INFLUENCE OF PIGMENTATION ON THE CODEINE CONTENT OF HAIR FIBERS IN GUINEA-PIGS

Tortoise shell guinea pigs (n = 7) were administered codeine (1 mg/mL codeine-base) in their drinking water for 3 weeks. Black, reddish-brow n and white hair was collected separately from each animal before and after treatment. The hair samples were analyzed by GC/MS. The experime nt showed positive results for all hair fibers with large individual v ariability of drug incorporation. Low drug intake resulted in small di fferences of the drug content in hair fibers different in color wherea s in cases of high drug intake a strong influence of hair pigmentation on the analytical results was observed. The highest drug content was always found in black hair samples, non-pigmented hair showed the lowe st drug concentrations and the drug content in reddish-brown fibers wa s less than in black hair samples from the same animal. From the resul ts it was concluded, that eumelanins rather than pheomelanins are the decisive factor for codeine-melanin binding in hair and the amount of drug intake was suggested to determine the relevance of hair pigmentat ion on the analytical results.