Ocular formulations are tailored dosage forms for delivering therapeutic agents to the eye, designed to overcome ocular barriers while ensuring efficacy, safety, and patient comfort.
Types of Ocular Formulations
Solutions and Suspensions
Solutions: Simple, aqueous-based formulations with preservatives.
Suspensions: Disperse insoluble drug particles, offering prolonged release but require shaking before use.
Ointments
Semisolid preparations with prolonged ocular contact but may cause temporary blurred vision.
Gels
Semisolid systems that liquefy upon application, combining clear vision with prolonged drug release.
Nanoparticulate Systems
Nanoparticles: Enhance stability, penetration, and controlled release.
Liposomes: Encapsulate hydrophilic and lipophilic drugs, improving delivery.
Nanoemulsions: Enhance solubility and absorption of lipophilic drugs.
Inserts
Soluble Inserts: Dissolve in tear fluid, releasing the drug.
Insoluble Inserts: Slowly release drugs and require removal after use.
Microneedles
Deliver drugs minimally invasively, bypassing ocular barriers.
Implants
Sustained drug release devices, either biodegradable or non-biodegradable.
Prodrugs
Modified drugs that enhance solubility and penetration, reverting to the active form within the eye.
Contact Lens Drug Delivery
Drug-impregnated lenses provide sustained release during wear.
Factors Influencing Choice of Formulations
Drug Properties: Solubility, stability, and molecular size.
Release Profile: Immediate vs. sustained release needs.
Target Site: Anterior vs. posterior segment delivery.
Patient Compliance: Ease of use (e.g., drops vs. ointments).
Safety: Minimizing irritancy and ensuring biocompatibility.