抄録
This study examined the effect of thiotriazinone impurity on the generation of insoluble microparticles (IMPs) associated with ceftriaxone-calcium salt precipitation in original (Rocephin®) and Japanese generic ceftriaxone (A; Sawai, B; Nichi-Iko) products when mixed with Ca2＋ 4.3mEq/l. We found that the generation rate of IMPs associated with ceftriaxone-calcium salt precipitation among the three ceftriaxone products tested was in the order of generic (A)＜original＜generic (B), as assessed by light obscuration particle counting. Typically, after 60 min, one of the generic ceftriaxone (B)-calcium mixtures was highly opaque with numerous aggregates of milky-white precipitates, the original ceftriaxone-calcium mixture exhibited noticeable IMPs, and the second generic ceftriaxone (A)-calcium mixture was transparent. The levels of thiotriazinone contaminants, known to be a major impurity in ceftriaxone products, were determined by HPLC and found to be in the order of generic A＞original＞generic B. Moreover, the addition of a small amount of thiotriazinone into the generic ceftriaxone (B)-calcium mixture significantly decreased the amount of IMPs, suggesting that the impurity retards ceftriaxone-calcium crystal growth. We thus concluded that the thiotriazinone impurity acts as a suppressive factor of ceftriaxone-calcium salt precipitation, and that the high level of thiotriazinone impurity in the ceftriaxone (B) product could underlie its lowest rate of IMP generation when mixed with calcium. We thus recommend caution regarding the clinical risk of ceftriaxone-calcium compatibility due to impurity contamination in ceftriaxone products.
