VIAGRA : IS IT A WONDER DRUG ?

VIAGRA : IS IT A WONDER DRUG ?

Male erectile dysfunction is common and frustrating after the age of forty years. Erectile dysfunction is a cause of misery, relationship difficulties, and significantly reduced quality of life. Sildenafil citrate (Viagra) has shown promising results in recently published clinical trials. Sildenafil is a potent and competitive inhibitor of cGMp specific phosphodiesterase-5, predominant isoenzyme in the human corpus cavernosum. It is effective in erectile dysfunction of diverse origin, however it requires a patent vascular system to be effective. It is not effective in patients with endocrinal impotence, loss of libido, premature ejaculation or infertility. Its main adverse effects are headache, flushing, dyspepsia, diarrhoea, nasal congestion, indigestion, visual disturbances, dizziness and rash. Ventricular tachycardia and acute myocardial infraction have been reported in patients of ischaemic heart disease after consumption of sildenafil. Six deaths have been reported in patients taking nitrates. In India it is likely to be prescribed by a primary care physician without complete evaluation of patient on complaint of impotence. Hence the ethical question of who should prescribe this drug should be addressed by medical fraternity and proper guidelines formulated to avoid misuse of sildenafil. Phosphodiesterase is distributed in nerve, central nervous system, and systemic vasculature, hence long-term effects of drug on these tissues has to be ascertained. It should be made mandatory to report all adverse drug reactions to ADR monitoring centres. It is a wonder for those who require it, but has potentially dangerous adverse effects and drug interactions and hence is and not a wonder pill for all kinds of impotence.KEY WORDS: Erectile dysfunction, Impotence, Phosphodiesterase inhibitor, Sildenafil citrateMale erectile dysfunction has been defined as the persistent inability to attain and/or maintain penile erection sufficient for satisfactory sexual performance [1]. The prevalence of erectile dysfunction ranges from 52% in men aged 40-70 years to greater than 95% in men over 70 [2]. Improved understanding of peripheral and central mechanism for erection [3] has resulted in trials of various drugs [4, 5, 6, 7]. Dr Simon Campbell while working on newer molecules for angina discovered sildenafil citrate, which has shown promising results in recently published clinical trials [8, 9, 10]. This drug was approved in USA by the FDA on 27 March 98 [11] and licence was granted for sale in Europe by European Medicine Evaluation Agency in third week of September 98 [12]. In India various companies are exploring the possibilities of its sale [13].