A group of activists and physicians has asked the World Health Organization (WHO) to prevent the proposed reclassification of buprenorphine as a narcotic. If successful, this will allow the use of the drug as a treatment for heroin addiction to continue, helping to curb the transmission of HIV through intravenous drug use.
Buprenorphine can help heroin users to move from illicit substance use to recovery programmes by reducing craving and withdrawal symptoms and reducing the ‘high’ experienced after taking heroin. Unlike the similar drug methadone, which is used for the treatment of heroin addiction under restricted access, buprenorphine has a low abuse potential and can be given to patients in a primary care setting.
The United Nations Commission on Narcotic Drugs has recently reviewed buprenorphine and is proposing changing its scheduling from the 1971 Psychotropics Convention to the 1961 Single Convention on Narcotic Drugs. This change can only be made after the WHO has agreed to alter the current guidelines following their meeting between May 24th and 27th. If the change is approved, the reclassification of buprenorphine may limit its availability and reduce the number of people who can be treated.
In their letter to the WHO, the group of community advocates, harm reduction programme directors and drug use experts headed by Mauro Guarinieri, Chairperson of the European AIDS Treatment Group, say that “the adoption of the proposed amendments will result in further limiting access to one of the existing options for substitution therapy.” Additionally, “it will probably introduce further barriers for accomplishing the goal of equal and universal access to antiretroviral treatment in countries where injecting drug use is closely related to HIV/AIDS.”
Methadone and buprenorphine work in similar ways to control the craving and withdrawal symptoms characteristic of heroin addiction. By binding to the receptor molecules that heroin stimulates in the brain (µ-opioid receptors), they act as a substitute for the drug.
Since withdrawal from methadone and buprenorphine is much slower than from heroin, patients can be maintained on substitution therapy indefinitely, stabilising mood swings and avoiding the harsh physical side-effects of withdrawal. Patients usually need to take methadone or buprenorphine for years, if not a lifetime, in order to stave off the intense cravings that can lead to a return to heroin abuse.
Unlike the “full agonists” heroin and methadone, which activate µ-opioid receptors very strongly, buprenorphine is a “partial agonist” that only stimulates the receptors with around 40% of this activity, even at high doses. Buprenorphine stimulates the heroin receptors enough to prevent craving and withdrawal symptoms, but without running the risk of side-effects such as respiratory depression and addiction.
There is limited evidence that treatment of addiction with buprenorphine may increase the level of adherence to antiretroviral therapy in HIV-positive patients. However, there is a risk that buprenorphine may interact with NNRTIs and protease inhibitors, as does methadone, although this remains to be tested.