OBJECT DRUGS

• Lamotrigine (Lamictal, etc.)

PRECIPITANT DRUGS

Enzyme Inducers:

• Barbiturates
• Carbamazepine (Tegretol, etc.)
• Dabrafenib (Tafinlar)
• Efavirenz (Sustiva)
• Nevirapine (Viramune, etc.)
• Oxcarbazepine (Trileptal, etc.)
• Phenytoin (Dilantin, etc.)
• Primidone (Mysoline)
• Rifabutin (Mycobutin)
• Rifampin (Rifadin, etc.)
• Rifapentine (Priftin)
• St. John's wort

Comment:

Enzyme-inducing drugs have been shown to reduce lamotrigine serum concentrations, probably by increasing lamotrigine glucuronidation. Some evidence suggests that lamotrigine may increase the risk of carbamazepine toxicity, but this has not been a consistent finding.

Class 3: Assess Risk & Take Action if Necessary

• Monitor: Monitor for altered lamotrigine effect if enzyme inducers are initiated, discontinued, or changed in dosage. Adjustments in lamotrigine dosage may be necessary. Keep in mind that enzyme induction is usually gradual and may take days to weeks for onset and offset, depending on the specific inducer.