In vivo ocular availability of ketorolac following ocular instillations of aqueous, oil, and ointment formulations to normal corneas of rabbits: a technical note

Pre-Emptive Topical Ketorolac Tromethamine 0.5% for Panretinal Photocoagulation

Purpose: To evaluate the efficacy of topical ketorolac tromethamine 0.5% given pre-emptively a day before, for alleviating pain in patients undergoing panretinal photocoagulation (PRP) treatment. Methods: A controlled single-blinded study was conducted on 33 patients with diabetic retinopathy (DR; severe nonproliferative DR, proliferative DR, or advanced diabetic eye disease) who required PRP treatment in both eyes simultaneously. Each eye of the patients was randomly assigned for ketorolac tromethamine 0.5% eyedrop or placebo. Both eyedrop bottles were randomly labeled. Eyedrops were self-administered by the patients, 4 times a day before the procedure (at 6 am, 12 noon, 6 pm, and 12 midnight) and every 15 min for 1 h (4 times) before the laser. Each patient was subjected to PRP using a Visulas 532s Zeiss device set to spot size 200 μm, time 0.10 s, and ∼600 burns in each eye. The pain score was evaluated immediately after treatment in each eye independently with Scott's visual analog scale (VAS) and the McGill Pain Questionnaire (MPQ). Results: VAS pain score in ketorolac-treated eyes (median 3.0, interquatile range [IQR] ±2.5) was lower than in placebo-treated eyes (median 5.0, IQR ±3.0). Total Pain Rate Index score from MPQ was lower in ketorolac-treated eyes (median 3.0, IQR ±3.0) than in placebo-treated eyes (median 3.0, IQR ±2.5). Both pain score differences are statistically significant with P ˂ 0.05. Conclusion: Topical ketorolac tromethamine 0.5% given pre-emptively a day before is effective in alleviating pain in patients undergoing PRP treatment.

Relevance of Lipid-Based Products in the Management of Dry Eye Disease

Components of the ocular surface synergistically contribute to maintaining and protecting a smooth refractive layer to facilitate the optimal transmission of light. At the air-water interface, the tear film lipid layer (TFLL), a mixture of lipids and proteins, plays a key role in tear surface tension and is important for the physiological hydration of the ocular surface and for ocular homeostasis. Alterations in tear fluid rheology, differences in lipid composition, or downregulation of specific tear proteins are found in most types of ocular surface disease, including dry eye disease (DED). Artificial tears have long been a first line of treatment in DED and aim to replace or supplement tears. More recently, lipid-containing eye drops have been developed to more closely mimic the combination of aqueous and lipid layers of the TFLL. Over the last 2 decades, our understanding of the nature and importance of lipids in the tear film in health and disease has increased substantially. The aim of this article is to provide a brief overview of our current understanding of tear film properties and review the effectiveness of lipid-based products in the treatment of DED. Liposome lid sprays, emulsion eye drops, and other lipid-containing formulations are discussed.

Design and Evaluation of Voriconazole Loaded Solid Lipid Nanoparticles for Ophthalmic Application

Voriconazole is a second-generation antifungal agent with excellent broad spectrum of antifungal activity commercially available for oral and intravenous administration. Systemic administration of voriconazole is associated with side effects including visual and hepatic abnormalities. This study assessed the feasibility of using solid lipid nanoparticles for ocular delivery of voriconazole adopting stearic acid as lipidic material, tween 80 as a stabilizer, and Carbopol 934 as controlled release agent and for increasing the precorneal residence time in eye. The systems were prepared using two different methods, that is, ultrasonication method and microemulsion technique. The results indicated that the larger particle size of SLNs was found with microemulsion technique (308 ± 3.52 nm to 343 ± 3.51) compared to SLN prepared with ultrasonication method (234 ± 3.52 nm to 288 ± 4.58 nm). The polydispersity index values were less than 0.3 for all formulations and zeta potential of the prepared formulations by these two methods varied from −22.71 ± 0.63 mV to −28.86 ± 0.58 mV. Powder X-ray diffraction and differential scanning calorimetry indicated decrease in crystallinity of drug. The in vitro release study and the SLN formulations prepared with ultrasonication method demonstrated sustained release up to 12 hours. This study demonstrated that SLN prepared by ultrasonication method is more suitable than microemulsion technique without causing any significant effect on corneal hydration level.

Chondroitin sulfate-chitosan nanoparticles for ocular delivery of bromfenac sodium: Improved permeation, retention, and penetration

Introduction:

Superiority of topical instillation of drug into the cul-de-sac for the treatment of various ophthalmic complications can be validated with commercial availability of a large number of conventional formulations even though this mode of instillation still elicits limitations owing to poor ocular bioavailability. To overcome the drawbacks of conventional formulations, a large number of novel carriers have been investigated. In this perspective, a new novel nanocarrier, chondroitin sulfate (ChS)-chitosan (CS)-nanoparticles (NPs) are being evaluated for improved delivery of bromfenac sodium.

Materials and Methods:

Formulation was developed and optimized for CS, chondroitin, and initial drug concentration. Optimized formulation was evaluated for various in vitro aspects i.e., particles’ size, size distribution, zeta potential, shape and morphology, in vitro release profile, corneal permeation, corneal retention, corneal uptake, and ocular tolerance test.

Results:

The mean particle size, polydispersity index, zeta potential, and entrapment efficiency of optimized formulation were found to be 245.6 ± 14.22 nm, 0.187 ± 0.016, +37.59 ± 4.05 mV, and 71.72 ± 4.43%, respectively. Transmission electron microscopic analysis revealed a spherical shape of developed formulation. Further, formulation exhibited biphasic release profile and Korsmeyer–Peppas model was found to be the best fit model. Significantly high transcorneal permeation (1.62-fold) and corneal retention (1.92-fold) of bromfenac was observed through ChS-CS-NPs when compared with marketed eyedrops (P < 0.01). Furthermore, high corneal uptake of CHS-CS-NPs was confirmed by confocal laser scanning microscopy (CLSM). Safety profile of the developed formulation was established by hen's egg test-chorioallantoic membrane test.

Conclusion:

Encouraging outcomes of in vitro and ex vivo studies indicated that CHS-CS-NPs could be a potential substitute for improved ocular delivery.

Topical ocular delivery of NSAIDs

In ocular tissue, arachidonic acid is metabolized by cyclooxygenase to prostaglandins which are the most important lipid derived mediators of inflammation. Presently nonsteroidal anti-inflammatory drugs (NSAIDs) which are cyclooxygenase (COX) inhibitors are being used for the treatment of inflammatory disorders. NSAIDs used in ophthalmology, topically, are salicylic-, indole acetic-, aryl acetic-, aryl propionic- and enolic acid derivatives. NSAIDs are weak acids with pKa mostly between 3.5 and 4.5, and are poorly soluble in water. Aqueous ophthalmic solutions of NSAIDs have been made using sodium, potassium, tromethamine and lysine salts or complexing with cyclodextrins/solubilizer. Ocular penetration of NSAID demands an acidic ophthalmic solution where cyclodextrin could prevent precipitation of drug and minimize its ocular irritation potential. The incompatibility of NSAID with benzalkonium chloride is avoided by using polysorbate 80, cyclodextrins or tromethamine. Lysine salts and alpha-tocopheryl polyethylene glycol succinate disrupt corneal integrity, and their use requires caution. Thus a nonirritating ophthalmic solution of NSAID could be formulated by dissolving an appropriate water-soluble salt, in the presence of cyclodextrin or tromethamine (if needed) in mildly acidified purified water (if stability permits) with or without benzalkonium chloride and polyvinyl alcohol. Amide prodrugs met with mixed success due to incomplete intraocular hydrolysis. Suspension and ocular inserts appear irritating to the inflamed eye. Oil drop may be a suitable option for insoluble drugs and ointment may be used for sustained effect. Recent studies showed that the use of colloidal nanoparticle formulations and the potent COX 2 inhibitor bromfenac may enhance NSAID efficacy in eye preparations.

In vitro corneal permeation of diclofenac from oil drops

In vitro transcorneal permeation of diclofenac from oil drops was studied using freshly excised goat cornea. The maximum apparent corneal permeability coefficient (Papp) was obtained with 0.2% (w/v) diclofenac drops in sesame oil followed by safflower oil, while formulation in castor oil provided minimal Papp. The addition of benzyl alcohol, a preservative, in oil drops, increased the Papp value of diclofenac. Partition experiments indicated increased partitioning of diclofenac in the aqueous phase in the presence of benzyl alcohol, and the same could be responsible for the benzyl alcohol-induced increase in Papp. The solubility of diclofenac was higher in castor, arachis, and sunflower oil. But drug permeation from 0.5-1.0% (w/v) diclofenac drops in castor oil or 0.5% (w/v) drops in arachis /sunflower oil was less than that observed with 0.2% (w/v) drops in sesame oil. Thus diclofenac 0.2% (w/v) drops in sesame oil containing 0.5% (v/v) benzyl alcohol provides maximum Papp. The formulation increased corneal hydration indicating corneal damage. Since corneal hydration is less than 83% the damage appears to be reversible. The saturation solubility of diclofenac in sesame oil at 4 degrees C is 0.33% (w/v). Hence diclofenac 0.2% (w/v) solution in sesame oil will not precipitate at 4 degrees C and therefore the chances of crystallization of diclofenac from the formulation due to climatic change leading to physical instability appear to be remote.