A proton NMR study of the effect of a new intravasal injectable male contraceptive RISUG on seminal plasma metabolites

Nuclear magnetic resonance (NMR) spectroscopy was used to quantify citrate, glucose, lactate, glycerophosphorylcholine and choline in seminal plasma f rom subjects injected with a new male contraceptive RISUG, a copolymer of s tyrene maleic anhydride dissolved in dimethyl sulphoxide, and in seminal pl asma from normal ejaculates. No significant difference in the concentration of citrate was observed between the groups, indicating that the prostate i s not affected by the contraceptive. The concentrations of glucose, lactate , glycerophosphorylcholine and choline were significantly lower (P < 0.01) in subjects injected with RISUG compared with controls. In addition, metabo lite ratios such as choline:citrate, citrate: lactate, choline:lactate and glycerophosphorylcholine:choline were calculated. Citrate:lactate and glyce rophosphorylcholine:choline ratios were significantly lower in RISUG-inject ed subjects than in controls (P < 0.01), thereby indicating the occurrence of partial obstructive azoospermia. The most important finding of the prese nt study was that the intervention of RISUG in the vas deferens even for a period as long as 8 years is absolutely safe and does not lead to prostatic diseases.