Clinical evidence,mechanism, importance and management
A woman who had previously had bilateral lumbar sympathectomy for Raynaud’s disease developed total urinary incontinence when given methyldopa 500mg to 1.5 g with phenoxybenzamine 12.5mg daily,but not when she was taking either drug alone. This would seem to be outcome of additive effects of sympathectomy and two drugs on sympathetic control of bladder sphincters (See reference number 1). Stress incontinence has previously been described with these drugs. The general importance of this interaction is probably small.
1. Fernandez PG,Sahni S, Galway BA, Granter S, McDonald J. Urinary incontinence due to interaction of phenoxybenzamine and :5.5pt; font-weight:normal; color:#000000″>α-methyldopa. Can Med Assoc J (1981) 124, 174.