Efavirinez

Efavirenz treatment results in increases in CD4+ cell counts and a decrease in viral load comparable to that achieved by protease inhibitors when used in combination with NRTIs. Therefore, it is the preferred NNRTI on the DHHS guidelines. Following oral administration, efavirenz is well distributed, including to the CNS. It should be administered on an empty stomach to reduce adverse CNS effects. Most of the drug is bound to plasma albumin (99 percent) at therapeutic doses. A halflife of more than 40 hours accounts for its recommended once-aday dosing. Efavirenz is extensively metabolized to inactive products. Efavirenz is a potent inducer of CYP450 enzymes and, therefore, may reduce the concentrations of drugs that are substrates of the CYP450. Most adverse effects are tolerable and are associated with the CNS, including dizziness, headache, vivid dreams, and loss of concentration.,skin,rash Nearly half of the patients experience these complaints, which usually resolve within a few weeks. Rash is the other most common side effect, with an incidence of approximately 25 percent. Severe, life-threatening reactions are rare. Efavirenz should be avoided in pregnant women.