Cancer

Description and purpose
The 1961 Single Convention on Narcotic Drugs, as amended by the 1972 Protocol (6, 8), is the principal international treaty regulating availability of opioids. It classifies the opioids, and requires the registration of all handlers and the estimation of medical needs for opioids. It establishes rules concerning production, manufacture and distribution, and requires statistical reports. The Single Convention governs how opioids are shipped between countries, using a system of import and export approval. The treaty also defines to some extent the requirements for safe distribution within a country.
Governments that are party to the Single Convention have agreed to bring their laws and regulations into line with its requirements. A list of the parties is updated and published annually by the INCB (9). Countries that are not party to the Single Convention often follow its basic procedures.
The preamble of the Single Convention on Narcotic Drugs (6) recognizes that "the medical use of narcotic drugs continues to be indispensable for the relief of pain" [and] "addiction to narcotic drugs constitutes a serious evil".
Thus, the broad purpose of the treaty is to prevent the abuse of narcotics or opioids, while guaranteeing their availability for medical use.
The Single Convention classifies the opioids into four schedules, depending on each drug's dependence potential, abuse liability and therapeutic usefulness. These schedules do not necessarily correspond with those in national laws. The stronger opioid analgesics, such as fentanyl, morphine, hydromorphone and oxycodone are in Schedule I. Codeine and its derivatives, which are less strictly controlled, are in Schedule II. Schedule III contains specified preparations of codeine and dextropropoxyphene that are exempted from certain requirements. Schedule IV contains opioids that are considered to be particularly susceptible to abuse. Exceptions
Codeine
Preparations containing not more than 100 mg of codeine with one or more other ingredients per dosage unit, and those with a concentration of not more than 2.5% codeine in undivided preparations, such as syrups, are exempted from certain control measures under the Single Convention.
Buprenorphine and pentazocine
These drugs are controlled by the Convention on Psychotropic Substances, 1971.
The drug distribution system
A country obtains its supply of opioids for medical purposes by importing them from another country, manufacturing them itself, or both. These opioids are then distributed by manufacturers or wholesalers to hospitals and pharmacies, and subsequently dispensed to patients by health care personnel.
The Single Convention requires that all individuals and enterprises in the distribution system should be licensed or otherwise appropriately authorized, and that transfers of opioids take place only between properly registered parties. Patients may use opioids only according to a physician's prescription. Certain records must be kept, and reports on consumption must be filed with the national regulatory authority. These, along with security arrangements and inspections, permit the detection of "leakage" or "diversion" from the legitimate system of drug distribution.