Determination of assay and impurities of gamma irradiated chloramphenicol in eye ointment.
A sample preparation method was developed to isolate chloramphenicol and its radiolytic products from an oily ointment base. The isolation method suspended the eye ointment in n-hexane at 45 degrees C, and isolated the target compounds as residue by centrifugation. It was found that the main element to ensure a satisfactory isolation was keeping the sample solution at 45 degrees C during sample preparation. Linearity, precision, accuracy and suitability of the method were confirmed valid for both assay and impurity tests. This isolation method was ideal for assay, unique for extraction of unexpected and complex radiolysis products, and had a number of advantages compared to the pretreatment methods described in The United Stares Pharmacopoeia and British Pharmacopoeia, in terms of accuracy, precision, and easy handling. The effect of gamma-irradiation on chloramphenicol eye ointment was studied by HPLC, after applying the developed sample preparation method. The present assay and impurity test methods with HPLC were confirmed to be suitable for irradiated chloramphenicol in eye ointment. Formation of radiolytic products induced by gamma-irradiation was evidenced by the impurity test. The assay test showed that active ingredient of chloramphenicol eye ointment decreased by 3.3% at an irradiation dose of 25 kGy and by 11.1% at 50 kGy.
Institute of Pharmaceutical Science, Swiss Federal Institute of Technology (ETH), Zurich.
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Altorfer
D002498:Centrifugation; D002701:Chloramphenicol / Q000302:isolation & purification* / Q000528:radiation effects; D002851:Chromatography, High Pressure Liquid; D004340:Drug Contamination; D005720:Gamma Rays; D006358:Hot Temperature; D009824:Ointments / Q000737:chemistry / Q000528:radiation effects; D009883:Ophthalmic Solutions / Q000737:chemistry* / Q000528:radiation effects; D015203:Reproducibility of Results
D009824:Ointments; D009883:Ophthalmic Solutions; D002701:Chloramphenicol