Sequential concentration of chloroquine in human hair correlates with ingested dose and duration of therapy

Human scalp hair was analyzed for chloroquine using gas-chromatography. In 5 patients it was demonstrated that the amount of uptake of chloroquine into the hair varied proportionally with the dosage (from 500 mg/week to 10 g single dose) and with the time of administration. The chloroquine concentrations ranged from 8 to 1100 micrograms/g hair. Chloroquine could be determined quantitatively after a single toxic dosage used in a suicidal attempt and also after low therapeutic doses. The sequential examination of the hair shaft allows an assessment of the chloroquine amount taken over time, the individual dosage, the initiation and termination of therapy. As hairs can be collected easily, they are a unique specimen for investigation, and it is suggested that they can virtually be used as a "tachogram" of chloroquine drug-therapy or intoxication.