What is an Impurity?
The United States Pharmacopeia (USP) defines impurities as “any component of the drug substance that is not the chemical entity that is defined as the drug substance” or, “any component of a drug product that is not the drug substance or an excipient in the drug product.”
There are three types of impurities:
- Organic impurities: typically arise during drug manufacturing or storage
- Inorganic impurities: typically arise during drug manufacturing and include things like reagents heavy metals or inorganic salts
- Residual solvents: typically introduced during the preparation of the drug substance.
Impurities Testing for Pharmaceutical APIs and Drug Products
Emery Pharma offers comprehensive support in identifying and characterizing impurities in drug substances and drug products. We can perform stability testing, followed by method development, and method validation for quantitation of the impurity. We can work with a variety of sample matrices, including physiological matrices such as blood, serum, urine, etc. Additionally, we have extensive experience analyzing various formulations such as oral, topical, IV, rectal products, etc.
Since 2018, several impurities have been highlighted by the FDA as an area of concern. These include:
Why regulatory agencies are concerned about impurities?
The two major concerns surrounding drug impurities are:
- That they may cause a drug substance to degrade (thereby reducing its efficacy or safety)
- The impurities (or their effects on the drug substance) may be harmful to patients. This was seen in the cases of NDMA and Benzene contamination in consumer products.
The FDA requires that all starting materials and final drug products be evaluated for “identity, strength, quality, and purity.” The FDA has implemented the ICH Q3C guideline which outlines guidelines for residual solvents.