acids, cal-cium, iodine) and the clinical consequences for the foetus. For example, iron deficiency may affect cognitive abilities, behaviour, intelligence and increase the risk of preterm birth and low birth weight of infants. Plant food contains non-haem iron with variable absorption. Therefore, the vegan diet should include nutrients increasing the bioavailability of iron, e.g. ascorbic acid, carotene and retinol. Due to the fact that animal food is the main source of vitamin B12, vegans are at very high risk of vitamin B12 deficiency, which will affect the infant’s weight at birth. Low level of vitamin D, which is prevalent in animal food, is the most common deficiency among vegans and lacto-ovo vegetarians. This vitamin prevents gestational diabetes, reduces insulin resistance and guarantees normal function of the musculoskeletal system. Zinc deficiency during pregnancy may lead to preterm birth, neural tube defects or even miscarriage. In view of the clinical consequences of po-tential deficiencies of nutrients, the vegetarian/vegan diet should be well balanced.

The influence of cardiac output on propofol and fentanyl pharmacokinetics and pharmacodynamics in patients undergoing abdominal aortic surgery

Cardiac output (CO) is expected to affect elimination and distribution of highly extracted and perfusion rate-limited drugs. This work was undertaken to quantify the effect of CO measured by the pulse pressure method on pharmacokinetics and pharmacodynamics of propofol and fentanyl administrated during total intravenous anesthesia (TIVA). The data were obtained from 22 ASA III patients undergoing abdominal aortic surgery. Propofol was administered via target-controlled infusion system (Diprifusor) and fentanyl was administered at a dose of 2-3 µg/kg each time analgesia appeared to be inadequate. Hemodynamic measurements as well as bispectral index were monitored and recorded throughout the surgery. Data analysis was performed by using a non-linear mixed-effect population modeling (NONMEM 7.4 software). Three compartment models that incorporated blood flows as parameters were used to describe propofol and fentanyl pharmacokinetics. The delay of the anesthetic effect, with respect to plasma concentrations, was described using a biophase (effect) compartment. The bispectral index was linked to the propofol and fentanyl effect site concentrations through a synergistic Emax model. An empirical linear model was used to describe CO changes observed during the surgery. Cardiac output was identified as an important predictor of propofol and fentanyl pharmacokinetics. Consequently, it affected the depth of anesthesia and the recovery time after propofol-fentanyl TIVA infusion cessation. The model predicted (not observed) CO values correlated best with measured responses. Patients' age was identified as a covariate affecting the rate of CO changes during the anesthesia leading to age-related difference in individual patient's responses to both drugs.

The Influence of Paracetamol on the Penetration of Sorafenib and Sorafenib N-Oxide Through the Blood-Brain Barrier in Rats

Background and Objective

Sorafenib is an oral, multikinase inhibitor with established single-agent activity in several tumor types. Sorafenib was moderately transported by P-glycoprotein (P-gp) and more efficiently by breast cancer resistance protein. The constitutive androstane receptor (CAR) is a ligand-activated transcription factor involved in P-gp regulation in the brain microvasculature. Paracetamol is a CAR activator. The purpose of this study was to investigate the effect of paracetamol on the brain uptake of sorafenib and sorafenib N-oxide.

Methods

The rats were assigned to two groups—rats receiving oral paracetamol 100 mg/kg and sorafenib 100 mg/kg (n = 42, I_SR+PA) and rats receiving oral vehicle and sorafenib 100 mg/kg (n = 42, II_SR). The sorafenib and sorafenib N-oxide concentrations in blood plasma and brain tissue were determined by a high-performance liquid chromatography method with ultraviolet detection. Brain-to-plasma partition coefficient (K_p) was calculated as a ratio of the area under the curve from zero to 24 h (AUC) in the brain and plasma. A drug targeting index (DTI) was estimated as the group I_SR+PAK_p to group II_SRK_p ratio.

Results

Pharmacokinetic analysis revealed increased brain exposure to sorafenib and sorafenib N-oxide after co-administration of paracetamol. The brain maximum concentration (C_max) and the AUC of the parent drug in the I_SR+PA group compared with the II_SR group were greater by 49.5 and 77.8%, respectively, and the same parameters for the metabolite were higher by 51.4 and 50.9%. However, the K_p values of sorafenib and sorafenib N-oxide did not differ significantly between the two animal groups and the DTI values were close to 1.

Conclusion

Paracetamol increases exposure to sorafenib and sorafenib N-oxide in the brain, likely due to increased exposure in plasma.

The effect of genetic variations for interleukin-10 (IL-10) on the efficacy of immunosuppressive therapy in patients after kidney transplantation

Kidney transplantation is the target method of treating chronic kidney disorders. It improves the comfort of patient life by eliminating the need for repeated dialysis. The aim of the study was to examine the correlation between tacrolimus (TAC) dose and genetic variation for interleukin-10 (IL-10) and its effect on the therapeutic outcome. In addition, the correlations between the IL-10 polymorphism andthe clinical and the biochemical parameters of TAC patients were also analyzed. The study included 209 subjects after kidney transplantation, who received TAC every 12 and 24 h. Drug concentrations in blood, selected morphological and biochemical parameters, and the genetic variation of IL-10 (-1082A > G) which may affect immunosuppressant dosage and risk of acute graft rejection were analyzed. Genetic analyses were performed using real-time PCR. No significant correlations between the clinical and the biochemical parameters and IL-10-1082A > G polymorphism for patients receiving TAC after kidney transplantation were found. The analysis of the correlation between TAC dose and IL-10 genetic variation for the -1082A > G polymorphism revealed that patients with the AA genotype required lower immunosuppressive drug doses (AA: 3.54 ± 2.38 mg/day vs AG: 6.18 ± 5.10 mg/day, GG: 4.44 ± 3.01 mg/day). Furthermore, frequencies of the genotypes for the IL-10 -1082A > G polymorphism were characterized by a significantly higher frequency of the AA genotype among TAC 24 as compared to TAC 12 patients. The results of the study indicated that the IL-10 -1082A > G polymorphism may in fact influence the TAC dose. The biochemical parameters of the renal profile in relation to the IL-10 genetic variations were not indicative of higher risk of acute rejection after transplantation.

Ketoprofen and tramadol pharmacokinetics in patients with chronic pancreatitis

OBJECTIVE

Chronic pancreatitis (CP) is a disease leading to irreversible pancreas dysfunction. One of the main symptoms is pain. Many patients require pharmacological therapy which should be started with paracetamol or, in selected groups of patients, ketoprofen. If the effect of ketoprofen is irrelevant, patients receive tramadol. The aim of this study is the evaluation of ketoprofen and tramadol pharmacokinetics (PK) in CP patients.

PATIENTS AND METHODS

36 patients were divided into two groups: I - receiving ketoprofen (n=18; mean [SD] age, 48.61 [13.32] years; weight, 73.28 [20.48] kg), II - receiving tramadol (n=18; mean [SD] age, 46.78 [10.28] years; weight, 74.22 [14.04] kg, and BMI (Body Mass Index), 24.61 [4.51] kg/m2). The plasma concentrations of ketoprofen and tramadol with its active metabolite M1 (0-desmethyltramadol) were measured with the validated high-performance liquid chromatography method.

RESULTS

The main PK parameters for ketoprofen were as follows: Cmax (maximum plasma concentration), 3.41 [2.32] mg/L; AUC0-inf (area under the plasma concentration-time curve from time zero to infinity), 10.45 [5.57] mg⋅h/L; tmax (time to first occurrence of Cmax), 1.94 [1.25] h; Cl (clearance), 0.199 [0.165] L/kg·h, and Vd/kg (volume of distribution per kilogram of body weight), 0.71 [0.58] L/kg. The main PK parameters for TRM and M1 were as follows: Cmax, 226.4 [80.5] and 55.6 [23] ng/mL; AUC0-inf, 1903.3 [874.8] and 790.4 [512.4] ng⋅h/mL; tmax, 1.78 [0.73] and 2.67 [1.19] h, respectively.

CONCLUSIONS

Chronic pancreatitis led to a decrease in the total amount of absorbed ketoprofen. Consequently, the analgesic effect of the drug may be weaker. Cmax of tramadol for most CP patients was within the therapeutic range associated with its analgesic activity. M1/TRM ratios for Cmax and AUC were unchanged.

In vivo assessment of potential for UGT-inhibition-based drug-drug interaction between sorafenib and tapentadol

Sorafenib (SR) is one of the most potent UGT (1A1, 1A9) inhibitors (in in vitro tests). The inhibition of UGT1A1 may cause hyperbilirubinaemia, whereas the inhibition of UGT1A9 and 1A1 may result in drug-drug interactions (DDIs). Tapentadol (TAP) is a synthetic μ-opioid agonist and is used to treat moderate to severe acute pain. Tapentadol is highly glucuronidated by the UGT1A9 and UGT2B7 isoenzymes. The aim of the study was to assess the DDI between SR and TAP. Wistar rats were divided into three groups, with eight animals in each. The rats were orally treated with SR (100 mg/kg) or TAP (4.64 mg/kg) or in combination with 100 mg/kg SOR and 4.64 TAP mg/kg. The concentrations of SR and sorafenib N-oxide, TAP and tapentadol glucuronide were respectively measured by means of high-performance liquid chromatography (HPLC) with ultraviolet detection and by means of ultra-performance liquid chromatography-tandem mass spectrometry. The co-administration of TAP with SR caused TAP maximum plasma concentration (C_max) to increase 5.3-fold whereas its area under the plasma concentration-time curve (AUC_0-∞) increased 1.5-fold. The tapentadol glucuronide C_max increased 5.3-fold and whereas its AUC_0-∞ increased 2.0-fold. The tapentadol glucuronide/TAP AUC_0-∞ ratio increased 1.4-fold (p = 0.0118). TAP also increased SR C_max 1.9-fold, whereas its AUC_0-∞ increased 1.3-fold. The sorafenib N-oxide C_max increased 1.9-fold whereas its AUC_0-∞ increased 1.3-fold. The sorafenib N-oxide/SR AUC_0-t ratio increased 1.4-fold (p = 0.0127). The results show that the co-administration of sorafenib and tapentadol increases the exposure to both drugs and changes their metabolism. In consequence, the pharmacological effect may be intensified, but the toxicity may increases, too.

Population analysis to assess the influence of age and body weight on pharmacokinetics and pharmacodynamics of dexmedetomidine in New Zealand White rabbits

The purpose of this work was i) to develop a population pharmacokinetic (PK) and pharmacodynamic (PD) model of dexmedetomidine (DEX) in New Zealand White rabbits, ii) to investigate the influence of the age and weight of the animals on the model parameters, and iii) to assess the linearity of DEX PKs in the examined dose range. This was a prospective, crossover study, using a total of 18 New Zealand White rabbits. DEX was administered as a single intravenous bolus injection in the doses from 25 to 300 μg kg^-1 . Each New Zealand White rabbit was given the same dose of drug in its three developmental stages. To determine the DEX PK, seven blood samples were taken from each animal. The pedal withdrawal reflex was the PD response used to assess the degree of sedation. Nonlinear mixed effects modelling was used for the population PK/PD analysis. The typical value of elimination clearance was 0.061 L min^-1 and was 35% higher in younger New Zealand White rabbits compared with older animals. The PK of DEX was linear in the examined concentration range. Age-related changes in sensitivity to DEX were not detected. The results suggest that due to the pharmacokinetics, younger animals will have lower DEX concentrations and a shorter duration of sedation than older animals given the same doses of DEX per kg of body weight.

Pharmacokinetic Interaction between Sorafenib and Atorvastatin, and Sorafenib and Metformin in Rats

The tyrosine kinase inhibitor sorafenib is the first-line treatment for patients with hepatocellular carcinoma (HCC), in which hyperlipidemia and type 2 diabetes mellitus (T2DM) may often coexist. Protein transporters like organic cation (OCT) and multidrug and toxin extrusion (MATE) are involved in the response to sorafenib, as well as in that to the anti-diabetic drug metformin or atorvastatin, used in hyperlipidemia. Changes in the activity of these transporters may lead to pharmacokinetic interactions, which are of clinical significance. The study aimed to assess the sorafenib−metformin and sorafenib−atorvastatin interactions in rats. The rats were divided into five groups (eight animals in each) that received sorafenib and atorvastatin (I_SOR+AT), sorafenib and metformin (II_SOR+MET), sorafenib (III_SOR), atorvastatin (IV_AT), and metformin (V_MET). Atorvastatin significantly increased the maximum plasma concentration (C_max) and the area under the plasma concentration–time curve (AUC) of sorafenib by 134.4% (p < 0.0001) and 66.6% (p < 0.0001), respectively. Sorafenib, in turn, caused a significant increase in the AUC of atorvastatin by 94.0% (p = 0.0038) and its metabolites 2−hydroxy atorvastatin (p = 0.0239) and 4−hydroxy atorvastatin (p = 0.0002) by 55.3% and 209.4%, respectively. Metformin significantly decreased the AUC of sorafenib (p = 0.0065). The AUC ratio (II_SOR+MET group/III_SOR group) for sorafenib was equal to 0.6. Sorafenib did not statistically significantly influence the exposure to metformin. The pharmacokinetic interactions observed in this study may be of clinical relevance in HCC patients with coexistent hyperlipidemia or T2DM.

Population Pharmacokinetic Model of Dexmedetomidine in a Heterogeneous Group of Patients

Dexmedetomidine is a hepatically eliminated drug with sedative, anxiolytic, sympatholytic, and analgesic properties that has been increasingly used for various indications in the form of a short or continuous intravenous infusion. This study aimed to propose a population pharmacokinetic (PK) model of dexmedetomidine in a heterogeneous group of intensive care unit patients, incorporating 29 covariates potentially linked with dexmedetomidine PK. Data were collected from 70 patients aged between 0.25 and 88 years and treated with dexmedetomidine infusion for various durations at 1 of 4 medical centers. Statistical analysis was performed using a nonlinear mixed-effect model. Categorical and continuous covariates including demographic data, hemodynamic parameters, biochemical markers, and 11 single-nucleotide polymorphisms were tested. A 2-compartment model was used to describe dexmedetomidine PK. An allometric/isometric scaling was used to account for body weight difference in PK parameters, and the Hill equation was used to describe the maturation of clearance. Typical values of the central and peripheral volume of distribution and the systemic and distribution clearance for a theoretical adult patient were central volume of distribution = 22.50 L, peripheral volume of distribution  = 86.1 L, systemic clearance =  34.7 L/h, and distribution clearance = 40.8 L/h. The CYP1A2 genetic polymorphism and noradrenaline administration were identified as significant covariates for clearance. A population PK model of dexmedetomidine was successfully developed. The proposed model is well calibrated to the observed data. The identified covariates account for <5% of interindividual variability and consequently are of low clinical significance for the purpose of dose adjustment.

In vivo assessment of the drug interaction between sorafenib and paracetamol in rats

Purpose

Sorafenib is a multi-targeted tyrosine kinase inhibitor (TKI) used for the treatment of advanced renal cell carcinoma, hepatocellular carcinoma and radioactive iodine resistant thyroid carcinoma. Neoplastic diseases are the cause of pain, which may occur regardless of the stage of the disease. Paracetamol is a non-opioid analgesic used alone or in combination with opioids for the treatment of cancer pain. Numerous studies have pointed out changes in the pharmacokinetic parameters of TKIs when co-administered with paracetamol. The aim of the study was to assess drug–drug interactions (DDIs) between sorafenib and paracetamol.

Methods

Rats were divided into three groups, each consisting of eight animals. The first group received sorafenib (II_S), the second group received sorafenib + paracetamol (I_S+PA), whereas the third group received only paracetamol (III_PA). A single dose of sorafenib (100 mg/kg b.w.) and paracetamol (100 mg/kg b.w.) was administered orally. The plasma concentrations of sorafenib and its metabolite–N-oxide as well as paracetamol and its glucuronide and sulphate metabolites were measured using validated high-performance liquid chromatography (HPLC) method with ultraviolet detection.

Results

The co-administration of sorafenib and paracetamol increased the maximum concentration (C_max) of paracetamol by 33% (p = 0.0372). In the I_S+ PA group the C_max of paracetamol glucuronide was reduced by 48% (p =  < 0.0001), whereas the C_max of paracetamol sulphate was higher by 153% (p = 0.0012) than in the III_PA group. Paracetamol increased sorafenib and sorafenib N-oxide C_max by 60% (p = 0.0068) and 83% (p = 0.0023), respectively.

Conclusions

A greater knowledge of DDI between sorafenib and paracetamol may help adjust dose properly and avoid toxicity effects in individual patients.

Influence of obesity on pharmacokinetics and analgesic effect of ketoprofen administered intravenously to patients after laparoscopic cholecystectomy

BACKGROUND

Ketoprofen is an analgesic drug commonly applied in the postoperative period, e.g., to patients after laparoscopic cholecystectomy. Many patients who undergo this procedure are obese. As pathophysiological changes are observed in obesity, the efficacy of ketoprofen may be altered in this group of patients. The aim of the study was to compare the pharmacokinetic parameters and analgesic effect of ketoprofen administered to obese and non-obese patients after laparoscopic cholecystectomy.

METHODS

The study was conducted on 41 patients after laparoscopic cholecystectomy, who were divided into two groups: obese (n = 21) and non-obese (n = 20). Ketoprofen was administered intravenously at a dose of 100 mg. Plasma ketoprofen concentrations were measured by means of validated high-performance liquid chromatography with ultraviolet detection. The pharmacokinetic parameters of the drug were calculated using the non-compartmental method. Additionally, pain intensity was assessed during the study using NRS scale.

RESULTS

The obese patients had significantly lower AUC_0-∞ (1.4-fold), AUMC_0-t (1.8-fold), AUMC_0-∞ (3.2-fold), MRT_0-t (1.4-fold), MRT_0-∞ (2.3-fold), t_0.5 (2.3-fold) and V_z/kg (2.3-fold) and higher k_el (2.2-fold) than the non-obese group. Moreover, 4 h and 6 h after the administration of the drug, pain intensity was significantly higher in the obese patients.

CONCLUSIONS

The drug was eliminated faster and the analgesic effect of ketoprofen in the obese patients was decreased as compared with the non-obese subjects. However, pain intensity did not increase to the level, which required additional analgesic treatment. Therefore, it seems that dosage adjustment of intravenous ketoprofen is not necessary in obese patients.

Influence of Obesity and Type 2 Diabetes Mellitus on the Pharmacokinetics of Tramadol After Single Oral Dose Administration

Background and Objectives

The number of overweight, obese and diabetic patients is constantly increasing. Metabolic disorders may affect the pharmacokinetics of drugs, e.g., by altering the activity of cytochrome P450 (CYP) isoenzymes. Tramadol is a commonly used analgesic metabolised mainly via CYP2D6 to its active metabolite, O-desmethyltramadol. The aim of the study was to assess the influence of overweight, obesity and type 2 diabetes mellitus on tramadol and O-desmethyltramadol pharmacokinetics.

Methods

All patients received a single oral dose (100 mg) of tramadol. The plasma concentrations of tramadol and O-desmethyltramadol were measured with the validated high-performance liquid chromatography method with fluorescence detection. The pharmacokinetic parameters of tramadol and O-desmethyltramadol were calculated by non-compartmental methods.

Results

After nephrectomy, the patients were divided into four groups—a control group (n = 12, mean [SD] age 61 [14] years, body mass index (BMI) 22 [2] kg/m², CL_cr (creatinine clearance) 74 [30] mL/min); an overweight group (n = 15, mean [SD] age 63 [11] years, BMI 27 [1] kg/m², CL_cr 81 [35] mL/min); an obese group (n = 12, mean [SD] age 57 [8] years, BMI 33 [4] kg/m², CL_cr 113 [51] mL/min); and an obese and diabetic group (n = 9, mean [SD] age 64 [10] years, BMI 33 [4] kg/m², CL_cr 87 [35] mL/min). Apart from the time to first occurrence of maximal concentration (t_max), there were no significant differences in the pharmacokinetic parameters of tramadol and O-desmethyltramadol among the groups. Moreover, there were no significant differences in the O-desmethyltramadol/tramadol ratios among the four groups of patients after nephrectomy.

Conclusions

No significant differences were found in the pharmacokinetics of tramadol and O-desmethyltramadol, indicating that the opioid can be administered to overweight, obese and diabetic patients without dosage adjustment.

Effect of Multidrug-Resistant 1 (MDR1) and CYP3A4*1B Polymorphisms on Cyclosporine-Based Immunosuppressive Therapy in Renal Transplant Patients

Background

Immunosuppressive drugs such as cyclosporine A (CsA) are characterized by a narrow therapeutic range and high interindividual pharmacokinetic variations. Therefore, the effective monitoring of drug serum level is crucial for successful therapy. This variability can be caused by polymorphisms in genes encoding drug transporters and enzymes responsible for biotransformation. The aim of this study was to determine the relationship between CYP3A4*1B and MDR1 polymorphisms and dose requirements to achieve the target therapeutic range for CsA.

Material/Method

The study group consisted of 184 patients after kidney transplantation who were treated with immunosuppressive therapy. The MDR1 3435C>T and CYP3A4*1B polymorphisms were determined by the real-time PCR using the LightCycler^® 480 device (Roche Diagnostics).

Results

Patients with the CYP3A4*1/*1 genotype received the lowest mean dose of CsA compared to CYP3A4*1/*1B, and had a higher average drug concentration in the blood. In the case of MDR1 3435C>T polymorphism, we observed that patients with the CC genotype received lower doses of CsA than patients with the CT and TT genotypes. Average drug concentration in the blood was comparable to individuals with different MDR-1 genotypes. Analysis of dependence between both polymorphisms and concentration/dose ratio showed no statistically significant differences.

Conclusions

The characterization of CYP3A4*1B and 3435C>T MDR1 polymorphism cannot provide useful guidance for individualizing CsA dosages in renal transplant patients by indicating the optimal dose of these drugs without exposing patients to possible adverse effects associated mainly with nephrotoxicity.

Prediction of primal cuts by using an automatic ultrasonic device as a new method for estimating a pig-carcass slaughter and commercial value

The objective of the present work was to develop regression equations to estimate the percentage, weight (in g) and lean meat content (in %) of the primal cuts of a pig carcass by using Auto-Fom and to estimate the commercial value of the carcass on the slaughter line in a meat-processing plant. The research was conducted on 168 pig carcasses. From the whole pork carcass, only the most valuable cuts (i.e. belly, ham, loin, neck and shoulder) and also meat content in ham and shoulder were weighed at a 100 g accuracy and the percentage of each cut in carcass was calculated. Loin ‘eye’ height and belly-muscle thickness were also measured. The regression equations for the prediction of the primal-cut weights and their percentages in the pig carcasses were derived using the partial least-square procedure. The developed equations include 70 variables that are standard measurements taken with an Auto-Fom device. These equations have a satisfactory accuracy rate and are useful in estimating the yield of the elements, especially for loin, ham and belly content. Belly-muscle thickness (R2 = 0.98) and the percentage of meat in the ham (R2 = 0.93) can be estimated with a high precision. It was confirmed that the developed equations may be used in the current Auto-Fom software.

The pharmacodynamics of dexmedetomidine in elderly cardiac patients undergoing analgosedation in the ICU

Aim. This study aimed to evaluate the pharmacodynamics of dexmedetomidine in elderly cardiac patients.Material and Methods. Twelve patients of 60 years or older and need for analgesia after surgery or as a result of critical health conditions were included into our study. Dexmedetomidine was administered intravenously as a continuous infusion without the initial dose. At the beginning the infusion was started at the rate of 0.7 µg/kg/h and then it was continued in the range of 0.17–1.39 µg/kg/h according to desired level of sedation. Information about heart rate, systolic, diastolic and mean arterial blood pressure, bispectral index and cardiac index were collected a few minutes before, during and in 12 hours after infusion of dexmedetomidine.Results. The hemodynamic data as well as BIS level were collected from 12 patients. The duration of dexmedetomidine infusion was less than 9 hours. For each patient the reduction in blood pressure and heart rate compared to the value before dexmedetomidine infusion was observed. We did not observe bradycardia in any patient. Appropriate sedation level was achieved using only dexmedetomidine and ranged from 60 to 80. In only 2 cases it was necessary to give a single dose of another sedative.Conclusions. To conclude, in the patients’ population involved in the study, which included older cardiac patients dexmedetomidne has been shown as a sedative agent which enabled to achieve desire level of sedation in the recommended ranges without episodes of bradycardia, however hypotension events were noted.

Evaluation of efficacy and mechanisms of action of Cannabis sativa extracts with analgesic, anti-inflammatory and antiemetic properties in an in vivo model

University of Medical Sciences participates in the realization of the project titled: „Development of the technology of producing cannabinoids from low THC hemp for use as preparations supporting treatment in oncological patients” awarded by the National Centre for Research and Development under project number: INNOMED/I/11/NCBR/2014. The duration of the grant is 36 months, and the total value of the grant is 28011845 PLN. The project is run by University of Life Sciences in Poznan. Laboratory of Experimental Pharmacogenetics at the Department of Clinical Pharmacy and Biopharmacy, Poznan University of Medical Sciences (PUMS) is realizing the task number 4 titled “Evaluation of efficacy and mechanisms of action of Cannabis sativa extracts with analgesic, anti-inflammatory and antiemetic properties in an in vivo model.” The aim of this project is the development of cannabinoid extract with reduced psychoactive component (THC), which due to its high content of cannabidiol (CBD) is meant to provide analgesic properties, and at the same time to reduce the risk of addiction and overdose. University of Medical Sciences is evaluating the analgesic, anti-inflammatory and antiemetic properties of the extract of Cannabis sativa in animal models coupled with neuropathic pain. Pharmacodynamic effects of plant extracts will be later assessed taking into account the level of selected genes and proteins expression.

A pharmacokinetic study on lapatinib in type 2 diabetic rats

BACKGROUND

Diabetes mellitus (DM) is a complex metabolic disorder which affects the function of numerous tissues and alters the pharmacokinetic parameters of many drugs. As many oncological patients are diabetics, it is important to determine the influence of this chronic disease on the pharmacokinetics (PK) of anticancer drugs. Lapatinib is a tyrosine kinase inhibitor (TKI), approved for the treatment of human epidermal growth factor receptor 2 (HER2)-positive metastatic breast cancer. The aim of the study was to compare the PK of lapatinib in normal and type 2 diabetes mellitus (T2DM) model rats. Additionally, the effect of lapatinib on blood glucose concentrations was examined.

METHODS

The PK of lapatinib was studied in healthy rats (n=6, the healthy group) and T2DM model rats (n=6, the diabetic group). The rats received lapatinib orally as a single dose of 50mg. Plasma concentrations of lapatinib were measured with high-performance liquid chromatography method coupled with a tandem mass spectrometry.

RESULTS

The plasma concentrations of lapatinib were increased in the T2DM model rats. There were statistically significant differences between the groups in C_max (p=0.0104) and AUC_0-t (p=0.0265). The reduction of glycaemia in the range of 1.2-41.5% and in the range of 4.1-36.8% was observed in the diabetic and healthy animals, respectively.

CONCLUSIONS

Higher concentrations of lapatinib in the diabetic rats may suggest the need for application of lower doses of this TKI in patients with DM.

The influence of a single and chronic administration of venlafaxine on tramadol pharmacokinetics in a rabbit model

BACKGROUND

The combined use of tramadol with selective serotonin and norepinephrine reuptake inhibitors e.g. venlafaxine may be associated with serotonin syndrome. No previous studies exist examining the influence of a weak CYP2D6 inhibitor venlafaxine on the pharmacokinetics of tramadol. Therefore, the aim of this study was to determine the effect of a single and chronic administration of venlafaxine on the pharmacokinetics of tramadol using a rabbit model.

METHODS

Adult New Zealand white rabbits of both sexes (n = 21) were used. Animals received 100 mg of tramadol per os (one slow release tablet) and 75 mg of venlafaxine (one prolonged release capsule), and were divided into four groups: control group - a single dose of tramadol alone, 1 day group - a single dose of tramadol and venlafaxine, 7 and 14 days groups - seven and fourteen days administration of venlafaxine once daily plus a single dose of tramadol on the last day of the study.

RESULTS

Venlafaxine administration over a period of 7 and 14 days resulted in faster elimination of tramadol compared to the control group: significantly higher values of k_el, and lower values of t_1/2kel and MRT for the 7 and 14 days group were observed. Although no differences in bioavailability of tramadol were obtained.

CONCLUSION

Using a rabbit model, there is no evidence that the combined administration of tramadol and venlafaxine may increase the plasma exposure of tramadol and therefore increase the risk of serotonin syndrome.

Pharmacokinetic drug-drug interaction between erlotinib and paracetamol: A potential risk for clinical practice

BACKGROUND

Erlotinib is a tyrosine kinase inhibitor available for the treatment of non-small cell lung cancer. Paracetamol is an analgesic agent, commonly used in cancer patients. Because these drugs are often co-administered, there is an increasing issue of interaction between them.

OBJECTIVE

The aim of the study was to investigate the effect of paracetamol on the pharmacokinetic parameters of erlotinib, as well as the influence of erlotinib on the pharmacokinetics of paracetamol.

METHODS

The rabbits were divided into three groups: the rabbits receiving erlotinib (I_ER), the group receiving paracetamol (II_PR), and the rabbits receiving erlotinib+paracetamol (III_ER+PR). A single dose of erlotinib was administered orally (25mg) and was administered intravenously (35mg/kg). Plasma concentrations of erlotinib, its metabolite (OSI420), paracetamol and its metabolites - glucuronide and sulphate were measured with the validated method.

RESULTS

During paracetamol co-administration we observed increased erlotinib maximum concentration (C_max) and area under the plasma concentration-time curve from time zero to infinity (AUC_0-∞) by 87.7% and 31.1%, respectively. In turn, erlotinib lead to decreased paracetamol AUC_0-∞ by 35.5% and C_max by 18.9%. The mean values of paracetamol glucuronide/paracetamol ratios for C_max were 32.2% higher, whereas paracetamol sulphate/paracetamol ratios for C_max and AUC_0-∞ were 37.1% and 57.1% lower in the II_PR group, when compared to the III_ER+PR group.

CONCLUSIONS

Paracetamol had significant effect on the enhanced plasma exposure of erlotinib. Additionally, erlotinib contributed to the lower concentrations of paracetamol. Decreased glucuronidation and increased sulphation of paracetamol after co-administration of erlotinib were also observed.

The pharmacokinetics of oral ketoprofen in patients after gastric resection

BACKGROUND

Total and partial gastric resection may affect the pharmacokinetics of drugs, especially orally administered a few days after surgery. Ketoprofen is a non-steroidal anti-inflammatory drug (NSAID) broadly used to treat postoperative pain, including patients after gastric resection. The aim of the research was to analyse the pharmacokinetics (PK) of orally administered ketoprofen in patients after gastrectomy.

METHODS

The research was carried out on two groups of patients after total (TG; Roux-Y procedure) and partial (PG; Billroth II procedure) gastrectomy. The patients in group TG (n=15; mean [SD] age 61.86 [14.15] years; and BMI 24.20 [3.73] kg/m²) and group PG (n=5; mean [SD] age 62.40 [16.80] years; and BMI 23.98 [3.45] kg/m²) received ketoprofen in a single oral dose of 100mg. The measurement of ketoprofen plasma concentrations was made by means of the HPLC (high performance liquid chromatography) method.

RESULTS

The PK parameters in group TG and PG were as follows: maximum plasma concentration (C_max), 3.42 [0.99] and 4.66 [0.81] mg/l (p=0.0220); area under the plasma concentration-time curve from zero to infinity (AUC_0-∞), 9.12 [2.78] and 9.17 [2.87] mg×h/ml (p=0.9734); area under the first moment curve from zero to the time of infinity (AUMC_0-∞), 25.95 [8.52] and 26.53 [11.43] mg×h²/l (p=0.9056); time to reach maximum concentration (t_max), 0.47 [0.25] and 0.55 [0.27] h (p=0.5327), respectively.

CONCLUSIONS

Lower concentrations of ketoprofen in patients after gastrectomy suggest that it might be necessary to apply higher dose of the analgesic.

Maturation, pharmacogenomics and metabolomics as factors determining pharmacokinetic and pharmacodynamics profile of alpha‑agonist in pediatric intensive care unit patients

Research Project Objectives. Project entitled “Maturation, pharmacogenomics, and metabolomics as factors determining pharmacokinetic and pharmacodynamic profile of alpha‑agonist in pediatric intensive care unit patients” was founded by the Polish National Science Center (NCN) under project number: 2015/17/B/NZ7/03032. The duration of the grant is 36 months, and the total grant value is 688800 PLN. The project is run by the Medical University of Gdansk and Poznan University of Medical Sciences. The aim of this grant is to examine the influence of maturation, pharmacogenetics, metabolomics and physiological (or pathophysiological) status of the patients on the pharmacokinetics and pharmacodynamics (PK/PD) of α2-adrenergic drugs (dexmedetomidine and clonidine) in pediatric population. The project was proposed to explain the unusual PK of dexmedetomidine reported in literature and in our preliminary experiments, in which a two‑fold increase in dexmedetomidine clearance was observed during prolonged (lasting more than 24 hr) infusions in the intensive care unit patients. General information. Project entitled “Maturation, pharmacogenomics, and metabolomics as factors determining pharmacokinetic and pharmacodynamics profile of alpha‑agonist in pediatric intensive care unit patients” was founded by the Polish National Science Center (NCN) under project number: 2015/17/B/NZ7/03032. The duration of the grant is 36 months, from 2016-04-27 to 2019-04-26 and the total grant value is 688800 PLN. The project is run by the Medical University of Gdansk and Poznan University of Medical Sciences. The research group consists of: principal investigator dr hab. Paweł Wiczling and co‑investigators: dr hab. Agnieszka Bienert, dr Alicja Bartkowska‑Śniatkowska, dr Joanna Bartkowiak‑Wieczorek, mgr Justyna Mocarska, prof. Edmund Grześkowiak, dr Jan Matysiak, mgr Agnieszka Klupczyńska, dr Danuta Siluk, mgr Agnieszka Borsuk and prof. dr hab. Zenon J. Kokot. The Ethical Committee permission number is 261/15.

The alteration of pharmacokinetics of erlotinib and OSI420 in type 1 diabetic rabbits

BACKGROUND

Alterations in blood glucose levels observed in diabetes, may change the pharmacokinetics of co-administered drugs and in consequence, the efficacy and safety of therapy. Many oncological patients are diabetics and it is important to determine the interaction of anticancer drugs with this chronic disease. Erlotinib is a tyrosine kinase inhibitor (TKI), approved for the treatment of patients with non-small-cell lung cancer and pancreatic cancer in combination with gemcitabine. The aim of the study was to investigate the influence of the diabetes on the pharmacokinetics of erlotinib in rabbits. Additionally, the effect of erlotinib on glucose levels was examined.

METHODS

The pharmacokinetics of erlotinib was studied in healthy rabbits (n=6, control group) and type 1 diabetic rabbits (n=6, diabetic group). Erlotinib was administered in a single oral dose of 25mg. Plasma concentrations of erlotinib and its metabolite (OSI420) were measured with the validated method.

RESULTS

The plasma concentrations of erlotinib and OSI420 were markedly increased in diabetic rabbits. Statistically significant differences between the groups were revealed for almost all analysed pharmacokinetic parameters for erlotinib and OSI420. The maximum glycaemia drop of 7.7-33.5% was observed in the diabetic animals, but no significant changes in glucose concentration were observed in the control group.

CONCLUSIONS

The research proved the significant influence of diabetes on the pharmacokinetics of erlotinib and OSI420. Due to higher exposure to erlotinib, there may be an increased risk of adverse drug reactions in diabetic patients. Therefore, in some cases lower doses of the drug should be considered.

The pharmacokinetics of dexmedetomidine during long-term infusion in critically ill pediatric patients. A Bayesian approach with informative priors

The purpose of this study was to assess the pharmacokinetics of dexmedetomidine in the ICU settings during the prolonged infusion and to compare it with the existing literature data using the Bayesian population modeling with literature-based informative priors. Thirty-eight patients were included in the analysis with concentration measurements obtained at two occasions: first from 0 to 24 h after infusion initiation and second from 0 to 8 h after infusion end. Data analysis was conducted using WinBUGS software. The prior information on dexmedetomidine pharmacokinetics was elicited from the literature study pooling results from a relatively large group of 95 children. A two compartment PK model, with allometrically scaled parameters, maturation of clearance and t-student residual distribution on a log-scale was used to describe the data. The incorporation of time-dependent (different between two occasions) PK parameters improved the model. It was observed that volume of distribution is 1.5-fold higher during the second occasion. There was also an evidence of increased (1.3-fold) clearance for the second occasion with posterior probability equal to 62 %. This work demonstrated the usefulness of Bayesian modeling with informative priors in analyzing pharmacokinetic data and comparing it with existing literature knowledge.

Pharmacokinetics of paracetamol in patients with chronic pancreatitis

BACKGROUND

Chronic pancreatitis (CP) is a progressive, irreversible disease causing damage of the gland. Abdominal pains are a typical symptom of pancreatitis both in the chronic and acute form. Paracetamol is one of analgesics used for treating mild or moderate pain. Functional and anatomical changes in the gastrointestinal tract caused by pancreatitis may influence on the pharmacokinetics of administered drugs.

METHODS

In the present study we analysed the pharmacokinetics of paracetamol after oral and intravenous administration to patients with CP. The patients were allocated to one of the two groups of the drug under study: I iv, intravenous administration of paracetamol 1000mg (n=17; mean [SD] age, 46.18 [13.78] years; and BMI, 22.03 [2.62]kg/m(2)) and II po, oral administration of paracetamol 1000mg (n=17; mean [SD] age, 48.29 [10.08] years; and BMI, 22.50 [2.92]kg/m(2). The plasma concentrations of paracetamol and its metabolite (glucuronide) were measured with the validated high-pressure liquid chromatography (HPLC) method with ultraviolet (UV) detection.

RESULTS

The main pharmacokinetic parameters for paracetamol after iv and po administration to patients with CP were as follows: Cmax, 19.00 [4.50] and Cmax, 9.26 [3.35]μg/ml; AUC0-t, 42.37 [13.92] and 36.68 [11.7]μg×h/mL, respectively. After iv and po administration the AUC ratio between the metabolite (glucuronide) and paracetamol was enhanced.

CONCLUSIONS

The research findings revealed that patients with chronic pancreatitis had lower concentrations of paracetamol. Therefore, it may be necessary to apply additional analgesic therapy. Moreover, we observed enhanced glucuronidation in our patients.

The influence of the time-of-day administration of sunitinib on the penetration through the blood-brain and blood-aqueous humour barriers in rabbits

OBJECTIVE

Sunitinib is a multiple tyrosine kinase inhibitor (TKI) that exerts anti-tumor and antiangiogenic activity. It is used for the treatment of metastatic gastrointestinal stromal tumours, renal cell carcinoma and pancreatic neuroendocrine tumours. A few studies confirm the anti-tumour activity of sunitinib in brain tumours and uveal melanoma, as well as its efficacy in the reduction of brain metastases of some primary cancers. Therefore, the penetration of sunitinib through the blood-brain barrier (BBB) and blood-aqueous humour barrier (BAB) is an issue of growing interest. The aim of the study was to investigate the influence of the time-of-day administration on the penetration of sunitinib into the cerebrospinal fluid (CSF) and aqueous humour (AH).

MATERIALS AND METHODS

The rabbits were divided into two groups: I (control group)--receiving sunitinib at 8 a.m., and II--receiving sunitinib at 8 p.m. Sunitinib was administered p.o. at a single dose of 25 mg. The concentrations of sunitinib and its active metabolite (SU12662) in the plasma, CSF, AH were measured with the validated HPLC-UV method.

RESULTS

The plasma AUC0-t for sunitinib in group I was 2051.8 ng × h/mL, whereas in group II it was 3069.3 ng × h/mL. The aqueous humour AUC0-t for sunitinib in thr groups were 43.2 and 76.3 ng × h/mL, respectively. The cerebrospinal AUC0-t for sunitinib in groups I and II were 55.5 and 66.3 ng × h/mL, respectively.

CONCLUSIONS

After the evening administration (8 p.m.) the exposure to sunitinib in the rabbits' plasma, AH and CSF was higher than after the morning administration (8 a.m.), but the degree of sunitinib penetration through the BAB and BBB was very low (< 5%) and comparable in both groups.

Effects of Low-Dose Escherichia coli Lipopolysaccharide-Induced Endotoxemia on Morphine Pharmacokinetics in an Animal Model

OBJECTIVE

Systemic inflammation may change the bioavailability and pharmacokinetics of opioids. However, there are insufficient data on morphine pharmacokinetics in mild inflammatory conditions. This study aimed to determine the pharmacokinetics of morphine during low-dose endotoxemia in rabbits.

DESIGN

In two experiments (separated by a 14-day washout period), 10 rabbits received intravenous morphine at a dose of 3 mg/kg. In the second set of experiments, morphine infusion was preceded by low-dose endotoxemia induced with lipopolysaccharide (Escherichia coli 0111: B4) at a dose of 5 µg/kg. The kinetics of systemic morphine concentrations and chosen physiological parameters were measured at specific time intervals up to 6 hours after morphine administration.

RESULTS

In endotoxemia, decreased elimination half-life (P = 0.017), mean residence time (P = 0.022), and volume of distribution (P = 0.037) as well as an increased elimination rate constant (P = 0.013) and total body clearance (P = 0.023) were noted. The inverse linear correlation between morphine clearance versus the percentage (%) change in body temperature and pulse rate observed under control conditions was abolished under endotoxemia.

CONCLUSIONS

Low-dose endotoxemia is correlated with significant alterations in morphine pharmacokinetics in rabbits, leading to the faster elimination of the drug.

CLINICAL IMPLICATIONS

These findings may have important implications in patients with low-grade inflammation and imply the need to modify morphine dosing regimens to ensure optimal analgesia. The issue warrants further experimental and clinical investigation.

Pharmacokinetics of sufentanil during long-term infusion in critically ill pediatric patients

The aim of this study was to develop a population pharmacokinetic model of sufentanil and to assess the influence of covariates in critically ill children admitted to a pediatric intensive care unit. After institutional approval, 41 children were enrolled in the study. Blood samples for pharmacokinetic (PK) assessment were collected from routinely placed arterial catheters during and after discontinuation of infusion. Population nonlinear mixed-effects modeling was performed using NONMEM. A 2-compartment model described sufentanil PK sufficiently. Typical values of the central and peripheral volume of distribution and the metabolic and intercompartmental clearance for a theoretical patient weighing 70 kg were VC = 7.90 l, VT  = 481 L, Cl =  5.3 L/h, and Q = 38.3 L/h, respectively. High interindividual variability of all PK parameters was noted. Allometric/isometric principles to scale sufentanil PK revealed that to achieve the same steady-state sufentanil concentrations in plasma for pediatric patients of different body weights, the infusion rate should follow the formula (infusion rate for a 70-kg adult patient, μg/h) × (body weight/70 kg)(0.75). Severity of illness described by PRISM score, the monitored physiological and laboratory parameters, and coadministered drugs such as vasopressors were not found to be significant covariates.

The importance of rs1021737 and rs482843 polymorphisms of cystathionine gamma-lyase in the etiology of preeclampsia in the Caucasian population

INTRODUCTION

Recently an increasing number of reports indicate the participation of genetic factors in the pathogenesis of preeclampsia (PE). The genes involved in the synthesis of nitric oxide that participates in the vasolidation, may play an important role in the development of this disorder. Hydrogen sulfide (H2S) which is produced by cystathionine gamma-lyase exhibits a similar effect to nitric oxide. It is suggested that certain polymorphisms of the CTH gene may participate in the development of chronic hypertension and preeclampsia.

AIM OF THE STUDY

To evaluate the frequency of genotypes and alleles of rs1021737 and rs482843 polymorphisms of CTH gene in women with preeclampsia from Wielkopolska region.

MATERIAL AND METHODS

The study group consisted of 60 patients with diagnosed preeclampsia, into the control group 120 healthy pregnant women were enrolled. The examined rs1021737 and rs482843 polymorphisms of CTH gene were determined using PCR-RFLP method.

RESULTS

Analysis of rs482843 polymorphism in the CTH gene showed a statistically significant difference in the prevalence of mutated GG genotype (p<0.000001) and mutated G allele (p<0.000001) in the group of pregnant women with PE compared to the control group. There was no such correlation for the rs1021737 polymorphism. Furthermore, there are also no relationship between studied polymorphisms and selected clinical and biochemical parameters.

CONCLUSIONS

The results of rs482843 polymorphism analysis suggest that mutated GG genotype predisposes to preeclampsia occurrence. There was no such relationship for the rs1021737 polymorphism of CTH gene. Hence, further studies based on the determination of CSE expression level in women with PE may confirm the observed relationship between the rs482843 polymorphism and the risk of preeclampsia.

Pharmacokinetics and pharmacodynamics of propofol in cancer patients undergoing major lung surgery

Despite the growing number of cancer cases and cancer surgeries around the world, the pharmacokinetics (PK) and pharmacodynamics (PD) of anesthetics used in this population are poorly understood. Patients operated due to cancer are usually in severe state and often require chemotherapy. It might affect the PK/PD of drugs used in this population. Therefore, in this study we explored the PK/PD of propofol in cancer patients having a major lung surgery. 23 patients that underwent a propofol-fentanyl total intravenous anesthesia were included in the analysis. A large set of demographic, biochemical and hemodynamic parameters was collected for the purpose of covariate analysis. Nonlinear mixed effect modeling in NONMEM was used to analyze the collected data. A three-compartment model was sufficient to describe PK of propofol. The anesthetic effect (AAI index) was linked to the propofol effect site concentrations through a sigmoidal E max model. A slightly higher value of clearance, a lower value of distribution clearance, and a decreased volume of peripheral compartment were observed in our patients, as compared with the literature values reported for healthy volunteers by Schnider et al. and by Eleveld et al. Despite these differences, both models led to a clinically insignificant bias of -8 and -1 % in concentration predictions, as reflected by the median performance error. The C e50 and propofol biophase concentration at the time of postoperative orientation were low and equaled 1.40 and 1.13 mg/L. The population PK/PD model was proposed for cancer patients undergoing a major lung surgery. The large body of studied covariates did not affect PK/PD of propofol significantly. The modification of propofol dosage in the group of patients under study is not necessary when TCI-guided administration of propofol by means of the Schnider model is used.

The pharmacokinetic interaction between levofloxacin and sunitinib

BACKGROUND

The aim of this study was to evaluate the impact of sunitinib on pharmacokinetics of levofloxacin. The previous study proved that levofloxacin co-administered with sunitib changes the following pharmacokinetic parameters i.e. Cmax and AUC for both sunitinib and SU012662 (sunitinib metabolite). We will also investigate if the limited sample strategy can be applied for levofloxacin.

METHODS

Rabbits were divided into two groups. In both groups there were six animals. In the control group levofloxacin was administered and in investigated group levofloxacin and sunitinib were co-administered. The dose of levofloxacin was 20mg/kg and the dose of sunitinib was 25mg. The concentration in plasma was determined by HPLC-FLD. The pharmacokinetic parameters were evaluated by WinNonLin software. The results were evaluated by the following statistical tests: Shapiro-Wilk, t-Student and Mann-Whitney test.

RESULTS

Pharmacokinetics of levofloxacin obeys the two-compartment model. Sunitinib influences the following pharmacokinetic parameters of levofloxacin: half-life, elimination constant and volume of distribution. Statistical analysis proved that there is a correlation between AUC and the following five time-points: 0.25 h, 4h, 6h, 10h and 12h.

CONCLUSIONS

The study proved that there is a potential pharmacokinetic interaction between sunitinib and levofloxacin. The statistical analysis proved that the limited sample strategy can be applied for levofloxacin.

The pharmacokinetics of oral oxycodone in patients after total gastric resection

OBJECTIVE

Oxycodone is a semi-synthetic opioid with a stronger analgesic effect than morphine and codeine. The efficacy of this opioid in the treatment of postoperative pain has been proved in different groups of patients. The drug has a favourable adverse reaction profile, which encourages doctors and patients to use it more and more widely. The drug is also used in the patients who underwent an abdominal surgery, e.g. stomach resection. Gastrectomy leads to pathophysiological changes within the gastrointestinal tract, which may cause changes in the drug absorption. In consequence this leads to a change in the pharmacokinetics and effect of the drug. The aim of the research was an analysis of the pharmacokinetics of oxycodone from prolonged release tablet in patients after total gastrectomy.

PATIENTS AND METHODS

The research was carried out on patients after gastrectomy with Roux-en-Y reconstruction. The patients (n=24; mean [SD] age, 67.6 [9.8] years; weight, 69.1 [13.6] kg; and BMI, 25.2 [4.0] kg/m(2)) received oxycodone in a prolonged release tablet in a single orally administered dose of 10 mg. Blood samples were collected within 12 h after the drug administration. The plasma concentrations of oxycodone and noroxycodone were measured with validated high-pressure liquid chromatography coupled with triple tandem mass spectrometery method.

RESULTS

The main pharmacokinetic parameters for oxycodone in men (n = 14) and women (n = 10) were as follows: Cmax, 14.40 (3.76) and 11.54 (6.98) ng/ml (p = 0.2066); AUC0-∞, 157.87 (56.89) and 106.44 (61.31) ng´h/ml (p = 0.0460); tmax, 2.18 (0.58) and 2.15 (0.58) h (p = 0.8008), respectively.

CONCLUSIONS

Total gastrectomy did not affect the pharmacokinetics of oxycodone administered in prolonged release tablets, but the exposure to the drug was significantly lower in women.

Biopharmaceutical evaluation of new slow release tablets obtained by hot tableting of coated pellets with tramadol hydrochloride

This study was aimed at a biopharmaceutical evaluation of a new oral dosage form of tramadol hydrochloride (TH)--slow release tablets obtained by hot tableting of coated pellets, 100 mg (TP), compared to the conventional slow release tablets, Tramal Retard, 100 mg (TR). Both TP and TR formulations showed a similar release profile of TH (f2 was 71) in in vitro release studies. The in vivo study was a two-treatment, two-period, two-sequence, single-oral dose 100 mg, crossover design using rabbit model with the phases separated by a washout period of 14 days. It was shown that the amount of TH absorbed into the systemic circulation is similar for TP and TR (the 90% confidence intervals for the AUC(0-1), AUC(0-infinity) and ratios were 85-122 and 92-107%, respectively). However, after administration of slow release tablets obtained by hot tableting of coated pellets, a prolonged absorption and elimination processes and a smoother and more extended plasma profile of TH were observed. It can be assumed that the use of a new oral dosage form of TH in patients affects the extension of analgesia after single administration of the drug, with its gradual absorption into the systemic circulation.

The problems of urinary tract infections with Candida spp. aetiology in women

Urinary tract infections (UTIs) in women are a growing clinical concern. The most frequent risk factors of UTIs with fungal aetiology in women are: antibiotic therapy (especially broad-spectrum antibiotics), immunosuppressive therapy, diabetes, malnutrition, pregnancy, and frequent intercourse. The aim of the study was to analyse urinary tract infections with Candida spp. aetiology in women hospitalised at the Clinical Hospital in Poznań, Poland, between 2009 and 2011. The investigations revealed that as many as 71% of positive urine cultures with Candida fungi came from women. The following fungi were most frequently isolated from the patients under analysis: C. albicans (47%), C. glabrata (31%), C. tropicalis (6%), C. krusei (3%). In order to diagnose a UTI the diagnosis cannot be based on a single result of a urine culture. Due to the small number of antifungal drugs and high costs of treatment, antifungal drugs should be applied with due consideration and care.

The influence of the time-of-day administration of the drug on the pharmacokinetics of sunitinib in rabbits

OBJECTIVES

At present it is known that the adjustment of the anticancer therapy to the circadian rhythms in tissues reduces the toxicity of the treatment. Chronotherapy also increases the efficacy of the anticancer treatment, which has been proved for many drugs. Sunitinib is a tyrosine kinase inhibitor, which is broadly used for the treatment of numerous cancers. The aim of the study was a comparison of the concentrations and pharmacokinetics of sunitinib after a single administration to rabbits at 08:00 (control group) and 20:00. Additionally, the effect of sunitinib on glucose levels was investigated.

MATERIALS AND METHODS

The research was carried out on two groups of rabbits: I08:00, a group with the drug administered at 08:00 (n=8) and II20:00, a group with the drug administered at 20:00 (n=8). The rabbits were treated with sunitinib at an oral dose of 25 mg. Plasma concentrations of sunitinib and its metabolite (SU12662) were measured with a validated HPLC method with UV detection.

RESULTS

The comparison of the sunitinib Cmax and AUC0-t in the group with sunitinib administered at 20:00 with the control group gave the ratios of 2.20 (90% confidence interval (CI) (2.17; 2.22) and 1.64 (1.61; 1.68), respectively. Statistically significant differences between the groups under analysis were revealed for Cmax (p < 0.0001), AUC0-t (p = 0.0079), AUC0-∞ (p = 0.0149), and tmax (p = 0.0085). The mean glycemia drop was higher in group I08:00. than in group II20:00 (22.7% vs. 14.3%; p = 0.0622). The glycemia values returned to the initial values in 24 h after the administration of the drug in both groups.

CONCLUSIONS

The research proved a significant influence of the time-of-day administration on the pharmacokinetics of sunitinib.

The influence of age and dosage on the pharmacodynamics of dexmedetomidine in rabbits

Aim. This study aimed to examine the influence of maturation and dosage on the sedative and haemodynamic response observed in rabbits after the administration of dexmedetomidine. Material and methods. The pharmacodynamics of dexmedetomidine was studied on 14 healthy New Zealand white rabbits at three periods of maturation; stage 1–1.5 months old, stage 2–2.5 months old and stage 3–6.5 months old ones. The administered dose of dexmedetomidine ranged from 25 µg/kg to 300 µg/kg of body weight. The pedal withdrawal reflex was used to measure the duration of anaesthesia. The heart rate and mean arterial pressure were measured at the third stage of the study to evaluate the haemodynamic response. A simple pharmacodynamic relationship between the dose and the duration of anesthesia was used to describe the data.Results. We observed that young rabbits were less sensitive to dexmedetomidine than adult animals, as was reflected by the pedal withdrawal reflex, and we found that the haemodynamic response to dexmedetomidine depended on dosage of the drug. Dexmedetomidine decreased the mean blood pressure in a dosage-dependent manner with the highest decrease observed for the lowest dose. As the dose increased, the hypotensive effect of the drug was less noticeable. After the administration of dexmedetomidine the heart rate decreased to the same value regardless of the dose applied.