In vitro formation of hydroxy metabolites of cocaine and amphetamines in hair after hair product exposure.

In hair drug testing for cocaine, the presence of hydroxycocaine metabolites has been suggested as a means of distinguishing between externally contaminated hair and positive hair due to ingestion of drug. However, hydroxy compounds can also be produced by the action of certain hair products containing peroxides or other reactive chemicals. In this study, hair samples contaminated with cocaine, benzoylecgonine, methamphetamine, and amphetamine were treated with three hair products: a relaxer containing calcium hydroxide, bleaching colorant containing hydrogen and ammonium hydroxide, and a dye containing hydrogen peroxide to determine the effect of the chemical agents on the drug compounds. Authentic positive hair from people who used drugs were treated with the same hair products. Analysis of the contaminated hair showed that the relaxer removed most of the contaminating drugs with trace production of hydroxy compounds. The peroxide-containing hair products resulted in less reduction in parent drug concentrations and higher concentrations of hydroxy compounds. Analysis of hydroxy to parent compound ratios, specifically for para- and meta-hydroxycocaine, showed that no samples produced ratios at 0.05% or higher-a ratio that has been suggested as indicating drug ingestion. With the authentic drug-positive hair, treatment with the products reduced parent and metabolite concentrations while not affecting hydroxy metabolite to parent ratios.