BioSante Pharmaceuticals, Inc. (NASDAQ: BPAX), today announced additional results from its principal LibiGel (testosterone gel) pharmacokinetic (pK) study. Top line data from this study were announced on September 12, 2011. The pK study results indicate that LibiGel increases levels of free testosterone (the active testosterone component) in the serum of postmenopausal women to within the normal ranges for younger, premenopausal women. LibiGel is in development for the treatment of female sexual dysfunction (FSD), specifically, hypoactive sexual desire disorder (HSDD) in postmenopausal women, for which there is no FDA-approved product.
The pK study was conducted in 24 surgically postmenopausal subjects in three contiguous 21 day periods for a total of 63 days, in the absence of estrogen therapy (study period 1), with a concomitant transdermal estradiol patch (study period 2) and finally with concomitant oral estrogen (study period 3). LibiGel was dosed at 0.22 grams daily, the same dose as included in the two LibiGel pivotal safety and efficacy trials and safety study. The mean free testosterone level at baseline was 1.4 pg/ml. During the study, subjects in the pK study demonstrated a mean free testosterone of approximately 3.5 pg/ml on day 14, and 4.1 pg/ml on day 21 (at the end of study period 1) and approximately 4.5 pg/ml on study day 42 (at the end of 21 days of transdermal estradiol co-therapy in period 2). During study period 3, the mean free testosterone level was approximately 3.7 pg/ml. Free testosterone returned to baseline levels within 24 hours after the last dose of LibiGel, indicating effective elimination after dosing is discontinued.
The levels of free testosterone in the LibiGel pK study were similar to those seen in the BioSante LibiGel Phase II efficacy trial which ranged from 2.8 pg/ml to 3.6 pg/ml. These levels also were similar to those reported in the two pivotal testosterone patch (Intrinsa) studies which showed efficacy in treating HSDD in estrogen-treated surgically menopausal women, which were 4.0 pg/ml at 12 weeks and 3.1 pg/ml at week 24 and 4.0 pg/ml at week 24, respectively. In a recent publication, it was shown that serum testosterone concentrations in normally cycling 30-year-old pre-menopausal women range from 1.2 pg/ml to 6.4 pg/ml. However, generally, blood levels are not compared between studies because different studies performed at different times with different assays can produce varying testosterone blood levels.
In the LibiGel Phase III clinical studies, baseline testosterone levels, although collected, are not an inclusion or exclusion criterion, per FDA suggestion, since therapy for HSDD is meant for symptomatic treatment of HSDD and not testosterone levels. BioSante plans to present the full pK study results at an upcoming medical meeting. The LibiGel pK study was conducted as part of the FDA-requested studies to be submitted in the LibiGel new drug application (NDA) which is anticipated in the fourth quarter of 2012.
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