Analysis of ranitidine in serum by high performance liquid chromatography

We describe a simple and rapid micro method for the high pressure liquid chromatographic analysis of ranitidine, N-[2[[[5-[(dimethylamino)-methyl]-2-furanyl]methyl]thio]-ethyl-N'-methyl-2-nitro-1,1-ethenediamine in serum or plasma. The percentage analytical recovery of ranitidine and internal standard (metiamide) was 99% and 81%, respectively. The between-day precision of the procedure (n = 20) at ranitidine plasma concentrations of 500, 250, and 125 microgram/liter generated coefficients of variation of 6.2, 8.7, and 8.9%, respectively. The method was applied in preliminary studies to correlate serum concentrations of ranitidine with gastric acid secretion after continuous pentagastrin stimulation (2 microgram/kg/hr) in patients receiving an oral dose of 20, 40, or 80 mg of the drug.