Assessment of Pregabalin Use by Hair Testing

The detection and analysis of drugs in hair has progressively emerged as a consequence of the enhanced sensitivity of analytical techniques used in forensic toxicology; a greater advantage in using this matrix respect to classical ones (i.e., urine and blood) is an easier and noninvasive sample collection, even when the careful supervision of law-enforcement officers is required to avoid the risk that the sample may be adulterated or replaced. Moreover, according to the length of the hair, the history of drug exposure can be retrospectively monitored from few weeks up to months or years since sample collection.

Given the potential negative effects of pregabalin, an antiepileptic and analgesic drug with a high risk of misuse and abuse, the laboratory was asked to test for the drug in hair.

A new ultrahigh-performance liquid chromatography coupled to tandem mass spectrometry was developed. The method involves incubation of 25 mg of cut hair in acetonitrile for 2 h in an ultrasonic bath and separation on an Acquity HSS C18 column (150 × 2.1 mm × 1.8 µm) maintained at 50°C in a thermostatically controlled oven. A gradient elution was performed.

The method was fully validated according to international standards. The limit of quantitation of the test was 10 pg/mg. Five authentic cases of pregabalin in hair segments were tested using the method and the results were in the range 17-1487 pg/mg.

This new method was found suitable to monitor both patients under pregabalin therapy and dependent subjects.