Methorphan in street heroin: Issues and challenges of the identification of a chiral compound in cases of opiate overdose in Italy

Giovanni Serpelloni

G. Serpelloni1, C. Rimondo2, C. Seri2,3, M. Cavallini2, S. Strano Rossi4, F. Bortolotti3, R. Gottardo3, G. Musile3, F. Tagliaro3. 1Department for Antidrug Policies, Presidency of the Council of Ministers, Italy; 2National Early Warning System, Department for Antidrug Policies, Presidency of the Council of Ministers, Italy; 3Department of Public Health and Community Medicine, Unit of Forensic Medicine, University of Verona, Italy; 4Institute of Legal Medicine, Catholic University of Sacred Heart, Italy

Background: Notifications on adulterating agents of illicit drugs registered by the Italian National Early Warning System (N.E.W.S.) show a significant number of heroin seizures methorphan was identified in. Methorphan exists as dextro or levo stereoisomer, with different pharmacological activity. As intoxications and deaths after use of adulterated heroin were recorded, identification of the specific stereoisomer is significant to evaluate health risks of such adulterated heroin. Methods: The N.E.W.S. has been collecting notifications on methorphan in heroin exhibits since 2010, either from law enforcement or toxicology laboratories. In order to evaluate the potential harm, the N.E.W.S. enquired its collaborating laboratories to unravel the nature of methorphan detected and the analytical methods used (chiral/non chiral). Results: Eight notifications on methorphan presence in seized heroin were registered in 2010, 13 in 2011, 15 in 2012, 22 in 2013; dextromethorphan was identified in three samples. This evidence led laboratories to seek it on biological samples in cases of opiate overdose. Methorphan (stereoisomer not determined) was detected in blood samples of two fatal heroin overdoses. Dextromethorphan was identified in one fatal heroin overdose by means of capillary zone electrophoresis with cyclodextrines (chiral selector). Studies are ongoing to evaluate the potential concurrent role of active metabolites (levorphanol/dextrorphan) in the drug’s toxicity. Conclusions: The sterochemical nature of methorphan in street heroin is still an issue since only few laboratories have access to chiral methods of analyses, leaving some concern on the potential harm that the presence of one stereoisomer over the other may pose at user’s level.

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