Step 1: Understanding the Concept:
Inventory rotation methods ensure that drugs are used before they expire.
Step 2: Detailed Explanation:
1. FIFO (First-In, First-Out): The batch that arrived first in the pharmacy is issued first. This assumes that the oldest stock arrived first.
2. FEFO (First-Expiry, First-Out): The batch with the earliest expiration date is issued first, regardless of when it arrived in the store.
3. Variation in Shelf Life: Sometimes, a newer batch of a drug might have a shorter shelf life than an older batch (due to different manufacturing dates or different manufacturers). In cases where batches have variation in shelf life, FIFO might lead to a situation where a newer (but soon-to-expire) batch stays on the shelf and goes waste. FEFO prevents this.
Step 3: Final Answer:
FEFO is the superior method whenever there is a risk that arrival dates do not align with expiration dates, ensuring minimum drug wastage due to expiry.