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TABLE G Saw Palmetto: Related Substances That Might Suggest Risk

Related Substance

Safety Issues

Functionally related therapeutic substancesabc

Steroid 5-α-reductase inhibitorsd

Pregnancy category X: Dutasteride is contraindicated for use in women (GlaxoSmithKline, 2001). Finasteride is contraindicated in pregnancy or in women who may become pregnant (Medical Economics Co., 2003) and is classified as not intended for use by women (Medsafe, 2001). Possible adverse effect: low plasma level of DHT caused by exposure of women to dutasteride may inhibit fetal development of male external genitalia and internal reproductive organs (GlaxoSmithKline, 2001).

Animal studies

Mice – the maximum tolerated dose of finasteride was 250 mg/kg/d.

Rats, teratogenicity studies – finasteride was not teratogenic in rats (320 mg/kg/d, 24 mo).

Rats, developmental studies – in pregnant rats treated with finasteride (0.1–100 μg/kg/d), male offspring developed hypospadias (penile defect, urethral opening is displaced to the under surface) in a dose-dependent manner (3.6% incidence at 0.1 μg/kg/d; 100% incidence at 100 μg/kg/d). In pregnant rats treated with finasteride (≥ 30 μg/kg/d), male offspring were observed to have smaller prostate, smaller seminal vesicles, delayed preputial/foreskin separation, and transient nipple development as compared to control animals. In pregnant rats treated with finasteride (≥ 3 μg/kg/d), male offspring displayed a decreased anogenital distance. The critical period is day 16 to day 17 during gestation (a total of 21 d in the rat) for male offspring exposed in utero to manifest the effects already described. No developmental effects were observed in female offspring exposed in utero to finasteride at any dose studied.

Rabbits, developmental studies – no developmental defects were observed in rabbit pups exposed to finasteride (up to 100 mg/kg/d) in utero (days 6–18 of gestation).

Monkeys, developmental studies – finasteride (0.8 μg/d, i.v.) was administered to pregnant rhesus monkeys (days 20–100 of gestation); no developmental abnormalities were observed in the male fetuses. In other studies, finasteride (2 mg/kg/d) administered orally to pregnant rhesus monkeys resulted in defects in the formation of the external genitalia of male fetuses; female fetuses were not affected.

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