Quantitative determination of prednisone and prednisolone in human plasma using GLC and chemical-ionization mass spectrometry.

A method for the quantitative determination of prednisolone and prednisone in human plasma utilizing GLC and chemical-ionization mass spectrometry is described. Corticosteroids are extracted from plasma into ether, and the extract is purified either by passing through a magnesium silicate column or by solvent partitioning. Interference from endogenous hydrocortisone is removed by selective derivatization with Girard Reagent T. Following derivatization, prednisolone can be quantitatively separated from the water-soluble hydrocortisone derivative by simple solvent partitioning. The extracted prednisone and prednisolone are converted to their corresponding methoxyimino trimethylsilyl derivatives, and subjected to GLC-mass spectrometry. Prednisone and prednisolone plasma profiles following a 15-mg oral dose of prednisone in a human volunteer are presented. The method can measure prednisone and prednisolone in plasma at the nanogram per milliliter level.