To increase our understanding of important subject characteristics and design variables affecting the performance of oral moxifloxacin in thorough QT studies, population pharmacokinetic and concentration-QTc models were developed by pooling data from 20 studies. A 1-compartment model with first-order elimination described the pharmacokinetics. Absorption delay was modeled using 8 transit compartments. Mean (95% confidence interval) values for oral clearance, apparent volume of distribution, the first-order absorption rate constant, and mean transit time were 11.7 (11.5-11.9) L/h, 147 (144-150) L, 1.9 (1.7-2.1) 1/h, and 0.3 (0.28-0.34) hours, respectively. Overencapsulating the moxifloxacin tablet increased mean transit time by 138% and delayed time to maximum concentration by 0.5 hours but had a minimal effect on overall exposure. Administration with food decreased absorption rate constant by 27%. Women had higher moxifloxacin exposure compared with men, which was explained by lower body weights. A linear model described the concentration-QTc relationship with a mean slope of 3.1 (2.8-3.3) milliseconds per µg/mL moxifloxacin. Mean slopes for individual studies ranged from 1.6 to 4.8 milliseconds per µg/mL. Hysteresis between moxifloxacin plasma concentrations and QTc was modest, and incorporating this delay did not result in a different slope (3.3 milliseconds per µg/mL). There were no differences in slope estimates between men and women or among race categories.

Women's participation in LPCTs averaged 43% for NDAs and 57% for BLAs in 2007-2009 and varied widely by indication. As a comparison, the 2001 U.S. Government Accountability Office (GAO) reported 52% of women's participation for drug clinical trials in1998-2000 and an FDA study reported 45% for BLAs approved from 1995 to 1999. This study showed that sex-analysis of both safety and efficacy in NDA has increased to 74% since the GAO report of 72%, while those for BLAs increased to 64% from 37% reported for therapeutic biologics approved in 1995-1999. Knowledge of disease prevalence and participation in clinical trials provides an understanding of recruitment and retention patterns of patients in these trials.

The requirement to establish safety of drugs prior to marketing has been in place since 1938 by the US Food, Drug and Cosmetic Act and is by no means a new concept. The efficacy regulations were enacted in 1962 via the Kefauver-Harris Amendment and the drug approval process has evolved thereafter. The assessment of safety and efficacy of drug products is made by pharmaceutical companies during drug development, which then goes through a regulatory review by the US FDA for the determination of market approval or nonapproval. The drug development and regulatory approval processes have endured close ongoing scrutiny by regulatory bodies, the public, US Congress and academic and private organizations and, as a result, have ensured continual refinement. Over the years, evidence has been emerging on varied drug responses in subgroup populations, and the underlying biology associated with age, race and sex as demographic variables have been examined. The resulting growing knowledge of disease burden, treatment response and disparate outcomes has generated opportunities to streamline and improve treatment outcomes in these populations. This article discusses the historical context of women's participation in clinical drug trials submitted to the FDA for regulatory review and approval purposes. The inadvertent consequences of women's exclusion or inadequate representation in past clinical trials and the evidentiary basis for understanding sex differences are also evaluated. Advances in the US regulatory processes to address treatment outcomes that are tied to the topic of this paper, specifically, adverse drug effects in women, are also discussed.

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