Potentiation of hypotensive effect of debrisoquine by insulin

A 36-year-old man who had been an insulin-dependent diabetic for 27 years developed severe postural hypotension only when taking debrisoquine and a short-acting insulin. Hourly recordings of lying and standing blood pressure after an oral dose of debrisoquine in the presence and absence of short-acting insulin confirmed an interaction between the drugs causing symptoms of postural hypotension which may be confused with hypoglycaemia.