Biol. Pharm. Bull. 28(1) 151—153 (2005)

is related to the imidazole. A long half-life permits once daily dosing. The mechanism of action of fluconazole is similar to that of other imidazole and triazole antifungal agents, specifically, the inhibition of cytochrome P-450-dependent ergosterol synthesis. The drug is effective when administered orally and intravenously for a variety of fungal infections, especially cryptococcosis in acquired immunodeficiency syndrome patients. Case reports have described QT prolongation and torsades de points associated with fluconazole. The concurrent administration of Class I antiarrhythmic agents and agents that prolong the QT interval, such as fluconazole, may increase the risk of cardiotoxicity. The toxicological and pharmacological effects of cardiovascular drugs are usually studied in mammals and the results obtained are extrapolated to humans. Chick embryonic heart develops through a similar process to that in mice, rats and humans, and also has a similar atrioventricular system. Chick embryos have been widely used in pharmacologic and toxicologic experiments for evaluating drug action on the fetus. With the recent concern for animal rights, experimental studies using mammals have been limited in number and methods. Thus, based on social acceptance, experimental studies using chick embryos have drawn attention. To develop alternative methods, we have studied the biologic effects of drugs on the cardiovascular system of chick embryos using physiologic techniques. And we have also reported that the chick embryonic model of hypothyrodism produced by treatment with thiamazole can be used to examine the pharmacological and toxicological effects of cardiovascular drugs. Drug drug interactions have been demonstrated for a variety of drugs, including disopyramide and propranolol, in the heart failure patients. We have evaluated the toxic interactions between propranolol and disopyramide in chick embryos. Toxic interaction between fluconazole and disopyramide may result in additive effects on QT prolongation. The present study evaluated the effect of fluconazole on the heart and the toxic interactions between fluconazole and disopyramide in chick embryos.