The effect of buffering on the stability of reconstituted benzylpenicillin injection

Abstract

Abstract The stability of benzylpenicillin sodium injection after reconstitution was investigated using a stability-indicating high pressure liquid chromatography (HPLC) method. Benzylpenicillin reconstituted in water for injections, diluted in 0.9 per cent sodium chloride infusion in Minibags and stored at 5C was stable for two days (based on t/90 per cent calculations). The effect of reconstituting benzylpenicillin in citrate buffer at pHs between 6 and 8 was investigated. Maximum stability was found to occur in the pH range 6.5-7.5. The stability of buffer-reconstituted benzylpenicillin diluted in 0.9 per cent sodium chloride infusion was then investigated. Results indicated that benzylpenicillin injection 600mg reconstituted in 3.6ml citrate buffer within the pH range 6.5 to 7.5, diluted in 50ml 0.9 per cent sodium chloride in Minibags and stored at 5C, may be assigned a shelf life of at least 28 days.