A Probabilistic Batch Size Model for Perishable Products

A batch size model developed for the therapeutic product problem has been instrumental in assisting the staff of a large general hospital to resolve problems associated with the transactional process of the preparation of intravenous medications for administration. The model is a variation of a basic profit maximisation model and is characterised by variable batch preparation cost, a variable planning period, fixed per unit base cost, and zero shortage costs since preparation of a new batch can take place without delay. The variable planning period is transformed into a fixed planning horizon which is at least several multiples of the planning period and is fixed. Development of the model is presented and illustrated with a hypothetical situation, followed by a real case — the determination of the optimal batch size for the intravenous drug, Cefazolin.