Oxidation

Oxidation

  • Definition: Oxidation is a chemical reaction that involves the transfer (loss) of electrons, resulting in an increase in the oxidation state of a molecule.

  • Concerns: Oxidation is chiefly a problem with stock solutions or inadequately formulated manufactured products, including certain pharmaceuticals.

  • Causes of Oxidation: Certain prescriptions may also oxidize if exposed to (AELOIP):

    • Air: Oxygen in the air can react with sensitive compounds.

    • Excessive Storage Temperatures: Elevated temperatures can increase the rate of oxidation.

    • Light: Photolytic reactions can activate oxidation processes.

    • Overdilution: Diluting certain solutions can expose them to a greater air surface area, enhancing oxidation.

    • Incorrect pH Adjustment: pH levels greatly influence the stability of drugs.

    • Presence of Catalysts: Some substances can accelerate oxidation.

Common Catalysts (HEB)

  • Heavy metal ions (e.g., ferric, ferrous, cupric, or chromium)

  • Excess hydrogen in hydroxyl ions

  • Bacterial or mold enzymes that promote chemical reactions

Examples of Heat-Sensitive Compounds Leading to Oxidation (EPADMMPPNASSSDP)

  • Epinephrine: Used in emergencies, prone to oxidation which can reduce efficacy.

  • Phenylephrine: A decongestant that can degrade through oxidation.

  • Isoproterenol: A bronchodilator that is also sensitive.

  • Apomorphine: A treatment for certain conditions, known for its instability.

  • Diamorphine: A potent opioid that can oxidize.

  • Menadione Sodium Bisulfite: Can undergo oxidation reducing its effectiveness.

  • Morphine Sulfate: An important analgesic that's subject to oxidation.

  • Phentolamine: An alpha-adrenergic antagonist that can oxidize.

  • Procainamide: An antiarrhythmic agent sensitive to oxidizing conditions.

  • Noradrenaline: Critical for blood pressure management, prone to oxidation.

  • Atropine Sodium Aminosalicylate: Used in various therapeutic contexts and sensitive to oxidation.

  • Sodium Antimonyl Citrate, Sodium Aminohippurate, Dextrose, Sodium Glutamate, Procaine Hydrochloride: All susceptible to oxidation under certain conditions.

Corrections for Oxidation Issues (ALA)

  • Addition of Antioxidants:

    • To improve or achieve maximum stability in heat-sensitive compounds which are prone to oxidation as mentioned earlier, antioxidants (ASS) like ascorbic acid, sodium metabisulfite, or sodium sulfite can be added.

  • Light Activation Corrections:

    • For compounds like sulfacetamide eyedrops, sulfonamide injections, and phenylephrine, which may be activated by light and catalysts, metal ion complexing agents (DS) like disodium edetate and sodium calcium edetate can be used.

    • These act as catalyst poisons or negative catalysts.

  • Auto-Oxidation:

    • Oils, fats, phenolic compounds, aldehydes, and vitamins may undergo auto-oxidation via chain-reaction types of oxidation.

    • To correct, more reactive inhibitors (PTPBBH) can be added to provide electrons and receive the excess energy, such as propyl gallate, thymol, phenyl-alpha-naphthylamine, butylated hydroxyanisole, butylated hydroxytoluene, hydroquinone, or similar antioxidants in oily solutions.

Safety Considerations

  • Implosion Risks:

    • Weak bottles with thin spots or flaws may break inward due to the development of a slight vacuum.

    • For instance, bottles of syrup sometimes were broken by implosion due to the removal of oxygen from the air in the bottle by oxidation of the syrup.