Importance and types of drug stability

 Introduction

Stability of a pharmaceutical product is related to its resistance to various chemical, physical and microbiological reactions that may change the original properties of the product during preparation, transportation, storage and use.

In another word, stability of a pharmaceutical product may be defined as the capability of that particular formulation, in a specific container or closure system, to remain within its chemical, physical, microbiological, therapeutic and toxicological specifications to assure its attributed quality, e.g., identity, purity, strength etc. until expiry. A pharmaceutical product may undergo physical, chemical and microbiological degradations during preparation as well as subsequent storage of the product.

Stability may be expressed in quantitative term as the shelf life, i.e., the time during which the medicinal product is predicted to remain fit (having 90% of the original potency of active chemicals and having desirable properties during storage) for its intended use under specified conditions of storage.

Importance of Drug Stability

The main objective of pharmaceutical product, to be stable during preparation, preservation, transportation and after administration into body, is that it has to go to the specified organ in proper concentration (Bioavailability) and minimize further complications.

Drug stability is important because of—

·        Safety of patients

·        To assure its attributed quality, e.g., identity, purity, strength etc. until expiry.

·        To maintain the activity of the product

·        To maintain a good constant business

Types of Drug Stability

There are five major types of drug stability and they are--

·     Physical stability

·     Chemical stability

·     Microbiological stability

·     Pharmacological stability

·     Toxicological stability

Deterioration

Many factors affect the stability of a pharmaceutical product, including the stability of the active ingredient(s); the potential interaction between active and inactive ingredients; the manufacturing process; the dosage form; the container-liner-closure system; and the environmental conditions encountered during shipment, storage, and handling; and time between manufacture and use.

Deterioration in the chemical, physical and microbiological properties of a medicament or preparation may affect its therapeutic value or increase its toxicity and cause product failure.

Factors affecting Stability

1. Environmental factors

   - Temperature                   

   -  Light 

   - Oxygen 

   - Moisture

   - Carbon dioxide

2. Drugs or excipients in the dosage form

    -Particle size of drug

    -pH of the vehicle

3. Microbial contamination

4. Trace metal Contamination

5. Leaching from containers 
DISCUSSIONON DRUG’S PHYSICAL STABILITY