The main impurity types found in pharmaceuticals are organic, inorganic, and residual solvents, arising from various stages of manufacturing, degradation, storage, or contamination.
Types of Pharmaceutical Impurities
Pharmaceutical impurities can be broadly categorized into three main groups: organic, inorganic, and residual solvents. These impurities can affect the safety and efficacy of drug products and must be carefully monitored and controlled.
Organic Impurities
- Definition: These impurities are typically introduced during the manufacturing process of the active pharmaceutical ingredient (API) or can arise from degradation products of the API itself.
- Sources:
- Starting materials
- Intermediates
- By-products
- Reagents
- Degradation products
- Examples: Process-related impurities (e.g., unreacted starting materials, unwanted side products), degradation products (e.g., oxidation products, hydrolysis products).
- Impact: Organic impurities can affect the drug's stability, efficacy, and safety profile.
Inorganic Impurities
- Definition: Inorganic impurities can originate from various sources during the manufacturing process, including raw materials, reagents, or manufacturing equipment.
- Sources:
- Reagents, ligands, and catalysts
- Heavy metals
- Filter aids
- Inorganic salts
- Examples: Metal catalysts (e.g., palladium, nickel), inorganic salts (e.g., sodium chloride), heavy metals (e.g., lead, mercury).
- Impact: Inorganic impurities, particularly heavy metals, can be toxic and pose a significant safety risk to patients.
Residual Solvents
- Definition: Residual solvents are volatile organic compounds (VOCs) used during the manufacturing process of the API or drug product that are not completely removed by the end of the process.
- Sources:
- Solvents used in synthesis
- Solvents used in purification
- Solvents used in formulation
- Examples: Ethanol, methanol, dichloromethane, acetone, toluene.
- Classification: Residual solvents are classified based on their potential toxicity:
- Class 1 Solvents: Solvents to be avoided (e.g., benzene, carbon tetrachloride).
- Class 2 Solvents: Solvents to be limited (e.g., acetonitrile, dichloromethane).
- Class 3 Solvents: Solvents with low toxic potential (e.g., ethanol, acetone).
- Impact: Residual solvents can be toxic or have adverse effects, and their levels must be controlled within acceptable limits.
In summary, organic, inorganic, and residual solvents are the main types of impurities found in pharmaceuticals, each arising from distinct sources and requiring specific control strategies to ensure product quality and patient safety.
