Decreased methadone effect after ritonavir initiation.
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.
Geletko
S M
SM
University of Rhode Island College of Pharmacy, Department of Pharmacy Practice, Veterans Affairs Medical Center, Providence 02908, USA.
Erickson
A D
AD
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
D000701:Analgesics, Opioid; D019380:Anti-HIV Agents; D017320:HIV Protease Inhibitors; D018119:Stavudine; D019258:Saquinavir; D019438:Ritonavir; D008691:Methadone