Evaluation of US Food and Drug Administration Drug Label Recommendations for Coadministration of Antivirals and Acid-Reducing Agents

Coadministration with acid-reducing agents (ARAs), including proton pump inhibitors (PPIs), histamine H2 -receptor antagonists (H2 blockers), and antacids has been demonstrated to reduce antiviral exposure and efficacy. Therefore, it is essential that US Food and Drug Administration (FDA) drug labels include recommendations to manage these drug-drug interactions (DDIs). This investigation analyzed information in FDA drug labels to manage DDIs between ARAs and antivirals approved from 1998 to 2019. To ascertain clinical adoption, we assessed whether FDA label recommendations were incorporated into current antiviral clinical practice guidelines. We identified 82 label recommendations for 43 antiviral approvals. Overall, 56.1% of recommendations were deemed clinically actionable, with the most common actionable management strategies being dose adjustment during coadministration (40.2%) and coadministration not recommended (9.8%). The sources informing DDI recommendations were clinical DDI studies (59.8%) and predictions of altered exposure (40.2%). Antivirals with low aqueous solubility were more likely to have label recommendations and were more commonly investigated using clinical DDI studies (P < 0.01). For recommendations informed by clinical DDI studies, changes in drug exposure were associated with actionable label recommendations (P < 0.01). The frequency of exposure changes in clinical DDI studies was similar across antiviral indications, but exposure changes were numerically higher for antacids (71.4%) relative to PPIs (42.9%) and H2 blockers (28.6%). Of DDI pairs identified within drug labels, 76.8% were included in guidelines, and recommended management strategies were concordant in 90.5% of cases. Our findings demonstrate that current regulatory oversight mostly (but not completely) results in actionable label recommendations to manage DDIs for high-risk antivirals.

Accelerating Drug Development in Pediatric Oncology With the Clinical Pharmacology Storehouse

Pediatric drug development is a challenging process due to the rarity of the population, the need to meet regulatory requirements across the globe, the associated uncertainty in extrapolating data from adults, the paucity of validated biomarkers, and the lack of systematic testing of drugs in pediatric patients. In oncology, pediatric drug development has additional challenges that have historically delayed availability of safe and effective medicines for children. In particular, the traditional approach to pediatric oncology drug development involves conducting phase 1 studies in children once the drug has been characterized and in some cases approved for use in adults. The objective of this article is to describe clinical pharmacology factors that influence pediatric oncology trial design and execution and to highlight efficient approaches for designing and expediting oncology drug development in children. The topics highlighted in this article include (1) study design considerations, (2) updated dosing approaches, (3) ways to overcome the significant biopharmaceutical challenges unique to the oncology pediatric population, and (4) use of data analysis strategies for extrapolating data from adults, with case studies. Finally, suggestions for ways to use clinical pharmacology approaches to accelerate pediatric oncology drug development are provided.

Pharmacokinetics of Upadacitinib With the Clinical Regimens of the Extended-Release Formulation Utilized in Rheumatoid Arthritis Phase 3 Trials

Upadacitinib is a Janus kinase 1 inhibitor under development for the treatment of several inflammatory disorders including rheumatoid arthritis (RA). Upadacitinib was administered in the phase 2 RA trials primarily as twice-daily regimens of an immediate-release (IR) formulation. The upadacitinib extended-release (ER) formulation was developed to enable once-daily dosing. In the present study, upadacitinib pharmacokinetics were characterized after the administration of single and multiple once-daily doses of the ER formulation in healthy subjects relative to single and multiple twice-daily doses of the IR formulation. Increase in upadacitinib exposure was dose-proportional over the evaluated 15- to 30-mg ER dose range. Single 15- and 30-mg ER doses provided equivalent AUC_0-inf compared with single 12- and 24-mg IR doses, respectively. A high-fat breakfast increased upadacitinib ER C_max and AUC_0-inf by only 20% and 17%, respectively, relative to fasting conditions. The median time to peak plasma concentrations was 2 to 4 hours for the ER formulation, and steady state was achieved by day 4 of once-daily dosing. Doses of 15 and 30 mg once daily using the ER formulation provided equivalent AUC_0-24 , comparable C_max and C_min , and a fluctuation index over a 24-hour period at steady state similar to 6 and 12 mg twice daily, respectively, using the IR formulation. These results supported the use of upadacitinib 15- and 30-mg doses of the ER formulation in the phase 3 trials in RA.

Application of Exposure-Response Analyses to Establish the Pharmacodynamic Similarity of a Once-Daily Regimen to an Approved Twice-Daily Dosing Regimen for the Treatment of HCV Infection

The triple direct-acting antiviral (3-DAA) regimen (two co-formulated tablets of ombitasvir/paritaprevir/ritonavir once daily and one tablet of dasabuvir twice daily) for patients with hepatitis C virus (HCV) genotype 1 infection has been reformulated for once-daily administration containing all three active DAAs (3QD regimen). Two bioequivalence studies compared the 3-DAA and 3QD regimens. In study 1, fed, single-, and multiple-dose crossover comparisons revealed exposures for drug components that were slightly outside the bioequivalence criteria, i.e., 21 to 29% lower dasabuvir C _trough, paritaprevir C _max, and ritonavir C _max. In study 2, fed and fasted single-dose crossover comparisons demonstrated a large impact of food on exposures, confirming the product's labeling requirement for administration only with food, and revealed a lack of bioequivalence under fasting conditions. Exposure-response analyses using efficacy data from phase 2/3 studies of the 3-DAA regimen demonstrated that the lower dasabuvir C _trough for the 3QD regimen (under fed condition) would have minimal impact on sustained virologic response at week 12 post-treatment (SVR₁₂). Thus, the pharmacodynamic similarity between the regimens was established and the analyses provided the basis for regulatory approval of the 3QD regimen to treat patients with chronic HCV genotype 1 infection.

Impact of pharmacometrics on drug approval and labeling decisions: a survey of 42 new drug applications

The value of quantitative thinking in drug development and regulatory review is increasingly being appreciated. Modeling and simulation of data pertaining to pharmacokinetic, pharmacodynamic, and disease progression is often referred to as the pharmacometrics analyses. The objective of the current report is to assess the role of pharmacometrics at the US Food and Drug Administration (FDA) in making drug approval and labeling decisions. The New Drug Applications (NDAs) submitted between 2000 and 2004 to the Cardio-renal, Oncology, and Neuropharmacology drug products divisions were surveyed. For those NDA reviews that included a pharmacometrics consultation, the clinical pharmacology scientists ranked the impact on the regulatory decision(s). Of about a total of 244 NDAs, 42 included a pharmacometrics component. Review of NDAs involved independent, quantitative evaluation by FDA pharmacometricians, even when such analysis was not conducted by the sponsor. Pharmacometric analyses were pivotal in regulatory decision making in more than half of the 42 NDAs. Of the 14 reviews that were pivotal to approval related decisions, 5 identified the need for additional trials, whereas 6 reduced the burden of conducting additional trials. Collaboration among the FDA clinical pharmacology, medical, and statistical reviewers and effective communication with the sponsors was critical for the impact to occur. The survey and the case studies emphasize the need for early interaction between the FDA and sponsors to plan the development more efficiently by appreciating the regulatory expectations better.

The product label: how pharmacokinetics and pharmacodynamics reach the prescriber

The product label, or package insert, is the 'manual' for the safe and effective use of a drug. Important pharmacokinetic and pharmacodynamic properties of a drug product should appear in the label under specific sections, as required in the Code of Federal Regulations (CFR), using a format and language recommended by the Food and Drug Administration (FDA) in various guidances to the industry. The relevant regulations and guidance documents impacting on how this information is conveyed to the healthcare professional are discussed, with special emphasis on how the new proposed rule will impact upon how information is to be conveyed. With the availability of new clinical pharmacology information not available at the time of approval, package inserts for older drugs should be updated to reflect the new data and recommend the proper dosage regimen, enabling prescribers to optimise drug therapy and minimise possible adverse events.

Utilisation of pharmacokinetic-pharmacodynamic modelling and simulation in regulatory decision-making

Modelling and simulation (M&S) play an important role in regulatory decision-making that affects both the public and industry. Technological advances in various fields related to drug development call for more focus on ways to optimise current drug development practices. Recognition of the potential of M&S by regulatory agencies inevitably has a substantial impact on drug development. The objective of the current review is to present the various regulatory initiatives for application of M&S to clinical drug development. The relevant parts of the various recommendations issued by the US Food and Drug Administration (FDA), via guidance documents and advisory committee meeting proceedings, are highlighted. Application of M&S to a variety of activities, such as integrating pharmacokinetic-pharmacodynamic knowledge across a new drug application and designing efficient trials, is discussed. Some of the challenges that pharmaceutical institutions currently face when implementing M&S projects, such as team structure, communication with regulators, training and time constraints, are also presented, and solutions are proposed.

In vivo drug-drug interaction studies--a survey of all new molecular entities approved from 1987 to 1997

Ninety-eight new molecular entities applications approved between 1987 to 1991 (period I) and 193 applications for new molecular entities between 1992 to 1997 (period II) were surveyed for drug-drug interaction studies. In period I (used as a comparator), 32 applications contained drug-drug interaction studies for a total of 117 studies. In period II, 106 applications reported drug-drug interaction studies, and the number of studies per new molecular entity ranged from 0 to 15. Most studies (77%) were performed in healthy subjects, with 44% using crossover designs, 7% using parallel designs, and the remaining using fixed sequence designs. The most common dosing scheme for new molecular entities/interacting drug was multiple dose (47%), whereas single dose/multiple dose was used in 31% of studies, and single dose/single dose was used in 18% of studies. Of the 540 drug-drug interaction studies submitted in period II, 80 (15%) resulted in clinically significant labeling statements. Submissions for new molecular entities to the Center for Drug Evaluation and Research divisions most likely to include drug-drug interaction studies were neuropharmacology, cardiorenal, antiviral, and antiinfective drugs. Some drug classes such as oncology drug products and radioimaging products were least likely to include drug-drug interaction studies in their submissions. We conclude that the use of drug-drug interaction studies in the drug development process has increased between the two periods.

Pharmacokinetics and pharmacodynamics of acepromazine in horses

A specific, sensitive, reverse-phase high-performance liquid chromatographic assay for acepromazine, with analytic sensitivity as low as 5 ng/ml of plasma, and electrochemical detection with an oxidation potential of 0.7 V, was used to study the pharmacokinetics of acepromazine given at a dosage of 0.15 mg/kg of body weight in horses. The relation between effect and pharmacokinetics of the drug was examined. The effects studied included those on blood pressure, pulse, PCV, measures of respiration function, and sedation. Intravenously administered doses led to a biphasic concentration decay pattern with an alpha-phase distribution half-life of < 3 minutes. The beta-phase half-life was in the range of 50 to 150 minutes. The CNS effects peaked at 20 minutes after administration, and the hemodynamic effects peaked at 100 minutes. In all horses, the most sensitive variable was the PCV, which decreased by up to 20% (P < 0.0001). Systolic, diastolic, and mean blood pressures decreased (P < 0.0001); heart rate was unchanged (P > 0.05). Neither blood gas tensions nor blood pH changed noticeably (P > 0.05). In all horses studied, acepromazine had a significant (P < 0.0001) sedative effect, as observed by posture and alertness. None of the observed pharmacodynamic effects correlated well with plasma acepromazine concentration. These effects persisted beyond the time of detectable acepromazine concentration, indicating that they might be caused by active metabolites, or that their timing could result from complex pharmacokinetic compartment influences.

Red blood cell partitioning, protein binding and lipophilicity of six phenothiazines

Hexane-water partition coefficients, pKa values, protein binding and red blood cell partitioning were studied with six phenothiazine drugs. Red cell partitioning was independent of drug concentration, and there was no correlation between partitioning and physicochemical characteristics. Red cell partitioning could be used indirectly to estimate protein binding, but two potential pitfalls of general importance were found. Failure to consider drug binding of glassware and haematocrit changes were shown to induce incorrect estimates of both red cell partitioning and protein binding, as well as hexane-water partition coefficients.