RESUMO
Background & objectives: For improved male contraception, a new polymeric drug molecule - Reversible Inhibition of Sperm under Guidance (RISUG) has been synthesized and has been found to be effective, safe and reversible in various animal species. Phase-I and phase-II clinical trials have confirmed its safety and contraceptive efficacy. The present study was undertaken as a multicentric-limited phase-III clinical trial to test the efficacy and safety of RISUG in human volunteers. Methods: One hundred and thirty nine young males each having at least two children and living with wife were given 120 µl of RISUG as bilateral vas intraluminal injection. After the single-dose administration, the individuals were followed in respect of general health and semen parameters. Their wives were also followed particularly to determine onset of pregnancy. Results: During the six month follow up, the health of male volunteers and their wives was normal with no significant adverse effects. Temporary scrotal enlargement and mild scrotal and inguinal region pain were manifested in most individuals and resolved within one month without any routine activity impairment. In six individuals, there was injection procedure failure and azoospermia was not achieved. The other 133 individuals had either severe oligozoospermia or azoospermia at the first semen examination one month following RISUG injection; 82.7 per cent individuals had continued azoospermia in the month following first semen examination onwards and the rest 17.3 per cent manifested azoospermia within three to six months. Interpretation & conclusions: RISUG intravasal injection appears to be a safe clinical procedure with no significant adverse effects and has high sustained contraceptive efficacy. The localized intervention and continued contraceptive action on single-dose administration were significant features of the RISUG technology.