Thioridazine Phenylpropanolamine

Also analyzed amitriptyline, amphetamine, chlorpromazine, desipramine, desmethyldox-epin, diethylpropion, doxepin, ephedrine, fenfluramine, imipramine, mesoridazine, meth-amphetamine, nortriptyline, phentermine, phenylpropanolamine, promazine, thioridazine, thiothixene, trifluoperazine... 

Noninterfering amitriptyline, amphetamine, atropine, benzoylecgonine, benztropine, caffeine, carbamazepine, carisoprodol, chlorpheniramine, chlorpromazine, chlorprothixene, cimetidine, cocaine, codeine, dextromethorphan, diazepam, diphenhydramine, diphenox-ilate, disopyramide, doxepin, dojylamine, emetine, erythromycin, flurazepam, gluteth-imide, hydrocortisone, hydromorphone, hydroxyzine, imipramine, lidocaine, loxapine, meperidine, meprobamate, methadone, methamphetamine, methapyrilene, methaqualone, methocarbamol, methylphenidate, nicotine, nordiazepam, nortriptyline, orphenadrine, papaverine, pentazocine, phenacetin, phencyclidine, phenmetrazine, phenolphthalein, phentermine, phenylpropanolamine, phenytoin, prazepam, procaineimide, procaine, propoxyphene, propranolol, protriptyline, pseudoephediine, pyrilamine, quinine, salicylam-ide, spironolactone, strychnine, terpin hydrate, thioridazine, thiothixene, triamterene, trifluoperazine, triflupromeizine, trihexyphenidyl, trimeprazine, trimethobenzamide, trimethoprim, tripeleimamine... 

There are anecdotal reports of fatal cardiac arrhythmia (ventricular fibrillation) with a combined phenylpropanolamine and thioridazine regimen. 

A single case report describes fatal ventricular fibrillation, which was attributed to the use of thioridazine with phenylpropanolamine. 

A 27-year-old schizophrenic woman who was taking thioridazine 100 mg daily and procyclidine 2.5 mg twice daily was found dead in bed 2 hours after taking a single capsule of Contac C (phenylpropanolamine 50 mg with chlorphenamine 4 mg). The principal cause of death was attributed to ventricular fibrillation. Just why this happened is not understood but it is suggested that it may have been due to the combined effects of the thioridazine (known to be cardiotoxic and to cause T-wave abnormalities) and the phenylpropanolamine (possibly able to cause ventricular arrhythmias). 

The general importance of this alleged interaction is uncertain but the authors of the report suggest that ephedrine-like drugs such as phenylpropanolamine should not be given to patients taking thioridazine or mesoridazine. 

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