REVERSIBLE CHEMICAL SPHINCTEROTOMY BY LOCAL APPLICATION OF GLYCERYL TRINITRATE

Nitric oxide has emerged as one of the most important neurotransmitter s mediating internal anal sphincter relaxation. The effect of glyceryl trinitrate, a nitric oxide donor, on anal tone was examined. Maximum resting pressure, predominantly a function of the smooth muscle intern al anal sphincter, was measured before and 20 min after application of 0.2 per cent glyceryl trinitrate ointment in ten patients. Pressure d ecreased by a mean of 27 per cent (95 per confidence interval 18-36 pe r cent) (P= 0.0004) after administration of the drug. A further 20 pat ients were then randomized to either active or placebo ointment. Anal pressure was significantly decreased (P=0.002) in those who received 0 .2 per cent glyceryl trinitrate, but there was no significant reductio n in the control patients. Mild headache occurred in two patients who were given the active preparation and in one who received placebo. Man ometry was repeated 9 h after application of glyceryl trinitrate and s howed a sustained decrease in pressure in two patients. Topical glycer yl trinitrate may have a role in the treatment of anal fissure, haemor rhoids, certain types of constipation and anal pain. It may also reduc e injury to the internal sphincter during peranal operations.