The effect of long-term diphenylhydantoin (DPH) treatment on thyroid hormone concentrations and protein binding was determined in a randomized controlled trial. As has been demonstrated previously, total thyroxine (T4) concentrations were significantly depressed in patients on DPH. There was no significant effect on indirect indices of protein binding of thyroid hormones, and the free thyroxine index (FTI) was also significantly depressed. Triiodothyronine (T3) and thyrotrophin (TSH) concentrations were either unaffected, or only very slightly affected by DPH. Significant effects on the FTI were still apparent 4 weeks after discontinuing treatment. It is concluded that the depression of total T4 levels observed in vivo is not due solely to diminished protein binding, but may instead be largely explained by reports suggesting enhanced degradation of T4 following DPH therapy.
The effects of tricyclic antidepressants on the heart are reviewed. Statistically significant increases in heart rate and in atrioventricular conduction times were found following the administration of tricyclic drugs to 32 depressed patients. The method of His bundle electrocardiography was used to study atrioventricular conduction in ambulant patients and in patients admitted after an overdose of tricyclic antidepressant drugs. Distal conduction defects were frequently found in patients following tricyclic overdosage, but these were not seen with doxepin overdosage. Impaired distal conduction was also found in occasional patients on therapeutic doses of tricyclic drugs. Some animal experiments giving similar results to the above clinical findings are also described. The clinical implications of these findings are discussed.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.