[A new cause of resistant arterial hypertension: coprescription with anticonvulsant treatments].
This article provides two case reports about pharmacokinetic interactions with hypertensive drug therapy and anticonvulsive treatment. First, a 49-year-old patient presenting severe hypertension had a non-traumatic cerebral hemorrhage with convulsions. Extensive etiologic investigations did not find any cause of secondary hypertension. Under an association of four antihypertensive drugs regimen, associated with carbamazepine blood pressure was not controlled. Finally, blood pressure was well controlled after replacement of carbamazepine with vigabatrin. The second case reports a 64-year-old treatment-resistant essential hypertensive patient, carbamazepine was associated with antihypertensive treatment because of aggressivity attributed to Alzheimer's disease. After withdrawal 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 cytochrome P450 3A4 isoform that could explain a significantly decreased half-life in association with enzymatic inducers, such as rifampicine or antiepileptic drugs (phenobarbital, phenytoin or carbamazepine).


CONCLUSIONS
When blood pressure is not controlled without cause of secondary hypertension, physicians must be careful with drug-drug interactions.
Iaria
P
P
Service de médecine interne-thérapeutique, hôpital Broussais, Paris.
Blacher
J
J
Asplanato
M
M
Edric
K
K
Safar
M
M
Girerd
X
X
D000927:Anticonvulsants / Q000493:pharmacokinetics / Q000627:therapeutic use*; D000959:Antihypertensive Agents / Q000493:pharmacokinetics / Q000627:therapeutic use*; D002121:Calcium Channel Blockers / Q000493:pharmacokinetics / Q000627:therapeutic use; D002220:Carbamazepine / Q000493:pharmacokinetics / Q000627:therapeutic use; D004347:Drug Interactions; D004351:Drug Resistance; D006801:Humans; D006973:Hypertension / Q000188:drug therapy*; D008297:Male; D008875:Middle Aged; D009529:Nicardipine / Q000493:pharmacokinetics / Q000627:therapeutic use
D000927:Anticonvulsants; D000959:Antihypertensive Agents; D002121:Calcium Channel Blockers; D002220:Carbamazepine; D009529:Nicardipine