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Radix Urticae
tion of a hydroalcoholic extract of the root to dogs with BPH (30 mg/kg
body weight) decreased prostate volume by 30% after 100 days of treatment
(49).
The effect of various root extracts was assessed after implantation of
the fetal urogenital sinus into the prostate gland of adult mice. Intragastric
administration of a butanol, cyclohexane or ethyl acetate extract of the
root (0.25 ml/daily for 3 weeks) had no effect on the development of BPH
in mice. However, intragastric administration of the same dose of a 20%
methanol extract of the root reduced the development of BPH by 51.4%
(50).
Toxicology
The LD 50
of an aqueous extract or infusion of the roots after intravenous
administration to rats was 1721 mg/kg body weight and 1929 mg/kg body
weight, respectively. Oral administration of an infusion of the roots to
rats was well tolerated at doses up to 1310 mg/kg body weight (3).
Clinical pharmacology
Benign prostatic hyperplasia
Placebo-controlled clinical trials
Three double-blind, placebo-controlled clinical trials have assessed the
efficacy of oral administration of Radix Urticae for the symptomatic
treatment of lower urinary tract disorders resulting from BPH (24, 27,
35). One study assessed the efficacy of a 20% methanol extract of the
roots in 50 men with BPH stages I and II (35). A significant increase in
urine volume (by 43.7%; P = 0.027) and a significant decrease in serum
levels of SHBG (P = 0.0005) was observed in patients treated with 600 mg
extract daily for 9 weeks. A modest increase in maximum urinary flow of
8% was also observed in the treated group; however, it was not significant
(35). Another study assessed the efficacy of a 20% methanol extract in
40 men with BPH. Treatment with 1200 mg extract daily for 6 weeks decreased
the frequency of micturition and serum levels of SHBG (27). The
third study assessed the efficacy of a methanol extract in the treatment of
32 men with BPH stage I (24). A 4–14% increase in average urinary flow
and a 40–53% decrease in postvoid residual volume were observed in patients
treated with 600 mg extract daily for 4–6 weeks (24).
Clinical trials without controls
Numerous clinical trials without controls have assessed the efficacy of
oral administration of various Radix Urticae extracts (20% methanol or
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