Efavirenz Disease Interactions

Efavirenz is not recommended for patients with moderate or severe liver dysfunction; insufficient data are available to determine whether dose adjustment is needed. Patients with mild liver dysfunction may receive efavirenz without dose adjustment. Due to extensive CYP450-mediated metabolism and limited clinical experience in patients with liver dysfunction, therapy with efavirenz should be administered cautiously in patients with mild liver dysfunction; careful monitoring is recommended for these patients. In addition, postmarketing cases of hepatitis (including fulminant hepatitis progressing to liver failure requiring transplantation or resulting in death) have occurred during therapy with efavirenz; reports have included patients with underlying liver disease (including coinfection with hepatitis B or C). Monitoring of liver enzymes before and during therapy is recommended for all patients.

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During clinical trials, efavirenz was associated with an increase in the occurrence of serious psychiatric events, including severe depression, suicidal ideation, nonfatal suicide attempts, aggressive behavior, paranoid reactions, and manic reactions. Other factors associated with an increased occurrence of these psychiatric symptoms were history of injectable drug use, psychiatric history, or use of psychiatric medications at study entry; similar associations were observed in the efavirenz and control groups. Therapy with efavirenz should be administered cautiously in patients with current/history of psychiatric illness, emotional instability, or substance abuse. Patients with serious psychiatric adverse reactions should receive prompt medical evaluation to assess the possibility that symptoms are related to efavirenz use, and if so, to determine whether the risks of continued therapy outweigh the benefits.

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QTc prolongation has been observed with the use of efavirenz. Alternatives to efavirenz should be considered when administered to patients at higher risk of torsade de pointes or when coadministered with a medication with known risk of torsade de pointes.

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Convulsions have been observed in adult and pediatric patients receiving efavirenz, generally in the presence of known medical history of seizures. Caution should be taken with any patient with history of seizures. Anticonvulsant medications primarily metabolized by the liver (e.g., phenytoin, phenobarbital) may require periodic monitoring of plasma levels.

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