Stability / Shelf Life

Stability testing establishes how long a product keeps its defined quality, and under what storage conditions. ICH Q1A(R2) sets the standard study design for temperate and Mediterranean markets: long-term at 25 °C / 60% RH, intermediate at 30 °C / 65% RH, and accelerated at 40 °C / 75% RH, on at least three primary batches in the packaging proposed for marketing. Hotter climatic zones use higher long-term conditions, which is why a product approved in one region may carry a different shelf life in another.

Accelerated data supports the initial shelf life but does not replace real-time data. A significant change under accelerated conditions triggers testing at the intermediate condition, and the approved shelf life is ultimately confirmed by long-term data as it accumulates. ICH Q1E governs how far you may extrapolate beyond the period actually observed — extrapolation is bounded, not open-ended.

Stability is not only a development activity. GMP requires an ongoing stability programme in commercial manufacture: at least one batch per product per year (where one is made) placed on study in the marketed pack, to confirm the approved shelf life continues to hold and to detect any drift introduced by process or supplier change. Photostability sits under ICH Q1B, and bracketing and matrixing designs under Q1D can legitimately reduce the testing burden where justified.

• —ICH Q1A(R2) conditions: long-term 25 °C/60% RH · intermediate 30 °C/65% RH · accelerated 40 °C/75% RH.
• —At least three primary batches, in the proposed marketing packaging.
• —Accelerated data supports but does not replace real-time long-term data.
• —Extrapolation beyond observed data is bounded by ICH Q1E.
• —Drug substances get a re-test period; drug products get a shelf life — the terms are not interchangeable.
• —Ongoing commercial stability: at least one batch per product per year in the marketed pack.

ICH Q1A(R2) (Stability Testing of New Drug Substances and Products); ICH Q1B (photostability), Q1D (bracketing and matrixing), Q1E (evaluation of stability data); ICH Q5C for biotechnological products; EU GMP Part I Chapter 6 §6.23–6.33 for the ongoing stability programme; 21 CFR 211.166.