Mechanism:
- Oxidation is a process involving electron loss, often initiated by oxygen or free radicals.
- It can be accelerated by light, heat, trace metals, or pH.
Basic pathway:
- $RH + O_2 \;\rightarrow\; ROOH \;\rightarrow\; RO\cdot + OH\cdot$
- $\mathrm{RH} + \mathrm{O}_2 \rightarrow \mathrm{ROOH} \rightarrow \mathrm{RO}^{\bullet} + \mathrm{OH}^{\bullet}$
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Commonly Affected Drug Classes:
- Phenols: epinephrine, morphine
- Thiols: captopril
- Aldehydes
- Ethers and unsaturated fatty acids
- Vitamins A, D, E, K, and some B-complex vitamins
Stabilization Strategies for Oxidation
Here is a clean, formatted table of Stabilization Strategies for Oxidation:
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| Strategy | Explanation |
| Use of antioxidants | Prevent or interrupt oxidative chain reactions. Aqueous: sodium metabisulfite, ascorbic acid Oily: tocopherols, BHT, BHA |
| Chelating agents | Bind trace metals that catalyze oxidation (e.g., EDTA, citric acid). |
| pH optimization | Adjust pH to less favorable environment for oxidation (e.g., low pH for ascorbic acid). |
| Protection from light | Use amber bottles or opaque containers to reduce photoinitiated oxidation. |
| Air-tight packaging | Use nitrogen flushing, vacuum sealing, or oxygen absorbers. |
| Minimize headspace oxygen | Fill containers with inert gas (e.g., N₂ or Ar). |
| Use of reducing agents | Add chemicals that preferentially oxidize (e.g., ascorbic acid). |
| Storage at low temperature | Slows oxidation rate by reducing kinetic energy. |
