The influence of oxygen and nitrogen on the radiolysis of chloramphenicol

This study investigates the influence of oxygen and nitrogen on the radioly sis of chloramphenicol (CAP). The drug substance was irradiated with 25, 50 and 100 kGy (Co-60-source) under nitrogen, oxygen and ambient atmosphere, respectively. The content and the impurity profile of CAP were determined w ith several analytical methods. The content was determined by HPLC as well as by DSC. No significant (p = 95%) difference was found between CAP irradi ated under oxygen and nitrogen atmosphere. Purity analysis of CAP was deter mined by liquid chromatography and by two thin-layer chromatographic system s. Nitrogen was found to act as a scavenger. Several degradation products d ecreased under nitrogen atmosphere. Oxygen neither increased the sum of imp urities significantly nor induced any new radiolytical products. Furthermor e, oxygen also showed a scavenging effect. The extent of the radiolysis of CAP (0.5-1.0%) was on an acceptable level. The known im purities 4-nitroben zaldehyde and 4-nitrobenzoic acid amounted to less than 0.10%. AMPD and two further known impurities were above a threshold of 0.1%.