Drug Precursors and Intermediates

Abstract

Most drugs of misuse require the use of chemical processes either to facilitate their extraction from natural products, or to form semi- or fully synthetic substances. A further means of restricting their use is to control the trade in precursor chemicals and other necessary reagents. This was one purpose of the United Nations Convention against Illicit Traffic in Narcotic Drugs and Psychotropic Substances, 1988 (as amended). Table 1 of the Annex to that Convention lists precursor chemicals used in the manufacture or extraction of: amphetamine; cocaine; fentanyl and its analogues; heroin; lysergide; methaqualone; methylamphetamine; and MDMA. The substances in Table II include general solvents and precursors to methaqualone and phencyclidine. In the United States, some precursors are treated as if they were drug substances. Thus 1-phenyl-2-propanone (listed as phenylacetone) is included in Schedule II of the Controlled Substances Act, 1971. Other precursor chemicals listed in that US legislation include 1-phenylcyclohexylamine and 1-piperidinocyclohexanecarbonitrile (both Schedule II and both precursors to phencyclidine; PCP). A few other precursors (so-called ‘intermediates’) remain listed in the United Nations Single Convention on Narcotic Drugs, 1961. The evolution of these controls mirrors the situation with ‘designer drugs’ insofar as restrictions on a precursor lead clandestine chemists to exploit other synthetic routes and different precursors.