Impurities in pharmaceutical substances are unwanted chemicals or compounds that can affect the drug's quality, safety, and efficacy.
They can originate from various sources and are classified as organic, inorganic, or residual solvents.
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Sources of Impurities:
1. Starting materials and reagents:
Impurities from raw materials, side reactions, or degradation products during drug synthesis.
2. Manufacturing process:
Introduced through incomplete reactions, by-products, or equipment contamination (e.g., metal ions or particulate matter).
3. Storage and transportation:
Exposure to heat, light, moisture, or oxygen during storage and transportation can lead to the degradation of the drug substance and the formation of impurities.
4. Packaging materials:
Chemicals from packaging (e.g., plasticizers, adhesives) can leach into the drug product.
5. Environmental contamination:
Contaminants like dust, microbes, or airborne chemicals may enter during manufacturing or storage.
Types of impurities:
1. Organic impurities:
Derived from the drug substance or synthesis process, including starting materials, by-products, and degradation products.
2. Inorganic impurities:
Mainly from manufacturing or environmental sources, such as metal ions or salts. These can also be residual reagents or catalysts.
3. Residual solvents:
Solvents used during synthesis may remain in the final product. Classified based on their toxicity and health risks.
4. Microbial contaminants:
Microorganisms (bacteria, fungi, viruses) that may contaminate the product during manufacturing or storage, compromising quality and safety.
Effects of impurities:
1. Safety concerns:
Some impurities may be toxic, cause allergic reactions, or result in drug interactions.
2. Reduced efficacy:
Impurities may interfere with the drug's action, reducing its therapeutic effectiveness.
3. Quality issues:
Impurities can alter physical and chemical properties (e.g., stability, color, odor), affecting product quality.
4. Regulatory compliance:
Impurities may lead to non-compliance with regulatory guidelines, causing drug batch rejections or recalls.
Regulatory Oversight:
Regulatory bodies like the FDA and EMA set strict guidelines for impurity limits in pharmaceuticals.
Companies must develop analytical methods to detect and control impurities, ensuring product safety and efficacy throughout the development and manufacturing process.