[Clinical and pharmacokinetic interactions between methadone and nelfinavir (Nemesia study)].
OBJECTIVE
Patients on methadone maintenance therapy who are administered nelfinavir show a decrease in methadone plasma levels. However, the clinical relevance of this fact is seldom significant because it does not correlate with the appearance of opioid withdrawal symptoms (OWS). The objective of this study was to assess the clinical and pharmacokinetic interactions between methadone and nelfinavir.


METHODS
A prospective multicenter study of human immunodeficiency virus (HIV) positive patients on stable methadone therapy who initiated nelfinavir was performed. To determine the presence of OWS, 2 questionnaires, objective and subjective, were administered at weeks 1, 2, 3 and 4. A pharmacokinetic study measuring the minimal plasmatic concentration of methadone was done at baseline and at week 4.


RESULTS
29 patient were included. In 7 patients who underwent pharmacokinetic studies, the minimal plasmatic concentration of methadone decreased after 4 weeks of nelfinavir treatment from 6.889 ng/ml to 4.354 ng/ml (37%; p = 0.046). However the results of the questionnaires did not show the significant OWS, which precluded an increase in the dose of methadone.


CONCLUSIONS
In patients under stable methadone treatment, antiretroviral therapy including nelfinavir does not require any significant modification of methadone dose. The decrease in methadone plasmatic levels does not correlate with OWS.
Marco
Andrés
A
Programa VIH/SIDA, CP La Modelo, Barcelona, Spain.
Deig
Elisabet
E
Cadafalch
Josep
J
Fuster
Montserrat
M
Valls
Inmaculada
I
Pedrol
Enric
E
D000328:Adult; D004347:Drug Interactions; D005260:Female; D017320:HIV Protease Inhibitors / Q000493:pharmacokinetics*; D006801:Humans; D008297:Male; D008691:Methadone / Q000493:pharmacokinetics*; D009294:Narcotics / Q000493:pharmacokinetics*; D019888:Nelfinavir / Q000493:pharmacokinetics*; D011446:Prospective Studies
D017320:HIV Protease Inhibitors; D009294:Narcotics; D019888:Nelfinavir; D008691:Methadone