Substitution of nevirapine for efavirenz in virologically controlled patients intolerant of efavirenz

Purpose of the Study

Efavirenz (EFV) is an important and frequently prescribed component of triple-combination antiretroviral therapy. However, many patients are unable to tolerate the neuropsychiatric side-effects of this medication. Nevirapine (NVP), another potent non-nucleoside RT inhibitor may be able to be substituted for EFV in patients who experience side-effects. This study is a retrospective review of patients in a large HIV specialty private practice who were switched from EFV to NVP from 1998 through 2007. Earlier results from a portion of this cohort have previously been published [1].

Methods

Patients who were virologically controlled (HIV-1 PCR < 50) or initiating therapy on an EFV-based regimen were switched to NVP, continuing the other components of their regimen. EFV was continued during the 2-week induction dosing of NVP; since 2003 for patients with T4 cell counts >400, NVP was started at 100 mg/day for 2 weeks then increased to 200 mg/day for another 2 weeks before increasing to full dose.

Summary of Results

63 patients were identified who switched from EFV to NVP. Patients had been on EFV from one to 69 months. Mean T4 cell count at the time of switch was 607/mm3 (range 176–1236); 53 (84%) patients had a T4 count greater than 400 at the time of switch. One patient had acute hepatic toxicity at day 8 and is excluded from further analyses. No patient developed a rash on initiation of NVP. All patients became or have stayed undetectable (HIV-1 PCR < 50) for periods from 6 to 116 months (mean 50 months) after switch. The most recent T4 cell count has increased by a mean 113 cells since switch (p < 0.001).

Lipid values (mean of last two values before switch compared to mean of first two after switch) improved significantly: total cholesterol decreased by 12 mg/dl (0.31 mmol/L) (p < 0.02), LDL decreased by 7 mg/dl (0.16 mmol/L) (p < 0.05), HDL increased by 6 mg/dl (0.18 mmol/L) (p < 0.001) and triglycerides decreased by 42 mg/dl (0.47 mmol/L) (p < 0.02).

Conclusion

NVP can be successfully substituted for EVF in patients unable to tolerate the neuropsychiatric side-effects of EFV, with maintenance of virologic control and improvement of lipid parameters.