Understanding drug stability and correct storage conditions is fundamental to safe medicines management. This guide covers ICH stability zones, cold chain requirements, photosensitivity, beyond-use dating for compounded preparations, and the regulatory standards governing sterile compounding (USP <797>).
| Term | Temperature range | Examples |
|---|---|---|
| Deep freeze (ultra-low) | −70°C (±10°C) | mRNA vaccines (Pfizer-BioNTech), some labile biologics |
| Freezer | −20°C (±5°C) | Some vaccines, extemporaneous frozen preparations |
| Refrigerator | 2–8°C | Insulin (unopened), most biologics, vaccines, latanoprost |
| Cool | 8–15°C | Some suppositories, certain eye preparations |
| Room temperature (CRT) | 15–25°C (excursion to 30°C) | Most oral solid dosage forms |
| Warm | 30–40°C | Stability testing for accelerated degradation studies |
The ICH Q1A(R2) guideline defines long-term stability testing conditions for different climatic zones. Temperature excursions: brief excursions outside stated range do not necessarily render a product unusable — consult manufacturer mean kinetic temperature (MKT) calculations. For cold chain excursion assessment tools see WHO guidance on vaccine vial monitor (VVM) interpretation.
Cold chain integrity is critical for biologics and vaccines. Common cold chain medicines:
Related: biosimilars guide, vaccines and immunopharmacology.
Expiry date (EXP): assigned by the manufacturer after ICH Q1A stability studies on the intact, original container. Guarantees ≥95% of labelled potency and compliance with all specifications. Expiry is stated to the end of the month unless a day is specified.
Beyond-use date (BUD): applies once a container is opened, punctured, or a preparation is compounded. BUD is always ≤ expiry date. For opened multi-dose vials: BUD = 28 days after first needle puncture (USP standard) unless manufacturer specifies shorter period. Reconstituted powders have manufacturer-assigned BUDs (e.g. reconstituted amoxicillin/clavulanate oral suspension: 7–10 days refrigerated).
IV admixtures BUD (examples):
| Preparation | BUD at RT | BUD refrigerated |
|---|---|---|
| Paracetamol 10 mg/mL IV infusion | 2 h | N/A (use immediately after prep) |
| Vancomycin in 0.9% NaCl | 24 h | 96 h |
| Morphine sulphate in 0.9% NaCl | 24 h | 24 h |
| Piperacillin-tazobactam in NS | 12 h | 24 h (standard); extended stability 72 h validated by some institutions |
| Furosemide IV (protect from light) | 4 h | 24 h |
Photodegradation occurs when UV or visible light energy breaks chemical bonds in the drug molecule. Products include toxic degradation products, reduced potency, or colour change (which may indicate degradation). Key photosensitive drugs:
Reconstituted medicines — both oral suspensions and IV preparations — have shortened stability once dissolved. Key factors affecting post-reconstitution stability:
| Zone | Region | Long-term test condition |
|---|---|---|
| I | Temperate (UK, Northern Europe) | 25°C/60% RH, 12 months |
| II | Mediterranean, subtropical (US, EU) | 25°C/60% RH or 30°C/65% RH |
| III | Hot, dry (Middle East, North Africa) | 30°C/35% RH |
| IVa | Hot, humid (India, Brazil) | 30°C/65% RH |
| IVb | Hot, very humid (SE Asia, Australia) | 30°C/75% RH |
Accelerated testing (40°C/75% RH, 6 months) supplements long-term data and allows early prediction of shelf life. Intermediate conditions (30°C/65% RH) are used for some Zone I/II submissions. ICH Q1B covers photostability testing.
USP Chapter <797> (2023 revision) governs pharmaceutical compounding of sterile preparations in the United States. Key BUD categories:
Related: drug recalls guide.
Room temperature (CRT): 15–25°C (excursions to 30°C). Refrigerator: 2–8°C. Freezer: −20°C ±5°C. Ultra-low: −70°C. ICH stability zones I–IVb correspond to climatic regions: Zone I (temperate, 25°C/60% RH) through Zone IVb (hot/very humid, 30°C/75% RH, applicable to SE Asia and Australia).
Biologics (insulin — until opened; mAbs including adalimumab, trastuzumab; erythropoiesis-stimulating agents), vaccines (most inactivated and live attenuated), latanoprost eye drops (unopened). Insulin pens/vials: once opened, stable 28–30 days at room temperature ≤25°C. Do not freeze insulin (causes aggregation/precipitation).
Expiry date: manufacturer-assigned end of stability from ICH Q1A studies — guarantees ≥95% potency in sealed original container. Beyond-use date (BUD): assigned once container is opened or preparation is compounded — always ≤ expiry date. Multi-dose vials: BUD = 28 days post first puncture. Reconstituted oral suspensions: typically 7–14 days refrigerated. IV admixtures: drug-specific (vancomycin in NaCl: 24 h RT, 96 h refrigerated).
Amphotericin B (amber tubing), furosemide IV (amber bags, cover during infusion), GTN/nitroglycerin (glass or non-PVC containers), doxorubicin/anthracyclines (amber bags for preparation), methotrexate IV, nifedipine immediate-release, amiodarone (counselling on photodermatitis). Protect using amber glass/plastic, foil wrapping, or opaque drip covers.