Buprenorphine

Buprenorphine 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. In the United States, the combination formulation of buprenorphine/naloxone (Suboxone) is usually prescribed to discourage misuse by injection. 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 opioid 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 (primarily when first starting treatment if one is not already opioid tolerant/dependent), 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. Being a partial MOR agonist, buprenorphine offers flexibility to prescribers treating opioid use disorder as the dosage can be easily adjusted. Side effects may include respiratory depression (decreased breathing), sleepiness, adrenal insufficiency, changes in heart electrophysiology (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. Buprenorphine was patented in 1965, FDA approved for medical use as an analgesic in 1981, and FDA approved for treating opioid use disorder in 2002. It is on the World Health Organization's List of Essential Medicines. Despite originally being marketed as an analgesic it is far more commonly prescribed and used to treat opioid use disorders, such as addiction to heroin. In 2020, it was the 186th most commonly prescribed medication in the United States, with more than 2.8 million prescriptions. Buprenorphine is generally used as a medication for treating opioid use disorder. In the United States, buprenorphine hydrochloride (and a combination formula, buprenorphine hydrochloride/naloxone,) are schedule III controlled substances. Buprenorphine does not produce the same sense of euphoria and/or "sense of well-being" as reported in use of full-agonist opioids. A "ceiling effect" is observed in regards to the potentially fatal side effects of other opioids, such as respiratory depression. While the medication may produce comparably mild side effects to that of other drugs in its classification, it still carries some abuse potential.