5.4 JIT, Kanban, Two-Bin & Seasonal/Emergency Forecasting
Key Takeaways
Just-In-Time (JIT) inventory receives goods close to the time they are needed to minimize holding cost, but it raises stockout risk if supply is disrupted — a key nuance for pharmacy because drug shortages make JIT especially risky
Kanban is a visual pull system in which a signal (card, bin, electronic flag) triggers a replenishment order only when stock is actually consumed; the two-bin system is a kanban variant
A two-bin system uses two bins per SKU: when the first bin empties, a reorder is placed and the second bin is used until the replenishment arrives
Seasonal forecasting anticipates recurring demand swings (flu vaccines in fall/winter, allergy medications in spring, back-to-school physicals in late summer); emergency forecasting prepares for disasters, pandemics, and recalls with buffer stock and contingency suppliers
The central trade-off is holding cost vs. stockout risk: JIT and kanban minimize holding cost but increase stockout risk; safety stock and two-bin buffers reduce stockout risk but increase holding cost
Sections 5.1 and 5.3 covered how inventory is tracked and sized. This section covers how inventory is timed — methods that decide when goods arrive relative to when they are needed. PTCB's own outline names just-in-time (JIT) and seasonal/emergency forecasting directly. Kanban and its two-bin variant are not itemized by name in PTCB's outline, but they are common real-world implementations of the pull-based, demand-triggered reordering that JIT relies on, so they are covered here as professional background.
Just-In-Time (JIT)
Just-In-Time (JIT) inventory is a strategy in which goods are received close to the time they are needed, rather than held in large quantities on the shelf. The objective is to minimize holding (carrying) cost — the cost of capital tied up in stock, storage space, insurance, and the risk of expiration, theft, or obsolescence. In a JIT pharmacy, the pharmacy orders smaller quantities more frequently and the wholesaler delivers on a tight schedule so that stock arrives just before it is dispensed.
The Stockout Risk — a Key Exam Nuance
The defining trade-off of JIT is that low holding cost comes at the price of higher stockout risk if supply is disrupted. If the wholesaler has a delay, a backorder, a recall, or a manufacturing disruption, the pharmacy has little buffer to fall back on. This is a particular concern in a pharmacy context because drug shortages are common and often affect exactly the drugs a JIT strategy would keep lean (generic sterile injectables, certain oncologics, controlled substances subject to quota). For this reason, JIT in pharmacy is usually applied to Class C generics with stable, short lead times and abundant wholesaler supply, not to shortage-prone drugs, controlled substances, or critical-care medications where a stockout could harm a patient.
Kanban and Pull Systems
Kanban is a visual pull system developed in manufacturing (Toyota) in which a signal — a card, a bin, an electronic flag in the PIS — triggers replenishment only when stock is actually consumed. The signal is pulled from the point of use back upstream to the supplier (internal or external); nothing is ordered until consumption signals it. This contrasts with a push system, where orders are scheduled in advance based on a forecast.
In a pharmacy, a kanban signal might be:
- A barcode-labeled card pulled from a bin and placed in a 'reorder' slot when the bin drops to a trigger level.
- An automated flag in the PIS generated when an ADC dispense drops the on-hand quantity to the reorder point (perpetual + kanban).
- The empty bin itself in a two-bin system (see below).
Kanban reduces overstock because replenishment is demand-driven, and it makes the reorder decision visual and unambiguous.
Two-Bin System
The two-bin system is a kanban variant. Each SKU is held in two bins. Staff draw from the first bin. When the first bin empties, that empty bin is the kanban signal: it triggers a reorder, and staff begin drawing from the second bin. The second bin is sized to cover demand during the replenishment lead time; when the replenishment arrives, it refills the empty first bin and the cycle continues. No separate count or system intervention is required — the empty bin is the signal.
Example
A clinic pharmacy keeps ondansetron 4 mg tablets in two bins of 100 each. The first bin empties on day 10. The empty bin is placed in the reorder slot, an order is placed, and the second bin is put on the shelf. The order arrives on day 13 (3-day lead time). The empty first bin is refilled and becomes the second bin the next time the (formerly second) bin empties.
Seasonal Forecasting
Seasonal forecasting anticipates recurring, predictable demand swings driven by the calendar. In pharmacy these include:
- Influenza vaccine — demand concentrates in September–November (with a smaller late-season tail), driven by vaccination campaigns and payer coverage rules.
- Allergy medications — oral antihistamines and intranasal steroids peak in spring (tree pollen) and again in late summer/fall (ragweed).
- Back-to-school physicals and vaccines — late summer pediatric and adolescent visits drive demand for school-required immunizations and physical exam supplies.
- Cold and flu season — OTC cough/cold preparations, zinc, vitamin C, and prescription antivirals (oseltamivir) peak in winter.
Seasonal forecasting is not 'JIT.' It is the opposite in one sense: the pharmacy pre-builds stock ahead of the predicted surge rather than waiting for demand to arrive, because stockouts during a seasonal surge (no flu vaccine in October) directly cost patient care and revenue. The forecasting is based on historical usage data for the same period in prior years, adjusted for population and program changes.
Emergency / Disaster Forecasting
Emergency (or disaster) forecasting is preparedness for non-recurring, unpredictable events: natural disasters (hurricane, wildfire, flood), pandemics, mass-casualty events, and recalls of a widely used drug that suddenly shift demand to alternatives. The pharmacy plans for these by:
- Maintaining a buffer stock of critical medications (often driven by an institutional emergency-preparedness plan).
- Identifying contingency suppliers (a secondary wholesaler, a 503B outsourcing facility, a networked sister pharmacy) in case the primary supplier is disrupted.
- Pre-defining therapeutic alternatives so that if Drug A is recalled or short, the pharmacy can rapidly switch to Drug B with a formulary update and prescriber communication.
- Drilling on the recall workflow (notification, quarantine, return, alternative supply) so the response is fast.
The COVID-19 pandemic and recurring generic-sterile-injectable shortages have made emergency forecasting a routine part of pharmacy supply-chain practice, not an edge case.
Balancing Cost vs. Availability
Every inventory method sits on a single trade-off: holding cost vs. stockout risk. The table below summarizes where each method falls on that trade-off and what it is best suited for in a pharmacy.
| Method | Holding Cost | Stockout Risk | Best Suited For |
|---|---|---|---|
| JIT | Low | High if supply disrupted | Stable Class C generics, short lead times, abundant supply |
| Kanban (pull) | Low–moderate | Lower than JIT (visual trigger) | SKUs with steady, visible consumption |
| Two-bin | Moderate (two bins of buffer) | Low (second bin covers lead time) | Low-cost, high-volume items; clinic and outpatient |
| Min-max with safety stock | Moderate–high | Low (buffer sized to variability) | Most formulary items; especially Class A and B |
| Seasonal pre-build | High (temporary) | Low during the surge | Predictable seasonal demand (vaccines, allergy) |
| Emergency buffer stock | High | Lowest (designed for disruption) | Critical-care drugs, shortage-prone drugs, preparedness |
Exam Strategy
The exam will frame this trade-off as a scenario: a pharmacy has adopted JIT for a drug that subsequently goes on backorder, and the patient is harmed; or a pharmacy carries six months of a cheap generic on the shelf and the question is whether that is appropriate (yes — Class C, low carrying cost, two-bin or bulk is fine). The correct answer almost always points back to the holding-cost vs. stockout-risk trade-off and the class of the drug (A/B/C).
A community pharmacy adopts a strict just-in-time strategy for a generic oral antibiotic, ordering only enough to cover the next two days of dispenses. The drug then goes on manufacturer backorder for three weeks. Which statement best describes the consequence, and the underlying trade-off?
JIT minimizes holding cost but raises stockout risk when supply is disrupted, so the pharmacy now has no buffer to cover the three-week backorder
JIT guarantees no stockouts because orders are placed more frequently
JIT and kanban are the same thing, so the pharmacy will automatically receive a reorder signal and avoid the stockout
JIT increases holding cost because it requires more frequent orders, but it eliminates stockout risk
A clinic pharmacy holds ondansetron 4 mg tablets in two bins of 100 each. Staff draw from the first bin until it is empty, then place the empty bin in the reorder slot and begin using the second bin, sized to cover demand during the lead time. Which inventory method does this describe?
Just-in-time (JIT)
ABC analysis
Two-bin system, a kanban variant
Periodic inventory
In late August a pharmacy manager increases stock of influenza vaccine, oseltamivir, and school-required immunizations. Which type of forecasting drives this decision, and how does it differ from JIT?
Emergency forecasting — it is identical to JIT because both pre-build stock
ABC forecasting — it reclassifies flu vaccine as Class C during the surge
JIT forecasting — it orders ahead of the surge to minimize holding cost
Seasonal forecasting — it pre-builds stock ahead of a predicted, recurring demand surge; JIT by contrast receives goods close to use to minimize holding cost
A pharmacy is selecting an inventory method for three different SKUs: (1) a cheap, stable, abundant generic oral solid; (2) a shortage-prone sterile injectable used in critical care; (3) a moderately expensive brand drug with steady demand. Which assignment best fits the holding-cost vs. stockout-risk trade-off?
Two-bin or bulk for the cheap generic; emergency buffer stock for the shortage-prone injectable; min-max with safety stock for the brand drug
JIT for the cheap generic; JIT for the shortage-prone injectable; JIT for the brand drug
Emergency buffer for the cheap generic; JIT for the shortage-prone injectable; two-bin for the brand drug
Seasonal pre-build for all three
Sections you finish are checked off in the contents.