title: Decreased methadone effect after ritonavir initiation.
abstract: Combination antiretroviral therapy including protease inhibitors such as ritonavir has added significant potency to therapy for human immunodeficiency viral (HIV) infection as well as substantial drug-drug interactions. Methadone metabolism is affected by cytochrome P450 (CYP) 3A4 inhibitors or inducers. Because ritonavir can induce CYP3A, it can decrease methadone plasma levels. An HIV-infected patient receiving methadone maintenance experienced withdrawal symptoms after ritonavir, saquinavir, and stavudine were added to his regimen; the most likely cause was ritonavir.
authors.affiliation: University of Rhode Island College of Pharmacy, Department of Pharmacy Practice, Veterans Affairs Medical Center, Providence 02908, USA.
authors.forename: S M
authors.initials: SM
authors.lastname: Geletko
authors.forename: A D
authors.initials: AD
authors.lastname: Erickson
mesh_terms: D000701:Analgesics, Opioid / Q000378:metabolism*; D019380:Anti-HIV Agents / Q000009:adverse effects* / Q000627:therapeutic use; D003937:Diagnosis, Differential; D004347:Drug Interactions; D004359:Drug Therapy, Combination; D015658:HIV Infections / Q000150:complications / Q000188:drug therapy*; D017320:HIV Protease Inhibitors / Q000009:adverse effects* / Q000627:therapeutic use; D006801:Humans; D008297:Male; D008691:Methadone / Q000378:metabolism*; D008875:Middle Aged; D019438:Ritonavir / Q000009:adverse effects* / Q000627:therapeutic use; D019258:Saquinavir / Q000009:adverse effects / Q000627:therapeutic use; D018119:Stavudine / Q000009:adverse effects / Q000627:therapeutic use; D013375:Substance Withdrawal Syndrome / Q000175:diagnosis; D019966:Substance-Related Disorders / Q000150:complications / Q000534:rehabilitation
chemical_list: D000701:Analgesics, Opioid; D019380:Anti-HIV Agents; D017320:HIV Protease Inhibitors; D018119:Stavudine; D019258:Saquinavir; D019438:Ritonavir; D008691:Methadone