Types of Drug Degradation (Hydrolysis, Oxidation, Photodegradation)
Start with the big picture
Hydrolysis involves water-driven bond cleavage and is especially relevant to aqueous solutions and suspensions; susceptibility depends on functional groups and conditions such as pH, temperature, and moisture. Oxidation involves electron loss and may proceed through radical, autoxidative, or peroxide pathways, with light, heat, oxygen, and trace metals among its accelerants. Photodegradation begins when a drug absorbs UV or visible light and can lead to bond cleavage, isomerization, or oxidation. The topic compares these pathways, their kinetics, and approaches such as pH adjustment, antioxidants, chelation, and light-protective packaging. It also introduces stability testing and t₉₀, the shelf-life measure associated with potency reaching 90% of its label claim.
What you'll learn
- Distinguish hydrolysis, oxidation, and photodegradation by their mechanisms.
- Identify functional groups and drug features vulnerable to each pathway.
- Describe conditions that accelerate degradation and strategies that can inhibit it.
- Compare the kinetics of the three degradation pathways.
- Explain how stability testing and t₉₀ relate to shelf-life.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
