Biol. Pharm. Bull. 29(4) 824—826 (2006)

search and education, alternative methods for animal testing came to be discussed on account of criticisms made on animal welfare and humanitarian grounds as well as awareness among scientists. Thus, based on social acceptance, experimental studies using chick embryos have drawn attention. In order to develop alternative methods, we have studied the biological effects of drugs on the cardiovascular system of chick embryos using physiological techniques. An experimental animal model with heart disease originating from abnormalities of the thyroid gland in chick embryos has been produced by treatment with thiamazole and the pharmacological and toxicological effects of cardiotonics were examined using this model. The pharmacological and toxicological activities of thiamazole have characteristics in common with that of thiourea. It has been reported that when thiourea derivatives were injected into the albumen of eggs, the time of the injection strongly affected in the body weight and thyroid gland weight from the 9th to 12th day of incubation. In addition, they showed that that a state of hypothyroidism could be produced in chick embryos by injection of these drugs. Amitriptyline is known to alter myocardial function manifested by electrocardiogram changes. Although tricyclic antidepressants may have cardiovascular effects at the therapeutic doses, it is generally thought to be dose-related and widening of the QRS complex is reported to correlate well with the severity of toxicity following acute overdose ingestion. We have evaluated the toxic interactions between propranolol and disopyramide in chick embryos. The present study evaluated the effect of hypothyroidism induced by thiamazole on the toxicity of amitriptyline in chick embryos.