Inhibitory effect of carbamazepine on hypotensive action of spironolactone in primary aldosteronism

Abstract

Despite progress made in recent years, interactions between various drugs are far from being fully understood. Moreover, a peculiarity of constitution causes that some individuals in particular situations respond differently to a drug or treatment than do most people. We report the case of a 68-year-old female with primary aldosteronism treated with spironolactone. The patient occasionally suffered from trigeminal neuralgia and was then prescribed with carbamazepine, which although alleviated pain worsened the control of blood pressure. To maintain blood pressure within normal limits the doses of spironolactone had to be increased. Replacement of carbamazepine with gabapentin prevented these drug-induced increases in blood pressure in our patient. This case shows for the first time the existence of a drug interaction between spironolactone and any anti-epileptic drug in primary aldosteronism.