High-pressure liquid chromatographic method for determination of metoclopramide in serum, urine, and saliva, with a pharmacokinetic study in patients

A method for determination of metoclopramide in serum, urine, and saliva is described that can be applied to both pharmacokinetic and clinical studies. Metoclopramide was extracted from alkalinised plasma into dichloromethane and chromatographed on a Micro-Pak Si-5 column using a mobile phase of dichloromethane/methanol/diethylamine (89:10:1, by volume). The column was maintained at 25 degrees C and the eluate monitored at 308 nm. The retention time for metoclopramide was 4.7 min. The limit of sensitivity in serum and urine was 15 nmol/L and 3 mumol/L, respectively, with coefficients of variation of 5.4 and 3.84%, respectively. Recovery was in the range of 93-110% for serum and 94-103% for urine. The limit of sensitivity in saliva was 15 nmol/L. In more than 210 samples analyzed to date, the only drugs known to have interfered with the assay are beta-adrenoceptor blockers (e.g., propranolol). The metabolites of metoclopramide did not interfere with the quantitation of the parent drug.