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Appropriate Dose of Efavirenz Is Unclear for HIV Patients with Tuberculosis
Receiving HAART and Rifampicin
The
concomitant use of efavirenz
(Sustiva) and rifampicin is common for treatment
of HIV and tuberculosis.
Plasma efavirenz levels can be reduced by rifampicin,
but the appropriate daily dosage of efavirenz is unclear.
In this study, HIV-infected patients with active tuberculosis,
receiving rifampicin > 1 month, were randomized to receive stavudine
(Zerit) and lamivudine
(Epivir) plus efavirenz 600 or 800 mg daily.
Plasma efavirenz levels were measured (at 12 h after
dosing and on day 14) by high-performance liquid chromatography.
Plasma HIV RNA was assessed at 16 and 24 weeks after antiretroviral
therapy.
Results
· Baseline
characteristics were comparable in the 84 patients (two groups of
42).
· Median
plasma efavirenz levels were 3.02 mg/l (range, 0.07-12.21) in the
600 mg group and 3.39 mg/l (range, 1.03-21.31) in the 800 mg group
(P = 0.632).
· Plasma
efavirenz levels were < 1 mg/l in 3 of 38 (7.9%) patients in
the 600 mg group and in none of the 800 mg group (P = 0.274).
· Approximately
40 and 45% of patients had efavirenz levels > 4 mg/l, respectively.
· There
was no significant difference in time to HIV RNA < 50 copies/ml
(P = 0.848).
Median plasma efavirenz levels were comparable among
both groups. Efavirenz 600 mg/day should be sufficient for most
Thai HIV-infected patients receiving rifampicin with body weight
approximately 50 kg, according to the study authors.
The authors conclude, “These results may not be applicable
to other ethic populations who have higher body weights. However,
the study of long-term virological and immunological outcomes is
needed and under further investigation.”
09/23/05
Reference
W Manosuthi and others. Efavirenz levels and 24-week
efficacy in HIV-infected patients with tuberculosis receiving highly
active antiretroviral therapy and rifampicin. AIDS 19(14):1481-1486.
September 23, 2005.
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