title: Methadone blood concentrations are decreased by the administration of abacavir plus amprenavir.
abstract: Abacavir and amprenavir, a nucleoside reverse transcription inhibitor and a protease inhibitor, respectively, are new drugs used for the treatment of HIV. Methadone blood concentrations were measured in five addict patients receiving methadone maintenance therapy before and after introduction of abacavir plus amprenavir. The administration of these two drugs for a median period of 14 days resulted in a significant reduction (P = 0.043) of methadone concentration, with a median decrease to 35% of the original concentration (range 28-87%). Two patients reported on several occasions nausea in the morning before the intake of the daily methadone dose, which is compatible with withdrawal reaction to opioids. Because amprenavir is a cytochrome P4503A4 substrate and is involved in the metabolism of methadone, reduction of methadone concentrations could be explained by an induction of cytochrome P4503A4.
authors.affiliation: Division of Immunology and Allergy, University Hospital of Lausanne, Switzerland.
authors.forename: P A
authors.initials: PA
authors.lastname: Bart
authors.forename: P G
authors.initials: PG
authors.lastname: Rizzardi
authors.forename: S
authors.initials: S
authors.lastname: Gallant
authors.forename: K P
authors.initials: KP
authors.lastname: Golay
authors.forename: P
authors.initials: P
authors.lastname: Baumann
authors.forename: G
authors.initials: G
authors.lastname: Pantaleo
authors.forename: C B
authors.initials: CB
authors.lastname: Eap
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000150:complications / Q000188:drug therapy; D000701:Analgesics, Opioid / Q000097:blood*; D002219:Carbamates; D015224:Dideoxynucleosides / Q000494:pharmacology*; D004347:Drug Interactions; D004359:Drug Therapy, Combination; D005663:Furans; D017320:HIV Protease Inhibitors / Q000494:pharmacology*; D015497:HIV-1 / Q000187:drug effects; D006801:Humans; D008691:Methadone / Q000097:blood*; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology*; D019966:Substance-Related Disorders / Q000150:complications; D013449:Sulfonamides / Q000494:pharmacology*; D000099227:Abacavir
chemical_list: D000701:Analgesics, Opioid; D002219:Carbamates; D015224:Dideoxynucleosides; D005663:Furans; D017320:HIV Protease Inhibitors; D008691:Methadone; D018894:Reverse Transcriptase Inhibitors; D013449:Sulfonamides; D000099227:Abacavir; C095108:amprenavir