Pyrolysis of drugs of abuse: a comprehensive review

Abstract

This review summarizes the literature to date relating to pyrolysis and heated vapour ingestion of drugs of abuse. In this context, heating is referred to as smoking or pyrolysis, but these are generic descriptors that encompass numerous methods of vapour generation and inhalation. Depending on the amount of drug used, diluents and contaminants present, heating conditions, and the oxidative/reductive environment, many thermal decomposition products can be formed. In addition to the recognized hazard of rapid onset of pharmacological effects of the parent drug, thermal decomposition products may be pharmacologically active as well as acutely/chronically toxic. For example, several published reports have linked heroin smoking to a form of brain encephalopathy and to the development of movement disorders. Early qualitative studies focusing on the thermal decomposition of drugs have evolved into more complex investigations employing mass spectral identification, confirmation, and elucidation of formation mechanism. In most cases, thermal decomposition begins with cleavage of the weakest bond (often C-N) to generate free radicals that then form the most stable sterically favoured products. Several reports of rearrangements at higher temperatures have been identified and hint at an underlying complexity that arises from the variety of smoking methods and conditions. Given that many designer drugs such as synthetic cannabinoids are ingested primarily through smoking, this issue has taken on new importance.

Identification of pyrolysis products of the new psychoactive substance 2‐amino‐1‐(4‐bromo‐2,5‐dimethoxyphenyl)ethanone hydrochloride (bk‐2C‐B) and its iodo analogue bk‐2C‐I

“…Two halogenated products were detected in the pyrolysis of mephedrone and identified as α-chloro ketones, 1-chloro-1-(4-methylphenyl)-2-propanone and 2-chloro-1-(4-methylphenyl)-1-propanone. [16] The pyrolysis products of bk-2C-B differed significantly from those observed with other phenethylamines [15] including methiopropamine and the ring-substituted cathinone, mephedrone. [15,16] Methylation [18] and N,O rearrangement did not occur.…”

“…[16] The pyrolysis products of bk-2C-B differed significantly from those observed with other phenethylamines [15] including methiopropamine and the ring-substituted cathinone, mephedrone. [15,16] Methylation [18] and N,O rearrangement did not occur. [19] Product (1b) was unique in that the C-C bond cleavage appeared to occur at the benzene ring and the corresponding product was not detected in either the pyrolysis of methamphetamine or mephedrone.…”

“…[15] The sample was heated with a butane lighter until yellow fumes appeared and an orange residue was deposited on the sides of the glass vial. The pyrolysis was repeated several times to determine which product were representative of those inhaled under the conditions used in drug abuse.…”

“…[14] A key concern associated with the conditions encountered during pyrolysis is the formation of degradation products that may be formed during smoking and knowledge about the behaviour of drugs under these harsh conditions provide important information on potential biomarkers and toxicity. [15] In the present study, bk-2C-B was subjected to pyrolysis conditions for analysis of condensed residues formed after vaporization. Furthermore, the analytical characterization and pyrolysis of 2-amino-1-(4-iodo-2,5-dimethoxyphenyl)ethanone hydrochloride(bk-2C-I) (Figure 1), a substance that has not yet been described in the literature, has also been included in this investigation.…”

Comprehensive monitoring of the occurrence of 22 drugs of abuse and transformation products in airborne particulate matter in the city of Barcelona

“…Its TP, 6ACM, was also found in about 50% of the samples that contained HER, at a maximum concentration of 32 pg/m 3 . 6ACM has been identified as a major pyrolytic product of heroin (Bell and Nida, 2015). Furthermore, the occurrence of 6ACM in PM10 could also be attributed to the natural degradation of heroin in airborne particles and/or its presence as impurity in streetheroin (El-Haj et al, 2004;Yoshioka and Valentino, 2002).…”