Clozapine drug-induced pancreatitis of intermediate latency of onset confirmed by de-challenge and re-challenge

Definitive causality for medication-induced illnesses is difficult to determine, as often there are other causes for the condition. Additionally, for disease management there are often alternative treatment paths, and it is therefore clinically unnecessary to re-challenge with the suspected drug causing an adverse reaction: however, that was not the case in this clinical situation. Providers augmented treatment for this patient, but returned to the only therapy that controlled her condition, clozapine, as there appeared to be limited suitable alternatives. As outlined in this medical case, because the patient clinically responded only to clozapine, this forced providers to order multiple de-challenges and re-challenges resulting in confirmed drug-induced pancreatitis. Through courses of re-challenge, they were forced to find an effective dose and timing to maximize options for care using the drug despite inducing pancreatitis. At the time of this submission, providers had resumed a tolerated lower dose of clozapine without inducing pancreatitis. This case adds to the literature of drug-induced pancreatitis confirmation due to clozapine therapy being dechallenge and re-challenge.