A Comparative Ocular Pharmacokinetics Study of Preservative-Free Latanoprost Unit-Dose Eye Drops and a Benzalkonium Chloride-Preserved Branded Product Following Topical Application to Rabbits

The PRAMOS Study: PRostaglandin Analogues Monotherapy-Awareness Survey on Ocular Surface Involvement

INTRODUCTION

Even though the local tolerance of prostaglandin (PG) analogues has improved drastically since the introduction of preservative-free (PF) eye drops, prescription patterns still vary widely among practitioners and between countries and could have an impact on the ocular surface of treated patients and, in consequence, their adherence. The aim of this study is to explore the prescribing patterns of PG analogues monotherapy in France and to evaluate their impact on ocular surface status.

METHODS

This was a national multicenter cross-sectional observational study that was conducted by 18 glaucoma experts in France. Patients over 18 years of age and receiving monotherapy with topical PG analogues for the treatment of ocular hypertension and/or glaucoma, with no history of prior glaucoma surgery, were consecutively selected from the glaucoma outpatient clinics of participating physicians and underwent an ocular surface examination.

RESULTS

A total of 344 eyes of 344 patients were enrolled between November 2022 and November 2023. Prescribed PG monotherapy was PF in 271 (78.7%) patients. Clinical history and ocular surface evaluation indicated that 79.4% of the study population (n = 273) presented with at least one symptom or clinical sign of dry eye and that three patients out of four had an unstable tear film. Subgroup analysis comparing preserved and PF PG analogues showed a higher prevalence of conjunctival hyperemia and corneal staining in the preserved group. Multivariate analysis identified conjunctival hyperemia as consistently associated with preservative use (odds ratio = 7.654; p = 0.003 for moderate conjunctival hyperemia).

CONCLUSIONS

This study highlights the growing trend toward PF PG analogue prescriptions by specialists in France. However, ocular surface issues remain prevalent, impacting patient adherence and treatment efficacy. Comprehensive ocular surface examinations are crucial in glaucoma management to enhance long-term tolerance, compliance, and overall treatment success.

Therapeutic Aqueous Humor Concentrations of Latanoprost Attained in Rats by Administration in a Very-High-Molecular-Weight Hyaluronic Acid Eye Drop

The temporal change in concentration of a novel medicine, Latanoprost (LP), was evaluated in the aqueous humor of rats (6-8-week-old Jcl:Wister rats) when delivered in a very-high-molecular-weight hyaluronic acid (vHiHA) eye drop. Animals were randomly assigned to three treatment groups (LP + vHiHA (LPvHiHA), commercial LP (cLP), and diluted LP (dLP)) and after instilling the eye drops, the aqueous humor (AH) was collected at 0.5, 1, 2, 4, and 6 h to measure the LP concentration using an enzyme-linked immunosorbent assay (ELISA). Although the LP concentration in the LPvHiHA eye drop formulation was 3.57 times lower than in the commercial eye drops used (cLP), the LP concentration in the AH following LPvHiHA administration reached a value close to that of cLP. The cLP was diluted to the same concentration of LP as in the LPvHiHA eye drops for the dLP group, but the LP concentration in the AH of these animals was lower than that of the LPvHiHA rats at all time points. The higher LP concentration in the AH of the LPvHiHA rats suggests that vHiHA may aid the transport of LP across the ocular surface epithelium.

Real-Time Measurement of Antiglaucoma Drugs in Porcine Eyes Using Boron-Doped Diamond Microelectrodes

The primary treatment for glaucoma, the most common cause of intermediate vision impairment, involves administering ocular hypotensive drugs in the form of topical eye drops. Observing real-time changes in the drugs that pass through the cornea and reach the anterior chamber of the eye is crucial for improving and developing safe, reliable, and effective medical treatments. Traditional methods for measuring temporal changes in drug concentrations in the aqueous humor employ separation analyzers such as LC-MS/MS. However, this technique requires multiple measurements on the eyes of various test subjects to track changes over time with a high temporal resolution. To address this issue, we have developed a measurement method that employs boron-doped diamond (BDD) microelectrodes to monitor real-time drug concentrations in the anterior chamber of the eye. First, we confirmed the electrochemical reactivity of 13 antiglaucoma drugs in a phosphate buffer solution with a pH of 7.4. Next, we optimized the method for continuous measurement of timolol maleate (TIM), a sympathetic beta-receptor antagonist, and generated calibration curves for each BDD microelectrode using aqueous humor collected from enucleated porcine eyes. We successfully demonstrated the continuous ex vivo monitoring of TIM concentrations in the anterior chambers of these enucleated porcine eyes. The results indicate that changes in intracameral TIM concentrations can be monitored through electrochemical measurements using BDD microelectrodes. This technique holds promise for future advancements in optimizing glaucoma treatment and drug administration strategies.

Comparison of In Vitro Corneal Permeation and In Vivo Ocular Bioavailability in Rabbits of Three Marketed Latanoprost Formulations

BACKGROUND AND OBJECTIVE

All latanoprost formulations currently available for the treatment of glaucoma or ocular hypertension contain the same concentration of latanoprost (0.005%) but differ in excipients, which may affect corneal drug permeability or stability. This study aimed at comparing corneal penetration of three marketed latanoprost solutions with different excipient formulations in in vitro and in vivo drug permeability studies.

METHODS

Three latanoprost formulations were tested under good laboratory practice conditions: a formulation containing benzalkonium chloride (BAK) but no surfactant (Preserved latanoprost); the same formulation except preservative-free (PF) without BAK or surfactant (SF) (PF SF latanoprost); and a different formulation without BAK but containing a non-ionic surfactant (MGHS 40 at 5%) combined with thickening agents (Carbomer 974P, Macrogol 4000) (PF latanoprost). Corneal permeation of latanoprost acid (LAT) was first determined in vitro using a reconstructed human corneal epithelium tissue. Then, in vivo pharmacokinetic studies were performed on pigmented rabbits, for which LAT concentration was measured in the aqueous humour (AH) and iris-ciliary body (ICB).

RESULTS

In vitro, the cumulative transport of LAT was linear between 1 h and 4 h for preserved latanoprost and PF SF latanoprost, and LAT concentrations matched exactly at each timepoint. By contrast, the permeation of PF latanoprost was linear between 2 h and 12 h and was significantly lower than that of preserved latanoprost and PF SF latanoprost at 4 and 8 h (p < 0.001). In rabbits, the concentrations of LAT in AH and ICB were not statistically different between preserved latanoprost and PF SF latanoprost at each timepoint, except at 1 h in ICB (p = 0.005). By comparison, the LAT concentration of PF latanoprost was statistically (p < 0.05) lower than that of preserved latanoprost and PF SF latanoprost in AH and ICB from 0.5 to 3 h.

CONCLUSION

BAK did not influence the corneal penetration of latanoprost in in vitro and in vivo studies. The formulation containing a non-ionic surfactant resulted in lower and slower ocular penetration compared with preserved or PF SF formulations. This raises questions about the relevance of BAK and some surfactants in enhancing corneal penetration of ocular formulations.

Development of Osthole-Loaded Microemulsions as a Prospective Ocular Delivery System for the Treatment of Corneal Neovascularization: In Vitro and In Vivo Assessments

Osthole (OST), a natural coumarin compound, has shown a significant inhibitory effect on corneal neovascularization (CNV). But, its effect on treating CNV is restricted by its water insolubility. To overcome this limitation, an OST-loaded microemulsion (OST-ME) was created to improve the drug's therapeutic effect on CNV after topical administration. The OST-ME formulation comprised Capryol-90 (CP-90), Cremophor® EL (EL-35), Transcutol-P (TSP) and water, and sodium hyaluronate (SH) was also included to increase viscosity. The OST-ME had a droplet size of 16.18 ± 0.02 nm and a low polydispersity index (0.09 ± 0.00). In vitro drug release from OST-ME fitted well to the Higuchi release kinetics model. Cytotoxicity assays demonstrated that OST-ME was not notably toxic to human corneal epithelial cells (HCECs), and the formulation had no irritation to rabbit eyes. Ocular pharmacokinetics studies showed that the areas under the concentration-time curves (AUC0-t) in the cornea and conjunctiva were 19.74 and 63.96 μg/g*min after the administration of OST-ME, both of which were 28.2- and 102.34-fold higher than those after the administration of OST suspension (OST-Susp). Moreover, OST-ME (0.1%) presented a similar therapeutic effect to commercially available dexamethasone eye drops (0.025%) on CNV in mouse models. In conclusion, the optimized OST-ME exhibited good tolerance and enhanced 28.2- and 102.34-fold bioavailability in the cornea and conjunctiva tissues compared with suspensions in rabbit eyes. The OST-ME is a potential ocular drug delivery for anti-CNV.

Sorafenib-loaded nanostructured lipid carriers for topical ocular therapy of corneal neovascularization: development, in-vitro and in vivo study

Sorafenib (SRB), a multikinase inhibitor, is effective in reducing experimental corneal neovascularization (CNV) after oral administration; however, its therapeutic use in ocular surface disorders is restricted due to poor solubility and limited bioavailability. This study aimed to develop and optimize SRB-loaded nanostructured lipid carriers (SRB-NLCs) for topical ocular delivery by a central composite design response surface methodology (CCD-RSM). It was spherical and uniform in morphology with an average particle size of 111.87 ± 0.93 nm and a narrow size distribution. The in vitro drug release from the released SRB-NLC formulation was well fitted to Korsmeyer Peppas release kinetics. The cell counting kit-8 (CCK-8) cell viability assay demonstrated that SRB-NLC was not obviously cytotoxic to human corneal epithelial cells (HCECs). An in vivo ocular irritation test showed that SRB-NLC was well tolerated by rabbit eyes. Ocular pharmacokinetics revealed 6.79-fold and 1.24-fold increase in the area under concentration-time curves (AUC_0-12h) over 12 h in rabbit cornea and conjunctiva, respectively, treated with one dose of SRB-NLC compared with those treated with SRB suspension. Moreover, SRB-NLC (0.05% SRB) and dexamethasone (0.025%) similarly suppressed corneal neovascularization in mice. In conclusion, the optimized SRB-NLC formulation demonstrated excellent physicochemical properties and good tolerance, sustained release, and enhanced ocular bioavailability. It is safe and potentially effective for the treatment of corneal neovascularization.

Development of a naringenin microemulsion as a prospective ophthalmic delivery system for the treatment of corneal neovascularization: in vitro and in vivo evaluation

Naringenin, a flavonoid, possesses antiangiogenic potential and inhibits corneal neovascularization (CNV); however, its therapeutic use is restricted due to poor solubility and limited bioavailability. In this study, we developed a naringenin microemulsion (NAR-ME) for inhibiting CNV. NAR-ME formulation was composed of triacetin (oil phase), Cremophor RH40 (CRH40), PEG400, and water, its droplet size was 13.22 ± 0.13 nm with a narrow size distribution (0.112 ± 0.0014). The results demonstrated that NAR-ME released higher and permeated more drug than NAR suspension (NAR-Susp) in in vitro drug release and ex vivo corneal permeation study. Human corneal epithelial cells (HCECs) toxicity study showed no toxicity with NAR-ME, which is consistent with the result of ocular irritation study. NAR-ME had high bioavailability 1.45-fold, 2.15-fold, and 1.35-fold higher than NAR-Susp in the cornea, conjunctiva, and aqueous humor, respectively. Moreover, NAR-ME (0.5% NAR) presented efficacy comparable to that of dexamethasone (0.025%) in the inhibition of CNV in mice CNV model induced by alkali burning, resulting from the attenuation of corneal vascular endothelial growth factor (VEGF) and matrix metalloproteinase (MMP-14) expression. In conclusion, the optimized NAR-ME formulation demonstrated excellent physicochemical properties and good tolerance, enhanced ocular bioavailability and corneal permeability. This formulation is promising, safe, and effective for the treatment of CNV.

3D printed ocusert laden with ultra-fluidic glycerosomes of ganciclovir for the management of ocular cytomegalovirus retinitis

Cytomegalovirus (CMV) retinitisis a vision-threatening disease that principally afflicts immunosuppressed patients. For the management of the disease, Ganciclovir (GCV) is usually administered systemically, where patients may suffer severe untoward effects. The ocularly-applied alternatives are either the intravitreal injections, which are frequently administered due to GCV short half-life, or the sustained-release implants, which require surgical removal upon drug depletion. Both therapies are invasive and should be completed by a medical expert. The objective of this research was to formulate a non-invasive alternative represented in GCV loaded ultra-fluidic glycerosomes (UFGs), which are glycerosomes containing sodium taurocholate as an edge activator (EA), then incorporating the optimal UFGs in polylactic acid (PLA)-based 3D printed ocusert to prolong the release of GCV. The experimental design, the statistical analysis, and the optimization were performed via Design-Expert® software. The optimal formulation (UFGs 6; composed of 600 mg Phosphatidylcholine (PC), 20 mg cholesterol, 0.1:1 weight molar ratio of EA: PC and 1 gm glycerol) possessed nanovesicles (441.70 ± 1.13 nm) that entrapped 69.33 ± 0.28 % of GCV, with zeta potential value of -37.00 ± 0.42 mV and deformability index value of 74.68 ± 0.71. The confocal microscopy results showed the supreme penetration power of UFGs through the rabbit's cornea, compared to edge-activated vesicles and conventional glycerosomes from the laden ocusert. Moreover, the topical application of the ocusert laden with the optimal GCV loaded UFGs to the rabbits' eyes evidenced their safety as per the histopathological findings. Furthermore, a pharmacokinetic study in the rabbit's aqueous humor demonstrated the sustained release of GCV from the ocusert laden with the optimal GCV loaded UFGs over 5 days. Inclusively, the ocusert laden with UFGs could be considered as a non-invasive sustaining drug delivery system of GCV for the management of CMV retinitis.

Pharmacokinetics and Pharmacology of Latanoprost 0.005% without Benzalkonium Chloride Vs Latanoprost 0.005% with Benzalkonium Chloride in New Zealand White Rabbits and Beagles

Purpose: Many intraocular pressure (IOP)-lowering medications contain benzalkonium chloride (BAK), a preservative associated with unfavorable outcomes.A formulation of latanoprost 0.005% ophthalmic without BAK is approved by the FDA and indicated for reduction of IOP in patients with open-angle glaucoma or ocular hypertension. We present two preclinical studies of latanoprost 0.005% BAK-free vs latanoprost with BAK; one examining plasma and ocular tissue pharmacokinetics (PK) in New Zealand white rabbits, and one comparing in vivo IOP-lowering efficacy in healthy beagles.Methods: In the PK study, one drop of treatment (latanoprost BAK-free or latanoprost with BAK) was instilled into both eyes of rabbits in each treatment group (n = 18). At 0.25, 0.5, 1, 4, 6, and 24 hours postdose, three rabbits per study group underwent terminal blood and tissue collection.In the IOP study, in the first dosing period, both eyes of each beagle received either 1 drop latanoprost BAK-free or latanoprost with BAK, once daily for 10 days. After a 10-day washout period, a second 10-day dosing period was conducted and latanoprost BAK-free or latanoprost with BAK were dosed in the opposite eyes, respectively. IOP measurements were taken at 1, 6, and 12 hours postdose.Results: The maximum plasma concentration for latanoprost BAK-free and latanoprost with BAK occurred 0.25 hours after administration (174.1 vs 217.2 pg/mL, respectively). Area under the concentration time curve from zero to infinity was highest in aqueous humor for latanoprost BAK-free and latanoprost with BAK (133.1 vs 119.6 hr·ng/mL, respectively) and was not estimable in vitreous humor. In beagles, once-daily administration of latanoprost BAK-free or latanoprost with BAK led to a significant reduction in IOP vs baseline (P < .001); there was no difference between groups (P > .05).Conclusions: Latanoprost BAK-free showed comparable activity in reducing IOP, and comparable plasma and ocular PK parameters to latanoprost with BAK.