Factors in Selecting Opioid Replacement Therapy – Methadone or Buprenorphine/Naloxone
Jiamin Liau is a clinical pharmacist in Australia who donated this piece on opioid replacement therapy!
Ms DF, 27 years old, has been on opioid replacement therapy in the past. Treatment ceased about 20 months ago when she fell pregnant. Stating that she had started to abuse codeine tablets, Ms DF recently requested to be enrolled in opioid replacement therapy.
Methadone or buprenorphine/ naloxone combination – which is better for Ms DF?
Buprenorphine, like methadone, is used to treat opioid dependence and is a substitute for either pharmaceutical opioid analgesics or heroin. Buprenorphine is a partial opioid agonist, it possesses a ‘ceiling’ effect where even with increasing dosage there is little increase in respiratory or central nervous system depression, making it less risky than methadone. Having said that, buprenorphine is indeed an opioid and is still subject to development of tolerance and dependence, and ceasing use abruptly may cause an opioid withdrawal syndrome.
Buprenorphine has a strong affinity for opioid receptors, and will replace other opioids and precipitate a withdrawal syndrome if treatment initiation is not carefully managed. It is best to commence treatment with buprenorphine/ naloxone at a suitable time to allow early opioid withdrawal symptoms to be observed and treated if necessary.
Start with a low dose (e.g. 4 mg, with the subsequent day’s dose increment if required). Treatment for opioid replacement therapy should be commenced upon noticing physical signs of the withdrawal syndrome -including one or more of the following: dilated pupils, pulse; 90/min, BP ; 140/90, sweatiness, sniffing, yawning, watery eyes, anxiety, piloerection/goose bumps. The onset of withdrawal is usually 8 to 12 hours after the last use of a short-acting opioid and may be delayed for longer acting opioids.
Thus, methadone or buprenorphine/ naloxone?
Factors to consider include patient preference, previous response to treatment, concurrent treatment with other medications, adverse effects profile etc. Nevertheless, having less risk of fatal overdose than methadone, buprenorphine possess a risk of precipitated withdrawal during induction. Reference
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