HPLC reveals famotidine in the urine up to five days after a single 20 mg oral dose.

Using a simple method for the HPLC determination of famotidine (FMTD), a new inhibitor of histamine H2-receptors, it is possible to evaluate the urine levels of the drug in patients undergoing treatment. FMTD is excreted mostly in the urine, in the unmetabolized form. The authors evaluated the endpoint of FMTD levels in the urine in five patients given a single oral dose of 20 mg and found measurable levels of the drug up to 106 h (5 days) after the patients began the medication. This method may be useful for assessing patient compliance in taking the drug: this will allow the gastroenterologist to distinguish patients with true relapses of peptic ulcer disease from false relapses, in clinical trials using this histamine H2-inhibitor.