Pharmacokinetics and tolerability of a novel progesterone intravaginal ring in sheep

Evaluation of 28-day estradiol and progesterone vaginal rings in a phase 1 clinical pharmacokinetic study

OBJECTIVE

The aim of this work is to develop a combination of 17β-estradiol (E2) and progesterone (P4) in a single-dose intravaginal ring (IVR) for the treatment of vasomotor symptoms (VMS) and genitourinary syndrome of menopause while providing endometrial protection. The objective of this study was to evaluate DARE-HRT1, a 28-day IVR that continuously delivers E2 and P4, in a phase 1 clinical trial to assess its pharmacokinetics.

METHODS

This was an open-label, three-arm (group) study. Thirty-two (32) healthy postmenopausal women were recruited at two Australian sites. The average age was 57.2 years (47-69 y). The first arm received one ring for 28 days designed to release E2 at a rate of 80 μg/d and P4 at 4 mg/d (80/4 IVR); the second arm received a ring releasing E2 at 160 μg/d and P4 at 8 mg/d (160/8 IVR). The third arm received oral Estrofem (1 mg E2) and Prometrium (100 mg P4) both daily for 29 days. Blood samples were taken predose then intensively over the first day (day 1) and periodically thereafter over the remaining 27 days. After removal of the rings on the morning of day 29, intensive samples were collected. Similar procedures were conducted with women enrolled in the oral group. The plasma samples were analyzed for E2, estrone (E1), and P4 using validated bioanalytical methods.

RESULTS

The baseline-adjusted steady-state plasma levels of E2 and P4 from 80/4 IVR were 20.4 ± 17.1 pg/mL and 1.32 ± 0.19 ng/mL (n = 10), respectively. The baseline-adjusted steady-state plasma levels of E2 and P4 from 160/8 IVR were 30.9 ± 8.7 pg/mL and 2.08 ± 0.50 ng/mL (n = 10), respectively. The baseline-adjusted average plasma concentrations of E2 and P4 at day 29 of the oral group were 35.4 ± 11.2 pg/mL and 0.79 ± 0.72 ng/mL (n = 11), respectively. The baseline-adjusted steady state of E1 from the 80/4 IVR and the 160/8 IVR were 22.1 ± 16.6 pg/mL (n = 10) and 25.2 ± 12.3 pg/mL (n = 10), respectively. The baseline-adjusted concentration of E1 in the oral arm was 209 ± 67.7 ng/mL (n = 11). The IVR were well tolerated, and no serious adverse events were reported.

CONCLUSIONS

The 80/4 IVR and 160/8 IVR gave similar steady-state concentrations of E2 as seen with drug products approved by the US Food and Drug Administration for treatment of VMS and genitourinary symptoms of menopause. The E2 concentrations of this study support the potential of DARE-HRT1, a promising new option for hormone therapy for treatment of VMS and vaginal symptoms associated with menopause.

Next generation strategies for preventing preterm birth

Preterm birth (PTB) is defined as delivery before 37 weeks of gestation. Globally, 15 million infants are born prematurely, putting these children at an increased risk of mortality and lifelong health challenges. Currently in the U.S., there is only one FDA approved therapy for the prevention of preterm birth. Makena is an intramuscular progestin injection given to women who have experienced a premature delivery in the past. Recently, however, Makena failed a confirmatory trial, resulting the Center for Drug Evaluation and Research's (CDER) recommendation for the FDA to withdrawal Makena's approval. This recommendation would leave clinicians with no therapeutic options for preventing PTB. Here, we outline recent interdisciplinary efforts involving physicians, pharmacologists, biologists, chemists, and engineers to understand risk factors associated with PTB, to define mechanisms that contribute to PTB, and to develop next generation therapies for preventing PTB. These advances have the potential to better identify women at risk for PTB, prevent the onset of premature labor, and, ultimately, save infant lives.

In Vitro Methods for Evaluating Drug Release of Vaginal Ring Formulations-A Critical Review

The vagina is a promising site for both local and systemic drug delivery and represents an interesting administration route for compounds with poor oral bioavailability. Whereas most of the currently marketed dosage forms were designed as immediate release formulations, intravaginal rings (IVRs) offer the possibility of a controlled vaginal drug delivery over several weeks or months. For a long time, the development of IVRs was limited to steroid-releasing formulations. Recently, IVRs have witnessed a surge of new interest as promising delivery systems for microbicides. Therefore, various novel IVR designs have been introduced. To ensure that only safe and effective IVRs will be administered to patients, it is important to properly distinguish between IVRs with desired and undesired release performance. In vitro methods for evaluating drug release of IVRs that present with sufficient predictive capacity for in vivo drug release, and discriminatory power with regard to IVRs quality, are an essential tool for this purpose. The objective of the present review article is to present the current status of in vitro drug release testing of IVRs and to critically discuss current compendial and non-official in vitro drug release methods with regard to their discriminatory power and in vivo predictivity.