Application of exposure bracketing to streamline the development of contraceptive products.

Developing new long-acting products of well-characterized contraceptive drugs is one way to address some of the reasons for unmet need for modern methods of family planning among women in low- and middle-income countries. Development and approval of such products traditionally follow a conventional paradigm that includes large Phase 3 clinical trials to evaluate efficacy (pregnancy prevention) and safety of the investigational product. Exposure-bracketing is a concept that applies known pharmacokinetics and pharmacodynamics of a drug substance to inform its safe and efficacious use in humans. Several therapeutic areas have applied this concept by leveraging established drug concentration-response relationships for approved products to expedite development and shorten the timeline for the approval of an investigational product containing the same drug substance. Based on discussions at a workshop hosted by the Bill & Melinda Gates Foundation in December 2020, it appears feasible to apply exposure-bracketing to develop novel contraceptive products using well-characterized drugs.

Use of Model-Informed Drug Development to Streamline Development of Long-Acting Products: Can These Successes Be Translated to Long-Acting Hormonal Contraceptives?

Long-acting contraceptives are the most effective reversible contraceptive methods. Increasing patients' access to these contraceptives may translate into fewer unintended pregnancies and lead to substantial individual and public health benefits. However, development of long-acting products can be complex and challenging. This review provides (a) an overview of representative development programs for long-acting antipsychotics as cases for conceptual translation to long-acting contraceptives, (b) several case examples on how modeling and simulation have been used to streamline the development of long-acting products, and (c) examples of challenges andopportunities in developing long-acting contraceptives and information on how exposure-response relationships of commonly used progestins may enable regulators and developers to rely on prior findings of effectiveness and safety from an approved contraceptive to streamline the development of long-acting contraceptives. The US Food and Drug Administration is seeking assistance from stakeholders to provide data from studies in which pharmacokinetic and pharmacodynamic or clinical outcomes of hormonal contraceptives were evaluated and not previously submitted.

Efficacy and Safety of an Injectable Combination Hormonal Contraceptive for Men.

CONTEXT: The development of a safe and effective reversible method of male contraception is still an unmet need. OBJECTIVE: Evaluation of suppression of spermatogenesis and contraceptive protection by coadministered im injections of progestogen and testosterone. DESIGN: Prospective multicentre study. SETTING: Ten study centers. PARTICIPANTS: Healthy men, aged 18-45 years, and their 18- to 38-year-old female partners, both without known fertility problems. INTERVENTION: Intramuscular injections of 200-mg norethisterone enanthate combined with 1000-mg testosterone undecanoate, administered every 8 weeks. MAIN OUTCOMES MEASURES: Suppression of spermatogenesis by ejaculate analysis, contraceptive protection by pregnancy rate. RESULTS: Of the 320 participants, 95.9 of 100 continuing users (95% confidence interval [CI], 92.8-97.9) suppressed to a sperm concentration less than or equal to 1 million/mL within 24 weeks (Kaplan-Meier method). During the efficacy phase of up to 56 weeks, 4 pregnancies occurred among the partners of the 266 male participants, with the rate of 1.57 per 100 continuing users (95% CI, 0.59-4.14). The cumulative reversibility of suppression of spermatogenesis after 52 weeks of recovery was 94.8 per 100 continuing users (95% CI, 91.5-97.1). The most common adverse events were acne, injection site pain, increased libido, and mood disorders. Following the recommendation of an external safety review committee the recruitment and hormone injections were terminated early. CONCLUSIONS: The study regimen led to near-complete and reversible suppression of spermatogenesis. The contraceptive efficacy was relatively good compared with other reversible methods available for men. The frequencies of mild to moderate mood disorders were relatively high.

Treatment of vaginal bleeding irregularities induced by progestin only contraceptives.

BACKGROUND: Despite their high effectiveness, progestin-only contraceptives are considered less than ideal by the many women who experience irregular vaginal bleeding when using them. Current treatments to control these bleeding problems are not sufficiently effective. OBJECTIVES: We evaluated preventive and therapeutic approaches to normalise bleeding irregularities associated with the use of progestin-only contraceptives. SEARCH METHODS: Literature was identified through database searches, reference lists, organisations and individuals, covering the period until May-June 2012. SELECTION CRITERIA: Trials with random or systematic allocation, testing interventions for the prevention or treatment of bleeding irregularities associated with the use of progestin-only contraceptives were eligible. DATA COLLECTION AND ANALYSIS: Results are expressed as relative risks (RR) with 95% confidence interval (CI) for categorical data and as weighted mean difference (WMD) with 95% CI for continuous data. When we encountered heterogeneity (visual or statistical) we used the random-effects model (quantitative) or did not produce a summary estimate (qualitative). MAIN RESULTS: Thirty-three randomised controlled trials enrolling 3677 participants were included. Two thirds of the trials were determined to reflect low to moderate risk of bias.Estrogen treatments reduced the number of days of an ongoing bleeding episode in DMPA and Norplant users. However, treatment frequently led to more discontinuation due to gastrointestinal upset.Combinations of oral ethinyl estradiol and levonorgestrel improved bleeding patterns in Norplant users, but method discontinuation rates were unchanged. One trial reported successful use of combined oral contraceptives in treating amenorrhea among DMPA users.Norplant users, but not Implanon users, administered the anti-progestin mifepristone reported fewer days of bleeding during treatment than those given placebo. Mifepristone used monthly by new Norplant acceptors reduced bleeding, when compared to placebo.A variety of NSAIDS have been evaluated for their ability to treat abnormal bleeding, with mixed results.Norplant users receiving SERM (tamoxifen) had less unacceptable bleeding after treatment and were more likely to continue using Norplant than those receiving placebo.Tranexamic acid, mifepristone combined with an estrogen and doxycycline were more effective than placebo in terminating an episode of bleeding in women using progestin-only contraceptives, according to three small studies. AUTHORS' CONCLUSIONS: Some women may benefit from the interventions described, particularly with cessation of current bleeding. Several regimens offer promise in regulating bleeding, but findings need to be reproduced in larger trials. The results of this review do not support routine clinical use of any of the regimens included in the trials, particularly for long-term effect.

Treatment of vaginal bleeding irregularities induced by progestin only contraceptives.

BACKGROUND: Despite their high effectiveness, progestin-only contraceptives are considered less than ideal by the many women who experience irregular vaginal bleeding when using them. Current treatments to control these bleeding problems are not sufficiently effective. OBJECTIVES: We evaluated preventive and therapeutic approaches to normalise bleeding irregularities associated with the use of progestin-only contraceptives. SEARCH METHODS: Literature was identified through database searches, reference lists, organisations and individuals, covering the period until May-June 2012. SELECTION CRITERIA: Trials with random or systematic allocation, testing interventions for the prevention or treatment of bleeding irregularities associated with the use of progestin-only contraceptives were eligible. DATA COLLECTION AND ANALYSIS: Results are expressed as relative risks (RR) with 95% confidence interval (CI) for categorical data and as weighted mean difference (WMD) with 95% CI for continuous data. When we encountered heterogeneity (visual or statistical) we used the random-effects model (quantitative) or did not produce a summary estimate (qualitative). MAIN RESULTS: Thirty-three randomised controlled trials enrolling 3677 participants were included. Two thirds of the trials were determined to reflect low to moderate risk of bias.Estrogen treatments reduced the number of days of an ongoing bleeding episode in DMPA and Norplant users. However, treatment frequently led to more discontinuation due to gastrointestinal upset.Combinations of oral ethinyl estradiol and levonorgestrel improved bleeding patterns in Norplant users, but method discontinuation rates were unchanged. One trial reported successful use of combined oral contraceptives in treating amenorrhea among DMPA users.Norplant users, but not Implanon users, administered the anti-progestin mifepristone reported fewer days of bleeding during treatment than those given placebo. Mifepristone used monthly by new Norplant acceptors reduced bleeding, when compared to placebo.A variety of NSAIDS have been evaluated for their ability to treat abnormal bleeding, with mixed results.Norplant users receiving SERM (tamoxifen) had less unacceptable bleeding after treatment and were more likely to continue using Norplant than those receiving placebo.Tranexamic acid, mifepristone combined with an estrogen and doxycycline were more effective than placebo in terminating an episode of bleeding in women using progestin-only contraceptives, according to three small studies. AUTHORS' CONCLUSIONS: Some women may benefit from the interventions described, particularly with cessation of current bleeding. Several regimens offer promise in regulating bleeding, but findings need to be reproduced in larger trials. The results of this review do not support routine clinical use of any of the regimens included in the trials, particularly for long-term effect.

World Health Organization reference values for human semen characteristics.

BACKGROUND: Semen quality is taken as a surrogate measure of male fecundity in clinical andrology, male fertility, reproductive toxicology, epidemiology and pregnancy risk assessments. Reference intervals for values of semen parameters from a fertile population could provide data from which prognosis of fertility or diagnosis of infertility can be extrapolated. METHODS: Semen samples from over 4500 men in 14 countries on four continents were obtained from retrospective and prospective analyses on fertile men, men of unknown fertility status and men selected as normozoospermic. Men whose partners had a time-to-pregnancy (TTP) of < or =12 months were chosen as individuals to provide reference distributions for semen parameters. Distributions were also generated for a population assumed to represent the general population. RESULTS: The following one-sided lower reference limits, the fifth centiles (with 95th percent confidence intervals), were generated from men whose partners had TTP < or = 12 months: semen volume, 1.5 ml (1.4-1.7); total sperm number, 39 million per ejaculate (33-46); sperm concentration, 15 million per ml (12-16); vitality, 58% live (55-63); progressive motility, 32% (31-34); total (progressive + non-progressive) motility, 40% (38-42); morphologically normal forms, 4.0% (3.0-4.0). Semen quality of the reference population was superior to that of the men from the general population and normozoospermic men. CONCLUSIONS: The data represent sound reference distributions of semen characteristics of fertile men in a number of countries. They provide an appropriate tool in conjunction with clinical data to evaluate a patient's semen quality and prospects for fertility.

The acceptability of an injectable, once-a-month male contraceptive in China.

PURPOSE: An acceptability study of an injectable preparation of the synthetic steroid testosterone undecanoate as a once-a-month male contraceptive method was carried out concurrently with, but independently from, a clinical safety and efficacy trial of this preparation in China, from 1997 to 1999. METHOD: Three hundred eight men, the entire group of volunteers enrolled in the clinical trial, were interviewed using a structured questionnaire. In addition, 24 sessions of focus group discussions and 54 in-depth interviews were conducted with a broad range of stakeholders, including men enrolled in the trial and their wives, potential users, service providers, principal investigators of the six participating clinical trial centers, provincial and national policy makers, and experts engaged in research and development of male methods of contraception. RESULTS: Overall, men found the regimen to be acceptable, and most reported no change or an improvement in their well-being as a result of participating in the clinical study. The frequency of the injections, monthly semen analyses and the need to use another contraceptive method during the period of sperm suppression were reported inconveniences of the trial. CONCLUSION: Further research is needed to assess the long-term safety, continuation rates, satisfaction among users and issues related to service delivery.