Two sensitive and simple spectrophotometric methods are developed for the determination of trazodone HCl, famotidine, and diltiazem HCl in pure and pharmaceutical preparations. The methods are based on the oxidation of the cited drugs with iron(III) in acidic medium. The liberated iron(II) reacts with 1,10-phenanthroline (method A) and the ferroin complex is colorimetrically measured at 510 nm against reagent blank. Method B is based on the reaction of the liberated Fe(II) with 2,2-bipyridyl to form a stable colored complex with λ_max at 520 nm. Optimization of the experimental conditions was described. Beer's law was obeyed in the concentration range of 1–5, 2–12, and 12–32 μg mL^–1 for trazodone, famotidine, and diltiazem with method A, and 1–10 and 8–16 μg mL^–1 for trazodone and famotidine with method B. The apparent molar absorptivity for method A is 1.06×10⁵, 2.9×10⁴, 1.2×10⁴ and for method B is 9.4×10⁴ and 1.6×10⁴, respectively. The suggested procedures could be used for the determination of trazodone, famotidine, and diltiazem, both in pure and dosage forms without interference from common excipients.