Efficacy and tolerability of timolol maleate ophthalmic gel-forming solution versus timolol ophthalmic solution in adults with open-angle glaucoma or ocular hypertension: a six-month, double-masked, multicenter study

Seeing the Future: A Review of Ocular Therapy

Ocular diseases present a unique challenge and opportunity for therapeutic development. The eye has distinct advantages as a therapy target given its accessibility, compartmentalization, immune privilege, and size. Various methodologies for therapeutic delivery in ocular diseases are under investigation that impact long-term efficacy, toxicity, invasiveness, and delivery range. While gene, cell, and antibody therapy and nanoparticle delivery directly treat regions that have been damaged by disease, they can be limited in the duration of the therapeutic delivery and have a focal effect. In contrast, contact lenses and ocular implants can more effectively achieve sustained and widespread delivery of therapies; however, they can increase dilution of therapeutics, which may result in reduced effectiveness. Current therapies either offer a sustained release or a broad therapeutic effect, and future directions should aim toward achieving both. This review discusses current ocular therapy delivery systems and their applications, mechanisms for delivering therapeutic products to ocular tissues, advantages and challenges associated with each delivery system, current approved therapies, and clinical trials. Future directions for the improvement in existing ocular therapies include combination therapies, such as combined cell and gene therapies, as well as AI-driven devices, such as cortical implants that directly transmit visual information to the cortex.

Comparative efficacy and safety of preserved versus preservative-free beta-blockers in patients with glaucoma or ocular hypertension: a systematic review

Preservative-free topical medications have been introduced for glaucoma care to reduce ocular adverse events associated with preservatives. This is a systematic review and meta-analysis of randomized clinical trials (RCTs) comparing the efficacy and safety of beta-blockers, or combination using beta-blockers, with and without preservatives. PubMed, EMBASE and Web of Science were examined. Risk of bias was assessed using the Cochrane Handbook for Systematic Reviews. The primary outcome was change in intraocular pressure (IOP) from baseline to final follow-up. Secondary outcomes included ocular and systemic side effects, and other clinical and quality of life outcomes. Of 242 records identified, seven RCTs (1125 patients) were included. The follow-up period ranged from one to 12 months. Timolol was used in five studies, and two studies used a combination (timolol with bimatoprost or dorzolamide). The difference in mean change (MD) in IOP between the preservative-free and the preserved drugs was statistically significant but not clinically relevant: (MD 0.29 mmHg, 95% confidence interval 0.07-0.51 mmHg, p = 0.010; moderate-certainty evidence). Regarding adverse events: Level of evidence for all ocular surface outcome was low or very low and reported in few studies. No significant difference was observed on ocular surface symptoms. Tear break-up time (TBUT) was better with preservative-free drops (p < 0.001). Schirmer's test was better in the preservative-free group (p < 0.001). Level of evidence for all ocular surface outcomes was low or very low. There was no difference in other secondary outcomes. We found no clinically relevant difference in mean change in IOP between the preserved and the preservative-free treatments. Data on adverse events used different methods and were incompletely reported. Although some measures of ocular surface health favoured preservative-free medications, more evidence is needed. The increasing use of preservative-free drops may be associated with better ocular surface and tolerability, but strong evidence from RCTs would be welcome.

Repurposing of nifedipine loaded in situ ophthalmic gel as a novel approach for glaucoma treatment

Glaucoma is a chronic eye disease characterized by elevated intraocular pressure (IOP) which causes severe complications to the eyes and may lead to vision loss. The effective treatment of such diseases motivated the search for novel and unique drugs and delivery systems. It has been reported that, nifedipine (NF) is effective in reducing the elevated IOP due to vasodilatation of eye vascular smooth muscles. NF loaded thermo-sensitive in situ gels were prepared by the cold method using poloxamer 407 (P407) and hydroxypropyl methyl cellulose (HPMC) polymers adopting Box-Behnken experimental design. All the prepared formulae were tested for homogeneity, clarity, pH, isotonicity, gelling capacity, rheological behavior, in vitro drug release and were tested in vivo on rabbits. The prepared in situ gels were homogenous, transparent, having a pH ranged from 5 to 5.5 and undergo sol-gel transition within few seconds physiological temperature. The in situ gels showed sustained in vitro release of NF where about 76% of the loaded drug was released over 12 h. NF loaded in situ gels showed a 45.83 ± 2.91% reduction in the IOP, with no sign of toxicity or irritation to the eye in rabbits. The current investigations clarified the efficiency of this novel and unique NF loaded in situ gel for the control of the IOP compared to the conventional ophthalmic dosage forms.

Strategies to prolong the residence time of drug delivery systems on ocular surface

Ocular diseases may be treated via different routes of administration, such as topical, intracameral, intravitreal, oral and parenteral. Among them the topical route is most accepted by patients, although it provides in many cases the lowest bioavailability. Indeed, when a topical formulation reaches the precorneal area, i.e., the drug absorption and/or action site, it is rapidly eliminated due to eye protection mechanisms such as blinking, basal and reflex tearing, and naso-lacrimal draining. To avoid this and to reduce the frequency of dosing, various strategies have been developed to prolong drug residence time after topical administration. These strategies include the use of viscosity increasing and mucoadhesive excipients as well as combinations thereof. From the drug delivery system point of view, liquid and semisolid formulations are preferred over solid formulations such as ocular inserts and contact lenses. Furthermore, liquid and semisolid formulations can contain nano- and microcarrier systems that contribute to a prolonged residence time. Within this review an overview about the different types of excipients and formulations as well as their performance in valid animal models and clinical trials is provided.

Review of Contemporary Self-Assembled Systems for the Controlled Delivery of Therapeutics in Medicine

The novel and unique design of self-assembled micro and nanostructures can be tailored and controlled through the deep understanding of the self-assembly behavior of amphiphilic molecules. The most commonly known amphiphilic molecules are surfactants, phospholipids, and block copolymers. These molecules present a dual attraction in aqueous solutions that lead to the formation of structures like micelles, hydrogels, and liposomes. These structures can respond to external stimuli and can be further modified making them ideal for specific, targeted medical needs and localized drug delivery treatments. Biodegradability, biocompatibility, drug protection, drug bioavailability, and improved patient compliance are among the most important benefits of these self-assembled structures for drug delivery purposes. Furthermore, there are numerous FDA-approved biomaterials with self-assembling properties that can help shorten the approval pathway of efficient platforms, allowing them to reach the therapeutic market faster. This review focuses on providing a thorough description of the current use of self-assembled micelles, hydrogels, and vesicles (polymersomes/liposomes) for the extended and controlled release of therapeutics, with relevant medical applications. FDA-approved polymers, as well as clinically and commercially available nanoplatforms, are described throughout the paper.

Gelling hypotonic polymer solution for extended topical drug delivery to the eye

Eye-drop formulations should hold as high a concentration of soluble drug in contact with ocular epithelium for as long as possible. However, eye tears and frequent blinking limit drug retention on the ocular surface, and gelling drops typically form clumps that blur vision. Here, we describe a gelling hypotonic solution containing a low concentration of a thermosensitive triblock copolymer, for extended ocular drug delivery. On topical application, the hypotonic formulation forms a highly uniform and clear thin layer that conforms to the ocular surface and resists clearance from blinking, significantly increasing the intraocular absorption of hydrophilic and hydrophobic drugs and extending the drug–ocular-epithelium contact time with respect to conventional thermosensitive gelling formulations and commercial eye drops. We also show that the conformal gel layer allows for therapeutically relevant drug delivery to the eyeball’s posterior segment in pigs. Our findings highlight the importance of formulations that conform to the ocular surface prior to viscosity enhancement, for increased and prolonged ocular-surface contact and drug absorption.

Absorption and Safety of Topically Applied Timolol for Treatment of Chronic Cutaneous Wounds

Objective: There are no safety or absorption studies to guide topical timolol therapy for treatment of chronic wounds. This study was undertaken to address this gap. Approach: A prospective, observational, cross-sectional comparative study of timolol plasma levels in patients after topical administration to a chronic wound, compared with levels in patients after timolol ocular administration for the indication of glaucoma. Results: There was no statistically significant difference in the average plasma level of timolol in wound as compared with glaucoma patients. No bradycardia or wheezing was observed after administration. Innovation: We determined the single time point concentration of timolol in plasma 1 h after application of timolol 0.5% gel-forming solution to debrided chronic wounds, providing insight as to the safety of this emerging off-label treatment. Conclusion: The topical application of timolol for chronic wounds shares the same safety profile as the widely used application of ocular administration for glaucoma.

Efficacy of Timolol 0.1% Gel and a Prostaglandin Analog in an Unfixed Combination Compared to the Corresponding Fixed Combinations

PURPOSE

To investigate the intraocular pressure (IOP) reduction with prostaglandin analogs (PGAs)-timolol fixed combinations versus the unfixed combination of the same PGAs and timolol 0.1% in gel-forming carbomer.

METHODS

Patients with primary open-angle glaucoma (POAG) receiving for at least 4 weeks the fixed combinations of PGA-timolol, administered once a day in the evening (0.005% latanoprost with 0.5% timolol, 0.004% travoprost with 0.5% timolol, 0.03% bimatoprost with 0.5% timolol) were switched to an unfixed combination of the same PGA (once a day in the evening) with timolol 0.1% in gel-forming carbomer (once a day in the morning) for at least 4 weeks. The primary endpoint was to compare efficacy of fixed vs unfixed combinations in lowering IOP. The effects of both regimens on short-term IOP fluctuations were also assessed.

RESULTS

A total of 32 patients (64 eyes) fulfilled inclusion criteria: 17 patients received latanoprost-timolol fixed combination, 9 travoprost-timolol fixed combination, 6 bimatoprost-timolol fixed combination. For all considered time periods each unfixed combination induced an IOP reduction significantly higher than the corresponding fixed combination (paired t test: p<0.05 in all measurements). The diurnal IOP reduction was significantly higher during the unfixed combinations (p<0.001). Unfixed combinations significantly decreased IOP diurnal fluctuations and increased the percentage of patients with daily IOP fluctuation ≤2 mm Hg.

CONCLUSIONS

In this pilot study, PGA and timolol seems to be more effective in POAG treatment when administered as unfixed combinations, reducing both IOP and daily fluctuations. The once a day timolol 0.1% gel-forming carbomer may be a valuable option in PGA-timolol unfixed combination regimen.

Development of topical ophthalmic In Situ gel-forming estradiol delivery system intended for the prevention of age-related cataracts

The goal of this study was to develop and characterize an ion-activated in situ gel-forming estradiol (E2) solution eye drops intended for the prevention of age-related cataracts. Accordingly, in situ gelling eye drops were made using gellan gum as an ion-activated gel-forming polymer, polysorbate-80 as drug solubilizing agent, mannitol as tonicity agent, and combination of potassium sorbate and edetate disodium dihydrate (EDTA) as preservatives. The formulations were tested for the following characteristics: pH, clarity, osmolality, antimicrobial efficacy, rheological behavior, and in vitro drug release. Stability of the formulation was also monitored for 6 months at multiple storage conditions per ICH Q1A (R2) guidelines. The solution eye drops resulted in an in-situ phase change to gel-state when mixed with simulated tear fluid (STF). The gel structure formation was confirmed by viscoelastic measurements. Drug release from the gel followed non-fickian mechanism with 80% of drug released in 8 hr. The formulations were found to be clear, isotonic with suitable pH and viscoelastic behavior and stable at accelerated and long-term storage conditions for 6 months. In vitro results suggest that the developed formulation is suitable for further investigation in animal models to elucidate the ability of estrogen to prevent and delay cataracts.

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.

Topical Timolol Maleate Treatment of Infantile Hemangiomas

BACKGROUND

There has been a dramatic increase in the off-label use of ophthalmic timolol maleate, a β-blocker used for infantile hemangioma (IH) treatment as a topical counterpart to oral propranolol. Its safety and efficacy in a pediatric population with IH have not been evaluated in a large cohort. Our goal was to retrospectively assess timolol's effectiveness, discern characteristics associated with response, and document reported adverse events.

METHODS

A multicenter retrospective cohort study of 731 patients treated with topical timolol was completed at 9 centers. Inclusion required an IH suitable for timolol in the treating physician's judgment and access to clinical details including photographs. Logistic regression analysis and descriptive statistics were performed. Primary outcome measures were efficacy assessed by using visual analog scales for color and for size, extent, and volume from review of digital photographs taken as standard of care.

RESULTS

Most IHs were localized (80.1%) and superficial (55.3%). Risk of disfigurement was the most common indication for therapy (74.3%). Duration of therapy (P < .0001), initial thinness (P = .008), and subtype (P = .031) were significant predictors of response. Best response occurred in superficial IHs <1 mm thick. Fifty-three (7.3%) required subsequent therapy with systemic β-blocker. Adverse events were mild, occurring in 25 (3.4%) patients. No cardiovascular side effects were documented.

CONCLUSIONS

Timolol seems to be a well-tolerated, safe treatment option with moderate to good effectiveness, demonstrating best response in thin, superficial IHs regardless of pretreatment size. Timolol can be recommended as an alternative to systemic β-blockers and watchful waiting for many patients.

Advantages of Efficacy and Safety of Fixed-Dose Tafluprost/Timolol Combination Over Fixed-Dose Latanoprost/Timolol Combination

Purpose

To compare the safety and efficacy of fixed-dose tafluprost/timolol combination (Taf/T-FDC) with those of fixed-dose latanoprost/timolol combination (Lat/T-FDC) by measuring the intraocular pressure (IOP)-lowering effect, ocular pharmacokinetics, and ocular surface toxicity.

Methods

The IOP-lowering effect of Taf/T-FDC and Lat/T-FDC in ocular normotensive monkeys was evaluated at 4 and 8 h after instillation in study A, at 12, 14, 16, and 18 h after instillation in study B, and at 24, 26, 28, and 30 h after instillation in study C. Drug penetration into the eye was evaluated by measuring the concentrations of timolol, tafluprost acid (active metabolic form of tafluprost), and latanoprost acid (active metabolic form of latanoprost) using liquid chromatography coupled with tandem mass spectrometry after single instillation of Taf/T-FDC or Lat/T-FDC to Sprague Dawley rats. Cytotoxicity following 1–30 min exposure of SV40-transformed human corneal epithelial cells to Taf/T-FDC or Lat/T-FDC was analyzed using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assays. Undiluted and 10-fold diluted solutions of each FDC were evaluated.

Results

The IOP-lowering effect of Taf/T-FDC was almost equivalent to that of Lat/T-FDC at 4–8 h after instillation. The peak IOP reduction of Taf/T-FDC and Lat/T-FDC was observed at 8 h after instillation, and there is no difference between the two. The difference between them was observed at 24–30 h after instillation, and Taf/T-FDC demonstrated a significantly greater IOP-lowering effect than Lat/T-FDC at 24–30 h after instillation. The IOP-lowering effect of Taf/T-FDC was sustained up to 30 h after instillation, while that of Lat/T-FDC had almost disappeared at 28 h after instillation. Timolol concentrations in aqueous humor after Taf/T-FDC instillation were higher than those after Lat/T-FDC instillation (C_max, 3870 ng/mL vs 1330 ng/mL; AUC_inf, 3970 ng·h/mL vs 1250 ng·h/mL). The concentrations of tafluprost acid and latanoprost acid in aqueous humor after instillation of Taf/T-FDC and Lat/T-FDC, respectively, were similar to those after instillation of mono-preparations of tafluprost and latanoprost, respectively. The cytotoxic effect of Taf/T-FDC to the human corneal epithelial cells was significantly lower than that of Lat/T-FDC at all evaluated time points in both undiluted and 10-fold diluted FDCs.

Conclusion

Taf/T-FDC provides increased IOP-lowering effect duration and lower potential ocular surface toxicity than Lat/T-FDC.

24-h Efficacy of Glaucoma Treatment Options

Current management of glaucoma entails the medical, laser, or surgical reduction of intraocular pressure (IOP) to a predetermined level of target IOP, which is commensurate with either stability or delayed progression of visual loss. In the published literature, the hypothesis is often made that IOP control implies a single IOP measurement over time. Although the follow-up of glaucoma patients with single IOP measurements is quick and convenient, such measurements often do not adequately reflect the untreated IOP characteristics, or indeed the quality of treated IOP control during the 24-h cycle. Since glaucoma is a 24-h disease and the damaging effect of elevated IOP is continuous, it is logical that we should aim to understand the efficacy of all treatment options throughout the 24-h period. This article first reviews the concept and value of diurnal and 24-h IOP monitoring. It then critically evaluates selected available evidence on the 24-h efficacy of medical, laser and surgical therapy options. During the past decade several controlled trials have significantly enhanced our understanding on the 24-h efficacy of all glaucoma therapy options. Nevertheless, more long-term evidence is needed to better evaluate the 24-h efficacy of glaucoma therapy and the precise impact of IOP characteristics on glaucomatous progression and visual prognosis.

Effect of timolol maleate gel-forming solution on intraocular pressure, pupil diameter, and heart rate in normal and glaucomatous cats

OBJECTIVE

To determine the effects of once-daily topical treatment with timolol maleate gel-forming solution (GFS) on intraocular pressure (IOP), pupil diameter (PD), and heart rate (HR) in normal cats and cats with feline primary congenital glaucoma (FCG).

ANIMALS STUDIED AND PROCEDURES

A single drop of timolol maleate 0.5% GFS was administered topically to one randomly assigned eye of 18 adult cats (8 normal, 10 FCG) at 8 am for 8 days; the opposite eye served as the untreated control. IOP was measured in both eyes (OU) every 2 h (PD and HR were measured every 4 h), for 14 h total, 1 day prior to and on days 1 and 8 of treatment. In a second treatment phase, a single drop of timolol was administered at 8 pm for 3 nights and IOP, PD, and HR were measured, as above, beginning at 8 am on day 4. Slit-lamp examinations were conducted prior to and after treatment phases. Comparisons of mean IOP, PD, and HR were made at each time point and between treated and untreated eyes by repeated-measures ANOVA and Tukey-Kramer post hoc test, with P < 0.05 considered significant.

RESULTS

Timolol maleate 0.5% GFS had an inconsistent effect on IOP, with maximum IOP-lowering effect (mean = 5.6 mmHg, 17.4%) observed 6 h post-treatment in FCG. The drug caused significant miosis (from 4 to 8 h post-treatment), but had no effect on HR.

CONCLUSION

Once-daily application of timolol maleate 0.5% GFS may be of limited clinical benefit in the management of feline congenital glaucoma.

Neuroprotection in the treatment of glaucoma--A focus on connexin43 gap junction channel blockers

Glaucoma is a form of optic neuropathy and a common cause of blindness, affecting over 60 million people worldwide with an expected rise to 80 million by 2020. Successful treatment is challenging due to the various causes of glaucoma, undetectable symptoms at an early stage and inefficient delivery of drugs to the back of the eye. Conventional glaucoma treatments focus on the reduction of elevated intraocular pressure (IOP) using topical eye drops. However, their efficacy is limited to patients who suffer from high IOP glaucoma and do not address the underlying susceptibility of retinal ganglion cells (RGC) to degeneration. Glaucoma is known as a neurodegenerative disease which starts with RGC death and eventually results in damage of the optic nerve. Neuroprotective strategies therefore offer a novel treatment option for glaucoma by not only preventing neuronal loss but also disease progression. This review firstly gives an overview of the pathophysiology of glaucoma as well as current treatment options including conventional and novel delivery strategies. It then summarizes the rational for neuroprotection as a novel therapy for glaucomatous neuropathies and reviews current potential neuroprotective strategies to preserve RGC, with a focus on connexin43 (Cx43) gap junction channel blockers.

Efficacy and safety of brinzolamide/timolol fixed combination compared with timolol in Japanese patients with open-angle glaucoma or ocular hypertension

Purpose

To evaluate the efficacy and safety of brinzolamide 1%/timolol 0.5% fixed-combination (BRINZ/TIM-FC) therapy compared with timolol 0.5% (TIM) monotherapy in Japanese patients with open-angle glaucoma or ocular hypertension.

Methods

This randomized, double-masked, multicenter study included Japanese patients aged ≥20 years. Patients were treated during a 4-week observation period with TIM monotherapy in advance of randomization to treatment with topical BRINZ/TIM-FC or TIM monotherapy twice daily for 8 weeks. The primary endpoint was mean reduction in intraocular pressure (IOP) from baseline to week 8 at 2 hours postinstillation. Adverse events (AEs) were recorded at each visit.

Results

A total of 301 patients (BRINZ/TIM-FC, n=150; TIM, n=151; age [mean ± standard deviation], 61±13 years) were enrolled. Mean IOP reductions from baseline were greater with BRINZ/TIM-FC than with TIM at weeks 4 and 8 at 0 and 2 hours postinstillation (all P≤0.0001), with mean reductions of −3.2 mmHg with BRINZ/TIM-FC and −1.4 mmHg with TIM at week 8, 2 hours postinstillation. Although AEs were observed in 19% of all patients (BRINZ/TIM-FC, 20%; TIM, 19%), all AEs were mild or moderate.

Conclusion

BRINZ/TIM-FC therapy was associated with significantly greater reductions in IOP compared with TIM, and it was well tolerated in Japanese patients with open-angle glaucoma or ocular hypertension.

Safety and efficacy of a fixed versus unfixed brinzolamide/timolol combination in Japanese patients with open-angle glaucoma or ocular hypertension

Background

The purpose of this study was to assess the safety and efficacy of fixed-combination brinzolamide 1%/timolol 0.5% (BRINZ/TIM-FC) compared with concomitant brinzolamide 1% and timolol 0.5% (BRINZ + TIM) in Japanese patients with open-angle glaucoma (primary open-angle, exfoliation, pigmentary) or ocular hypertension.

Methods

This randomized, double-masked, multicenter, parallel-group, positive-control, Phase III study was conducted in Japan and included patients aged ≥20 years. Baseline intraocular pressure was assessed after 4 weeks of treatment with timolol 0.5%. Patients were randomized to twice-daily BRINZ/TIM-FC or BRINZ + TIM for 8 weeks (treatment phase). The primary endpoint was mean intraocular pressure reduction from baseline to week 8 at 11 am, at which time noninferiority of BRINZ/TIM-FC versus BRINZ + TIM was evaluated. Data were analyzed using repeated-measures analysis of covariance and t-tests. Adverse events and ophthalmic/physiologic variables were assessed.

Results

In total, 319 patients of mean age 64±12 years were enrolled in the treatment phase. BRINZ/TIM-FC and BRINZ + TIM were associated with reductions in mean intraocular pressure from baseline throughout the study (ranges −2.5 to −3.4 mmHg and −2.7 to −3.3 mmHg, respectively). Mean between-group differences in intraocular pressure reduction ranged from 0 to −0.3 mmHg; the upper limit of the 97.5% confidence interval for week 8 at 11 am was <1.1 mmHg, indicating noninferiority of BRINZ/TIM-FC. Treatment-related adverse events were observed in 3% and 12% of patients receiving BRINZ/TIM-FC and BRINZ + TIM, respectively. No substantial changes in other safety parameters were reported.

Conclusion

Twice-daily BRINZ/TIM-FC reduced intraocular pressure by levels similar to concomitant BRINZ + TIM in Japanese patients with open-angle glaucoma or ocular hypertension and was noninferior to BRINZ + TIM. Both treatments were well tolerated.

Stimuli sensitive hydrogels for ophthalmic drug delivery: A review

Amongst the various routes of drug delivery, the field of ocular drug delivery is one of the most interesting and challenging endeavors facing the pharmaceutical scientist for past 10-20 years. As an isolated organ, eye is very difficult to study from a drug delivery point of view. Despite this limitation, improvements have been made with the objective of maintaining the drug in the biophase for an extended period. A major problem in ocular therapeutics is the attainment of an optimal drug concentration at the site of action. To achieve effective ophthalmic therapy, an adequate amount of active ingredient must be delivered and maintained within the eye. The most frequently used dosage forms, i.e., eye solution, eye ointments, eye gels, and eye suspensions are compromised in their effectiveness by several limitations leading to poor ocular bioavailability. Ophthalmic use of viscosity-enhancing agents, penetration enhancers, cyclodextrins, prodrug approaches, and ocular inserts, and the ready existing drug carrier systems along with their application to ophthalmic drug delivery are common to improve ocular bioavailability. Amongst these hydrogel (stimuli sensitive) systems are important, which undergo reversible volume and/or sol-gel phase transitions in response to physiological (temperature, pH and present of ions in organism fluids, enzyme substrate) or other external (electric current, light) stimuli. They help to increase in precorneal residence time of drug to a sufficient extent that an ocularly delivered drug can exhibit its maximum biological action. The concept of this innovative ophthalmic delivery approach is to decrease the systemic side effects and to create a more pronounced effect with lower doses of the drug. The present article describes the advantages and use stimuli sensitive of hydrogel systems in ophthalmic drug delivery.

Mixed treatment comparison of repeated measurements of a continuous endpoint: an example using topical treatments for primary open-angle glaucoma and ocular hypertension

Mixed treatment comparison (MTC) meta-analyses estimate relative treatment effects from networks of evidence while preserving randomisation. We extend the MTC framework to allow for repeated measurements of a continuous endpoint that varies over time. We used, as a case study, a systematic review and meta-analysis of intraocular pressure (IOP) measurements from randomised controlled trials evaluating topical ocular hypotensives in primary open-angle glaucoma or ocular hypertension because IOP varies over the day and over the treatment course, and repeated measurements are frequently reported. We adopted models for conducting MTC in WinBUGS (The BUGS Project, Cambridge, UK) to allow for repeated IOP measurements and to impute missing standard deviations of the raw data using the predictive distribution from observations with standard deviations. A flexible model with an unconstrained baseline for IOP variations over time and time-invariant random treatment effects fitted the data well. We also adopted repeated measures models to allow for class effects; assuming treatment effects to be exchangeable within classes slightly improved model fit but could bias estimated treatment effects if exchangeability assumptions were not valid. We enabled all timepoints to be included in the analysis, allowing for repeated measures to increase precision around treatment effects and avoid bias associated with selecting timepoints for meta-analysis.The methods we developed for modelling repeated measures and allowing for missing data may be adapted for use in other MTC meta-analyses.

Timogel® vs Timolol 0.5% Ophthalmic Solution: Efficacy, Safety, and Acceptance

Purpose

To evaluate the efficacy, safety, and tolerability of Timogel® preservative-free once daily compared to timolol 0.5% ophthalmic solution bid in patients with ocular hypertension (OHT) and patients with primary open-angle glaucoma (POAG).

Methods

A total of 75 patients with OHT and patients with POAG treated with timolol 0.5% bid with intraocular pressure (IOP) ≤21 mmHg were enrolled. They underwent complete ophthalmologic examination, IOP measurements (at trough and daytime curve), evaluation of side effects, Schirmer test, break-up time [BUT], blood pressure, heart rate, ocular diastolic perfusion pressure measurements, and acceptance (Comparison of Ophthalmic Medications for Tolerability). Patients switched to Timogel® and were re-evaluated 3 months later. The analysis of variance and the Pearson χ2 tests were used to test differences between the treatments.

Results

Intraocular pressure reduction at trough was 23.6% with timolol 0.5% and 22.3% with Timogel®. No statistical differences were observed in IOP values at trough and in the daytime curve between the 2 treatments. Local and systemic side effects were less frequent with Timogel® (hazard ratio: p<0.05). Patients demonstrated a significant improvement of Schirmer test and BUT (p<0.05) and a reduction of dryness and foreign body sensation (42.6% vs 15.4%; p<0.01) after switching to Timogel®. Mild and short-lasting blurred vision after Timogel® instillation occurred in about 18.5% of patients. A total of 82% of patients were satisfied or very satisfied with Timogel® vs 61% with previous treatment (p<0.01).

Conclusions

Timogel® preservative-free dosed once every morning has a 24-hour hypotensive effect with a better safety profile than timolol 0.5% bid and it is well-accepted by patients. The once-daily dosing improved acceptance and compliance.

Novel drug delivery systems for glaucoma

Reduction of intraocular pressure (IOP) by pharmaceutical or surgical means has long been the standard treatment for glaucoma. A number of excellent drugs are available that are effective in reducing IOP. These drugs are typically applied as eye drops. However, patient adherence can be poor, thus reducing the clinical efficacy of the drugs. Several novel delivery systems designed to address the issue of adherence and to ensure consistent reduction of IOP are currently under development. These delivery systems include contact lenses-releasing glaucoma medications, injectables such as biodegradable micro- and nanoparticles, and surgically implanted systems. These new technologies are aimed at increasing clinical efficacy by offering multiple delivery options and are capable of managing IOP for several months. There is also a desire to have complementary neuroprotective approaches for those who continue to show progression, despite IOP reduction. Many potential neuroprotective agents are not suitable for traditional oral or drop formulations. Their potential is dependent on developing suitable delivery systems that can provide the drugs in a sustained, local manner to the retina and optic nerve. Drug delivery systems have the potential to improve patient adherence, reduce side effects, increase efficacy, and ultimately, preserve sight for glaucoma patients. In this review, we discuss benefits and limitations of the current systems of delivery and application, as well as those on the horizon.

Efficacy of Garcinia kola 0.5% Aqueous Eye Drops in Patients with Primary Open-Angle Glaucoma or Ocular Hypertension

Purpose:

To evaluate the intraocular pressure (IOP) lowering efficacy of Garcinia kola 0.5% aqueous solution eye drops in patients with newly diagnosed primary open-angle glaucoma or ocular hypertension (POAG/OH).

Materials and Methods:

A randomized, double-masked, multicenter, active-controlled prospective study. Patients who met the inclusion criteria were randomly assigned in equal numbers to receive Timolol 0.5% eye drops as a control medication (A = Group 1 eyes) or Garcinia kola 0.5% eye drops as the study medication (B = Group 2 eyes). All drops were instilled at 6 am and 6 pm daily. Goldman applanation tonometry was performed at 9 am, 12 pm and 3 pm at baseline, week-6, week-12 and week-24 visits. Voluntary and actively elicited reports of adverse events were documented. The mean change in IOP over 24 weeks was the primary outcome measure. Both groups were compared for statistically significant differences at all visits. A P < 0.05 was considered statistically significant.

Results:

A total of 178 patients were randomly assigned to G. kola and Timolol groups. At baseline there were no differences in mean IOP between groups, based on age, sex, or diagnosis. At the end of the study period (24^th week), the mean (± SD) reduction in IOP was 12.93 ± 2.3 mmHg (47.8% ± 0.8% reduction) in G. Kola group and 13.09 ± 2.8 mm Hg (48.2% ± 1.03% reduction) in the Timolol group (P > 0.05). Adverse events were mild in nature with no statistically significant differences between groups (P > 0.05).

Conclusions:

Garcinia kola ophthalmic solution significantly reduces IOP as compared to baseline. The IOP lowering effect of both treatments was equivalent.

Improved ocular absorption kinetics of timolol maleate loaded into a bioadhesive niosomal delivery system

BACKGROUND

Application of timolol maleate (TM) in a conventional dosage form (solution) into the eye results in almost 80% of the instilled dose being lost either through spillage or due to drainage into the nasolacrimal duct. Later results in systemic side-effects especially in patients suffering from heart diseases or bronchial asthma thus limiting the usefulness of TM for the control of glaucoma. Earlier we had reported on the development of a mucoadhesive coated niosomal system for TM (TM REV(bio)) containing 0.25% TM. Presently we establish and report the pharmacokinetic and pharmacodynamic superiority of the developed ocular formulation of TM.

METHODS

Aqueous humor concentration of TM in male albino rabbits, after instillation of one drop of TM solution (TMS) or TMREV(bio) was measured using the microdialysis method.

RESULTS

Peak concentration of drug in aqueous humor from TMREV(bio) (12.46 microg/ml achieved at 60 min) was almost 1.7 times that of the control drug solution (TMS, 0.25%; 7.2 microg/ml). An important observation was that the high drug concentrations achieved upon TMREV(bio) administration were maintained for up to 2 h. AUC for TMREV(bio) formulation was 2.34 times that of the TMS.

CONCLUSIONS

This study confirms a sustained and controlled effect of the developed formulation.

Role of fixed-combination brinzolamide 1%/timolol 0.5% in the treatment of elevated intraocular pressure in open-angle glaucoma and ocular hypertension

Brinzolamide 1%/timolol 0.5% is a new fixed-combination for the treatment of open-angle glaucoma or ocular hypertension. Brinzolamide/timolol has a favorable safety profile, with an incidence of ocular burning and stinging <5%. Published data show that brinzolamide 1%/timolol 0.5% and dorzolamide 2%/timolol 0.5% have similar efficacies for lowering intraocular pressure (IOP). There is some evidence that brinzolamide/timolol may be more comfortable. Although patients receiving brinzolamide/timolol may experience more blurred vision on instillation, some data show a preference for brinzolamide/timolol over dorzolamide/timolol. Although available data to assess the role of brinzolamide/timolol in daily clinical practice are still limited, these first results suggest the agent to be a reasonable alternative for patients who do not reach target IOP with monotherapy.

Sustained delivery of timolol maleate from poly(lactic-co-glycolic acid)/poly(lactic acid) microspheres for over 3 months

It is estimated that 2.2 million people have glaucoma in the US and 67 million people worldwide. The majority of cases are associated with elevated intraocular pressure (IOP) and decreasing IOP eliminates or greatly reduces degeneration in most cases, including cases in which the IOP is in the normal range but optic neuropathy occurs. Timolol maleate has the longest record of safety and efficacy to lower IOP and is administered via eye drops one or more times per day. Unfortunately, compliance is poor across patient populations leading to degeneration. Patients typically see their ophthalmologist once every 3-4 months. If one could administer a long-acting treatment while in the doctor's office, one might overcome the compliance issue and effectively preserve sight. The critical step is to develop a formulation for timolol maleate that leads to sustained delivery for greater than 90 days and would permit a different treatment paradigm, namely subconjunctival administration once every 3-4 months. By using a 50 : 50 blend of PLGA 502H and PLA, this study was able to fabricate microspheres that delivered timolol maleate continually over 107 days, well within the time frame needed to make subconjunctival administration feasible and permit a new approach to treating glaucoma and diseases of the eye more broadly.

Evaluation of aqueous humor concentrations of Istalol and Betimol following a single ocular instillation in rabbit eyes

PURPOSE

The aim of this study was to evaluate the pharmacokinetic absorption profiles of two commercially available ophthalmic solutions following a single instillation into each eye of New Zealand white rabbit eyes.

METHODS

A single dose of either timolol maleate with potassium sorbate (TLA) or timolol hemihydrate (THH) was instilled into each eye of New Zealand white rabbits (15 rabbits/drug preparation, 50-microL dose). Animals were euthanized 15, 30, 60, 120, and 180 min after instillation, with 3 animals/drug/time intervals. Aqueous humor from both eyes of each animal was pooled and analyzed for timolol concentration, using the high-performance liquid chromatography method.

RESULTS

TLA reached a mean peak concentration of 3.705 +/- 0.3012 microg/mL at 15 min, tapering to 0.539 +/- 0.1431 microg/mL by 180 min. THH reached a mean peak concentration of 2.239 +/- 0.1430 microg/mL at 15 min postinstillation, tapering to 0.148 +/- 0.0282 microg/mL by 180 min.

CONCLUSIONS

TLA containing potassium sorbate demonstrated an absorption profile of more rapid absorption (1.7 fold greater at 15 minutes) and longer residences time (3.6 fold greater at 180 minutes) than the THH. At every time point throughout the study, TLA demonstrated greater drug concentration than THH.

Cardiovascular and respiratory considerations with pharmacotherapy of glaucoma and ocular hypertension

Glaucoma and ocular hypertension are highly prevalent conditions in individuals over the age of 40 and are commonly seen together in patients with cardiovascular disease. Many of the antiglaucoma medications, when systemically absorbed, affect the sympathetic and parasympathetic nervous systems of patients and can cause cardiovascular toxicity. Such adverse effects are frequently associated with the long-term use of potentially toxic agents in elderly people, who are most prone to chronic eye disease. Moreover, patients may not associate their symptoms with the topical eye medications, and consequently may not report adverse drug effects. Drug-drug interactions can also occur when patients are taking medications for both cardiovascular disease and glaucoma. In this review, the systemic toxicity of these agents is reviewed, along with possible drug-drug interactions. Mention is made of other antiglaucoma medications used alone and in combination with topical beta-blockers. Identification of genetic loci-a bold new step toward glaucoma treatment-is mentioned briefly at the end of the article.

Efficacy and systemic side-effects of topical 0.5% timolol aqueous solution and 0.1% timolol hydrogel

PURPOSE

The objective of this randomized, double-blind, controlled crossover trial was to compare 0.1% timolol hydrogel formulation eyedrops with 0.5% timolol aqueous solution in terms of systemic effects, hypotensive efficacy and pharmacodynamics.

METHODS

Twenty-four healthy subjects underwent careful ocular, cardiovascular and pulmonary function evaluation before and after 2 weeks of topical treatment with 0.1% timolol hydrogel or 0.5% aqueous timolol maleate. Intraocular pressure (IOP), heart rate, blood pressure, forced expiratory volume and plasma levels of timolol were measured.

RESULTS

There was a statistically significant difference in the systemic absorption of timolol between these two ophthalmic timolol solutions. The peak concentration and mean area under the plasma drug concentration-time curve (AUC) were about 10-fold higher after 0.5% timolol aqueous solution. The mean peak heart rate during exercise was reduced by 19 bpm (SD 6.4 bpm) after 0.5% timolol aqueous solution and by only 4.6 bpm (SD 3.8 bpm) after 0.1% timolol hydrogel (p < 0.0001). There was no difference between the two formulations in efficacy in reducing IOP. No differences between treatments were found in respect of pulmonary function.

CONCLUSIONS

The lower timolol concentration in the hydrogel vehicle and its better bioavailability resulted in reduced systemic absorption and side-effects without loss of efficacy.

Viscoelastic properties of a new in situ gelling thiolated chitosan conjugate

The aim of this study was the synthesis of a new thiolated chitosan conjugate and the evaluation of its viscoelastic properties in vitro. The modification of chitosan was achieved by covalent attachment of isopropyl-S-acetylthioacetimidate to chitosan. The resulting conjugate (chitosan-TEA; chitosan-thioethylamidine) exhibited 300.7+/-27.4 micromol thiol groups per gram polymer and no disulfide bond. For rheological studies, the pH of 0.5% and 1% polymer solutions was adjusted to 6.5 in order to simulate a physiological pH-level. Both, 0.5% and 1% chitosan-TEA solutions showed the transition from sol to gel within 30 min. Within 6 h of incubation, the storage modulus of 0.5% and 1% chitosan-TEA increased 3354-fold and 6199-fold, whereas the loss modulus increased 11-fold and 38-fold, respectively. Frequency sweep measurements demonstrated an increase in crosslinking of the thiolated polymer as a function of time. The formation of inter- and/or intramolecular disulfide bonds was monitored indirectly via determining the decrease of thiol groups. Unmodified chitosan did not exhibit in situ gelling properties. The release of a fluorescent marker being incorporated in a 0.5% chitosan-TEA solution was significantly (p<0.001) slower, when the formulation was preincubated for one hour and consequently already highly crosslinked. The polymer generated within this study represents a promising novel tool for various drug delivery systems, where in situ gelling properties are advantageous.

The Effects of a Timolol Maleate Gel-Forming Solution on Normotensive Beagle Dogs

The effects of a timolol maleate gel-forming solution (TMGS) on intraocular pressure (IOP), blood pressure (BP), and pupil size (PS) were evaluated in normotensive dogs. TMGS was administered once daily to six normotensive beagle dogs. TMGS administration reduced IOP and PS. The hypotensive effect persisted for 24 hr after the administration. The mean reduction in IOP was 5.3 mm Hg (P<0.01). The changes in BP and PS were not significant. These results suggest that TMGS can potentially be used in the treatments of glaucoma and ocular hypertension in dogs.

Continuous Monitoring of Circadian Variations in Intraocular Pressure by Telemetry System Throughout a 12-Week Treatment with Timolol Maleate in Rabbits

AIM

The aim of this study was to examine the effect of a 12-week treatment with two formulations of timolol maleate on the amplitude of the circadian fluctuation in intraocular pressure (IOP).

METHODS

Conscious Japanese White rabbits housed under a controlled 12-hour light-dark cycle were used. IOP was measured by a telemetry system. Each animal was treated topically for 12 weeks with 0.5% timolol solution (TM) twice-daily, 0.5% timolol gel-forming solution (TM-gel) once-daily, or saline twice-daily, and the circadian variation in IOP was measured every week.

RESULTS

Administration of TM or TM-gel did not change IOP in the light phase, but significantly reduced it in the dark phase in each of the 12 weeks. The IOP reductions at 2 h after administration in the TM and TM-gel groups over the 12 weeks were, respectively, 3.6 +/- 0.3 mmHg and 3.4 +/- 0.2 mmHg versus the Saline group. The amplitudes of the circadian fluctuations in IOP in the TM group in weeks 3, 6, and 12 were 15%, 15%, and 18% smaller than those in the Saline group, while the corresponding values for the TM-gel group were 18%, 16%, and 19%, respectively.

CONCLUSIONS

TM-gel administered once-daily was as effective at lowering IOP as TM administrated twice-daily over the 12-week experimental period. This study reveals that, in rabbits, both formulations of the timolol maleate induced significant IOP reductions in the dark phase and decreased the amplitudes of the circadian fluctuations in IOP for 12 successive weeks.

The efficacy of timolol in gel-forming solution after morning or evening dosing in Asian glaucomatous patients

AIMS

The aim of this study was to determine the effectiveness of timolol gel-forming solution as a monotherapy and to compare the efficacy of timolol gel-forming solution morning instillation versus at night application in Asians with newly diagnosed open-angle glaucoma.

METHODS

A retrospective, comparative, parallel group study was conducted on 78 eligible patients diagnosed with open-angle glaucoma who received topical timolol gel-forming solution either on morning (AM dosing group; 39 patients) or evening (PM dosing group; 39 patients) as monotherapy treatment. Intraocular pressure was taken at baseline, 1, 3, 6, and 12 months post-treatment.

RESULTS

Mean baseline intraocular pressure (IOP) for timolol gel-forming solution in general was 22.7 +/- 6.6 mmHg with the mean IOP reduction of 5.7 +/- 5.3 mmHg (23.1% reduction). The mean IOP reduction of the AM dosing group was 7.5 +/- 5.2 mmHg (31.0% reduction) and 3.9 +/- 4.9 mmHg (15.1% reduction) in the PM dosing group (P = 0.0002). There was a statistically significant difference of IOP reductions between AM and PM dosing group at 1 month (P = 0.041), 3 months (P = 0.037) and 12 months (P = 0.015) post-treatment. Seventy-five percent (24) of good responders was in the AM group and 67.4% (31) of poor responders were patients in the PM group.

CONCLUSION

Timolol gel-forming solution is effective in reducing IOP in Asian eyes. Morning dosing was more effective in lowering the IOP compared to evening dosing.

PEG-grafted chitosan as an injectable thermosensitive hydrogel for sustained protein release

Thermosensitive polymer hydrogels that undergo a sol-to-gel transition in response to temperature changes are of great interest in therapeutic delivery and tissue engineering as injectable depot systems. A chitosan-based, injectable thermogel was prepared by grafting an appropriate amount of PEG onto the chitosan backbone and studied for drug release in vitro using bovine serum albumin (BSA) as a model protein. When more than approximately 40 wt.% of PEG was grafted to chitosan chains via covalent bonding, the aqueous solution of the resultant copolymer was an injectable liquid at low temperature and transformed to a semisolid hydrogel at body temperature. After an initial burst release in the first 5 h, a steady linear release of protein from the hydrogel was achieved for a period of approximately 70 h. Prolonged quasi-linear release of protein up to 40 days was achieved by crosslinking the hydrogel with genipin in situ, in a fashion suitable for protein encapsulation while maintaining the injectability of the hydrogel. The crosslinkage transformed the copolymer from a physical gel to an insoluble chemical gel and substantially reduced the initial burst release of protein. Both high performance liquid chromatography (HPLC) and gel electrophoresis indicated that the primary structure of BSA released from the hydrogels with or without genipin-crosslinking was generally conserved. The hydrogel can be prepared in solutions with a physiological pH, allowing the safe incorporation of bioactive molecules for a broad range of medical applications, particularly for sustained in vivo drug release and tissue engineering.

Management of glaucoma: focus on pharmacological therapy

Glaucoma represents a major cause of vision loss throughout the world. Primary open-angle glaucoma, the most common form of glaucoma, is a chronic, progressive disease often, though not always, accompanied by elevated intraocular pressure (IOP). In this disorder, retinal ganglion cell loss and excavation of the optic nerve head produce characteristic peripheral visual field deficits. Patients with normal-tension glaucoma present with typical visual field and optic nerve head changes, without a documented history of elevated IOP. A variety of secondary causes, such as pigment dispersion syndrome and ocular trauma, can result in glaucoma as well. Treatment of all forms of glaucoma consists of reducing IOP. With proper treatment, progression of this disease can often be delayed or prevented. Treatment options for glaucoma include medications, laser therapy and incisional surgery. Laser techniques for the reduction of IOP include argon laser trabeculoplasty and selective laser trabeculoplasty. Both techniques work by increasing outflow of aqueous humour through the trabecular meshwork. Surgical options for glaucoma treatment include trabeculectomy, glaucoma drainage tube implantation and ciliary body cyclodestruction. While each of these types of procedures is effective at lowering IOP, therapy usually begins with medications. Medications lower IOP either by reducing the production or by increasing the rate of outflow of aqueous humour within the eye. Currently, there are five major classes of drugs used for the treatment of glaucoma: (i) cholinergics (acetylcholine receptor agonists); (ii) adrenoceptor agonists; (iii) carbonic anhydrase inhibitors (CAIs); (iv) beta-adrenoceptor antagonists; and (v) prostaglandin analogues (PGAs). Treatment typically begins with the selection of an agent for IOP reduction. Although beta-adrenoceptor antagonists are still commonly used by many clinicians, the PGAs are playing an increasingly important role in the first-line therapy of glaucoma. Adjunctive agents, such as alpha-adrenoceptor agonists and CAIs are often effective at providing additional reduction in IOP for patients not controlled on monotherapy. As with any chronic disease, effective treatment depends on minimising the adverse effects of therapy and maximising patient compliance. The introduction of a variety of well tolerated and potent medications over the past few years now allows the clinician to choose a treatment regimen on an individual patient basis and thereby treat this disorder more effectively.

Comparison of the nocturnal effects of once-daily timolol and latanoprost on intraocular pressure

PURPOSE

To compare the nocturnal effects of once-daily timolol and latanoprost on intraocular pressure (IOP) in patients with ocular hypertension or early glaucomatous changes.

DESIGN

Prospective, open-label, experimental study with crossover design.

METHODS

Eighteen patients with ocular hypertension or early glaucomatous changes (aged 41 to 79 years) each received topical treatments with timolol (0.5% Timoptic-XE), latanoprost (0.005% Xalatan), and no IOP-lowering medication, for at least 4 weeks. Timolol was given once in the morning upon awakening and latanoprost once in the evening at bedtime. At the end of each treatment period, the patient was housed in a sleep laboratory for 24 hours and IOP was measured every 2 hours using a pneumatonometer. Measurements were taken sitting and supine during the 16-hour diurnal/wake period and only supine during the 8-hour nocturnal/sleep period. Mean diurnal and nocturnal IOP levels were compared among the treatments with timolol, latanoprost, and no medication.

RESULTS

In the diurnal period, the mean IOP under the timolol or the latanoprost treatment was significantly less than the mean IOP under no medication in both the sitting and the supine positions. There was no statistical difference between the timolol and latanoprost treatments. In the nocturnal period, supine IOP with timolol treatment was not different from the supine IOP with no medication but was significantly higher than supine IOP with the latanoprost treatment.

CONCLUSION

Although both once-daily timolol and latanoprost were effective in lowering IOP during the diurnal period, only latanoprost reduced IOP during the nocturnal period.