Low trough plasma concentrations of nevirapine associated with virologic rebounds in HIV-infected patients who switched from protease inhibitors.
BACKGROUND
The substitution of a nonnucleoside reverse-transcriptase inhibitor (NNRTI) for protease inhibitors (PIs) has demonstrated its suitability to maintain virologic response. However, the switch from PIs to an NNRTI could fail for a number of reasons, including NNRTI-associated toxicity and emergence of NNRTI-resistant variants.


OBJECTIVE
To describe the virologic failures among 74 HIV-infected patients who switched from PIs to nevirapine.


METHODS
Virologic failure was defined as any rebound of the plasma HIV-RNA (pVL) levels >1000 copies/mL on one occasion or 2 consecutive intermittent viremia episodes defined as increases of the pVL >20 copies/mL but <1000 copies/mL. Virologic failures were investigated retrospectively by determining nevirapine trough concentrations and performing genotypic resistance analysis.


RESULTS
The mean nevirapine concentration was significantly lower in patients with virologic failure in comparison with patients with virologic response (2572 +/- 1642 vs 4550 +/- 2084 ng/mL, respectively; p = 0.003). In multivariate analysis, the mean duration of undetectable pVL before the switch and the mean plasma concentration of nevirapine were significantly associated with virologic success with relative rates of 1.39 (95% CI 1.10 to 1.76, p = 0.006) and 2.7 (95% CI 1.37 to 5.41, p = 0.01), respectively. In patients with pVL >1000 copies/mL, nevirapine mutations and nucleoside reverse-transcriptase inhibitor mutations were found in 80% of the cases.


CONCLUSIONS
The risk of virologic failure after the switch from PI to nevirapine is higher in cases of inadequate nevirapine plasma concentrations. Our data support prospective monitoring of nevirapine plasma concentrations to detect low concentrations prior to the emergence of resistance mutations.
Duong
Michel
M
Department of Infectious Diseases, Hôpital du Bocage, Dijon, France. michel.duong@chu-dijon.fr
Buisson
Marielle
M
Peytavin
Gilles
G
Kohli
Evelyne
E
Piroth
Lionel
L
Martha
Benoit
B
Grappin
Michèle
M
Chavanet
Pascal
P
Portier
Henri
H
D000328:Adult; D024882:Drug Resistance, Viral / Q000187:drug effects / Q000502:physiology; D005260:Female; D005500:Follow-Up Studies; D015658:HIV Infections / Q000097:blood* / Q000188:drug therapy / Q000821:virology; D017320:HIV Protease Inhibitors / Q000627:therapeutic use*; D015497:HIV-1 / Q000187:drug effects*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019829:Nevirapine / Q000097:blood* / Q000627:therapeutic use*; D011446:Prospective Studies; D019562:Viral Load
D017320:HIV Protease Inhibitors; D019829:Nevirapine