Prof Sujoy Guha, a biomedical engineer from India, invented Reversible Inhibition of Sperm Under Guidance (RISUG). RISUG is a polymer gel that’s injected into Vas deferens, the sperm-carrying (tubes) duct in the scrotum which conveys sperm from the testicle to the urethra. It can be reversed with a second shot that breaks down the gel.
RISUNG is a synthetic polymer. It is Styrene Maleic Anhydride (SMA), is a chemical compound for providing reversible male contraception through the injection. Polymer SMA or SMAnh) is a synthetic polymer that synthesised by maleic anhydride monomers and styrene. The monomers can be almost perfectly alternating, making it an alternating copolymer, or random co-polymerisation with less than 50% maleic anhydride content. The polymer is formed by a radical polymerization, using an organic peroxide as the initiator. The characteristics of SMA copolymer are its transparent appearance, high heat resistance, high dimensional stability, and the specific reactivity of the anhydride groups. The latter feature results in the solubility of SMA in alkaline (water-based) solutions and dispersion.
SMA is available in a broad range of molecular mass and maleic anhydride (MA) contents; SMA is available as a crystal clear granule that can be used in a wide variety of applications. SMA polymers with a high molecular weight are widely used in engineering plastic applications, normally in the impact modified and optional glass fibre filled variants.
SMA can be combined with the solvent Dimethyl Sulphoxide (DMSO) RISUG The process is under phase III clinical trials in India and is a non-surgical method of male sterilisation. It is inexpensive, highly effective, and reversible. It involves an injection of the solution into each of the patient's Vas deferens.
Over the last two decades, RISUG has been drawing attention in the field of male contraception. It promises to sterile men for a period of up to 10-15 years. According to recent studies in animal models, it proves to be completely reversible. Reversal of contraception with RISUG through dimethyl sulphoxide (DMSO) further, sodium bicarbonate (NaHCO3) was used as another mode of reversal which also showed a complete resumption of fertility. For Human, Reversible process is not tried so far. No side effect is observed such as mutagenicity, genotoxicity and carcinogenicity are being evaluated at many centres in India.
Mode of action of SMA and the mechanism of bio-adhesion and bio-sustainability in the vas deferens was poorly explained. Early experiments carried out in rats and monkeys showed loss of fertility by -lowering pH effect and convinced to be an effective contraceptive. Morphological alterations in vas deferens are also documented. The most convincing argument put forward by Prof Guha Polymer forms a layer around the vas walls ( ducts wall or tube wall) partially (but not completely) blocking the flow of sperm cells. As cells pass by the substance, in this process cell wall of sperm get destroyed thus sperm become inactive.
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