Naltrexone and bupropion and Nirmatrelvir and ritonavir interaction
Naltrexone and bupropion and Nirmatrelvir and ritonavir: both prescribing labels flag this combination with the strongest language, such as a contraindication, a boxed warning, or an instruction to avoid it.
Do not combine without a prescriber's guidance. The label language below is the strongest FDA uses.
What the FDA labels say
From the Naltrexone and bupropion (Contrave Extended-Release) label · effective 2025-11-10
CYP2B6 Inducers (e.g., ritonavir, lopinavir, efavirenz, carbamazepine, phenobarbital, and phenytoin) may reduce efficacy by reducing bupropion exposure, avoid concomitant use.
Avoiding concomitant use with ritonavir, lopinavir, or efavirenz is recommended [see Clinical Pharmacology (12.3) ] .
Inducers of CYP2B6: Ritonavir, Lopinavir, and Efavirenz: Concomitant treatment with these drugs can decrease bupropion and hydroxybupropion exposure and may reduce efficacy.
From the Nirmatrelvir and ritonavir (Paxlovid) label · effective 2026-02-19
…Migraine medications: eletriptan, ubrogepant • Mineralocorticoid receptor antagonists: finerenone • Non-opioid analgesic (selective blocker of Na v 1.8 sodium channels): suzetrigine • Opioid antagonists: naloxegol • PDE5 inhibitor: sildenafil (Revatio ® ) when used for pulmonary arterial hypertension (PAH) • Sedative/hypnotics: triazolam, oral midazolam • Serotonin…
Opioid antagonists naloxegol ↑ naloxegol Co-administration contraindicated due to the potential for opioid withdrawal symptoms [see Contraindications (4) ] .
Antidepressants bupropion ↓ bupropion and active metabolite hydroxy-bupropion Monitor for an adequate clinical response to bupropion. trazodone ↑ trazodone Adverse reactions of nausea, dizziness, hypotension, and syncope have been observed following co-administration of trazodone and ritonavir.
Potential for PAXLOVID to Affect Other Drugs PAXLOVID (nirmatrelvir co-packaged with ritonavir) is a strong inhibitor of CYP3A, and an inhibitor of CYP2D6, P-gp and OATP1B1.
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Open in the checkerNot medical advice. Interaction Checker quotes FDA label text and NIH fact sheets. Whether an interaction matters for you depends on doses, timing, kidney and liver function, and other conditions. Confirm with a pharmacist or prescriber.