Shelf-life of drugs

When configurational stability is truly low and results in half-lives of racemization or epimerization, which are on the order of minutes or hours, the phenomenon has pharmacological significance. On the other hand, when the half-lives are on the order of months or years, the phenomenon has pharmaceutical significance and may shorten the shelf life of drugs [47],... 

Shelf life of drugs can be extended by increasing their stability. 

A preservative is a substance that extends the shelf-life of drug products by preventing oxidation or inhibiting microbial growth.14 Preservatives must be monitored in the products since they are considered to be active components. Generic HPLC assays are typically developed for preservatives such as buty-lated hydroxytoluene (BHT), an antioxidant for solid dosage forms, and antimicrobials such as parabens, sodium benzoate, or sorbic acid in liquid formulations. For these additive components, typical assay specifications are 85-115% of label claim. 

CREAM.dat A batch of cream containing two drug substances was put on stability and tested for at f = 0, 3, 7, and 24 months. Active component 1 remains stable, while AC2 degrades so fast that a shelf-life of only 26 months can be demonstrated for SL = 90%. Use with SHELFLIFE. 

Various drugs are known to exist in different polymorphic forms (e.g., cortisone and prednisolone). The rate of conversion from a metastable into the stable form is an important criteria to be considered with respect to the shelf life of a pharmaceutical product. Polymorphic changes have also been observed during the manufacture of steroid suspensions. When steroid powders are subjected to dry heat sterilization, subsequent rehydration of anhydrous steroid in the presence of an aqueous vehicle results in the formation of large, needle-like crystals. A similar effect may be... 

It has now been established beyond any reasonable doubt that quality of a drug product cannot simply be ensured by inspection or analysis, but a control system has to be built into, from the very beginning of manufacture of a drug. Besides effective quality control measures exercised in every aspects of production including environment, screening of raw materials, process controls, intermediate shelf-life of finished products the most important aspect is to assess the bioavailability of the active principle. 

To extend the stability and shelf life of the drug (e.g., with antioxidants or preservatives)... 

A preservative is a substance that prevents or inhibits microbial growth and extends the shelf life of the drug products. In most pharmaceutical drug products, only a few compounds are typically selected as preservatives. For efficiency, a generic method should be developed for the types of preservatives that are more commonly used. For example, butylated hydroxytoluene (BHT) is an antioxidant commonly used in many solid dosage formulations to retard oxidative degradation of the excipients. 

An ideal bioadhesive should be nontoxic, nonabsorbable, and nonirritating to the mucus membrane, form a strong noncovalent bond with the mucin-epithelial cell surfaces, allow easy incorporation of drug and should not offer hindrance to drug release, and should not decompose on storage or during the shelf-life of the dosage form. Some of the other desirable characteristics of the polymer have been discussed under bioadhesion. 

What is the stability of a drug in the formulation and hence the shelf-life of the product ... 

The shelf-life of a drug, the time required for 10% degradation (where jc is 0.1 a), is given by the following expression ... 

As with drugs and purified biomarkers, thermal- and photostability of botanical products are the factors that must be considered. Commercial dried extract and capsules of SJW were evaluated under harmonized test conditions (25). Photostability testing showed all the constituents to be photosensitive in the tested conditions. However, different opacity agents and pigments influenced the stability of the constituents. Amber containers had little effect on the photostability of the investigated constituents. Long-term thermal stability testing showed a shelf life of less than four months for hyperforins and hypericins, even when ascorbic and citric acids were added to the formulation. 

A third alternative may occur if hypothesis (15) is rejected it is concluded in this case that the batches do not belong to a single population and the shelf life should be computed for each individual batch. The minimum of the expiration periods of the individual batches is the shelf life of the drug product. 

Chen et al. [11] show that there are 16 different models of Equation (52) however, these models reduce to 9. The general procedure consists in identifying the class of model that is associated to a given assay information. Once the model is determined, the appropriate procedure is implemented to determine the shelf life of the drug product. Chen et al. [11] established the procedure for estimating the shelf life. 

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