Formulating ophthalmic preparations involves addressing unique challenges due to the sensitivity of ocular tissues and the need for precise drug delivery.
Key considerations include:
Physiological Constraints
Tear Dynamics: Rapid drainage and tear turnover can dilute or wash away the drug.
pH and Osmolarity: Must align with tear fluid to prevent irritation.
Viscosity: Influences retention time on the ocular surface.
Compatibility and Stability
API Stability: Certain drugs degrade in aqueous environments or with preservatives.
Excipient Compatibility: Additives must not adversely interact with the API or ocular tissues.
Sterility
Aseptic Processing: Prevents microbial contamination.
Preservatives: Maintain sterility for multi-dose applications.
Particle Size and Clarity
Suspensions: Require uniform particle size to avoid irritation and ensure consistent dosing.
Solutions: Must be clear to prevent vision disturbances.
Regulatory Compliance
Good Manufacturing Practices (GMP): Ensures product quality.
Pharmacopoeial Standards: Compliance with official pharmacopeia specifications.