(212) Reversibility of Plan A™’s Vasalgel®, an On-Demand Reversible Hydrogel Occlusive Device

Abstract Authors: Kyla M. Raoult1; Chris Groberg2; Chadrick Jennings2; Husain Sodowalla2; Andrew Allen2; Aaron J. Tabor1,2; Robert S. Kellar1,2; Darlene R. Walley1

1.      NEXT Life Sciences, Inc., San Luis Obispo, CA, USA

2.      Development Engineering Sciences, LLC., Flagstaff, AZ, USA

Abstract Text:

A recent breakthrough in male reproduction is the successful use of hydrogel technology to create long-lasting, reversible male contraceptive options.^1–4 Plan A^TM is a proprietary medical device contraceptive system consisting of a hydrogel solution (Vasalgel®), a Delivery Lumen Access Device (DLAD) and a Reversal Lumen Access Device (RLAD). The Plan A^TM Male Contraceptive System is intended for adult men who desire a long-acting, on-demand reversible contraceptive method by occlusion of the vas deferens. The efficacy of the occlusion system of Plan A^TM, Vasalgel® hydrogel, to block the passage of sperm has been shown in one and two year rabbit and rhesus macaques animal studies, respectively.^2,3 The ability of Plan A^TM occlusion to be on-demand reversed has been demonstrated in a published in vivo rabbit study, after 14 months of occlusion⁴, and in ex vivo laboratory experiments using bovine and human cadaver vas deferens, under physiologically relevant conditions.

Vasalgel® is composed of styrene maleic acid copolymer (SMA) dissolved in dimethylsulfoxide (DMSO), with tunable properties that allow the one-component polymer solution to be transformed into a physically crosslinked hydrogel. This physically crosslinked hydrogel swells within the lumen of the vas deferens, adhering to the walls of the lumen, creating a barrier to sperm while allowing the passage of fluid.  The addition of sodium bicarbonate leads to a pH change and dilution of the hydrogel, facilitating the on-demand reversal and ultimate collapse of the polymer structure, creating a water-like solution. The focus of this poster will be on the on-demand reversibility of Plan A^TM’s Vasalgel® occlusion system.

Vasalgel® hydrogel’s on-demand reversal was demonstrated in an ex vivo study whereby occlusions formed in bovine vas deferens were reversed in under 5 min, using 5 mL or less of 8.4% sodium bicarbonate solution.  The reversal procedure was performed in conjunction with light mechanical agitation to fully restore patency post-reversal.

Collective animal studies have shown that Vasalgel® is on-demand reversible after over one year of effective occlusion. Furthermore, ex vivo experiments have shown that the reversal of Vasalgel® is simple, fast and effective, requiring small volumes of reversal solution and light mechanical agitation. Vasalgel® has proven to be a promising effective, long acting, on-demand reversible hydrogel for use as a non-hormonal male contraceptive.