| OBSERVATION'S |
Substantial literature on the pharmacokinetics & toxicology of COLCHICINE appears to be quite inconsistent with the data presented by Petty et al. [Chem. Res. Toxicol., published Aug 4 ASAP, http://pubs.acs.org/journals/crtoec/] Ferron et al. [J. Clin. Pharmacol., 36, p. 874 (1996)] reported that the bioavaila bility of a 1-mg oral dose of colchicines is about 47%, with a Cmax of 6.5 ng per mL; steady-state trough plasma concn averaged about 0.8 ng per mL in vo lunteers taking 1 mg per day for 15 days. Using the data provided by Petty et al., six tablets/day of the suspect ginkgo product would give a dose of 156 micro.g per day of colchicines, < than one-sixth the dose used by Ferron et al.; yet Petty et al. found placental blood levels 8-117 times the Cmax & 60-954 times the steady-state concn reported by Ferron et al While Petty et al respond that fetal & placental tissues are known to concentra te ingredients from mother’s blood, available literature does not support this argument in the case of colchicines. Amoura et al. [J. Rheumatol. 21, p. 383 (1994)] reported the case of a woman who had taken 1 mg/day of colchicine for 10 years, including the duration of her pregnancy. Analysis of maternal & umbilical cord blood samples revealed 3.15 ng/mL in the mother’s blood & mere 0.47 ng/mL in the cord blood. Note that this cord blood concn, after constant dosing of 1 mg/day of colchicines, is 2 orders of magnitude lower than the lowest colchicines blood level reported by Petty et al for the herb- consuming mothers. Even if one considers person-to-person variation in biochemistry & metabolism, these dramatic differences in dosing & blood levels are difficult, if not impossible, to rationalize. Still, the dietary supplement industry takes its responsibility about the sa fety of its prodts & the welfare of its consumers quite seriously. Analyses of samples of powdered ginkgo leaves & extract from various suppliers are already under way. The intent is to determine whether colchicines is a unantici pated trace natural constituent of GINKGO BILOVA or whether any part of the ginkgo supply line has been contaminated with colchicine |
| UPDATE | 09.01 |
| AUTHOR | This data is not available for free |
| LITERATURE REF. | This data is not available for free |
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