Review of FTC (Emtricitabine, Emtriva) Clinical Trials and Side Effects

The Food and Drug Administration based its July approval of Emtriva for use in combination with other antiretroviral agents on data from two 48-week clinical trials. The nucleoside reverse transcriptase inhibitor Emtriva may be considered for antiretroviral treatment-experienced adults 18 and older with HIV strains that are expected to be susceptible, as assessed by genotypic or phenotypic testing.

The first trial involved 571 antiretroviral patients in a double-blind, active-controlled multicenter study comparing Emtriva (200 mg once daily) administered in combination with didanosine and efavirenz versus stavudine, didanosine, and efavirenz. The proportion of patients who achieved and maintained confirmed HIV RNA < 400 copies/mL (< 50 copies/mL) through week 48 was 81 percent (78 percent) for the Emtriva, didanosine, and efavirenz group versus 61 percent (59 percent) for the stavudine, didanosine, and efavirenz group, respectively. Mean baseline CD4 cell increase was 168 cells/mm³ for the Emtriva arm compared to 134 cells/mm³ for the control arm.

A second open-label, active-controlled study was conducted comparing Emtriva to lamivudine, in combination with stavudine or zidovudine and a protease inhibitor or NNRTI in 440 treatment experienced patients who were on a lamivudine-containing triple-antiretroviral drug regimen for at least 12 weeks prior to study entry, and had HIV-1 RNA = 400 copies/mL.

In the second trial, the proportion of patients who achieved confirmed HIV RNA < 400 copies/mL (<50 copies/mL) through week 48 was 77 percent (67 percent) for the Emtriva group versus 82 percent (72 percent) for the lamivudine group. The mean increase from baseline CD4 cell count was 29 cells/mm³ for the Emtriva arm compared to 61 cells/mm³ for the lamivudine arm.

The most common side effects of patients receiving Emtriva with other antiretroviral agents in clinical trials were headache, diarrhea, nausea, and rash, and generally ranged from mild to moderate severity. Approximately 1 percent of patients discontinued participation in the two studies due to these events. With the exception of skin discoloration, which was reported with higher frequency in the Emtriva-treated group, all other adverse events were reported with similar frequency in Emtriva and control treatment groups. Skin discoloration was predominantly observed in non-Caucasian patients; its mechanism and clinical significance are unknown.

As with other NRTIs, Emtriva may cause lactic acidosis, hepatotoxicity, with hepatomegaly, and steatosis.

Emtriva is not indicated for the treatment of chronic hepatitis B virus (HBV) infection, and the safety and efficacy of Emtriva have not been established in patients co-infected with HIV and HBV. Flare-ups of HBV, where the illness can return in a worse way than before, have been reported in patients after discontinuation of Emtriva.

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