WHO Expert Committee on Specifications for Pharmaceutical Preparations - WHO Technical Report Series, No. 885 - Thirty-fifth Report
(1999; 168 pages) [Spanish] View the PDF document
Table of Contents
View the documentWHO Expert Committee on Specifications for Pharmaceutical Preparations
View the document1. Introduction
Open this folder and view contents2. The international pharmacopoeia and related issues
Open this folder and view contents3. International Chemical Reference Substances and Infrared Reference Spectra
Open this folder and view contents4. Quality control - national laboratories
Open this folder and view contents5. Good manufacturing practices
Open this folder and view contents6. Quality systems and inspection
Open this folder and view contents7. Other quality assurance topics
Open this folder and view contents8. Nomenclature and terminology
Open this folder and view contents9. Legal aspects of pharmaceuticals
Open this folder and view contents10. Regulatory issues
Open this folder and view contents11. Training activities
View the document12. Pharmaceuticals contaminated with diethylene glycol
View the documentAcknowledgements
View the documentReferences
View the documentAnnex 1. List of available International Chemical Reference Substances1
View the documentAnnex 2. List of available International Infrared Reference Spectra1
Open this folder and view contentsAnnex 3. General guidelines for the establishment, maintenance and distribution of chemical reference substances
Open this folder and view contentsAnnex 4. Good manufacturing practices: authorized person - role, functions and training
Close this folderAnnex 5. Good manufacturing practices: supplementary guidelines for the manufacture of pharmaceutical excipients
View the document1. General considerations
View the document2. Glossary
View the document3. Self-inspection and quality audits
Open this folder and view contents4. Equipment
Open this folder and view contents5. Materials
Open this folder and view contents6. Documentation
Close this folder7. Good practices in production and quality control
View the document7.1 Change control and process validation
Open this folder and view contents7.2 Good practices in production
Close this folder7.3 Good practices in quality control
View the document7.3.1 General
View the document7.3.2 Control of starting materials
View the document7.3.3 In-process testing
View the document7.3.4 Quality records and retention samples
View the document7.3.5 Stability studies
View the document7.3.6 Expiry/re-evaluation dating
View the document7.3.7 Calibration of measuring and test equipment
Open this folder and view contentsAnnex 6. Guidelines for inspection of drug distribution channels
View the documentAnnex 7. Good pharmacy practice in community and hospital pharmacy settings
Open this folder and view contentsAnnex 8. National drug regulatory legislation: guiding principles for small drug regulatory authorities
Open this folder and view contentsAnnex 9. Provisional guidelines for developing training programmes: inspection and examination of counterfeit pharmaceuticals
View the documentWorld Health Organization Technical Report Series
View the documentSelected WHO Publications of Related Interest
View the documentBack Cover
7.3.5 Stability studies

Many excipient products are very stable and may not require extensive testing to check stability. The stability of some excipients may be affected by undetected changes in starting material specifications, or subtle changes in manufacturing procedures. Excipients may also be shipped in a large variety of different packaging types that can affect their stability (e.g. metal and plastic drums, bags, plastic and glass bottles, bulk tankers).

Some excipients may be similar in chemical structure to other excipients, and some may be mixtures or blends of other excipients. These excipients may be very similar to others within a product group. Minor quantitative differences of some of the components may be the only significant variation from one product to another. For these excipients, a "model product" approach to assess the stability may be appropriate. Stability studies of this type should involve selection of several "model products" that would be expected to simulate the stability of the product group being assessed. This selection must be scientifically based. Data from stability studies of these "model products" can be used to determine the theoretical stability of similar products.

The full stability testing programme, when needed, usually contains the following features and takes into account historical data:

• The programme should be formalized in writing and ongoing studies should be reviewed at least annually.


• The programme should periodically include a sample from at least one commercial size batch.

• Stability samples should be stored in containers that approximate the primary market container. Simulations of all types of containers are not required, unless there are theoretical reasons to indicate that stability may be affected by container type.

• The samples should be stored under conditions similar to those recommended for the marketed excipient product.

• Additional samples may be stored under stress conditions (e.g. elevated temperature, light, humidity or freezing) if such conditions might reasonably be encountered during distribution and storage.

• Stability-indicating test methods should be used.

• Where stability of the excipient appears to be a significant issue in its use in pharmaceutical manufacturing, additional periodic testing of either the specific material or "model products" may have to be performed to ensure that the expected stability does not significantly change with future batches. The frequency of testing should be determined by the impact that the excipient's stability may have on its usage.


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