Millennium Development Goal 8E aims for affordable access to essential medicines. Essential medicines, as defined by WHO, are those that “satisfy the health-care needs of the majority of the population” and that should therefore “be available at all times in adequate amounts”. However, there is a category of medicines that faces a unique challenge in terms of availability. These are the medicines governed by the international conventions on narcotic and psychotropic substances. “Controlled medicines” is the common definition for pharmaceuticals whose active principles are listed under the 1961 United Nations Single Convention on Narcotic Drugs as amended by the 1972 Protocol, such as morphine and methadone; the 1971 United Nations Convention on Psychotropic Substances, such as diazepam and buprenorphine; and the 1988 United Nations Convention against Illicit Traffic in Narcotic Drugs and Psychotropic Substances, such as ergometrine and ephedrine. The conventions list substances in “Schedules” according to their different levels of potential for abuse and harm, and the commensurate severity of control measures to be applied by countries.