Azoospermia in rabbits following an intravas injection of Vasalgel ™.

Donald Waller,Elaine Lissner,Christopher Premanandan,Gary Gamerman,David Bolick

doi:10.1186/s12610-016-0033-8

Donald Waller, Elaine Lissner + Show 3 more

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https://doi.org/10.1186/s12610-016-0033-8

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Journal: Andrologie	Publication Date: Mar 30, 2016
Citations: 61	License type: CC BY 4.0

Affiliation: The Ohio State University

Abstract

BackgroundVasectomy is currently the only long-acting contraceptive option available for men, despite increasing demand and potentially significant positive impacts on human health of additional male contraceptive options. Vasalgel ™ is a high molecular weight hydrogel polymer being developed as a non-hormonal long-acting reversible male contraceptive. Vasalgel consists of styrene-alt-maleic acid dissolved in dimethyl sulfoxide, which is distinct from styrene-alt-maleic anhydride materials previously studied.MethodsThe goal of the study was to determine the contraceptive efficacy of two test articles with different levels of styrene maleic acid (100 %, and 80 % acid/20 % anhydride). The test articles were injected bilaterally in the vasa deferentia of mature male rabbits. Post-implantation analyses of semen parameters were completed over a 12 month period and compared to baseline measures of sperm concentration, motility and forward progression.ResultsBoth test articles were effective in blocking the passage of spermatozoa through the vasa deferentia in the 12 subjects completing the study. A significant decrease in sperm concentration occurred following implantation of the test material, with no measurable sperm concentration except for a few samples in one animal that were markedly oligospermic. Vasalgel produced a rapid onset of azoospermia, with no sperm in semen samples collected as early as 29–36 days post-implantation, and was durable over a 12 month period.ConclusionThis study indicated that Vasalgel is an effective non-hormonal long-acting male contraceptive in a rabbit model.

Highlights

Vasectomy is currently the only long-acting contraceptive option available for men, despite increasing demand and potentially significant positive impacts on human health of additional male contraceptive options
The average molecular weight (Mw) of the SMA anhydride (Poly(Styrene-co-Maleic Anhydride, CAS Registry Number: 9011-13-6) was 330 kDa according to standardized gel permeation chromatography (GPC) methodology (Jordi Labs, Mansfield, MA, USA)
Extravasation of a small amount of test material occurred in four vasa deferentia and one became distended when the material was injected

Summary

Introduction

Vasectomy is currently the only long-acting contraceptive option available for men, despite increasing demand and potentially significant positive impacts on human health of additional male contraceptive options. Vasalgel TM is a high molecular weight hydrogel polymer being developed as a non-hormonal long-acting reversible male contraceptive. The unmet need for modern contraception in developing countries was estimated at 222 million in 2012 Serving this need would prevent 54 million unintended pregnancies, including 26 million abortions [2]. Male and female contraceptive methods are often used inconsistently or discontinued early for a myriad of reasons (e.g., lack of access to product supply or prescriptions; unwanted side effects or health concerns; seeking a more effective method), accounting for 33 million of the accidental pregnancies worldwide [3, 4].

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