Opioid Addiction
Opioid Addiction
Characteristics of drugs used as opioid substitution therapy (OST)(i)
Feature | Methadone | Buprenorphine |
---|---|---|
Dose required to prevent withdrawal symptoms according to degree of opioid dependency | Linear relationship (from 10-300 mg per day) | Linear relationship for persons with less opioid dependency only – ceiling effect (max daily dose 24 mg) |
Interaction with ARVs | Methadone plasma concentrations are reduced if used together with: • NVP & EFV: ↓ 50% • LPV/r: ↓ 50% • No clinically significant alterations of methadone PK with other commonly used ART agents |
Buprenorphine (B) and active metabolite norbuprenorphine (N) plasma concentrations are reduced if combined with NNRTIs and increased if combined with some PIs or INSTIs |
CAVE: withdrawal symptoms if combined with ARV that decreases plasma concentration and risk of drug toxicity if such ARVs are interrupted – reverse if ARVs increase plasma concentration | ||
Risk of overdose | Yes | No, if used as a co-formulation with naloxone |
Causing QT prolongation on ECG | Yes (dose-response relationship)(ii) | No |
Risk of obstipation | High | High |
Type of administration | Tablet or liquid | Tablet applied sublingual |
Risk of further impairment in persons with existing liver impairment | Yes | Yes |
- See Drug-drug Interactions between Analgesics and ARVs
- ECG recommended for daily methadone doses exceeding 50 mg; special caution with concomitant use of other drugs known to cause QT prolongation (e.g. certain ARVs (such as LPV/r, RPV, FTR), amiodarone, astemizole, azithromycin, clarithromycin, chloroquine, citalopram, domperidone, escitalopram, fluconazole and moxifloxacin)