Bioavailability study of triamterene and xipamide using urinary pharmacokinetic data following single oral dose of each drug or their combination

► We develop HPLC-DAD methods for estimation of urinary triamterene and/or xipamide. ► Pharmacokinetic data for a single and combination oral doses were compared. ► Bioavailability of triamterene was increased from the combined formulation. ► Combination tablets are analyzed with a well-developed isocratic HPLC-DAD method.