Abstract In the present study, the effects of different doses of gamma radiation on two different members of sulfonamide (sulfacetamide and sulfametoxazole) commercial preparation were studied for the evaluation of the physibility of radiation as a sterilization method for this group of antibacterial agent. HPLC technique was performed to determine the radiolytic intermediates. All investigations were done in accordance with the requiring pharmacopoeia specification for pharmaceutical dosage forms. Because of being antibacterial in nature antimicrobial activity loss was also investigated in irradiated samples. Studies performed under normal environmental conditions were repeated for samples stored under accelerated stability conditions to investigate possible degradation mechanism and kinetics of irradiated dosage forms. Sulfanilamide was determined as degradation product by HPLC method. Both because of the low quantity and this group of drugs’ showing their pharmacological effects by this metabolite, irradiated samples were considered chemically stable. No microbial activity loss and no harmful effect resulting from degradation products were seen in biological investigations also. As a result these commercial preparations were found to be stable in studied radiation doses. This study could be a model for industrial physibility studies of the radiosterilization of sulfa group drugs. Özet Bu çalismada konvansiyonel sterilizasyon tekniklerine alternatif olarak gamma radyasyonun etkileri sulfonamit grubu iki etkin madde (sulfametoksazol ve sulfasetamit) içeren piyasa preparatlari üzerinde arastirilmistir. Radyolitik ara ürünler yüksek basinçli sivi kromotografisi (HPLC) ile belirlemistir. Isinlama sonrasi farmasötik dozaj formlari farmakope uygunluklari bakimindan degerlendirilmistir.Bunun yanisira radyasyona tabii tutulan numunelerde antimikrobiyal aktivite kaybi olup olmadigi da incelenmistir.Isinlanan numunelerin raf ömürlerinin belirlenmesi için farkli saklama kosullarindaki stabiliteleri de üç aylik periyotlarda incelenmistir.Isinlama sonrasi sulfonamit bozunma ürünü olarak saptanmis olsa da gerek miktarinin çok düsük olmasi gerekse sülfa grubu ajanlarin antimikrobiyal etkilerinden bu metabolitin sorumlu olmasi nedeni ile çalisilan radyasyon dozlarinda numuneler kimyasal olarak stabil bulunmustur. Mikrobiyal aktivite kaybinin olmamasi da bu sonucu desteklemektedir.Bu çalisma sülfa grubu ilaçlarin endüstriyel olarak radyasyonla sterilizasyonu için model teskil etmektedir.

Keywords: Gamma irradiation; Sterilization;Rradiation sterilization; Sulfonamides