Major Degradation Pathways in Pharmaceuticals

There are four major degradation pathways that an analytical chemists must focus on for pharmaceutical analysis thermolytic (heat), hydrolytic (water), oxidative (oxygen, light, peroxide), and photolytic (UV and Vis light). 

Many typical organic reactions that are potential degradation pathways are discussed in the addendum to this chapter as they pertain to an analytical 

All of the background information discussed in the addendum (Common Functional Groups) will help an analytical chemist with development of a stability-indicating method (SIM) that will assist in the development of an optimized formulation that will become a drug product in the marketplace. Remember, an analytical chemist must be able to provide knowledge, not just data. 

By the time an active pharmaceutical ingredient (API) is made available to an analytical chemist in the formulation development group, most or all of the physical characteristics of an API has already been studied and the information should be available in some sort of a report from the drug substance group or preformulation group. Some of the key parameters that an analytical chemist in formulation development requires from such a report are the solubility and solution stability. 

Many times, depending upon the active-to-excipient ratio, the solubility of active in presence of excipients in certain solvents will be different. When an API is mixed with excipients, its solubility is usually lower when compared to its solubility in the same solvent by itself. 

---