Nevirapine vs efavirenz: the SENC trial

Preliminary results of the SENC Trial (Spanish efavirenz versus nevirapine comparison trial) were presented; this is a prospective, randomised, controlled, open-label study of the efficacy and safety of these two NNRTIs.

Fifty anti-retroviral naive, HIV-positive patients were randomised to either, the efavirenz arm (26 patients) or the nevirapine arm (24 patients), and both groups used the nucleosides didanosine and stavudine. The patients included in this study had plasma HIV-RNA 500-100,000 copies/ml and CD4 counts >100 cells/mm3, and the characteristics of the two groups were similar at baseline. Median CD4 was 362 and 352, and HIV-RNA was 22,254 and 20,052 in the efavirenz and nevirapine arms respectively. Follow up visits were made every 3 months, and the median follow up time overall was 9 months.

Similar results in terms of suppression of HIV-RNA were found in both arms at follow up (see Table 9 below).

Table 1. Percentage of patients with HIV-RNA <50 copies

Baseline 3 months 6 months
Nevirapine 0/24 12/19 (63.2%) 21/26 (80.8%)
Efavirenz 0/24 12/19 (63.2%) 19/24 (79.2%)

In both arms side effects were uncommon. Four patients using nevirapine and three using efavirenz developed a rash, although in no case was this severe enough to lead to drug discontinuation. Mostly mild elevation of transaminases was significantly more frequent within the nevirapine group (59%) compared to those using efavirenz (p<0.05). One patient experienced interactions between methadone and nevirapine causing discontinuation of nevirapine. One patient experienced severe cholestasis and stopped all antiretrovirals (nevirapine/didanosine/stavudine). Didanosine was stopped in four patients (two from each group) due to gastro-intestinal intolerance in three cases, and pancreatitis in one. There was no report (or even mention) of any CNS side effects in the 26 patients using efavirenz.

The investigators concluded that ‘nevirapine and efavirenz, combined with didanosine and stavudine, were equally effective in reducing HIV-RNA to <50 copies in naive patients with >100 CD4 cells/ml and <100,000 copies/ml.’ It is useful to have head-to-head studies such as this that directly compare commonly used agents, and nevirapine and efavirenz have not been addressed in this way so far.


It is strange that efavirenz specific adverse events (CNS side effects) were not reported in this presentation. It is reassuring that these early results support equivalence in virological efficacy for these two NNRTIs.


  1. M. Nunez, R Rodriguez-Rosado et al. The SENC Trial: Spanish efavirenz versus nervirapine comparison trial. Preliminary results of a prospective, randomised, controlled, open-label study in HIV-positive naive individuals. 4th International Workshop on HIV Drug Resistance & Treatment Strategies. 4th International Workshop on HIV Drug 12-16 June 2000, Sitges, Spain. Abstract 134.

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