Clinical Pharmacokinetics of Atypical Antipsychotics: An Update The pharmacokinetics of CRP was tested in small short-term studies in both healthy volunteers and in subjects with schizophrenia, with similar results [242].

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Calculation of the Coefficient of Variation of Log-Normally Distributed Parameter Values

Reply to Periclou et al.: “Clinical Pharmacokinetics of Atypical Antipsychotics: An Update”

Clinical Pharmacokinetics and Pharmacodynamics of Rifampicin in Human Tuberculosis Abstract The introduction of rifampicin (rifampin) into tuberculosis (TB) treatment five decades ago was critical for shortening the treatment duration for patients with pulmonary TB to 6 months when combined with pyrazinamide in the first 2 months. Resistance or hypersensitivity to rifampicin effectively condemns a patient to prolonged, less effective, more toxic, and expensive regimens. Because of cost and fears of toxicity, rifampicin was introduced at an oral daily dose of 600 mg (8–12 mg/kg body weight). At this dose, clinical trials in 1970s found cure rates of ≥ 95% and relapse rates of < 5%. However, recent papers report lower cure rates that might be the consequence of increased emergence of resistance. Several lines of evidence suggest that higher rifampicin doses, if tolerated and safe, could shorten treatment duration even further. We conducted a narrative review of rifampicin pharmacokinetics and pharmacodynamics in adults across a range of doses and highlight variables that influence its pharmacokinetics/pharmacodynamics. Rifampicin exposure has considerable inter- and intra-individual variability that could be reduced by administration during fasting. Several factors including malnutrition, HIV infection, diabetes mellitus, dose size, pharmacogenetic polymorphisms, hepatic cirrhosis, and substandard medicinal products alter rifampicin exposure and/or efficacy. Renal impairment has no influence on rifampicin pharmacokinetics when dosed at 600 mg. Rifampicin maximum (peak) concentration (Cmax) > 8.2 μg/mL is an independent predictor of sterilizing activity and therapeutic drug monitoring at 2, 4, and 6 h post-dose may aid in optimizing dosing to achieve the recommended rifampicin concentration of ≥ 8 µg/mL. A higher rifampicin Cmax is required for severe forms TB such as TB meningitis, with Cmax ≥ 22 μg/mL and area under the concentration–time curve (AUC) from time zero to 6 h (AUC6) ≥ 70 μg·h/mL associated with reduced mortality. More studies are needed to confirm whether doses achieving exposures higher than the current standard dosage could translate into faster sputum conversion, higher cure rates, lower relapse rates, and less mortality. It is encouraging that daily rifampicin doses up to 35 mg/kg were found to be safe and well-tolerated over a period of 12 weeks. High-dose rifampicin should thus be considered in future studies when constructing potentially shorter regimens. The studies should be adequately powered to determine treatment outcomes and should include surrogate markers of efficacy such as Cmax/MIC (minimum inhibitory concentration) and AUC/MIC.

Population Pharmacokinetic and Pharmacodynamic Analysis of GLPG1690, an Autotaxin Inhibitor, in Healthy Volunteers and Patients with Idiopathic Pulmonary Fibrosis Abstract Background and Objectives GLPG1690 is an autotaxin inhibitor in development for the treatment of idiopathic pulmonary fibrosis. Several publications suggested a role of autotaxin in the control of disease-affected lung function and of lysophosphatidic acid in lung remodeling processes. The aim of the current article was to describe the exposure–response relationship of GLPG1690 and further develop a rational basis to support dose selection for clinical trials in patients with idiopathic pulmonary fibrosis. Methods Two trials were conducted in healthy volunteers: in the first trial, GLPG1690 was administered as single doses from 20 mg up to 1500 mg, and subsequently in multiple daily doses of 300–1000 mg. In a second trial, the interaction of rifampin with 600 mg of GLPG1690 was evaluated. A third trial was conducted in patients with idiopathic pulmonary fibrosis administered 600 mg of GLPG1690 once daily for 12 weeks. The exposure–response (lysophosphatidic acid C18:2 reduction) relationship of GLPG1690 was first described using non-linear mixed-effects modeling and the model was subsequently deployed to simulate a lysophosphatidic acid C18:2 reduction as a biomarker of autotaxin inhibition in the dose range from 50 to 1000 mg once or twice daily. Results The population pharmacokinetics and lysophosphatidic acid C18:2 response of GLPG1690 were adequately described by a combined population pharmacokinetic and pharmacokinetic/pharmacodynamic model. Dose, formulation, rifampin co-administration, health status (healthy volunteer vs. patient with idiopathic pulmonary fibrosis), and baseline lysophosphatidic acid C18:2 were identified as covariates in the model. The effect of dose on systemic clearance indicated that GLPG1690 followed a more than dose-proportional increase in exposure over the simulated dose range of 50–1000 mg once daily. Model-based simulations showed reductions in lysophosphatidic acid C18:2 of at least 80% with doses greater or equal to 200 mg once daily. Conclusion Based on these results, 200 and 600 mg once-daily doses were selected for future clinical trials in patients with idiopathic pulmonary fibrosis.

Clinical Pharmacokinetics and Pharmacodynamics of Eravacycline Abstract On 27 August, 2018, the US Food and Drug Administration approved eravacycline, a fluorocycline antimicrobial agent within the tetracycline class of antibacterial drugs, for the treatment of complicated intra-abdominal infections in patients aged 18 years and older. This decision was based on substantial clinical and pre-clinical data, including rigorous pharmacokinetic and pharmacodynamic work. This paper examines the in-vivo pharmacokinetic/pharmacodynamic work that led to the approval of eravacycline and explores how this important new antibiotic may be used to treat aggressive multidrug-resistant infections in the years ahead.

Microdosed Cocktail of Three Oral Factor Xa Inhibitors to Evaluate Drug–Drug Interactions with Potential Perpetrator Drugs Abstract Objectives The aim of this study was to prove the suitability of simultaneously administered microdoses of the factor Xa inhibitors (FXaIs) rivaroxaban, apixaban and edoxaban (100 µg in total). To evaluate drug–drug interactions, the impact of ketoconazole, a known strong inhibitor of cytochrome P450 3A4 and P-glycoprotein, was studied. Methods In a crossover clinical trial, 18 healthy volunteers were randomized to the two treatments using microdoses of rivaroxaban, apixaban and edoxaban alone and when coadministered with ketoconazole. Plasma and urine concentrations of microdosed apixaban, edoxaban and rivaroxaban were quantified using a validated ultra-performance liquid chromatography–tandem mass spectrometry assay with a lower limit of quantification of 2.5 pg/ml. Results The microdosed FXaI cocktail showed similar pharmacokinetic parameters compared with published data, using normal therapeutic doses of each FXaI. Ketoconazole significantly increased exposure, with geometric mean AUC ratios of 1.90 (apixaban), 2.35 (edoxaban) and 2.27 (rivaroxaban). Conclusion The microdosed FXaI cocktail approach was able to precisely predict the drug interaction with ketoconazole. This is the first study that has been conducted to evaluate drug–drug interactions with a drug class, and the low administered doses also allow evaluation in vulnerable target populations. Study Protocol EudraCT 2016-003024-23.

Effect of Oral Semaglutide on the Pharmacokinetics of Lisinopril, Warfarin, Digoxin, and Metformin in Healthy Subjects Abstract Background Oral semaglutide is a tablet co-formulation of the human glucagon-like peptide-1 (GLP-1) analog semaglutide with the absorption enhancer sodium N-(8-[2-hydroxybenzoyl] amino) caprylate (SNAC). The absorption of coadministered oral drugs may be altered due to enhancement by SNAC, potential gastric emptying delay by semaglutide, or other mechanisms. Two one-sequence crossover trials investigated the effect of oral semaglutide on the pharmacokinetics of lisinopril, warfarin, digoxin, and metformin. Methods In trial 1, 52 healthy subjects received lisinopril (20 mg single dose) or warfarin (25 mg single dose) with subsequent coadministration with SNAC alone (300 mg single dose), followed by oral semaglutide 20 mg once daily (steady state). In trial 2, 32 healthy subjects received digoxin (500 μg single dose) or metformin (850 mg twice daily for 4 days), with subsequent coadministration with SNAC alone followed by oral semaglutide, as in trial 1. Results There were no apparent effects of oral semaglutide on area under the plasma concentration–time curve (AUC) and maximum plasma concentration (Cmax) for lisinopril, warfarin, and digoxin. The AUC of metformin was increased by 32% (90% confidence interval 1.23–1.43) by oral semaglutide coadministration versus metformin alone, whereas the Cmax was unaffected. SNAC alone did not affect exposure of lisinopril, warfarin, digoxin, or metformin. Adverse events were in line with those previously observed for GLP-1 receptor agonists. Conclusions Oral semaglutide or SNAC alone did not appear to affect the exposure of lisinopril, warfarin, or digoxin, and, based on its wide therapeutic index, the higher metformin exposure with oral semaglutide was not considered clinically relevant.

Clinical Pharmacokinetics and Pharmacodynamics of Nintedanib Abstract Nintedanib is an oral, small-molecule tyrosine kinase inhibitor approved for the treatment of idiopathic pulmonary fibrosis and patients with advanced non-small cell cancer of adenocarcinoma tumour histology. Nintedanib competitively binds to the kinase domains of vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF) and fibroblast growth factor (FGF). Studies in healthy volunteers and in patients with advanced cancer have shown that nintedanib has time-independent pharmacokinetic characteristics. Maximum plasma concentrations of nintedanib are reached approximately 2–4 h after oral administration and thereafter decline at least bi-exponentially. Over the investigated dose range of 50–450 mg once daily and 150–300 mg twice daily, nintedanib exposure increases are dose proportional. Nintedanib is metabolised via hydrolytic ester cleavage, resulting in the formation of the free acid moiety that is subsequently glucuronidated and excreted in the faeces. Less than 1% of drug-related radioactivity is eliminated in urine. The terminal elimination half-life of nintedanib is about 10–15 h. Accumulation after repeated twice-daily dosing is negligible. Sex and renal function have no influence on nintedanib pharmacokinetics, while effects of ethnicity, low body weight, older age and smoking are within the inter-patient variability range of nintedanib exposure and no dose adjustments are required. Administration of nintedanib in patients with moderate or severe hepatic impairment is not recommended, and patients with mild hepatic impairment should be monitored closely and the dose adjusted accordingly. Nintedanib has a low potential for drug–drug interactions, especially with drugs metabolised by cytochrome P450 enzymes. Concomitant treatment with potent inhibitors or inducers of the P-glycoprotein transporter can affect the pharmacokinetics of nintedanib. At an investigated dose of 200 mg twice daily, nintedanib does not have proarrhythmic potential.