Preparation of 99mTc-cefoperazone complex, a novel agent for detecting sites of infection

Prompt localization of infection sites is essential for initiating appropriate therapeutic measures. There have been major advances in the management of patients suffering from infective and/or inflammatory disorders as a result of introduction of newer drugs with high sensitivity and specificity. Since the last decade, ^99mTc-ciprofloxacin was used as a biologically active radiopharmaceutical to diagnose inflammation but it has some problems related to radiochemical purity and stability. The aim of this study is to develop simple and easy formulation of cefoperazone (other broad spectrum antimicrobial agent) with ^99mTc a ready to use labeling kit for infection imaging. The optimum condition that gives high labeling yield of ^99mTc-cefoperazone complex, 97.9%, was achieved by using 3 mg cefoperazone, 100 μg Sn(II), at pH 8 and 10-minute reaction time. For in vivo binding of ^99mTc-cefoperazone pharmacokinetic studies were carried in experimentally induced infection, in the left thigh, using Staphylococcus aureus in rats. Both thighs of the rats were dissected and counted and the ratio of bacterial infected thigh/contralateral thigh was then evaluated. The time for maximum accumulation of ^99mTc-cefoperazone at the site of infection (T/NT = 4.5) was 45-minute post intravenous injection, followed by gradual decline. So, ^99mTc-cefoperazone complex is simple and stable preparation for infection imaging after 45-minute post injection.