Potential Interactions Between Valproate and HAART Regimens

Key Interaction Mechanisms

NNRTIs have variable effects on CYP450: nevirapine is an inducer, delavirdine is an inhibitor, and efavirenz is a mixed inducer/inhibitor, according to the American College of Physicians, as reported in the Annals of Internal Medicine 1, 2
Integrase inhibitors without pharmacologic boosters have lower potential for drug-drug interactions with valproate, as recommended by the National Comprehensive Cancer Network 3

NNRTIs have variable effects on drug metabolism: nevirapine induces, delavirdine inhibits, and efavirenz both induces and inhibits CYP450 enzymes, which may impact valproate metabolism, as reported in the Annals of Internal Medicine 1
These effects may indirectly impact valproate metabolism, though the clinical significance is less pronounced than with PIs, according to the American College of Physicians, as reported in the Annals of Internal Medicine 2

NRTIs can cause mitochondrial toxicity, which may theoretically compound valproate's rare but serious adverse effect of lactic acidosis, as reported in the Annals of Internal Medicine 1, 4
Zidovudine-associated bone marrow suppression could potentially compound valproate's effects on platelets, according to the American College of Physicians, as reported in the Annals of Internal Medicine 2

Unboosted integrase inhibitors (raltegravir, dolutegravir) have fewer drug interactions and are preferred in patients requiring valproate, as recommended by the National Comprehensive Cancer Network 3

Consider using integrase inhibitor-based regimens without pharmacologic boosters when possible in patients requiring valproate, as recommended by the National Comprehensive Cancer Network 3
Monitor for overlapping toxicities, particularly hepatotoxicity, which can be caused by both valproate and several antiretrovirals, as reported in the Annals of Internal Medicine 4