Retrospective monitoring of long-term recreational and dependent cocaine use in toenail clippings/scrapings as an alternative to hair.

Toenails were assessed as an alternative matrix to hair for retrospective monitoring of cocaine consumption of recreational and dependent users. Results/methodology: Toenail clippings, scrapings and hair samples from recreational and dependent cocaine users were analyzed for cocaine and metabolites. Dependent users displayed significantly higher concentrations in hair and toenail samples compared to recreational users. Cocaine abstinence could be monitored in hair and toenail samples. One postmortem fingernail was analyzed in layers to investigate the cocaine and metabolite concentration profile. Highest concentrations were observed in the dorsal layer, being indicative of contamination. Having led to comparable results, toenails may be an alternative for retrospective monitoring of cocaine consumption/abstinence. Hair should remain the first choice for assessment of temporal evidence of drug intake.