Interactions
Valproic acid may interact with carbamazepine, as valproates inhibit microsomal epoxide hydrolase (mEH), the enzyme responsible for the breakdown of carbamazepine-10,11 epoxide (the main active metabolite of carbamazepine) into inactive metabolites. By inhibiting mEH, valproic acid causes a buildup of the active metabolite, prolonging the effects of carbamazepine and delaying its excretion.
Valproic acid also decreases the clearance of amitriptyline and nortriptyline.
Aspirin may decrease the clearance of valproic acid, leading to higher-than-intended serum levels of the anticonvulsant. Also, combining valproic acid with the benzodiazepine clonazepam can lead to profound sedation and increases the risk of absence seizures in patients susceptible to them.
Valproic acid and sodium valproate reduce the apparent clearance of lamotrigine (lamictal). In most patients, the lamotrigine dosage for coadministration with valproate must be reduced to half the monotherapy dosage.
Valproic acid is contraindicated in pregnancy, as it decreases the intestinal reabsorption of folate (folic acid), which leads to neural tube defects. Because of a decrease in folate, megaloblastic anemia may also result. Phenytoin also decreases folate absorption, which may lead to the same adverse effects as valproic acid.
Read more about this topic: Valproic Acid
Famous quotes containing the word interactions:
“In child rearing it would unquestionably be easier if a child were to do something because we say so. The authoritarian method does expedite things, but it does not produce independent functioning. If a child has not mastered the underlying principles of human interactions and merely conforms out of coercion or conditioning, he has no tools to use, no resources to apply in the next situation that confronts him.”
—Elaine Heffner (20th century)
“The exercise of power is determined by thousands of interactions between the world of the powerful and that of the powerless, all the more so because these worlds are never divided by a sharp line: everyone has a small part of himself in both.”
—Václav Havel (b. 1936)
“In our interactions with people, a benevolent hypocrisy is frequently required—acting as though we do not see through the motives of their actions.”
—Friedrich Nietzsche (1844–1900)