An herbal combination formula, known as VigRX, has been studied for purity, safety and for efficacy in a
Sprague-Dawley rat model. Two separate assays determined that VigRX was free from pharmaceutical adulterants, including
phosphodiesterase type 5 (PDE-5) inhibitors and related analogues. An in vitro assay determined that VigRX is
able to inhibit the enzyme Rho-kinase, suggesting a potential mechanism of action for this product. A 2-week (14-day)
study in rats demonstrated a marked enhancement in sexual behavior, including decreased intromission and ejaculation latencies,
and increased intromission, ejaculation and mounting frequencies, upon oral administration of 30 mg/kg/day. A
longer 12-week study using 15 mg/kg/day showed only a decrease in ejaculation latency with respect to sexual behavior.
In both studies, the treatment led to increased intracavernosal pressure, increased sperm concentration, and increased
width of erect penis (and an increase in erect penile length in the 14-day study only). There was a statistically significant
increase in blood testosterone levels in rats at the end of the 12-week study, which did not occur in the 14-day study. A
non-dose dependent decrease in kidney and liver weights was found in the 14-day study that was not seen in the 12-week
study, and neither study found any notable histopathological changes in any tissues studied. In conclusion, these preliminary
results demonstrate safety and efficacy of VigRx for use in supporting male erectile function, and justify further investigation
in these areas.