Buprenorphine (BuTrans/Temgesic/Transtec)

Buprenorphine (BuTrans / Temgesic / Transtec) is an opioid drug that is used both as a painkiller and as a treatment for addiction to opioid drugs such as heroin.

Buprenorphine works by binding to the receptors on nerve cells in the brain and spinal cord that are responsible for transmitting pain signals. Drugs such as heroin and morphine also bind to these receptors, causing the drugs’ sedating, euphoric and pain-killing properties. By mimicking the effects of heroin and morphine, buprenorphine can replace the abused drug, allowing addicts to overcome their addiction and stop injecting drugs.

In contrast to methadone hydrochloride (Methadose), which is a full ‘agonist’ of these receptors, buprenorphine is a partial agonist, meaning that it binds to the receptors less strongly than methadone. This means that buprenorphine is less likely to be abused by addicts. It is also difficult to overdose on buprenorphine as its effects plateau at high doses.

Buprenorphine is taken as a tablet, which is dissolved under the tongue every day or three times a week. It was added to the World Health Organization’s list of essential drugs in July 2005.¹ This lists all medicines that should be available in adequate amounts and at an affordable price within all health systems. Drugs on this list are selected according to public health relevance, efficacy, safety and cost-effectiveness.

Side-effects can include and vomiting, drowsiness, dizziness, headache, itch, dry mouth, difficulty ejaculating, decreased sex drive, urinary retention, and constipation.

In addition to reducing injection rates and HIV infections through this route, treatment of opiate addiction with buprenorphine can improve adherence to anti-HIV treatment combinations.²

Buprenorphine interacts with fewer anti-HIV drugs than methadone. Although AZT (zidovudine, Retrovir) can increase buprenorphine levels, its ceiling effect means that this is unlikely to be dangerous. However, three cases of an interaction with ritonavir (Norvir)-boosted atazanavir (Reyataz) have been reported, which resulted in patients becoming sedated due to high buprenorphine levels. A dose reduction resolved these effects.³ Dose reductions may also be necessary with other protease inhibitors with the exception of ritonavir-boosted tipranavir (Aptivus), which may lower buprenorphine levels. Further studies are required.

Efavirenz (Sustiva) causes a reduction in buprenorphine levels, although this did not lead to the development of withdrawal symptoms in a study of ten patients.⁴ A similar interaction may exist with the other non-nucleoside reverse transcriptase inhibitor (NNRTI) nevirapine (Viramune).