Reversible Inhibition Of Sperm Under Guidance

B. Pharm, S.P.E.R, Jamia Hamdard, New Delhi Race With Dreams! © 2015-2016

Reversible inhibition of sperm under guidance (RISUG), formerly referred to as the synthetic polymer styrene maleic anhydride(SMA), is the development name of a male contraceptive injection developed at IIT Kharagpur in India by the team of Dr. Sujoy K. Guha. Phase III clinical trials are underway in India, slowed by insufficient volunteers. It has been patented in India, China, Bangladesh, and the United States. A method based on RISUG, Vasalgel, is currently under development in the US however there has been little or no progress in terms of bringing the product to market.

Mechanism of action

RISUG works by an injection into the vas deferens, the vessel through which the sperm moves before ejaculation. RISUG is similar to vasectomy in that a local anesthetic is administered, an incision is made in the scrotum, and the vasa deferentia are injected with a polymer gel (rather than being cut and cauterised). In a matter of minutes, the injection coats the walls of the vasa with a clear gel made of 60 mg of the copolymer styrene/maleic anhydride (SMA) with 120 µl of the solvent dimethyl sulfoxide. The co-polymer is made by irradiation of the two monomers with a dose of 0.2 to 0.24 megarad for every 40 g of co-polymer and a dose rate of 30 to 40 rad/s. The source of irradiation is cobalt-60 gamma radiation.

The effect the chemical has on sperm is not completely understood. Originally it was thought that it lowered the pH of the environment enough to kill the sperm. More recent research claims that this is not enough to explain the effect.

Professor S. K. Guha theorizes that the polymer surface has a negative and positive electric charge mosaic. Within an hour after placement the differential charge from the gel will rupture the sperm's cell membrane as it passes through the vas, deactivating it before it can exit from the body.

Advantages

Some of the advantages, according to Dr. Guha, are:

• Effectiveness - There has been only one unplanned pregnancy among partners of the 250 volunteers who have been injected RISUG  apparently due to an improperly administered injection. Out of the 250 volunteers who have been injected RISUG, 15 received the injection more than 10 years ago.
• Convenience - There is no interruption before the sexual act.
• Cost - The shot itself costs less than the syringe used to administer it, and its long term effectiveness would make it theoretically only a four or five time cost, in the entire lifetime of someone who chose to continue to be on it.
• Outpatient procedure - Patients can leave the hospital immediately after an injection and resume their normal sex lives within a week.
• Duration of effect - According to Dr. Guha, a single 60 mg injection can be effective for at least 10 years.
• Reduced side effects - After testing RISUG on more than 250 volunteers, neither Guha nor other researchers in the field report have reported any adverse side effects other than a slight scrotal swelling in some men immediately following the injection which goes away after a few weeks. Because semen, including inactive sperm, still exits the body following ejaculation, patients do not experience the pressure or granulomas that sometimes result after a vasectomy procedure.

Potential hazards

The thoroughness of carcinogenicity, teratogenicity, and toxicity testing in clinical trials has been questioned. In October 2002, India's Ministry of Health aborted the clinical trials due to reports of albumin in urine and scrotal swelling in Phase III trial participants. Although the ICMR has reviewed and approved the toxicology data three times, WHO and Indian researchers say that the studies were not done according to recent international standards. Due to the lack of any evidence for adverse effects, trials were restarted in 2011.