September 15, 2003
A common strategy for the treatment of HIV-infected patients is switching to a non-nucleoside reverse transcriptase inhibitor (NNRTI) from a protease inhibitor (PI) for various reasons including virologic failure, side effects, intolerance and treatment simplification. There is limited data on the long-term safety and efficacy of this. Gil and colleagues conducted a prospective, observational, longitudinal study of 143 subjects who were switched from a PI to nevirapine (NVP, Viramune).
To enter the study, patients had to have a HIV viral load of less than 200 copies/mL for at least three months prior to entry.
The characteristics of this cohort were as follows: mean age was 41 years (range 25-69), 82.5 percent were male, 60 percent CDC category A, 17.5 percent were co-infected with hepatitis C (HCV) and 70 percent were naive to antiretroviral therapy (ART) at the time they started the PI regimen prior to the switch. The mean CD4 cell count at the time of the switch was 608 +/- 341 cells/µL.
|Reasons for Switching||Number||Percentage|
Follow-up data was available for 114 subjects for one year, 106 subjects for two years and 96 subjects for three years.
The efficacy of the treatment for maintaining undetectable viral load (less than 200 copies/mL) in the first, second and third years were 79.7 percent, 74.1 percent and 67.3 percent using an "intention to treat" analysis (missing = failure) and 96.6 percent, 98.1 percent and 97 percent using an "on treatment" analysis, respectively.
Overall, nine patients (6.3 percent) had a viral rebound: four in the first year, two in the second year and three in the third year. Sixteen patients (11.2 percent) stopped nevirapine due to side-effects: rash (n=7 all of which occurred in the first 15 days); clinical hepatitis (n=2); transaminase elevations (n=5) and methadone interaction (n=2).
The liver toxicity was associated with patients who were co-infected with hepatitis C and two subjects developed hepatitis A. All but two of the side-effects occurred in the first year after the switch.
Other reasons for treatment discontinuation included subjects who voluntarily stopped all ART (n=8), who were lost to follow-up (n=9) and who changed to a more simplified treatment (n=3).
The mean CD4 cell count increased by 8.7 percent, 12.6 percent and 17.7 percent in years one, two and three, respectively. By my calculations, this would be an increase of 108 cells by year three. They also reported the percent reduction of total cholesterol and triglycerides in years one, two and three as 21 percent, 20 percent, 19 percent and 71 percent, 69 percent, 72 percent, respectively. These are large percent reductions in triglyceride (TG) levels.
I spoke with Dr. Gil who explained that many of the patients had TG levels greater than 1,000 mg/dL which decreased to about 300 mg/dL after switching to nevirapine. However, the numbers with fasting lipids were small with only 28 subjects having a mean total cholesterol more than 240 mg/dL at baseline and 18 subjects with a mean TG more than 400 mg/dL at baseline which were used for the lipid analysis.
The investigators concluded that a simplified highly active antiretroviral therapy (HAART) with nevirapine and two nucleotide/nucleoside reverse transcriptase inhibitors (NRTIs) maintains viral control in 97 percent of patients on treatment. This high success rate may be attributed to the fact that the majority of these subjects were naive to ART when they started their PI-containing regimen and switched after achieving sustained virologic suppression. Nevirapine side-effects rarely occurred after the first year of therapy. This study is consistent with other switch studies reported and remains a viable option for those patients not tolerating a PI regimen due to side effects, metabolic complications or simply a desire for treatment simplification.
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