A new antimicrobial quinolone (AM-1155) analysed in hair as an index of drug exposure and as a time-marker.

Scalp hair samples were obtained at one-month intervals for up to four months after the administration from each of twelve healthy male volunteers participating in a phase I study of a new antimicrobial quinolone, AM-1155, (+/-)-1-cyclopropyl-6-fluoro-1, 4-dihydro-8-methoxy-7-(cis-3,5-dimethyl-1-piperazinyl)-4-oxo-3-quinoline carboxylic acid. After hair was sectioned into 1 cm lengths from the scalp end, corresponding portions from five pieces of hair were dissolved in 1 M NaOH and assessed for AM-1155 by HPLC. In all subjects who had taken a single dose (600 mg, n = 6) or repeated doses (300 mg twice daily for 6.5 days, n = 6), the drug was detected in hair. The hair portions containing the drug were shown in most subjects to move outwards month by month at the rate of about 1 cm month-1. A single hair, which was obtained from each subject of the repeated-dose study 3 months after the completion of administration, was cut into 2.5-mm lengths from the scalp side and analysed for AM-1155. The drug was shown to be contained in 4 to 6 consecutive 2.5-mm lengths, showing that there was no large axial diffusion of the drug along the hair shaft even after 3 months. These findings indicate the utility of measuring this quinolone derivative in hair as an index of drug exposure and, furthermore, as a time marker for analysing other drugs in hair.