Melanin binding

Melanin-binding studies have shown that the affinity of salbutamol for melanin-containing tissues should be lower than that of clenbuterol (40, 23). A residue depletion study in calves orally treated with 1 mg salbutamol/kg bw/day for 7 days showed that liver residues of salbutamol were almost 4 ppm at 0 withdrawal, falling to about 0.11 ppb after a 7 day withdrawal period (37). 

Considerable inference has been made from melanin binding to ocular toxicity. Analysis of the data by Leblanc et al. (1998) indicates that in aU cases, there are no direct consequences of drug-melanin binding. Any drug-related toxicity of the retina in humans and animals was described... 

Potentials problems with the use of hair include a strong influence of hair pigmentation on nicotine and cotinine binding and uptake (Dehn et al. 2001). Nicotine and cotinine are bound to melanin. As a result, dark hair binds much more nicotine than does blond or white hair. This makes comparison across individuals difficult. Also, hair is exposed to nicotine and cotinine from sweat and from sebaceous gland secretions, and to nicotine from environmental tobacco smoke exposure. Washing the hair before analysis may reduce this problem of environmental contamination, but it is not likely to remove all environmental nicotine and cotiiune. 

Seizures There have been rare reports of seizures following sumatriptan use. Binding to melanin-containing tissues Accumulation in melanin-rich tissues (such as the eye) could occur over time, raising the possibility that toxicity in these tissues could occur after extended use. 

Melanin-containing tissues Lamotrigine binds to melanin and may cause toxicity in... 

Eye. Several drugs have an affinity for the retinal pigment melanin and thus may accumulate in the eye. Chlorpromazine and other phe-nothiazines bind to melanin and accumulate in the uveal tract, where they may cause retino-toxicity. Chloroquine concentration in the eye can be approximately 100 times that found in the liver. 

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