Chemical Degradation Pathways

Introduction to Chemical Degradation

Chemical degradation refers to the process of breakdown or transformation of a drug substance or product resulting from chemical reactions. Understanding the various degradation pathways is essential for assessing and managing the stability of pharmaceutical formulations.

Common Chemical Degradation Pathways

Let’s explore some of the most common chemical degradation pathways observed in pharmaceutical products:

1. Hydrolysis

Hydrolysis involves the cleavage of chemical bonds in the presence of water. Common hydrolytic reactions in pharmaceuticals include:

• Hydrolysis of ester bonds
• Hydrolysis of amide bonds
• Hydrolysis of lactones

2. Oxidation

Oxidation reactions involve the addition of oxygen or removal of hydrogen from a molecule, leading to the formation of oxidized products. Common oxidation reactions in pharmaceuticals include:

• Oxidation of alcohols to aldehydes or ketones
• Oxidation of primary and secondary amines
• Oxidation of sulfur-containing compounds (e.g., thiol oxidation)

3. Photodegradation

Photodegradation occurs when pharmaceutical compounds undergo chemical reactions upon exposure to light, particularly ultraviolet (UV) or visible light. Common photodegradation reactions include:

• Photoisomerization
• Photodecomposition
• Photooxidation

4. Polymerization

Polymerization involves the

formation of polymer chains from monomeric units present in drug formulations. Polymerization can occur under certain conditions, leading to changes in drug stability and efficacy.

5. Other Degradation Pathways

Additional chemical degradation pathways observed in pharmaceuticals include:

• Decarboxylation
• Dehydration
• Isomerization
• Reduction