Opioid use disorder — assessment, overdose, and OAT (MEQ)

(i) Overdose and post-naloxone care. In severe respiratory depression, restoration of ventilation and oxygenation takes precedence over the history, examination or diagnostic testing.^[1] The naloxone label gives an initial adult dose of 0.4 mg to 2 mg intravenously, repeated at two-to-three-minute intervals if respiratory function does not improve, and advises continued surveillance after a response because the duration of action of some opioids may exceed that of naloxone.^[8] Once the respiratory rate improves, observe for 4 to 6 hours before discharge is considered; recurrent respiratory depression or a need for a naloxone infusion warrants intensive care admission.^[1]

(ii) Withdrawal and restart choice. The COWS rates eleven common opiate withdrawal signs or symptoms, and its summed score assesses the level of withdrawal. Buprenorphine, a partial agonist, can precipitate withdrawal in highly dependent patients who are not yet in withdrawal.^[2]

His old methadone dose is unsafe to restart. Use lower initial doses for patients whose tolerance is expected to be low at treatment entry. Any patient who has not taken opioids for more than 5 days may no longer be tolerant, and initial doses should not be based on previous treatment episodes.^[5]

Methadone first dose. An initial single dose of 20 to 30 mg will often suppress withdrawal, and the initial dose should not exceed 30 mg.^[5]

Benzodiazepines. Use of opioids with benzodiazepines may result in profound sedation, respiratory depression, coma and death.^[5]

(iii) OAT plan. In 329 opioid-dependent emergency department patients, ED-initiated buprenorphine/naloxone engaged 78% in addiction treatment at 30 days, versus 37% with referral and 45% with brief intervention.^[6] Induct when objective and clear signs of withdrawal are evident; for patients dependent on short-acting opioids, Day 1 is up to 8 mg/2 mg and Day 2 a single dose of up to 16 mg/4 mg, with maintenance generally 4 mg/1 mg to 24 mg/6 mg per day. Strongly consider recommending or prescribing an overdose reversal agent when initiating and renewing treatment.^[7] Methadone retains patients in treatment and decreases heroin use better than treatments without opioid replacement.^[3]

(iv) Benzodiazepines and the pregnant partner. If he is also benzodiazepine dependent, NICE says to consider benzodiazepine detoxification. If his partner is opioid dependent, NICE advises that detoxification during pregnancy should only be undertaken with caution.^[9]

(v) Mortality counselling. Pooled all-cause mortality was 11.3 versus 36.1 per 1000 person-years in and out of methadone treatment, and 4.3 versus 9.5 in and out of buprenorphine treatment; the time immediately after leaving treatment carries particularly increased risk.^[4] After a non-fatal overdose, methadone maintenance (adjusted HR 0.47) and buprenorphine (adjusted HR 0.63) were associated with decreased all-cause mortality.^[10] NICE asks that people be told about the loss of opioid tolerance after detoxification and the ensuing increased risk of overdose and death.^[9]