Buprenorphine

Buprenorphine, sold under the brand name Subutex among others, is an opioid used to treat opioid use disorder, acute pain, and chronic pain. It can be used under the tongue (sublingual), in the cheek (buccal), by injection (intravenous and subcutaneous), as a skin patch (transdermal), or as an implant. For opioid use disorder, it is typically started when withdrawal symptoms have begun and for the first two days of treatment under direct observation of a health-care provider. In the United States, the combination formulation of buprenorphine/naloxone (Suboxone) is usually prescribed to discourage misuse by injection. However, more recently the efficacy of naloxone in preventing misuse has been brought into question, and preparations of buprenorphine combined with naloxone could potentially be less safe than buprenorphine alone. Maximum pain relief is generally within an hour with effects up to 24 hours. Buprenorphine affects different types of opioid receptors in different ways. Depending on the type of receptor, it may be an agonist, partial agonist, or antagonist. Buprenorphine's activity as an agonist/antagonist is important in the treatment of opioid use disorder: it relieves withdrawal symptoms from other opioids and induces some euphoria, but also blocks the ability for many other opioids, including heroin, to cause an effect. Unlike full agonists like heroin or methadone, buprenorphine has a ceiling effect, such that taking more medicine past a certain point will not increase the effects of the drug. Side effects may include respiratory depression (decreased breathing), sleepiness, adrenal insufficiency, QT prolongation, low blood pressure, allergic reactions, constipation, and opioid addiction. Among those with a history of seizures, a risk exists of further seizures. Opioid withdrawal following stopping buprenorphine is generally less severe than with other opioids. Whether use during pregnancy is safe is unclear, but use while breastfeeding is probably safe, since the dose the infant receives is 1-2% that of the maternal dose, on a weight basis.