The effects of nasolacrimal canal blockage on topical medications for glaucoma

Preparation and performance of latanoprost-loaded hydrogels as a lacrimal suppository for the treatment of glaucoma

Glaucoma is the leading cause of irreversible blindness, and its treatment is attracting widespread attention. Drug-loaded lacrimal suppositories can effectively treat xerophthalmia, but there is little research on the treatment of glaucoma with drug-loaded lacrimal suppositories. This article explored and expanded the non-pharmacological model of lacrimal suppository therapy for glaucoma by using a combination of lacrimal suppository and medication. The drug-loaded lacrimal suppository was rationally designed through the conjugation of gelatin with polyamide (PAM) via the formation of amide linkages, followed by Schiff base reaction grafting with latanoprost. In vitro drug release studies showed that latanoprost released from drug-loaded lacrimal embolus had sustained-release properties with a release time of 33 days and a drug release volume of 82.6%. The biological evaluation of drug-loaded lacrimal thrombus was carried out by IOP test, retinal potential test, and retinal H&E staining. The results showed that the IOP decreased to 27.125 ± 1.1254 mmHg, and the a and b waves of retinal potential increased to 4.39 ± 0.16 μV and 67.9 ± 2.17 μV, respectively. It indicated that latanoprost lacrimal suppository has a good therapeutic effect on glaucoma.

There’s Danger in the Drops: Systemic Effects of Ophthalmic Drops Used to Treat Glaucoma

Glaucoma is a common eye disorder and an irreversible cause of blindness worldwide. There are several treatment options for this condition, with the traditional first-line treatment being ophthalmologic drops. Although administered topically, it is associated with inadvertent systemic absorption leading to a potential for both local and systemic side effects. We discuss the case of a 71-year-old male who presented with a complaint of recurring episodes of distressing sensations including lightheadedness, dyspnea, chest pressure, and faintness. His past medical history included congestive heart failure, hypertension, hyperlipidemia, Barrett’s esophagus, and glaucoma. Upon a thorough review of the patient’s medications, it was discovered that he had recently been started on timolol ophthalmic drops. The patient then noted that his symptoms had begun after he started using the eye drops. After we recommended that the patient hold the use of the eye drops, these episodes stopped. When prescribing topical ophthalmologic drops, providers must educate patients on common systemic side effects of such drugs.

Vildagliptin plasticized hydrogel film in the control of ocular inflammation after topical application: study of hydration and erosion behaviour

Vildagliptin (VID) is a dipeptidyl peptidase-4 (DPP-4) inhibitor used in controlling blood glucose level in type 2 diabetes. Vildagliptin improves beta cells function and is also suggested to effectively control the inflammation. The possible ocular anti-inflammatory property of vildagliptin has been explored using topically applied plasticized ocular film formulation. Film formulation was prepared by solvent cast and evaporation method using triethanolamine (TEA), dimethyl sulphoxide (DMSO), and polyethylene glycol 400 (PEG 400) as the plasticizer in HPMC hydrogel matrix base. Anti-inflammatory study was carried out in the carrageenan induced ocular rabbit model. Analytical methods confirmed that the drug was present almost in completely amorphized form in the film formulation. Level of hydration, swelling and erosion rate of the film played the controlling factor in the process of drug release, ocular residence and permeation. Maximum swelling rate of 363 h−1 has been shown by VHT compared to other formulation of VHD and VHP (174 and 242 h−1 respectively). Film containing DMSO exhibited highest in vitro release as well as ex vivo ocular permeation. Film formulation has shown a fast recovery of ocular inflammation in contrast to the untreated eye after inducing inflammation. Plasticized vildagliptin hydrogel film formulation could be utilized in the management and control of ocular inflammation particularly with diabetic retinopathy after proper clinical studies in higher animal and human individuals.

Review of Approaches for Increasing Ophthalmic Bioavailability for Eye Drop Formulations

Ophthalmic diseases represent a significant problem as over 2 billion people worldwide suffer from vison impairment and blindness. Eye drops account for around 90% of ophthalmic medications but are limited in success due to poor patient compliance and low bioavailability. Low bioavailability can be attributed to short retention times in the eye caused by rapid tear turnover and the difficulty of drug diffusion through the multi-layered structure of the eye that includes lipid-rich endothelial and epithelial layers as well as the stroma which is high in water content. In addition, there are barriers such as tight junctional complexes in the corneal epithelium, lacrimal turnover, nasolacrimal drainage, blinking reflexes, efflux transporters, drug metabolism by ocular enzymes, and drug binding to or repulsion from conjunctival mucins, tear proteins, and melanin. In order to maximize transport through the cornea while minimizing drug loss through other pathways, researchers have developed numerous methods to improve eye drop formulations including the addition of viscosity enhancers, permeability enhancers, mucoadhesives, and vasoconstrictors, or using formulations that include puncta occlusion, nanocarriers, or prodrugs. This review explains the mechanism behind each of these methods, examines their history, analyzes previous and current research, evaluates future applications, and discusses the pros and cons of each technique.

The physical properties of generic latanoprost ophthalmic solutions are not identical

PURPOSE

To compare various characteristics of Xalatan^® and five generic latanoprost ophthalmic solutions.

METHODS

Drop size, volume, pH values, buffer capacity, viscosity, hardness of bottles and costs were determined. Drop sizes were measured in triplicates by micropipettes, and the number of drops counted in three separate bottles of each generic product was determined. pH values were measured in triplicates by a calibrated pH meter. Buffer capacity was exploited by titrating known quantities of strong base into 2.5 ml of each brand and interpolated to neutral pH. Kinematic viscosity was determined by linear regression of timed gravity flow from a vertical syringe through a 21-G cannula. The hardness of the bottles was evaluated by gradually increasing tension on a hook placed around each bottle until a drop was expelled reading the tension on an attached spring scale.

RESULTS

Drop sizes and the number of drops in the bottles varied significantly between the generic drugs. The control value of pH in the brand version (Xalatan^® ) was markedly lower compared to the generic latanoprost products. Titration of Xalatan^® to neutrality required substantially more NaOH compared to the generic latanoprost products. Finally, the viscosity revealed a significant variability between brands. Remarkable differences were found in bottle shapes, bottle hardness and costs of the latanoprost generics.

CONCLUSION

Generic latanoprost eye drops should not be considered identical to the original brand version as regards to drop size, volumes, pH values, buffer capacity, viscosity, hardness of bottles and costs. It is likely that these issues affect compliance and intraocular pressure (IOP)-lowering effect. Therefore, re-evaluation of the requirements for introducing generic eye drops seems reasonable.

Topical medication instillation techniques for glaucoma

BACKGROUND

Glaucoma is a leading cause of irreversible blindness worldwide and the second most common cause of blindness after cataracts. The primary treatment for glaucoma aims to lower intraocular pressure (IOP) with the use of topical medicines. Topical medication instillation techniques, such as eyelid closure and nasolacrimal occlusion when instilling drops, have been proposed as potential methods to increase ocular absorption and decrease systemic absorption of the drops.

OBJECTIVES

To investigate the effectiveness of topical medication instillation techniques compared with usual care or another method of instillation of topical medication in the management of glaucoma or ocular hypertension.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (which contains the Cochrane Eyes and Vision Trials Register) (2016, Issue 12), MEDLINE Ovid (1946 to 8 December 2016), Embase Ovid (1947 to 8 December 2016), PubMed (1948 to 8 December 2016), LILACS (Latin American and Caribbean Health Sciences Literature Database) (1982 to 8 December 2016), International Pharmaceutical Abstracts Database (1970 to 8 December 2016), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com) (last searched 13 May 2013), ClinicalTrials.gov (www.clinicaltrials.gov) (searched 8 December 2016) and the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en) (searched 8 December 2016). We did not use any date or language restrictions in the electronic searches for trials.

SELECTION CRITERIA

We included randomized controlled trials which had compared any topical medication instillation technique with usual care or a different method of instillation of topical medication.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened records from the searches for eligibility, assessed the risk of bias, and extracted data. We followed methods recommended by Cochrane.

MAIN RESULTS

We identified two trials (122 eyes of 61 participants) that had evaluated a topical medication instillation technique. We also identified two ongoing trials. Both included trials used a within-person design and administered prostaglandin monotherapy for glaucoma or ocular hypertension. Because the trials evaluated different instillation techniques and assessed different outcomes, we performed no meta-analysis.One trial, conducted in the US, evaluated the effect of eyelid closure (one and three minutes) versus no eyelid closure on lowering IOP. At one to two weeks' follow-up, reduction in IOP was similar in the eyelid closure group and the no eyelid closure group (mean difference (MD) -0.33 mmHg, 95% confidence interval (CI) -0.8 to 1.5; 51 participants; moderate-certainty evidence).The second trial, conducted in Italy, evaluated the effect of using an absorbent cloth to wipe excess fluid after instillation (fluid removal) versus not using an absorbent cloth (no removal) on reducing dermatologic adverse events. At four months' follow-up, eyelashes were shorter among eyes in the fluid removal group compared with the no fluid removal group (MD -1.70 mm, 95% CI -3.46 to 0.06; 10 participants; low-certainty evidence). Fewer eyes showed skin hyperpigmentation in the eyelid region towards the nose in the fluid removal group compared with the no removal group (RR 0.07, 95% CI 0.01 to 0.84; 10 participants; low-certainty evidence); however, the difference was uncertain in the eyelid region towards the temples (RR 0.44, 95% CI 0.07 to 2.66; 10 participants; low-certainty evidence). The effect hypertrichosis (excessive hair growth) was uncertain between groups (RR 1.00, 95% CI 0.17 to 5.98; 10 participants; low-certainty evidence).Neither trial reported other outcomes specified for this review, including the proportion of participants with IOP less than 21 mmHg; participant-reported outcomes related to the ease, convenience, and comfort of instillation techniques; physiologic measurements of systemic absorption; escalation of therapy; mean change in visual fields; optic nerve progression; mean change in best-corrected visual acuity; proportion in whom glaucoma developed; quality of life outcomes; or cost-effectiveness outcomes. Neither trial reported data at follow-up times of more than four months.

AUTHORS' CONCLUSIONS

Evidence to evaluate the effectiveness of topical medication instillation techniques for treatment of glaucoma is lacking. It is unclear what, if any, effects instillation techniques have on topical medical therapy for glaucoma.

Multi-arm PEG/silica hydrogel for sustained ocular drug delivery

In the present study, a series of sustained drug delivery multiarm poly(ethylene glycol) (PEG)/silica hydrogels were prepared and characterized. The hydrogels were formed by hydrolysis and condensation of poly(4-arm PEG silicate) using the sol-gel method. The relationships between water content in the PEG/silica hydrogel and stability as well as rheological properties were evaluated. Scanning electron microscopy analysis of the PEG/silica hydrogels revealed water content-dependent changes in microstructure. An increase in water content resulted in larger pores within the hydrogel, longer gelation time and higher viscosity. The PEG/silica hydrogels were loaded with dexamethasone (DMS) or dexamethasone sodium phosphate (DMSP), drugs that are hydrophobic and hydrophilic in nature, respectively. Evaluation of in vitro release revealed a zero-order release profile for DMS over the first 6 days, suggesting that degradation of the silica hydrogel matrix was the primary mechanism of drug release. It was also found that the drug-release profile could be tailored by varying the water content used during hydrogel preparation. In contrast, more than 90% of DMSP was released within 1 h, suggesting that DMSP release was only controlled by diffusion. Overall, results from this study indicate that PEG/silica hydrogels may be promising drug-eluting depot materials for the sustained delivery of hydrophobic, ophthalmic drugs.

Epidemiology of major eye diseases leading to blindness in Europe: a literature review

The objective of this work was to study the epidemiology of major eye diseases leading to blindness in Europe through a systematic literature review. The literature search was performed using the Medline database (PubMed), with MeSH and free text search terms. Inclusion criteria for the studies were: (a) performed on a healthy population of Caucasian origin aged between 50 and 75 years; (b) diagnosed by ophthalmological examination in accordance with the International Classification of Diseases 10; (c) contained a detailed description of the sampling and diagnostic procedures and data resources; (d) sample size>500, and (e) published between 1990 and 2008. The results of 57 studies on the prevalence and incidence of age-related macular degeneration, diabetic retinopathy and glaucoma are reported, providing an up-to-date and comprehensive overview of these diseases in Europe from an epidemiological perspective.

Preventive effect of lacrimal occlusion on topical timolol-induced bronchoconstriction in asthmatics

AIM

To evaluate the potential preventive role of lacrimal occlusion on the topical timolol-induced bronchoconstriction in asthmatics.

METHODS

This was a prospective and single-masked study. Fourteen volunteer subjects with asthma were included. Collagen plugs were inserted into both canaliculi on one side to inhibit lacrimal drainage. The effect of lacrimal occlusion on lung function tests was measured before and 60 min after the instillation of a timolol drop in unplugged and plugged eyes. The spirometric measurements include forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), FEV1/FVC, and mid expiratory flow-rate (FEF25-75).

RESULTS

The timolol (0.5%) drop administration into the eye caused a significant decrease in pulmonary functions in patients with asthma in whom the lacrimal punctae had not been occluded by collagen plug. P values were 0.008 for FVC and 0.001 for FEV1 and FEF25-75. The occlusion of the lacrimal duct by intracanalicular plugs significantly reduced this decrease in pulmonary function. P values were 0.6 for FVC, 0.8 for FEV1, and 0.5 for FEF25-75. The lacrimal occlusion did not affect heart rate and blood pressures. Three subjects complained of epiphora.

CONCLUSIONS

Lacrimal occlusion with intracanalicular collagen plugs may almost completely prevent the bronchoconstriction caused by topical timolol in asthmatics by inhibiting or decreasing systemic absorption of the medication.

Five-year follow up of selective laser trabeculoplasty in Chinese eyes

PURPOSE

To study the effectiveness and safety of selective laser trabeculoplasty (SLT) on primary open-angle glaucoma and ocular hypertension in Chinese eyes.

METHODS

This was a prospective randomized controlled clinical study in which 58 eyes of 29 patients with primary open-angle glaucoma or ocular hypertension were included. One eye of each patient was randomized to receive SLT (Group 1) and the fellow eyes received medical treatment (Group 2). Patients were evaluated after laser treatment at 2 h, 1 day, 1 week, 2 weeks, 1 month, 3 months, 6 months, and then yearly.

RESULTS

All patients (13 male, 16 female) were Chinese. The mean age was 51.9 +/- 14.7 years. The mean baseline intraocular pressure was 26.8 +/- 5.6 mmHg in group 1 and 26.2 +/- 4.2 mmHg in group 2 (P = 0.62). The failure rate, defined as intraocular pressure >21 mmHg with maximal medications, was 17.2% in group 1 and 27.6% in group 2 at 5-year follow-up (P = 0.53). Eight eyes (27.6%) in group 1 required medications to control the intraocular pressure to below 21 mmHg. There was no statistically significant difference in the intraocular pressure reductions between the two groups at all time intervals (P > 0.05). The mean number of antiglaucoma medications was significantly lower in the SLT than the medical treatment group up to 5 years of follow up (P < 0.001). Transient post-SLT intraocular pressure spike >5 mmHg was observed in three eyes (10.3%).

CONCLUSION

With fewer medications, SLT gives similar intraocular pressure reduction to medical therapy alone in Chinese patients with primary open-angle glaucoma or ocular hypertension.

Punctal Plugs in the Management of Dry Eyes

Punctal plugs appear to be a relatively safe, effective, and reversible method of preserving aqueous and artificial tears on the ocular surface to reduce the signs and symptoms of dry eye. An absorbable plug may be used temporarily to assess the effectiveness of this therapy prior to insertion of a longterm nonabsorbable plug (Freeman-type, Herrick Lacrimal Plug, or SmartPlug) or cautery. Indications and contraindications for use of punctal plugs are discussed, as are features of various plugs, techniques of insertion and removal, complications, and outcomes.