HIV Treatment - Efavirenz [T88.7]
OMIM number: 123930 (CYP2B6)
Dipl.-Biol. Birgit Busse
Genetic disposition of a patient is one factor determining the compatibility of HIV treatment with efavirenz. The enzyme CYP2B6 is involved in the metabolism of various NNRTIs (non-nucleoside reverse transcriptase inhibitors), such as efavirenz.
The CYP2B6*6 allele (c.516G>T) is associated with a reduced enzyme activity. Several studies showed an elevated plasma level of the active agent in homozygous carriers of the CYP2B6*6 allele (T/T genotype). In these patients, side-effects caused by efavirenz arise with higher frequency (prescribing information Sustiva®). Among all Caucasians, the frequency for the homozygous T/T genotype is approximately 5%.