Metabolism and Excretion

The major metabolites of isotretinoin in the blood following oral administration have been identified as 4-oxo-isotretinoin and 4-hydroxy-isotretinoin, and several glu-curonide conjugates are measurable in the bile. In addition, tretinoin, its 4-oxo-metabolite, and 4-hydroxy-retinoic acid have also been detected. Approximately 20%-30% of isotretinoin isomerizes to tretinoin and is metabolized by this route. Excretion of isotretinoin occurs after conjugation with the feces or after metabolism with urine. Acitretin is metabolized into at least four compounds, the major metabolite being 13-czs-acitretin (Fig. 27.3). Because of their polar carboxylic acid group, both compounds are less lipophilic than etretinate and therefore do not accumulate in adipose tissue and are eliminated more rapidly in feces and urine. However, it is known that acitretin is in part converted into etretinate and that subsequently etreti-nate is stored in adipose tissue. It has been reported that the consumption of alcohol stimulates the formation of etretinate from acitretin, but it is not a necessary precondition for back-metabolization (Allen and Bloxham 1989, Lucek and Colburn 1985, Orfanos et al. 1997, Wiegand and Chou 1998b).

Hair Loss Prevention

Hair Loss Prevention

The best start to preventing hair loss is understanding the basics of hair what it is, how it grows, what system malfunctions can cause it to stop growing. And this ebook will cover the bases for you. Note that the contents here are not presented from a medical practitioner, and that any and all dietary and medical planning should be made under the guidance of your own medical and health practitioners. This content only presents overviews of hair loss prevention research for educational purposes and does not replace medical advice from a professional physician.

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