A rapid high-performance thin-layer chromatographic urine screen for laxative abuse.

Laxative abuse, if unrecognized, can lead to unnecessary and costly investigations. The stimulants and cathartics are the most commonly abused laxatives and have the potential for causing the most long-term damage. We have optimized a solid-phase extraction coupled with high-performance thin-layer chromatography (HPTLC) to provide rapid, simple, and sensitive detection of phenolphthalein, danthron, rhein, aloin, and bisacodyl and its metabolites in urine. Positive screens have revealed laxative abuse in 3 of 42 samples from patients presenting with diarrhea of unknown origin.