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4658965 
Journal Article 
Azoospermia in rabbits following an intravas injection of Vasalgel ™ 
Waller, D; Bolick, D; Lissner, E; Premanandan, C; Gamerman, G 
2016 
26 
1 
6 
English 
27030808 
MEDLINE:27030808 
BACKGROUND: 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 ™ 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.

METHODS: The 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.

RESULTS: Both 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.

CONCLUSION: This study indicated that Vasalgel is an effective non-hormonal long-acting male contraceptive in a rabbit model.