Stability testing drug products

HHS/FDA International Conference on Harmonisation Stability Testing of New Drug Substances and Products Guideline Availability Notice, Federal Register, September 22, 1994... 

For drug substances and drug products, applications for enantiomers and racemates should include a stereochemically specific identity test and/or a stereochemically selective assay. The choice of control tests should be based on the method of manufacture and stability characteristics and, in the case of the finished product, its composition. 

Methods of assessing the stereochemical integrity of enantiomeric drug substances and drug products should be included in the stability protocols for both, but stereoselective tests may not be required once it has been shown that racemization does not occur. 

GL3 Stability 1 Stability testing of new drug substances and products... 

Drug substance/drug product purity, potency, and other testing Drug substance/drug product stability testing Method development, validation, and transfer Drug product formulation development... 

There shall be a written assessment of stability based at least on testing or examination of the drug product for compatibility of the ingredients, and based on marketing experience with the drug product to indicate that there is no degradation of the product for the normal or expected period of use. 

The purpose of stability testing is to assess the effects of temperature, humidity, light, and other environmental factors on the quality of a drug substance or product. The data produced are used to establish storage conditions, retest periods, shelf loss, and to justify overages included in products for stability reasons. The most useful equation relating temperature and reaction rate is the Arrhenius equation. This equation (27) may be integrated and rewritten as Eqs. (31) and (32). 

Stability testing is another quantitative test that is routinely used in TLC. A drug substance or drug product is placed on stability and pulled at an appropriate time point. These samples are examined for visual changes as well as purity and potency changes. TLC testing can be done... 

Guidance on Nonclinical Safety Studies for the Conduct of Human Clinical Trials for Pharmaceuticals Notice Stability testing of new drug substances and products Stability testing Stability testing... 

Independent of existing intra-lot variability, a sample size of six dosage units is generally recognized to suffice the needs of quality control (QC). In very early development less than six specimens may be used to create data, but as soon as possible tests should be run with at least n = 6. It is advisable to create statistically valid and sound data for manufacturing prototypes even at very early phases of development, in order to be able to identify formulations/batches with unwanted dissolution behavior. In the early phases of a drug product s development, formulations may not be of acceptable stability. This means that stability phenomena may mask... 

Finally, the protein assay for the drug product will also be used for realtime and accelerated stability testing if it has been validated to be stability indicating. A stability-indicating protein concentration method usually translates to a method that can reveal how much protein can be recovered from the dosage form. Many protein instabilities result in precipitation of the protein and adsorption to the container. An instability that results in only a modification of the protein structure but not in loss of protein from solution will not be detected by a sequence-independent protein assay such as a colorimetric assay. 

ICH Guidance for Industry Topic Q 1 A Stability testing of New Drug Substances and Products, 2003. 

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