Sexual stimulants

OBJECTIVES: Tadalafil was examined in vitro and in vivo for its ability to affect human cytochrome P450 (CYP) 3A-mediated metabolism. METHODS: Reversible and mechanism-based inhibition of CYP3A by tadalafil was examined in human liver microsomes. The ability of tadalafil to influence CYP3A activity was also examined in primary cultures of human hepatocytes. The effect of tadalafil on the pharmacokinetics of CYP3A probe substrates was evaluated in human volunteers before and after coadministration with either a single dose or multiple doses of tadalafil (10 or 20 mg). RESULTS: Negligible competitive inhibition of CYP3A was observed in vitro. Mechanism-based inhibition of CYP3A was detected, albeit with a low potency. In human hepatocytes, exposure to 1 micromol/L or greater of tadalafil resulted in increased CYP3A protein expression; however, as with a combined effect of induction and inhibition, a corresponding increase in CYP3A activity did not occur. The clinical pharmacokinetics of midazolam and lovastatin, probe substrates of CYP3A, were unaffected by up to 14 days of tadalafil administration (90% confidence intervals for the ratio of least squares means for the pharmacokinetic parameters of tadalafil were contained within the no-effect boundaries of 0.7 to 1.43). CONCLUSIONS: In vitro results suggested that tadalafil would have little effect on the pharmacokinetics of drugs metabolized by CYP3A. Clinical studies demonstrated that the pharmacokinetics of 2 different CYP3A substrates, midazolam and lovastatin, were virtually unchanged after tadalafil coadministration. Thus therapeutic concentrations of tadalafil do not produce clinically significant changes in the clearance of drugs metabolized by CYP3A.

Despite the increasing availability of effective conventional medical treatments, plant-derived and herbal remedies continue to provide a popular alternative for men and women seeking to improve their sex life. Nevertheless, the efficacy of most herbal agents in treating sexual problems remains uncertain. Therapists and consumers alike would benefit from an increased understanding of commonly used herbal agents on the market, their purported or supported effects, and their potential side effects. To this end, we cataloged the major prosexual herbal agents currently sold in several representative health food stores. We also specify the sexual problem purportedly ameliorated by each herbal agent. Finally, we evaluate eight herbal agents commonly promoted for the treatment of sexual problems. This evaluation includes a review of the research supporting the use, efficacy, dose, adverse effects, contraindications, and possible mechanism of action of each. We conclude by commenting on the quality of current research, pointing out gaps in our knowledge, and noting the need for rigorous research and product control to adequately address questions regarding the efficacy of these agents.

Penile erection is a complex neurovascular event that represents a balance between corporal smooth muscle relaxation and contraction. This balance is determined by the interaction between proerectile and antierectile neurotransmitters. It is believed that nitric oxide is the primary erectogenic neurotransmitter and that noradrenaline (norepinephrine) is the primary erectolytic neurotransmitter. There are a number of pharmacological approaches to the management of erectile dysfunction and manipulation of the neurotransmitter systems. These involve direct delivery of drugs into the erectile chambers (intracavernosal injection therapy), administration of medications into the urethra (transurethral delivery), application of medications to the skin (transdermal delivery) and it is hoped that oral agents will be available in the very near future. This article reviews the world literature on the medications that have been investigated to date and their delivery routes.

The treatment for male impotence has undergone a radical change during these last years. This change is due mainly to the use of vasoactive drugs and more and more sophisticated prosthesis. The Authors discuss old and new drugs used, considering that often pharmacotherapy for impotence doesn't require the giving of a drug, but its suspension. The Authors mention, among the most active drugs, trazodone, yohimbine, pentoxifylline and L-arginine hydrochloride. However these pharmacological agents found only application to well defined and unfortunately limited cases. To day the ideal therapeutic agent is still not available. There is a need for continued research in this field; the initial results, like the ones on the erective mechanisms NO-dependents, give hope for the future.