[Assay of cefaclor in serum and urine (including stability test) using high pressure liquid chromatography (author's...

Using high pressure liquid chromatography (reverse phase method) a study was made of the stability of cefaclor dissolved in sodium citrate buffer, normal serum and urine and stored for different periods of time at 4 degrees C and 37 degrees C. In sodium citrate buffer (pH 4.0) and in urine (pH 6.0) no appreciable loss of activity of cefaclor occurred at either 4 degrees C or 37 degrees C, even after longer periods of storage (up to 24 h). Serum containing cefaclor stored at 37 degrees C lost about 4% of the active cefaclor after 30 min, 13% after 1 h and 20% after 2 h; no cefaclor could be detected after 24 h. The loss was lower during storage of serum containing cefaclor at 4 degrees C, and after 24 h 60% of the initial concentration of active cefaclor was found. Using a lichrosorb-NH2 column, it could be demonstrated that after 24 h storage of serum containing cefaclor, only phenylglycine, but not amino-chloro-cephem-carboxylic acid or cefaclor was present. After oral administration of 1 g cefaclor, cefaclor was present in the serum and urine of adult volunteers and only small amounts of phenylglycine and amino-chloro-cephem-carboxylic acid.