A hospital pharmacy manages reordering for five drugs. For each drug it tracks the current stock on hand, the average daily usage, and the supplier lead time, the number of days between placing an order and receiving it. To avoid stockouts, the pharmacy places a reorder when the projected days of cover, current stock divided by average daily usage, falls to or below the lead time.
The rule is that a drug must be reordered now if its days of cover is less than or equal to its lead time, because otherwise stock would run out before a fresh order could arrive. A drug whose days of cover exceeds its lead time has enough buffer and is not reordered this cycle.
When a drug is reordered, the standing target is to bring its total stock after delivery up to 50 days of cover, the full buffer. Separately, the pharmacy will not stockpile a drug beyond what it can use before expiry. A reorder is therefore capped so that total stock after delivery, measured in days of cover, does not exceed the drug's days of remaining shelf life. The expiry cap is checked only for drugs that are being reordered, and it binds, that is, it trims the order below the 50-day full-buffer target, only when 50 days of cover would exceed that drug's remaining shelf life.
| Drug | Current stock (units) | Average daily usage (units per day) | Supplier lead time (days) |
|---|---|---|---|
| Albumin | 240 units | 30 per day | 10 days |
| Beractant | 90 units | 15 per day | 8 days |
| Cefazolin | 600 units | 50 per day | 7 days |
| Dopamine | 180 units | 20 per day | 12 days |
| Enoxaparin | 350 units | 25 per day | 9 days |
From: Inventory Control
Days of remaining shelf life by drug, expressed as the number of days of average usage the drug can still cover before it would expire. After a delivery, total stock in days of cover must not exceed this figure.
Albumin: 60 days of usage remaining. Beractant: 55 days of usage remaining. Cefazolin: 30 days of usage remaining. Dopamine: 45 days of usage remaining. Enoxaparin: 20 days of usage remaining.
Note: a drug not being reordered this cycle is unaffected by its shelf-life figure for now.
When a drug is reordered, the pharmacy aims to bring total stock after delivery up to the 50-day full-buffer target, but the expiry cap trims that order whenever 50 days of cover would exceed the drug's remaining shelf life. For which reordered drug does the expiry cap bind, that is, hold the order below the 50-day full buffer?
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