Buprenorphine
General Information
Buprenorphine is a partial opioid agonist, that is derived from thebaine, a natural constituent of poppies. Buprenorphine was first marketed as Buprenex as an injectable formulation, and was schedule V. More recently on October 7th, 2002, the DEA rescheduled the drug from V to III and approved the drug for treatment of opiate addiction under the brand names Suboxone(with naltrexone) and Subutex (no naltrexone).
Pharmacology & Pharmacokinetics
Buprenorphine binds to the mu-opioid receptor; however, it is only a partial opioid agonist, and it does not produce the same “high” or “rush” of full agonists (morphine, oxycodone, heroin), and also makes overdoses less likely, but still possible. It also has a high binding affinity, meaning once it attaches to the receptor, it does not leave for a while. This property makes it good for opiate treatment, but also complicates overdose cases. In addition, since it is a partial agonist, it can trigger precipitated withdrawal in opiate dependent persons if taken too closely to their last opiate dose.
Buprenorphine or buprenorphine hydrochloride can be administered via intravenous or intramuscular injection, transdermally with a patch, or in the form of a sublingual tablet. The drug is broken down into norbuprenorphine, which is an active metabolite, and glucuronidation. This is completed via N-dealkylation mediated by cytochrome P-450 3A4 isozyme. The average elimination half-life of buprenorphine is 37 hours.
| Method of Administration | Bioavailability | Peak Plasma | Half-Life |
|---|---|---|---|
| Sublingual | 13 – 51.4% | 2 hours | 37 hours |
| Intraarterial | 100% | — | — |
| Intravenous | 98% | 1.5 minutes | < 37 hours |
| Intrahepatoportal | 49% | — | — |
| Intraduodenal | 9.7% | — | — |
| Buccal | 27.8% | — | — |
Legal Status
This drug is a Schedule III substance, making it illegal to use or possess without a prescription. Schedule III substances meet the following criteria according to the Controlled Substances Act:
- The drug or other substance has a potential for abuse less than the drugs or other substances in Schedules I and II.
- The drug or other substance has a currently accepted medical use in treatment in the United States of America.
- Abuse of the drug or other substance may lead to moderate or low physical dependence or high psychological dependence.
Side Effects
- Pain relief
- Sedation
- Nausea
- Vomiting
- Dizziness
- Headache
- Constipation
- Sweating
- Insomnia
- Urinary retention
- Miosis
- Confusion
- Euphoria or dysphoria
Withdrawal
As with any opiate, extended use of buprenorphine will lead to withdrawals upon discontinuation. These can be unpleaant due to the long half life (it takes longer to fully leave your system). This does not mean that the drug is causing the agony, rather, it takes longer for your body to up its natural supply.; however, buprenorphine withdrawal is generally milder than that which is experienced from full agonist. Buprenorphine must be tapered slowly due to its long half-life, which can cause withdrawal to kick in later than with the traditional fast-acting opiates. Buprenorphine withdrawal symptoms can linger for a few months, which is why a slow, modest taper is preferred to a quicker taper. Below are some possible withdrawal symptoms:
- Depression/dysphoric mood
- Nausea and vomiting
- Muscle aches and cramps
- Insomnia
- Mild fever
- Lacrimation
- Rhinorrhea
- Profuse sweating
- Piloerection
- Diarrhea
- Frequent yawning
- Drug craving
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