Stability study terms explained: ICH Q1A conditions, time points and shelf life

What are the standard ICH stability conditions?

Claims such as 'stable for 24 months at −20 °C' come from stability studies, which follow a standard design set out in ICH Q1A(R2). Knowing its terms makes it possible to judge what a storage statement is based on, and what it is not.

• Long-term (general case): 25 °C ± 2 °C / 60% RH ± 5%, or 30 °C / 65% RH.
• Intermediate: 30 °C / 65% RH.
• Accelerated: 40 °C / 75% RH.
• Refrigerated products: long-term 5 °C ± 3 °C, with accelerated testing at 25 °C / 60% RH.
• Frozen products: long-term −20 °C ± 5 °C.

Source: ICH Q1A(R2) Stability testing of new drug substances and products (EMA)

How often are samples tested?

Long-term testing is typically every 3 months in the first year, every 6 months in the second and annually after that; accelerated studies usually test at 0, 3 and 6 months. A 'significant change' at accelerated conditions, for example failure of the purity specification, triggers testing at the intermediate condition and limits how far shelf life can be extrapolated.

What is the difference between a retest period and a shelf life?

• Retest period: for a drug substance, the time during which it is expected to remain within specification, after which it should be re-tested before use.
• Shelf life (expiry): the time during which a product is expected to remain within specification under the labelled storage conditions.
• Extrapolation: proposing a period beyond the real-time data, allowed only within limits.

How does this apply to research peptides?

• Lyophilised peptides are usually stored frozen or refrigerated, so the relevant long-term condition is −20 °C or 5 °C.
• Storage statements for research materials are often based on general peptide stability knowledge rather than a formal ICH study; ask which.
• Moisture and light are the main accelerating factors outside temperature.

Where is Sable's storage data?

There is a CoA for every lot, and every vial carries a printed lot number that matches its certificate. A CoA is emailed within 2 hours of a request. Storage reference data for listed compounds is on the storage and solubility page.

Frequently asked questions