Promethazine is metabolized through the liver to various compounds; the sulfoxides of promethazine and N-demethylpromethazine are the predominant metabolites showing inside the urine. If concomitant usage of a CYP3A4 inhibitor is essential or if a CYP3A4 inducer is discontinued, consider dosage reduction of TYLENOL® with Codeine till stable drug effects https://wockusa.com/