Buprenorphine/naloxone (trade name Suboxone) is a combination drug formulation of buprenorphine, a ?-opioid receptor (MOR) weak partial agonist and ?-opioid receptor antagonist, and naloxone, a MOR silent antagonist, in a 4:1 ratio. It is used in the treatment of opioid dependence. The purpose of naloxone is to deter intravenous abuse; parenteral administration rapidly induces opioid withdrawal symptoms, while regular, intended use does not (as naloxone is minimally bioavailable with sublingual ingestion).
This combination is available as sublingual tablets or film.
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Medical uses
Buprenorphine/naloxone is used for the treatment of opioid dependence in combination with psychosocial support and counseling for the patient. It has been found to be effective for treating opioid dependence, as is the first line medication according to U.S. National Institute on Drug Abuse.TV
Contraindications
Contraindications are severe respiratory or liver impairment and acute alcoholism.
Adverse effects
Side effects are basically the same as those of buprenorphine and other opioids. In addition, naloxone can induce withdrawal symptoms in people who are addicted to opioids. Buprenorphine/naloxone has a milder side effect profile than methadone, and has limited respiratory effects, due to both agonist/antagonist effects. However, buprenorpine/naloxone is less safe than methadone in patients with stable liver disease.
Dependence and withdrawal
Buprenorphin/naloxone in a 4:1 combination, when taken parenterally, produces dysphoric symptoms due to the naloxone, which acts to deter abuse. However when taken orally or sublingually as directed, the naloxone is not absorbed, allowing buprenorphine to act. The Suboxone formulation still has potential to produce an opioid agonist "high" if injected by non-dependent persons, which may provide some explanation to street reports indicating that the naloxone is an insufficient deterrent to injection of Suboxone. The addition of naloxone and the reasons for it are conflicting. Published data show that the ?-opioid receptor binding affinity of buprenorphine is higher than naloxone's (K(i) = 0.2157 nM for buprenorphine, K(i) = 1.1518 nM for naloxone; smaller K(i) mean higher affinity). Furthermore, the IC50 or the half maximal inhibitory concentration for buprenorphine to displace naloxone is 0.52 nM, while the IC50s of other opiates in displacing buprenorphine, is 100 to 1,000 times greater. These studies help explain the ineffectiveness of naloxone in preventing Suboxone abuse, as well as the potential dangers of overdosing on buprenorphine, since a continuous infusion of naloxone can be necessary in order to reverse its respiratory effects.
Interactions
The sedating/narcotic effect of buprenorphine is increased by other sedating drugs such as other opioids, benzodiazepines, older antihistamines, alcohol, and antipsychotics. In addition, opioids and especially benzodiazepines increase the risk for potentially lethal respiratory depression.
Strong inhibitors of the liver enzyme CYP3A4, such as ketoconazole, moderately increase buprenorphine concentrations; CYP3A4 inducers can theoretically decrease concentrations of buprenorphine.
Source of the article : Wikipedia
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