HPLC analysis of indomethacin and its impurities in capsule and suppository formulations.
Indomethacin and its impurities in suppository and capsule formulations were quantitatively determined by HPLC using a reversed-phase, octadecyl column and a mobile phase of methanol-water-acetonitrile-acetic acid (55:35:10:1). Analysis of the suppository formulations provided a mean potency for indomethacin of 103.8%. The same formulation was found to contain 4-chlorobenzoic acid (0.02%), 5-methoxy-2-methyl-3-indoleacetic acid (0.07%), 4-chlorobenzoic acid-alpha-monoglyceride (0.39%), and indomethacin-alpha-monoglyceride (0.9%) as impurities. The latter two impurities were a result of the interaction of indomethacin and 4-chlorobenzoic acid with glycerin used in the suppository base. Capsule formulations were likewise assayed with an average potency of 99.9 and 101.5% for 25- and 50-mg dosage forms, respectively. Only one of the two capsule formulations examined contained detectable quantities of 4-chlorobenzoic acid (0.05%).
D002214:Capsules / Q000032:analysis; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D004340:Drug Contamination / Q000032:analysis; D007213:Indomethacin / Q000032:analysis*; D013488:Suppositories / Q000032:analysis
D002214:Capsules; D013488:Suppositories; D007213:Indomethacin