Eye Drops

Introduction to Eye Drops:

• Eye Drops must be isotonic, pH-balanced, and preservative-free (for sensitive use), ensuring safety and effectiveness.
• Eye drops are sterile liquid preparations containing the drug in a solution or suspension form.
• They are the most commonly used ophthalmic formulations.

Components:

1. Active Ingredient: The drug, e.g., antibiotics, anti-inflammatory agents, or antihistamines.
2. Vehicle: Aqueous or non-aqueous solution (e.g., purified water or oils like castor oil).
3. Preservatives: Benzalkonium chloride, phenylmercuric nitrate.
4. Buffering Agents: Maintain pH (e.g., boric acid, phosphate buffers).
5. Tonicity Adjusters: Sodium chloride, dextrose.
6. Viscosity Enhancers: Methylcellulose, hydroxypropyl methylcellulose.
7. Antioxidants and Stabilizers: Protect drug from degradation.

Formulation Considerations:

• pH Adjustment: Must match the tear fluid to minimize irritation.
• Preservation: Balancing antimicrobial efficacy with ocular tolerance.
• Viscosity Enhancement: Using agents like hydroxypropyl methylcellulose to increase residence time.
• Clarity: Ensuring the solution is free from turbidity or particulate matter.

Examples of Eye Drops:

• Antibiotic Drops: Ciprofloxacin ophthalmic solution.
• Glaucoma Drops: Timolol maleate ophthalmic solution.

Preparation Steps for Eye Drop Solutions:

1. Dissolve drug and excipients in the vehicle (water or water-cosolvent mixture).
2. Adjust pH and tonicity.
3. Filter through a 0.22 μm (or finer) filter to remove particulates and achieve sterility if performing aseptic filtration.
4. Fill into sterile containers under aseptic conditions (if not performing a terminal sterilization).
5. Terminal Sterilization (e.g., autoclave at 121 °C for 15–20 min) if the formulation and container are heat-stable.

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