Ophthalmic Drug Dosage Forms: Characterisation and Research Methods

Abstract

This paper describes hitherto developed drug forms for topical ocular administration, that is, eye drops, ointments, in situ gels, inserts, multicompartment drug delivery systems, and ophthalmic drug forms with bioadhesive properties. Heretofore, many studies have demonstrated that new and more complex ophthalmic drug forms exhibit advantage over traditional ones and are able to increase the bioavailability of the active substance by, among others, reducing the susceptibility of drug forms to defense mechanisms of the human eye, extending contact time of drug with the cornea, increasing the penetration through the complex anatomical structure of the eye, and providing controlled release of drugs into the eye tissues, which allows reducing the drug application frequency. The rest of the paper describes recommended in vitro and in vivo studies to be performed for various ophthalmic drugs forms in order to assess whether the form is acceptable from the perspective of desired properties and patient's compliance.

Nanosponge-Mediated Drug Delivery Lowers Intraocular Pressure

“…Although more studies using our NS are required, we do feel the data presented here add to the growing body of work examining more effective ocular drug delivery methods for the treatment of diseases, like glaucoma and AMD. 24,[49][50][51][52][53][54] Compared to noncompliant patients, patients who adhere to treatment plans have lower ocular pressures, less disc cupping, and less visual field loss over time. 13 Given that glaucoma progresses to blindness, and this progression occurs faster with no treatment, one would think adherence rates for glaucoma therapy would be quite high.…”

“…52 Due to these challenges, more efficient drug delivery systems are being developed for ocular tissues that include ocular inserts, lipid-based nanocarriers, nanoparticles, and punctum inserts. 24,[49][50][51][52][53][54] Recent studies using topically applied nanoparticles loaded with ocular hypotensive drugs have shown promise. For example, topical administration of nanoparticles (256 nm) containing the carbonic anhydrase inhibitor methazolamide lowered IOP for 18 hours, with the maximal effect observed 2 to 8 hours after dosing.…”

In vitro and in vivo ocular safety and eye surface permanence determination by direct and Magnetic Resonance Imaging of ion-sensitive hydrogels based on gellan gum and kappa-carrageenan

“…With this aim, different strategies have been developed since the last decades, the main purpose was to increase the cornea permeability and contact time with the ocular surface. Several drug delivery systems have been studied to satisfy both conditions [1]. Some polymeric ocular formulations have been studied to improve the viscosity and/or mucoadhesivity, being hydrogels the most remarkable.…”

Corneal permeation properties of a charged lipid nanoparticle carrier containing dexamethasone

“…The degree of eye irritation was scored using the modified Draize test. 33 Rabbits were euthanized by air embolism, and eye tissue was fixed with 4% formaldehyde and embedded in paraffin for histopathological assessment.…”