ICH M9 Guideline in Development on Biopharmaceutics Classification System-Based Biowaivers: An Industrial Perspective from the IQ Consortium.

In October 2016, the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH) ICH began efforts to provide recommendations to harmonize guidances for biopharmaceutics classification system (BCS)-based biowaivers. Topics to be addressed included consideration of the dose used to classify solubility, tests, and criteria for establishing highly permeable, dissolution conditions, the influence of excipients, and aspects of product strength. The International Consortium for Innovation and Quality in Pharmaceutical Development (IQ) is a technically focused organization of pharmaceutical and biotechnology companies with a mission of advancing science and technology to augment the capability of member companies to develop transformational solutions that benefit patients, regulators, and the broader R&D community. Its members have substantial expertise in all scientific domains associated with BCS-based waivers and drug product quality, as well as considerable experience in the application of BCS-based biowaivers. The ICH process recognizes that harmonization is achieved through the development of guidelines via a process of scientific consensus with regulatory and industry experts working side-by-side. Thus, to facilitate these efforts and to encourage open and transparent discussion of other perspectives that may exist, IQ offers their perspective on these and related topics.

Exposure-response characterisation of tildrakizumab in chronic plaque psoriasis: Pooled analysis of 3 randomised controlled trials.

AIMS: In this exposure-response analysis, the dosing regimen for tildrakizumab, an antibody for treating moderate-to-severe chronic plaque psoriasis, was determined using data from 3 randomised controlled trials (P05495/NCT01225731: phase 2b, n = 355; reSURFACE 1/NCT01722331: phase 3, n = 772; reSURFACE 2/NCT01729754: phase 3, n = 1090). METHODS: A maximum drug effect (Emax ) logistic-regression exposure-efficacy model was used to describe the week 12 Psoriasis Area and Severity Index (PASI) responses with average concentration of tildrakizumab during weeks 1-12 (Cavg12 ) as exposure metric. The impact of covariates (e.g., body weight, region) was tested. Exposure-safety, longitudinal pharmacokinetic-pharmacodynamic and risk-benefit analyses were also conducted. RESULTS: At week 12, Emax was estimated at 62.2, 37.9 and 14.6% of responders for PASI75/90/100, respectively. Exposure-response curves plateaued at exposures >5 µg mL-1 . Heavier subjects had a lower response rate to placebo as measured by PASI75/90/100 than lighter subjects. PASI100 placebo response was less in subjects with higher baseline PASI score and older age. Simulated week 12 PASI75 increased by ≤4% on increasing the dose from 100 to 200 mg every 12 weeks (Q12W). The pharmacokinetic-pharmacodynamic model adequately described the time course of PASI change after treatment in the entire population and in each subject. Risk-benefit profiles were favourable for the 100- and 200-mg doses in different weight subgroups. CONCLUSIONS: Patients with moderate-to-severe psoriasis should receive 100-mg subcutaneous tildrakizumab Q12W. Patients with high body weight (>90 kg) may benefit from a higher dose (200-mg Q12W).

Population Pharmacokinetics of Doravirine and Exposure-Response Analysis in Individuals with HIV-1.

Doravirine is a novel nonnucleoside reverse transcriptase inhibitor for the treatment of human immunodeficiency virus 1 (HIV-1) infection. A population pharmacokinetic (PK) model was developed for doravirine using pooled data from densely sampled phase 1 trials and from sparsely sampled phase 2b and phase 3 trials evaluating doravirine administered orally as a single entity or as part of a fixed-dose combination of doravirine-lamivudine-tenofovir disoproxil fumarate. A one-compartment model with linear clearance from the central compartment adequately described the clinical PK of doravirine. While weight, age, and healthy versus HIV-1 status were identified as statistically significant covariates affecting doravirine PK, the magnitude of their effects was not clinically meaningful. Other intrinsic factors (gender, body mass index, race, ethnicity, and renal function) did not have statistically significant or clinically meaningful effects on doravirine PK. Individual exposure estimates for individuals in the phase 2b and 3 trials obtained from the final model were used for subsequent exposure-response analyses for virologic response (proportion of individuals achieving <50 copies/ml) and virologic failure. The exposure-response relationships between these efficacy endpoints and doravirine PK were generally flat over the range of exposures achieved for the 100 mg once-daily regimen in the phase 3 trials, with a minimal decrease in efficacy in individuals in the lowest 10th percentile of steady-state doravirine concentration at 24 h values. These findings support 100 mg once daily as the selected dose of doravirine, with no dose adjustment warranted for the studied intrinsic factors.

Pharmacokinetics of elbasvir and grazoprevir in subjects with end-stage renal disease or severe renal impairment.

PURPOSE: To describe the phase 1 and population pharmacokinetic investigations that support dosing recommendations for elbasvir/grazoprevir (EBR/GZR) in hepatitis C virus-infected people with advanced chronic kidney disease. METHODS: This was an open-label, two-part, multiple-dose trial (MK-5172 PN050; NCT01937975) in 24 non-HCV-infected participants with end-stage renal disease (ESRD) or severe renal impairment who received once-daily EBR 50 mg and GZR 100 mg for 10 days. Population pharmacokinetic analyses from the phase 3 C-SURFER study (PN052, NCT02092350) were also conducted. RESULTS: When comparing haemodialysis (HD) and non-HD days in participants with ESRD, geometric mean ratios (GMRs) (90% confidence intervals [CIs]) for EBR and GZR AUC0-24 were 1.14 (1.08-1.21) and 0.97 (0.87-1.09). When comparing ESRD and healthy participants, GMRs (90% CIs) for EBR and GZR AUC0-24 were 0.99 (0.75-1.30) and 0.83 (0.56-1.22) on HD days, and 0.86 (0.65-1.14) and 0.85 (0.58-1.25) on non-HD days. GMRs (90% CIs) for AUC0-24 in participants with severe renal impairment relative to healthy controls were 1.65 (1.09-2.49) for GZR and 1.86 (1.38-2.51) for EBR. In population modelling of data from C-SURFER, absolute geometric means of steady-state EBR AUC0-24 were 2.78 and 3.07 µM*h (HD and non-HD recipients) and GZR AUC0-24 were 1.80 and 2.34 µM*h (HD and non-HD recipients). CONCLUSIONS: EBR/GZR represents an important treatment option for HCV infection in people with severe renal impairment and those with ESRD. No dosage adjustment of EBR/GZR is required in people with any degree of renal impairment, including those receiving dialysis.

Leveraging model-informed approaches for drug discovery and development in the cardiovascular space.

Cardiovascular disease remains a significant global health burden, and development of cardiovascular drugs in the current regulatory environment often demands large and expensive cardiovascular outcome trials. Thus, the use of quantitative pharmacometric approaches which can help enable early Go/No Go decision making, ensure appropriate dose selection, and increase the likelihood of successful clinical trials, have become increasingly important to help reduce the risk of failed cardiovascular outcomes studies. In addition, cardiovascular safety is an important consideration for many drug development programs, whether or not the drug is designed to treat cardiovascular disease; modeling and simulation approaches also have utility in assessing risk in this area. Herein, examples of modeling and simulation applied at various stages of drug development, spanning from the discovery stage through late-stage clinical development, for cardiovascular programs are presented. Examples of how modeling approaches have been utilized in early development programs across various therapeutic areas to help inform strategies to mitigate the risk of cardiovascular-related adverse events, such as QTc prolongation and changes in blood pressure, are also presented. These examples demonstrate how more informed drug development decisions can be enabled by modeling and simulation approaches in the cardiovascular area.

Effect of Hepatic Impairment on the Pharmacokinetics of Grazoprevir, a Hepatitis C Virus Protease Inhibitor.

Grazoprevir (GZR) plus elbasvir is an approved treatment for chronic infection with hepatitis C virus (HCV) genotype 1 or 4. HCV infection complications include liver cirrhosis, end-stage liver disease, and hepatocellular carcinoma. The objective of this study was to evaluate the pharmacokinetics and safety of multiple-dose GZR (200, 100, or 50 mg) in non-HCV participants with mild, moderate, or severe hepatic impairment (HI), respectively, and in healthy matched controls (protocol MK-5172_p013; Merck & Co., Inc., Kenilworth, NJ). Participants with mild, moderate, or severe HI and controls (aged 18 to 65 years) matched for race, age, sex, and body mass index were enrolled in a 3-part, open-label, sequential-panel pharmacokinetic study. Participants received oral doses of GZR 200 mg (two 100-mg tablets), 100 mg (one 100-mg tablet), or 50 mg (two 25-mg tablets) once daily for 10 days. A total of 50 participants were enrolled: 8 with mild HI, 9 with moderate HI, 8 with severe HI, and a corresponding number of healthy matched controls for each hepatic cohort. Participants with HI demonstrated higher GZR exposure than healthy matched controls and showed an increase in exposure with increasing HI severity. The steady-state GZR AUC0-24 (area under the concentration-time curve from 0 to 24 h) for participants with mild, moderate, or severe HI was ≈2-, ≈5-, or ≈12-fold higher, respectively, than that for healthy matched controls. GZR was generally well tolerated in participants with HI. No dose adjustment is required for GZR in people with HCV with mild HI. GZR is contraindicated for those with moderate or severe HI (Child-Pugh class B or C), since they may have significantly increased GZR exposures that may lead to an increased risk of transaminase elevation.

Effects of Extended-Release Niacin and Extended-Release Niacin/Laropiprant on the Pharmacokinetics of Simvastatin in Healthy Subjects.

The use of multiple lipid-modifying agents with different mechanisms of action is often required to regulate lipid levels in patients with dyslipidemia. During combination therapy, alterations in the pharmacokinetics of any of the drugs used and their metabolites may occur. Three separate open-label, randomized, crossover studies evaluated the potential for pharmacokinetic interaction between extended-release niacin (with and without concomitant laropiprant) and simvastatin in healthy subjects. Study 1 used single doses of extended-release niacin and simvastatin; study 2 used multiple-dose coadministration of extended-release niacin/laropiprant and simvastatin in healthy subjects; and study 3 used single doses of both extended-release niacin and the coadministration of extended-release niacin/laropiprant and simvastatin in healthy Chinese subjects. During each treatment period, plasma samples were collected predose and at prespecified postdose time points for pharmacokinetic analyses. The safety and tolerability of simvastatin with and without coadministered extended-release niacin (or extended-release niacin/laropiprant) were assessed by clinical evaluation of adverse experiences. In 2 studies in healthy subjects, modest increases in exposure to simvastatin acid (by ∼60%) by extended-release niacin and extended-release niacin/laropiprant were observed. Based on the clinical experience with simvastatin, these effects are not believed to be clinically meaningful. In the third study on healthy Chinese subjects, no statistically meaningful increases in exposure to simvastatin by extended-release niacin and extended-release niacin/laropiprant were observed. In all populations examined in these studies, the coadministration of extended-release niacin and simvastatin was generally well tolerated.

Pharmacokinetics, safety, and 48-week efficacy of oral raltegravir in HIV-1-infected children aged 2 through 18 years.

BACKGROUND: IMPAACT P1066 is a phase I/II open-label multicenter trial to evaluate pharmacokinetics, safety, tolerability, and efficacy of multiple raltegravir formulations in human immunodeficiency virus (HIV)-infected youth. METHODS: Dose selection for each cohort (I: 12 to <19 years; II: 6 to <12 years; and III: 2 to <6 years) was based on review of short-term safety (4 weeks) and intensive pharmacokinetic evaluation. Safety data through weeks 24 and 48, and grade ≥ 3 or serious adverse events (AEs) were assessed. The primary virologic endpoint was achieving HIV RNA <400 copies/mL or ≥ 1 log10 reduction between baseline and week 24. RESULTS: The targeted pharmacokinetic parameters (AUC0-12h and C12h) were achieved for each cohort, allowing dose selection for 2 formulations. Of 96 final dose subjects, there were 15 subjects with grade 3 or higher clinical AEs (1 subject with drug-related [DR] psychomotor hyperactivity and insomnia); 16 subjects with grade 3 or higher laboratory AEs (1 with DR transaminase elevation); 14 subjects with serious clinical AEs (1 with DR rash); and 1 subjects with serious laboratory AEs (1 with DR transaminase increased). There were no discontinuations due to AEs and no DR deaths. Favorable virologic responses at week 48 were observed in 79.1% of patients, with a mean CD4 increase of 156 cells/µL (4.6%). CONCLUSIONS: Raltegravir as a film-coated tablet 400 mg twice daily (6 to <19 years, and ≥ 25 kg) and chewable tablet 6 mg/kg (maximum dose 300 mg) twice daily (2 to <12 years) was well tolerated and showed favorable virologic and immunologic responses. CLINICAL TRIALS REGISTRATION: NCT00485264.

The effects of laropiprant on the antiplatelet activity of co-administered clopidogrel and aspirin.

Laropiprant is an antagonist of the prostaglandin PGD2 receptor DP1. Laropiprant has a weak affinity for the thromboxane A2 receptor TP. Two double-blinded, randomized, placebo-controlled, crossover studies evaluated the effects of multiple-dose laropiprant at steady state on the antiplatelet effects of multiple-dose aspirin and clopidogrel. Study 1 had two treatment periods, in which each healthy subject received laropiprant 40 mg, clopidogrel 75 mg, and aspirin 80 mg (Treatment A), or placebo, clopidogrel 75 mg, and aspirin 80 mg (Treatment B) once daily for 7 days. Study 2 consisted of three treatment periods. In the first two, each patient with hypercholesterolemia or mixed dyslipidemia received laropiprant 40 mg, clopidogrel 75 mg, and aspirin 81 mg (Treatment A), or placebo, clopidogrel 75 mg, and aspirin 81 mg (Treatment B) once daily for 7 days. In period 3, patients received a single dose of two tablets of extended release nicotinic acid 1 g/laropiprant 20 mg (Treatment C). In both studies, pharmacodynamic endpoints included bleeding time at 24 (primary) and 4 hours (secondary) post-dose following 7 days of once-daily laropiprant in combination with clopidogrel and aspirin, and platelet aggregation in platelet-rich plasma at 4 and 24 hours post-dose on day 7 (secondary). After 7 days, increased bleeding time of 27% (Study 1) and 23% (Study 2) at 24 hours post-dose was observed with laropiprant compared to placebo (both combined with clopidogrel and aspirin), with corresponding upper bounds of the 90% CI marginally exceeding the prespecified upper comparability bound of 1.50 in both studies. The GMR and 90% CI for bleeding time of laropiprant compared to placebo (both combined with clopidogrel and aspirin) at 4 hours post-dose on day 7 was 0.92 (0.70, 1.21) in Study 1, and 1.46 (1.20, 1.78) in Study 2. Compared with placebo, laropiprant (both combined with clopidogrel and aspirin) increased the inhibition of collagen- and ADP-induced platelet aggregation, respectively, by ∼2.4% and ∼8.1% in Study 1 and by ∼4% and ∼5.4% in Study 2, at 24 hours post-dose on day 7. The inhibition of collagen- and ADP-induced platelet aggregation, respectively, was increased by ∼0.1% and ∼5.0% in Study 1, and by ∼5% and ∼12% in Study 2, at 4 hours post-dose on day 7. In conclusion, co-administration of multiple doses of laropiprant with aspirin and clopidogrel induced a prolongation of bleeding time and an inhibitory effect on platelet aggregation ex vivo in healthy subjects and patients with dyslipidemia.

Population pharmacokinetic modeling of sotatercept in healthy participants and patients with pulmonary arterial hypertension.

Sotatercept is a breakthrough, first-in-class biologic, that is FDA-approved for the treatment of pulmonary arterial hypertension (PAH). A population pharmacokinetic (PopPK) model was developed using data from two phase 1 studies in healthy participants, and two phase 2 studies and one phase 3 study in participants with PAH. The pooled sotatercept PK data encompassed single intravenous (IV) or subcutaneous (SC) doses ranging from 0.01 to 3.0 mg/kg, as well as multiple SC doses ranging from 0.03 to 1.0 mg/kg, with PK samples collected up to a maximum of ~150 weeks following Q3W and Q4W dosing regimens. The final PopPK analysis included 350 participants, with 30 and 320 participants receiving sotatercept IV and SC, respectively. A two-compartment model with a first-order absorption rate constant and a linear disposition from central compartment well-described sotatercept PK. The estimated bioavailability is ~66%; bioavailability, clearance (CL), and central volume (VC) have low to moderate inter-individual variability. Time-varying body weight and baseline albumin concentration were statistically significant predictors of PK; CL and VC were predicted to increase with increasing body weight, while CL was predicted to decrease with increasing baseline albumin concentration. However, the magnitude of covariate effects is not predicted to meaningfully alter the disposition of sotatercept. Altogether, the PopPK modeling results demonstrate favorable PK characteristics (low to moderate variability and typical bioavailability), supporting sotatercept as a SC biological agent for the treatment of patients with PAH.

Pharmacokinetic-pharmacodynamic studies of the 11ß-hydroxysteroid dehydrogenase type 1 inhibitor MK-0916 in healthy subjects.

AIMS: To characterize pharmacokinetic parameters of MK-0916 and its safety and tolerability in lean, healthy male subjects following single and multiple oral doses. To assess (by stable-isotope labelling) the in vivo inhibition of cortisone-to-cortisol conversion following oral MK-0916. METHODS: Data are presented from two randomized, controlled, double-blind, rising-dose phase I studies. In the first study, subjects received single oral doses of 0.4-100 mg MK-0916 (n = 16). In the second study, subjects received 0.2-225 mg MK-0916 followed by daily doses of 0.2-100 mg for 13 days beginning on day 2 or day 15 (n = 80). Plasma and urine drug concentrations were measured for pharmacokinetic analysis. For pharmacodynamic analysis, concentrations of plasma [(13)C4]cortisol were measured by high-pressure liquid chromatography and tandem mass spectrometry following a single oral dose of 5 mg [(13)C4]cortisone. RESULTS: Doses ≥3 mg were rapidly absorbed (time at which maximal concentration was achieved in plasma, 1.1-1.8 h). Exposure (measured as the area under the concentration-time curve from 0 to 168 h) increased approximately in proportion to dose. Values for the maximal plasma concentration and the plasma concentration at 24 h increased in excess of dose proportionality at doses <6 mg and roughly in proportion to dose at doses >6 mg. In subjects dosed with 6 mg MK-0916 once daily for 14 days, the mean trough plasma concentration was 240 nm and in vivo cortisone-to-cortisol conversion was inhibited by 84%. The relationship between plasma MK-0916 and hepatic 11ß-hydroxysteroid dehydrogenase type 1 inhibition was well represented by a simple Emax model with an IC50 of 70.4 nm. Exposure to MK-0916 was generally well tolerated. CONCLUSIONS: These findings indicate that 11ß-hydroxysteroid dehydrogenase type 1 is effectively inhibited in human subjects by doses of MK-0916 that are well tolerated.

An Overview of Renal Cell Carcinoma Hallmarks, Drug Resistance, and Adjuvant Therapies.

Renal neoplasms are highlighted as one of the 10 most common types of cancer. Renal cell carcinoma (RCC) is the most common type of renal cancer, considered the seventh most common type of cancer in the Western world. The most frequently altered genes described as altered are VHL, PBRM1, SETD2, KDM5C, PTEN, BAP1, mTOR, TP53, TCEB1 (ELOC), SMARCA4, ARID1A, and PIK3CA. RCC therapies can be classified in three groups: monoclonal antibodies, tyrosine kinase inhibitors, and mTOR inhibitors. Besides, there are targeted agents to treat RCC. However, frequently patients present side effects and resistance. Even though many multidrug resistance mechanisms already have been reported to RCC, studies focused on revealing new biomarkers as well as more effective antitumor therapies with no or low side effects are very important. Some studies reported that natural products, such as honey, epigallocatechin-3-gallate (EGCG), curcumin, resveratrol, and englerin A showed antitumor activity against RCC. Moreover, nanoscience is another strategy to improve RCC treatment and reduce the side effects due to the improvement in pharmacokinetics and reduction of toxicities of chemotherapies. Taking this into account, we conducted a systemic review of recent research findings on RCC hallmarks, drug resistance, and adjuvant therapies. In conclusion, a range of studies reported that RCC is characterized by high incidence and increased mortality rates because of the development of resistance to standard therapies. Given the importance of improving RCC treatment and reducing adverse effects, nanoscience and natural products can be included in therapeutic strategies.

Pharmacokinetics and pharmacodynamics of once-daily versus twice-daily raltegravir in treatment-naive HIV-infected patients.

QDMRK was a phase III clinical trial of raltegravir given once daily (QD) (800-mg dose) versus twice daily (BID) (400 mg per dose), each in combination with once-daily coformulated tenofovir-emtricitabine, in treatment-naive HIV-infected patients. Pharmacokinetic (PK) and pharmacokinetic/pharmacodynamic (PK/PD) analyses were conducted using a 2-step approach: individual non-model-based PK parameters from observed sparse concentration data were determined, followed by statistical analysis of potential relationships between PK and efficacy response parameters after 48 weeks of treatment. Sparse PK sampling was performed for all patients (QD, n = 380; BID, n = 384); selected sites performed an intensive PK evaluation at week 4 (QD, n = 22; BID, n = 20). In the intensive PK subgroup, daily exposures (area under the concentration-time curve from 0 to 24 h [AUC(0-24)]) were similar between the two regimens, but patients on 800 mg QD experienced ~4-fold-higher maximum drug concentration in plasma (C(max)) values and ~6-fold-lower trough drug concentration (C(trough)) values than those on 400 mg BID. Geometric mean (GM) C(trough) values were similarly lower in the sparse PK analysis. With BID dosing, there was no indication of any significant PK/PD association over the range of tested PK parameters. With QD dosing, C(trough) values correlated with the likelihood of virologic response. Failure to achieve an HIV RNA level of <50 copies/ml appeared predominantly at high baseline HIV RNA levels in both treatment arms and was associated with lower values of GM C(trough) in the 800-mg-QD arm, though other possible drivers of efficacy, such as time above a threshold concentration, could not be evaluated due to the sparse sampling scheme. Together, these findings emphasize the importance of the shape of the plasma concentration-versus-time curve for long-term efficacy.

Ultrasensitive liquid chromatography-tandem mass spectrometric methodologies for quantification of five HIV-1 integrase inhibitors in plasma for a microdose clinical trial.

HIV-1 integrase strand transfer inhibitors are an important class of compounds targeted for the treatment of HIV-1 infection. Microdosing has emerged as an attractive tool to assist in drug candidate screening for clinical development, but necessitates extremely sensitive bioanalytical assays, typically in the pg/mL concentration range. Currently, accelerator mass spectrometry is the predominant tool for microdosing support, which requires a specialized facility and synthesis of radiolabeled compounds. There have been few studies attempted to comprehensively assess a liquid chromatography-tandem mass spectrometry (LC-MS/MS) approach in the context of microdosing applications. Herein, we describe the development of automated LC-MS/MS methods to quantify five integrase inhibitors in plasma with the limits of quantification at 1 pg/mL for raltegravir and 2 pg/mL for four proprietary compounds. The assays involved double extractions followed by UPLC coupled with negative ion electrospray MS/MS analysis. All methods were fully validated to the rigor of regulated bioanalysis requirements, with intraday precision between 1.20 and 14.1% and accuracy between 93.8 and 107% at the standard curve concentration range. These methods were successfully applied to a human microdose study and demonstrated to be accurate, reproducible, and cost-effective. Results of the study indicate that raltegravir displayed linear pharmacokinetics between a microdose and a pharmacologically active dose.

Population Pharmacokinetics of Vericiguat in Patients With Heart Failure With Reduced Ejection Fraction: An Integrated Analysis.

Vericiguat, a novel stimulator of soluble guanylate cyclase (sGC), is indicated for the treatment of patients following a hospitalization for heart failure or need for outpatient intravenous diuretics, with symptomatic chronic heart failure and ejection fraction less than 45%. Pharmacokinetic (PK) data from the phase II trial SOCRATES-REDUCED (Soluble Guanylate Cyclase Stimulator in Heart Failure Study) and the phase III trial VICTORIA (Vericiguat Global Study in Patients With Heart Failure With Reduced Ejection Fraction) were used to characterize vericiguat PK. A total of 8,092 concentration records from 2,321 participants (362 from SOCRATES-REDUCED and 1,959 from VICTORIA) were utilized for the development of the population PK model. The final PK model was a one-compartment model with first-order absorption and linear elimination. Baseline body weight and time-varying body weight were identified as statistically significant covariates affecting apparent clearance (CL/F) and volume of distribution, respectively. Age, sex, race, bilirubin, estimated glomerular filtration rate, and albumin did not affect vericiguat PK. Baseline disease-related factors, such as left ventricular ejection fraction, New York Heart Association (NYHA) class, and N-terminal pro B-type natriuretic peptide, also did not influence vericiguat PK. Since vericiguat is a titrated drug, the impact of vericiguat PK on the titration to and maintenance of the target dose in VICTORIA was assessed. The distribution of steady-state doses in VICTORIA was similar across CL/F quartiles, suggesting that the ability to reach and maintain dosing at the target 10-mg dose was not related to vericiguat exposure.

Effect of raltegravir on estradiol and norgestimate plasma pharmacokinetics following oral contraceptive administration in healthy women.

AIMS: Oral contraceptives such as norgestimate-ethinyl estradiol (Ortho Tri-Cyclen®) are commonly prescribed in the HIV-infected patient population. A placebo-controlled, randomized, two-period crossover study in healthy HIV-seronegative subjects was conducted to assess the effect of raltegravir on the pharmacokinetics of the estrogen and progestin components of norgestimate-ethinyl estradiol [ethinyl estradiol (EE) and norelgestromin (NGMN), an active metabolite of norgestimate (NGT)]. METHODS: In each of two periods, nineteen healthy women established on norgestimate-ethinyl estradiol contraception (21 days of active contraception; 7 days of placebo) received either 400 mg raltegravir or matching placebo twice daily on days 1-21. Pharmacokinetics were analysed on day 21 of each period. RESULTS: The geometric mean ratio (GMR) and 90% confidence interval (CI) for the EE component of norgestimate-ethinyl estradiol when co-administrated with raltegravir relative to EE alone was 0.98 (0.93-1.04) for the area under the concentration-time curve from 0 to 24 h (AUC(0-24 h) ) and 1.06 (0.98-1.14) for the maximum concentration of drug in the plasma (C(max) ); the GMR (90% CI) for the NGMN component of norgestimate-ethinyl estradiol when co-administered with raltegravir relative to NGMN alone was 1.14 (1.08-1.21) for AUC(0-24 h) and 1.29 (1.23-1.37) for C(max) . There were no discontinuations due to a study drug-related adverse experience, nor any serious clinical or laboratory adverse experience. CONCLUSIONS: Raltegravir has no clinically important effect on EE or NGMN pharmacokinetics. Co-administration of raltegravir and an oral contraceptive containing EE and NGT was generally well tolerated; no dose adjustment is required for oral contraceptives containing EE and NGT when co-administered with raltegravir.

Magnesium sulfate pharmacokinetics after intramuscular dosing in women with preeclampsia.

BACKGROUND: Current intramuscular magnesium dosing regimens in low and middle-income countries are based on indirect absorption parameters to inform pharmacokinetic and pharmacodynamic response. OBJECTIVE: To determine if therapeutic serum magnesium levels are obtained in women with severe preeclampsia receiving intramuscular administration of magnesium sulfate using the Pritchard regimen and to compare the key pharmacokinetic variables to those previously published. STUDY DESIGN: Serum magnesium levels were obtained at multiple time points at baseline and after magnesium sulfate administration from women with severe preeclampsia receiving the standard Pritchard regimen for seizure prophylaxis at Bayero University, Kano, Nigeria. The pharmacokinetic profiles were constructed for the study cohort and the updated pharmacokinetic model was compared with the one that was previously published. RESULTS: A total of 80 blood samples were collected from 20 women with severe preeclampsia (45 collected before childbirth and 35 collected after childbirth). After 11.5 hours of magnesium sulfate administration, 63% of women in the cohort had serum magnesium levels of ≥2.0 mmol/L. Data from women receiving the Pritchard regimen combined with data from women previously modeled after the receipt of intravenous magnesium sulfate were adequately described using a 2-compartment model with first-order absorption and linear elimination from the central compartment. All structural pharmacokinetic parameters including clearance, central volume of distribution, peripheral volume of distribution, and intercompartment clearance were adjusted for maternal weight, and the clearance was further adjusted for serum creatinine level and antepartum or postpartum status. The simulated pharmacokinetic profiles of the updated pharmacokinetic model and the previously published pharmacokinetic model are similar. In previously published pharmacokinetic modeling, absorption rate constant=0.32 and absolute bioavailability=0.86. In the updated pharmacokinetic model, absorption rate constant=0.45 and absolute bioavailability=0.91. CONCLUSION: These data support the use of the Pritchard regimen as acceptable to achieve therapeutic serum magnesium levels and support the reported simulation of serum magnesium levels and eclampsia response associated with different intramuscular regimens.

Clinical Pharmacology Worldwide: A Global Health Perspective.

Low- and middle-income countries (LMICs) have the highest rates of mortality and morbidity globally, but lag behind high-income countries in the number of clinical trials and trained researchers, as well as research data pertaining to their populations. Lack of local clinical pharmacology and pharmacometrics expertise, limited training opportunities, and lack of local genomic data may contribute to health inequalities and limit the application of precision medicine. Continuing to develop health care infrastructure, including well-designed clinical pharmacology training and data collection in LMICs, can help address these challenges. International collaboration aimed at improving training and infrastructure and encouraging locally driven research and clinical trials will be of benefit. This review describes several examples where clinical pharmacology expertise could be leveraged, including opportunities for pharmacogenomic expertise that could drive improved recommendations for clinical guidelines. Also described are clinical pharmacology and pharmacometrics training programs in Africa, and the personal experience of a Tanzanian researcher currently on a training sabbatical in the United States, as illustrative examples of how training in clinical pharmacology can be effectively implemented in LMICs. These training efforts will benefit from advocacy for employment opportunities and career development pathways for clinical pharmacologists that are gradually being recognized and developed in LMICs. Clinical pharmacologists have a key role to play in global health, and development of training and research infrastructure to advance this expertise in LMICs will be of tremendous benefit.

Physiologically Based Pharmacokinetic Modeling of Doravirine and Its Major Metabolite to Support Dose Adjustment With Rifabutin.

Doravirine, a novel nonnucleoside reverse transcriptase inhibitor for the treatment of human immunodeficiency virus 1 (HIV-1), is predominantly cleared by cytochrome P450 (CYP) 3A4 and metabolized to an oxidative metabolite (M9). Coadministration with rifabutin, a moderate CYP3A4 inducer, decreased doravirine exposure. Based on nonparametric superposition modeling, a doravirine dose adjustment from 100 mg once daily to 100 mg twice daily during rifabutin coadministration was proposed. However, M9 exposure may also be impacted by induction, in addition to the dose adjustment. As M9 concentrations have not been quantified in previous clinical studies, a physiologically based pharmacokinetic model was developed to investigate the change in M9 exposure when doravirine is coadministered with CYP3A inducers. Simulations demonstrated that although CYP3A induction increases doravirine clearance by up to 4.4-fold, M9 exposure is increased by only 1.2-fold relative to exposures for doravirine 100 mg once daily in the absence of CYP3A induction. Thus, a 2.4-fold increase in M9 exposure relative to the clinical dose of doravirine is anticipated when doravirine 100 mg twice daily is coadministered with rifabutin. In a subsequent clinical trial, doravirine and M9 exposures, when doravirine 100 mg twice daily was coadministered with rifabutin, were found to be consistent with model predictions using rifampin and efavirenz as representative inducers. These findings support the dose adjustment to doravirine 100 mg twice daily when coadministered with rifabutin.

Clinical Pharmacokinetics of the Novel HIV-1 Non-Nucleoside Reverse Transcriptase Inhibitor Doravirine: An Assessment of the Effect of Patient Characteristics and Drug-Drug Interactions.

Doravirine (MK-1439) is a novel non-nucleoside reverse transcriptase inhibitor indicated for the combination treatment of human immunodeficiency virus type-1 (HIV-1) infection. The recommended dose is 100 mg once daily. This review summarizes the pharmacokinetics of doravirine, the influence of intrinsic factors, and its drug-drug interaction (DDI) profile. Following oral administration, doravirine is rapidly absorbed (median time to maximum plasma concentration, 1-4 h) and undergoes cytochrome P450 (CYP)3A-mediated oxidative metabolism. Steady-state geometric means for AUC0-24, C24, and Cmax in individuals with HIV-1 following administration of doravirine 100 mg once daily are 37.8 µM·h, 930 nM, and 2260 nM, respectively. Age, gender, severe renal impairment, and moderate hepatic impairment have no clinically meaningful effect on doravirine pharmacokinetics, and there is limited potential for DDIs. No dose adjustment is necessary when doravirine is co-administered with strong CYP3A inhibitors. However, doravirine is contraindicated with strong CYP3A inducers (e.g., rifampin), and dose adjustment of doravirine is recommended for co-administration with the moderate CYP3A inducer, rifabutin. Included in this review are clinical trial data from phase I pharmacokinetic trials, including DDI trials and trials in participants with renal and hepatic disease but without HIV-1 infection (N = 326), as well as phase I, II, and III safety and efficacy trials in participants living with HIV-1 (N = 991). Based on these data, the pharmacokinetic profile of doravirine supports its use in diverse populations living with HIV-1 and allows co-administration with various antiretroviral agents and treatments for commonly occurring co-morbidities.