Hypertension treatment resistance caused by drug-drug interactions with anti-epileptic drug treatment

This article provides two case reports about pharmacokinetic interactions w ith hypertensive drug therapy and anticonvulsive treatment. First, a 49-year-old patient presenting severe hypertension had a non-traum atic cerebral hemorrhage with convulsions. Extensive etiologic investigatio ns did not find any cause of secondary hypertension. Under an association o f four antihypertensive drugs regimen, associated with carbamazepine blood pressure was not controlled. Finally, blood pressure was well controlled af ter replacement of carbamazepine with vigabatrin. The second case reports a 64-year-old treatment-resistant essential hyperte nsive patient. carbamazepine was associated with antihypertensive treatment because of aggressivity attributed to Alzheimer's disease. After withdrawa l of carbamazepine treatment, blood pressure reached normal values with the same antihypertensive regimen. Those case reports suggest drug-drug interactions between antihypertensive and anticonvulsive drug therapies. Following explanation can be hypothesis: several antihypertensive drugs are liver-metabolised by microsomal cytochr ome P450 3A4 isoform that could explain a significantly decreased half-life in association with enzymatic inducers, such as rifampicine or antiepilept ic drugs (phenobarbital, phenytoin or carbamazepine). Conclusion:When blood pressure is not controlled without cause of secondary hypertension, physicians must be careful with drug-drug interactions.