Impurities

Impurities are considered any chemical substance present in a drug substance or pharmaceutical product that is not the Active Pharmaceutical Ingredient nor an excipient of formulation, independently of its origin.

These can be present in a drug can affect its efficiency and its safety, their analysis and study are currently one of the most important in pharma to meet regulatory requirements.

Its identification, quantitation, qualification and control are a critical part of the drug development process, affecting all phase or product life cycle, since they can arise during the manufacturing process and/or storage of the new drug substance, coming from starting materials, by-products, intermediates, degradation products, reagents, ligands and catalysts,  excipients, packaging, etc.

For conventional drugs obtained from chemical synthesis ICH Q3 guidelines considers the following categories:

• Organic impurities (process- and drug-related)
• Inorganic impurities
• Residual solvents

Specific challenges come from unusually highly toxic impurities such as mutagenic and carcinogenic ones, since the threshold of toxicological concern is very low and this poses a challenge requiring highly specific and sensitive analytical methods, capable of detecting sub-ppb levels. This is the scope of ICH M7 guideline

ICH Q11 makes guidance in biopharmaceuticals, since the nature and origin of impurities is dependent of the biotechnological manufacturing process.

API related impurities are usually easier to monitor using the method of assay of the drugs or modifications thereof. But the broad chemicall nature of the impuritires that can arise in a drug product requires a flexible analytical approach and strong analytical skills to develop specific methods, and LC-MS, our core technology, is a real winner for this purpose.