Cardiovascular considerations in using topical, oral, and intravenous drugs for the treatment of glaucoma and ocular hypertension: focus on beta-adrenergic blockade

Mitigation of pesticide-mediated ocular toxicity via nanotechnology-based contact lenses: a review

The xenobiotic stress exerted by pesticides leads to the deterioration of human and animal health including ocular health. Acute or prolonged exposure to these agricultural toxicants has been implicated in a number of pathological conditions of the eye such as irritation, epiphora or hyper-lacrimation, abrasions on the ocular surface, and decreased visual acuity. The issue is compounded by the fact that tissues of the eye absorb pesticides faster than other organs of the body and are more susceptible to damage as well. However, there is a lacuna in our knowledge regarding the ways by which pesticide exposure-mediated ocular insult might be counteracted. Topical instillation of drugs known to combat the pesticide induced toxicity has been explored to mitigate the detrimental impact of pesticide exposure. However, topical eye drop solutions exhibit very low bioavailability and limited drug residence duration in the tear film decreasing their efficacy. Contact lenses have been explored in this respect to increase bioavailability of ocular drugs, while nanoparticles have lately been utilized to increase drug bioavailability and increase drug residence duration in different tissues. The current review focuses on drug delivery and futuristic aspects of corneal protection from ocular toxicity using contact lenses.

Therapeutic contact lenses for the treatment of corneal and ocular surface diseases: advances in extended and targeted drug delivery

The eye is one of the most important organs in the human body providing critical information on the environment. Many corneal diseases can lead to vision loss affecting the lives of people around the world. Ophthalmic drug delivery has always been a major challenge in the medical sciences. Since traditional methods are less efficient (∼ 5%) at delivering drugs to ocular tissues, contact lenses have generated growing interest in ocular drug delivery due to their potential to enhance drug bioavailability in ocular tissues. The main techniques used to achieve sustained release are discussed in this review, including soaking in drug solutions, incorporating drug into multilayered contact lenses, use of vitamin E barriers, molecular imprinting, nanoparticles, micelles and liposomes. The most clinically relevant results on different eye pathologies are presented. In addition, this review summarizes the benefits of contact lenses over eye drops, strategies for incorporating drugs into lenses to achieve sustained release, results of in vitro and in vivo studies, and the recent advances in the commercialization of therapeutic contact lenses for allergic conjunctivitis.

Cardiac Hypertrophy May Be a Risk Factor for the Development and Severity of Glaucoma

The purpose of this study was to examine the relationship between glaucoma and cardiac abnormalities. We evaluated 581 patients with open-angle glaucoma (285 men and 296 women) and 595 individuals without glaucoma (273 men and 322 women). All of the participants underwent visual field testing using a Humphrey Visual Field Analyzer (30-2 program), an electrocardiogram (ECG), and blood pressure measurement. We examined the ECG abnormalities and other factors (age, intraocular pressure (IOP) and systemic hypertension) involved in the development and severity of glaucoma. Logistic regression analyses revealed significant correlations of glaucoma with IOP (OR = 1.43; 95% CI: 1.36−1.51; p < 0.00001), atrial fibrillation (OR = 2.02; 95% CI: 1.01−4.04; p = 0.04), left ventricular hypertrophy (LVH) (OR = 2.21; 95% CI: 1.15−4.25; p = 0.02), and bradycardia (OR = 2.19; 95% CI: 1.25−4.70; p = 0.02). Regression analyses revealed significant correlations of the mean deviation of the visual field with age (t = −6.22; 95% CI: −0.15, −0.08; p < 0.00001), IOP (t = −6.47; 95% CI: −0.42, −0.23; p < 0.00001), and LVH (t = −2.15; 95% CI: −3.36, −0.29; p = 0.02). Atrial fibrillation, LVH and bradycardia may decrease the cerebral blood flow, and may also affect the ocular blood flow. Cardiac abnormalities may be associated with the development and severity of glaucoma.

Association of glaucoma with 10-year mortality in a population-based longitudinal study in urban Southern China: the Liwan Eye Study

OBJECTIVES

To investigate the association between glaucoma and 10-year mortality rate in an adult population in China.

DESIGN

Population-based cohort study.

SETTING

The Liwan Eye Study, China.

PARTICIPANTS

1405 baseline participants aged 50 years and older were invited to attend a 10-year follow-up examination.

PRIMARY AND SECONDARY OUTCOME MEASURES

The International Society of Geographic and Epidemiologic Ophthalmology criteria was used to define glaucoma. Detailed information of mortality was confirmed using the Chinese Centre for Disease Control and Prevention. Presenting visual impairment (PVI) was defined as a presenting visual acuity of less than 20/40 in the better-seeing eye. The 10-year mortality rates were compared using the log-rank test. Cox proportional hazards regression models were used to investigate the association between glaucoma and mortality.

RESULTS

A total of 1372 (97.7%) participants with available gonioscopic data were included in the analysis. Of these, 136 (9.9%), 33 (2.4%) and 21 (1.5%) participants had primary angle closure (PAC) suspect (PACS), PAC and PAC glaucoma (PACG), and 29 (2.1%) had primary open angle glaucoma (POAG). After 10 years, 306 (22.3%) participants were deceased. The 10-year mortality was significantly associated with PACG (HR, 2.15, 95% CI 1.14 to 4.04, p=0.018) but not associated with PAC (HR, 1.27, 95% CI 0.67 to 2.39, p=0.463), PACS (HR, 1.32, 95% CI 0.95 to 1.83, p=0.099) and POAG (HR, 0.74, 95% CI 0.36 to 1.49, p=0.395) when age and gender were adjusted for. This association was no longer statistically significant (HR, 1.60, 95% CI 0.70 to 3.61, p=0.263) when covariables, such as income, education, body mass index, PVI, history of diabetes and hypertension, were adjusted for. Larger vertical cup-to-disc ratio (VCDR >0.30) was only a significant risk factor in multivariable analysis (HR, 1.60, 95% CI 1.11 to 2.33, p=0.011).

CONCLUSIONS

PACG was significantly associated with higher long-term mortality, but this association was likely to be confounded by other systemic risk factors. VCDR >0.3 was the only independent predictor, implying that it may be a marker of ageing and frailty.

Causes, Predisposing Factors and Prevention Directions of Drug-induced Bradycardia (Based on the Results of the Hospital Register of Oardiac Medications Overdoses STORM)

Aim. Analysis of drug-induced bradiarrhythmia (DIB) causes and predisposing factors, followed by the development of recommendations for practitioners on its prevention.

Material and methods. The register included consistently all cases of hospitalization at the Regional Vascular Center (Ryazan) due to DIB in 2017 (n=114), 2018 (n=167), and retrospectively in 2014 (n=44). In total, 325 cases were reported: men - 26.1%, age 76.0 [68.0; 82.0] years; patients >65 years - 83.7%, and patients >75 years - 57.9%. The dose of medications with bradycardic action (BCA) taken the day before was known in 227 cases (69.8%), which allowed us to analyze the correctness of the intake regime in these cases.

Results. The excess of a single and / or daily medication dose (absolute overdose, AOD) occurred only in 10.6% of cases and was associated with the patient's attempt to cope with the deterioration of the disease or an acute clinical situation on their own. In other cases, there was no formal violation of the Instructions, but there was an inhibition of the heart's conducting system activity, characteristic of an overdose of medication (the so-called "relative” overdose, ROD). It was due to the summation/potentiation of BCA of several medications or changes in the medication pharmacokinetics. There were no differences in the clinical and demographic characteristics of patients and the provision of medical care in the groups with AOD and ROD (p>0.05). The exception was a high frequency of bradycardia <40 beats / min in AOD group (75.0% vs 49.8%, p=0.019) and, as a result, - management in the conditions of the Intensive Care Unit (66.7% vs 39.9%, p=0.012). Frequency of pre-admission receiving medications in AOD and ROD groups also did not differ (p>0.05): beta-blockers - an average of 64.3%, antiarrhythmic drugs with BCA- 41.0%, cardiac glycosides 25.1% (frequency each of these medicationsin DIB cases over the 5-year period has not changed), an agonist of the 11-imidazoline receptors - moxonidine (12.3%, its frequency has increased 8.9 times in 5 years, p=0.004), non-dihydropyridine calcium antagonists - 7.9% (decrease frequency over 5 years 4.0 times, p=0.002), other - 16.7%. In 56.8% of cases, medications with BCA were used in combination. At admission, a decrease in glomerular filtration rate (GFR) <45 ml/min/1.73 m2 was registered in 56.8% of cases, <30 ml/min/1.73 m2 - in 31.8%, <15 ml/min/1.73 m2 -in 10.9% (differences between groups with p>0.05). Hospital lethality in the AOD group is 4.2%, in the ROD group- 5.4% (p>0.05).

Conclusion. The main reasons of DIB are excess of the recommended dose, unrecorded summation/potentiation of BCA of several medications, and / or changes in the medication pharmacokinetics. Predisposing factors are self-medication of patients with worsening cardiovascular disease or acute clinical situations (e.g., hypertensive crisis), taking multiple medications with BCA, accession of heart disease, manifested by bradyarrhythmia, decrease in GFR, elderly and senile age.

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.

Using Esterase Selectivity to Determine the In Vivo Duration of Systemic Availability and Abolish Systemic Side Effects of Topical β-Blockers

For disorders of the skin, eyes, ears, and respiratory tract, topical drugs, delivered directly to the target organ, are a therapeutic option. Compared with systemic oral therapy, the benefits of topical treatments include a faster onset of action, circumventing the liver first pass drug metabolism, and reducing systemic side effects. Nevertheless, some systemic absorption still occurs for many topical agents resulting in systemic side effects. One way to prevent these would be to develop drugs that are instantly degraded upon entry into the bloodstream by serum esterases. Because topical β-blockers are used in glaucoma and infantile hemeangioma and cause systemic side effects, the β-adrenoceptor system was used to test this hypothesis. Purified liver esterase reduced the apparent affinity of esmolol, an ester-containing β-blocker used in clinical emergencies, for the human β-adrenoceptors in a concentration and time-dependent manner. However, purified serum esterase had no effect on esmolol. Novel ester-containing β-blockers were synthesized and several were sensitive to both liver and serum esterases. Despite good in vitro affinity, one such compound, methyl 2-(3-chloro-4-(3-((2-(3-(3-chlorophenyl)ureido)ethyl)amino)-2-hydroxypropoxy)phenyl)acetate, had no effect on heart rate when injected intravenously into rats, even at 10 times the equipotent dose of esmolol and betaxolol that caused short and sustained reductions in heart rate, respectively. Thus, ester-based drugs, sensitive to serum esterases, offer a mechanism for developing topical agents that are truly devoid of systemic side effects. Furthermore, differential susceptibility to liver and serum esterases degradation may also allow the duration of systemic availability for other drugs to be fine-tuned.

A comprehensive review on contact lens for ophthalmic drug delivery

With the prevalence of electronic devices and an aging population, the number of people affected with eye disease is increasing year by year. In spite of a large number of eye drops on the market, most of them do not perform sufficiently, due to rapid clearance mechanisms and ocular barriers. To enhance drug delivery to the eye, a number of novel formulations for ocular diseases have been investigated over recent decades, aiming to increase drug retention and permeation while also allowing for sustained drug release over prolonged periods. The contact lens, initially used to correct visual acuity and beautify female eyes, is one such novel formulation with outstanding potential. Recently, contact lenses have been extensively used for ocular drug delivery to enhance ocular bioavailability and reduce side effects, and are particularly suitable for the treatment of chronic diseases, and thus are of interest to ophthalmic scientists. This review summarizes contact lens classification, methods of preparation, strategies for integrating drugs into lenses, in vitro and in vivo studies, and clinical applications. This review also discusses the current state of ocular drug therapy and provides an outlook for future therapeutic opportunities in the field of ocular drug delivery.

Considerations of prescribers and pharmacists for the use of non-selective β-blockers in asthma and COPD patients: An explorative study

RATIONALE, AIMS, AND OBJECTIVES

Despite recommendations in prevailing guidelines to avoid the use of non-selective (NS) β-blockers in patients with asthma or COPD, on average, 10 patients per community pharmacy receive NS β-blockers monthly. The aim of our study was to identify the reasons of prescribers and pharmacists to treat asthma and COPD patients with NS β-blockers.

METHODS

Fifty-three community pharmacists in the Netherlands selected patients with actual concurrent use of inhalation medication and NS β-blockers. For at least 5 patients, each pharmacist screened all medication surveillance signals and actions taken at first dispensing. Each pharmacist selected 3 different initial prescribers for a short interview to explore their awareness of the co-morbidity and reasons to apply NS β-blockers.

RESULTS

Pharmacists identified 827 asthma/COPD patients with actual use of NS β-blockers. From these, 153 NS β-blocker prescribers were selected and interviewed (64 general practitioners, 45 ophthalmologists, 24 cardiologists, and 20 other prescribers). One hundred seven prescribers were aware of the drug-disease interaction of the asthma or COPD co-morbidity when initiating the NS β-blocker, and 46 were not. From these, 40 prescribers did not consider the contraindication to be relevant. For 299 patients, medication surveillance signals and actions at first dispensing were retrieved. Patients used predominantly ocular timolol (39.8%), and the oral preparations propranolol (30.8%) and carvedilol (15.1%). In 154 cases, the pharmacy system generated a warning alert.

CONCLUSIONS

A substantial number of prescribers was unaware of the co-morbidity or did not regard NS β-blockers contraindicated, despite prevailing clinical guidelines. Improvement programs should target prescribers' awareness and knowledge of NS β-blockers in patients with asthma or COPD.

Diadenosine tetraphosphate improves adrenergic anti-glaucomatous drug delivery and efficiency

The effect of the dinucleotide P(1), P(4)-Di (adenosine-5') tetraphosphate (Ap4A) in improving adrenergic anti-glaucomatous delivery by modifying the tight junction proteins of the corneal epithelium was evaluated. Stratified human corneal epithelial cells (HCLE) were treated with Ap4A (100 μM) for 5 min and TJ protein levels and barrier function were analysed by western blotting and transepithelial electrical resistance (TEER), respectively. Western blot experiments showed a significant reduction at 2 h (45% reduction of ZO-1 and 65% reduction of occludin protein levels) as compared to non-treated (control) cells. Two hours after Ap4A treatment, TEER values were significantly reduced (65% as compared to control levels (p < 0.001)), indicating an increase in corneal barrier permeability. Topical application of Ap4A in New Zealand white rabbits two hours before the instillation of the hypotensor compounds (the α2-adrenergic receptor agonist, brimonidine and the β-adrenergic receptor antagonist, timolol), improved the delivery of these compounds to the anterior chamber as well as their hypotensive action on the intraocular pressure. The results obtained showed that, when Ap4A was topically applied two hours before the adrenergic compounds, the concentration of brimonidine in the aqueous humour increased from 64.3 ± 5.3 nM to 240.6 ± 8.6 nM and from 58.9 ± 9.2 nM to 183.7 ± 6.8 nM in the case of timolol, which also produces a more profound effect on IOP. Therefore, Ap4A treatment results in a better entrance of adrenergic anti-glaucomatous compounds within the eye and consequently improved therapeutic efficiency by increasing corneal epithelial barrier permeability.

Bradyarrhythmias secondary to topical levobunolol hydrochloride solution

An 88-year-old man was admitted with fatigue, dizziness, and heart palpitations. Both the electrocardiogram and Holter confirmed the existence of sinus bradycardia and sinus arrest. One hour prior to the onset of symptoms, he received levobunolol hydrochloride solution topically. The levobunolol hydrochloride solution was discontinued and the bradycardia resolved. He was diagnosed as having intermittent sinus bradycardia and sinus arrest, induced by topical β-blocker therapy. Levobunolol hydrochloride solution is an effective therapy for ocular hypertension, probably by reducing aqueous fluid production. However, it can induce cardiac side effects such as bradyarrhythmia and should be used with caution in elderly patients or patients with cardiac disease.

Paroxetine markedly increases plasma concentrations of ophthalmic timolol; CYP2D6 inhibitors may increase the risk of cardiovascular adverse effects of 0.5% timolol eye drops

Although ophthalmic timolol is generally well tolerated, a significant fraction of topically administered timolol can be systemically absorbed. We investigated the effect of the strong CYP2D6 inhibitor paroxetine on the pharmacokinetics of timolol after ophthalmic administration. In a four-phase crossover study, 12 healthy volunteers ingested either paroxetine (20 mg) or placebo daily for 3 days. In phases 1-2, timolol 0.1% gel, and in phases 3-4, timolol 0.5% drops were administered to both eyes. Paroxetine increased the plasma concentrations of timolol with both timolol formulations to a similar degree. The geometric mean ratio (95% confidence interval) of timolol peak concentration was 1.53-fold (1.23-1.91) with 0.1% timolol and 1.49-fold (0.94-2.36) with 0.5% timolol, and that of timolol area under the plasma concentration-time curve (AUC) from time 0 to 12 hours was 1.61-fold (1.26- to 2.06-fold) and 1.78-fold (1.21-2.62), respectively. During paroxetine administration, six subjects on 0.5% timolol drops, but none on 0.1% timolol gel, had plasma timolol concentrations exceeding 0.7 ng/ml, which can cause systemic adverse effects in patients at risk. There was a positive correlation between the AUC from time 0 to 13 hours of paroxetine and the placebo phase AUC from time 0 to infinity of timolol after timolol 0.5% drops (P < 0.05), and a nonsignificant trend after timolol 0.1% gel, consistent with the role of CYP2D6 in the metabolism of both agents. In the orthostatic test, heart rate immediately after upright standing was significantly lower (P < 0.05) during the paroxetine phase than during the placebo phase at 1 and 3 hours after 0.5% timolol dosing. In conclusion, paroxetine and other CYP2D6 inhibitors can have a clinically important interaction with ophthalmic timolol, particularly when patients are using 0.5% timolol formulations.

Medical service encounters and payments associated with topical adjunctive therapy use of timolol for glaucoma

BACKGROUND

Topical β-blockers are commonly prescribed for primary open-angle glaucoma. Existing research is limited regarding respiratory or cardiovascular events that may result from using these topical β-blockers.

OBJECTIVE

To evaluate inpatient and outpatient service encounters and payments associated with the topical adjunctive use of the β-blocker timolol for glaucoma.

STUDY DESIGN

Retrospective data analysis using 2004-2011 IMS Lifelink Health Plan Claims Database.

PATIENTS

Beneficiaries were included if they had a diagnosis of glaucoma (International Classification of Diseases-Ninth Revision-Clinical Modification [ICD-9-CM] code 365.xx) and at least 4 years of continuous enrollment and glaucoma medication use (defined as at least one pharmacy claim each year). Beneficiaries who had 4 years of observation with no timolol use were categorized as "controls" and those with 2 years of non-timolol glaucoma medication use followed by consecutive years of adjunctive timolol use were considered "cases." Beneficiaries with 2 years of non-timolol glaucoma medication use followed by 1 year in which they used timolol adjunctively and then a year without timolol use were considered "discontinuers."

MAIN OUTCOME MEASURE

The rates of respiratory and cardiovascular disease in year 2 of the observation period were compared to the rates in year 3, and healthcare encounters and payments were also compared.

RESULTS

There were 24,271 glaucoma patients who did not receive timolol (controls), 1,406 beneficiaries who were prescribed timolol in addition to other glaucoma medications and continued its use (cases), and 299 beneficiaries who used adjunctive timolol for only a single year (discontinuers). More than half of each group was less than 65 years of age (58 % of controls, 53 % of cases, 54 % of discontinuers, p < 0.05). The rate of respiratory disease increased in all groups from year 2 to year 3 of the observation period, with increases of 1.0 %, 1.4 % and 5.0 % points among controls, cases and discontinuers, respectively (all between-group comparisons significant at p < 0.05). There were similar changes in the rate of cardiovascular disease, with increases of 1.3 %, 1.5 % and 4.7 % points among controls, cases and discontinuers, respectively (all between-group comparisons significant at p < 0.05). These increases were generally lower for younger beneficiaries and greater for those 65 years and older. Comparing years 2 and 3 of the observation period, discontinuers more than doubled their average rate of all-cause inpatient hospitalizations (0.35-0.83 encounters annually), while this rate remained steady for cases and controls (between-group comparisons significant at p < 0.05). There was little change in this rate among patients less than 65 years of age. Among those aged 65 years and older, there was a substantial increase for discontinuers, with a tripling of the average annual rate of inpatient hospitalizations from 0.45 to 1.48 (all between-group comparisons significant at p < 0.05). In this older group, both discontinuers and cases experienced more than a 20 % increase in outpatient service encounters compared to only 9 % for controls (all between-group comparisons significant at p < 0.05). Overall, discontinuers would be expected to have average annual medical payments US$3,600 greater than controls and US$3,200 greater than cases.

CONCLUSION

Adjunctive use of timolol by patients with glaucoma may be associated with increased respiratory and/or cardiovascular disease, hospitalizations and payments among patients for whom timolol may be contraindicated or who have yet undiagnosed manifestations of conditions for which it would be contraindicated.

Sustained ocular delivery of ciprofloxacin using nanospheres and conventional contact lens materials

PURPOSE

To formulate conventional contact lenses that incorporate nanosphere-encapsulated antibiotic and demonstrate that the lenses provide for sustained antibacterial activity.

METHODS

A copolymer composed of pullulan and polycaprolactone (PCL) was used to synthesize core-shell nanospheres that encapsulated ciprofloxacin. Bactericidal activity of the nanosphere-encapsulated ciprofloxacin (nanosphere/cipro) was tested by using liquid cultures of either Staphylococcus aureus or Pseudomonas aeruginosa. Nanosphere/cipro was then incorporated into HEMA-based contact lenses that were tested for growth inhibition of S. aureus or P. aeruginosa in liquid cultures inoculated daily with fresh bacteria. Lens designs included thin or thick lenses incorporating nanosphere/cipro and ciprofloxacin-HCl-soaked Acuvue lenses (Acuvue; Johnson & Johnson Vision Care, Inc., Jacksonville, FL).

RESULTS

Less than 2 μg/mL of nanosphere/cipro effectively inhibited the proliferation of cultures inoculated with 10(7) or 10(8) bacteria/mL of S. aureus and P. aeruginosa, respectively. HEMA-based contact lenses polymerized with nanosphere/cipro were transparent, effectively inhibited the proliferation of greater than 10(7)/mL of bacteria added daily over 3 days of culture, and killed up to 5 × 10(9) total microbes in a single inoculation. A thicker lens design provided additional inhibition of bacterial growth for up to 96 hours.

CONCLUSIONS

Core-shell nanospheres loaded with an antibiotic can be incorporated into a conventional, transparent contact lens and provide for sustained and effective bactericidal activity and thereby provide a new drug delivery platform for widespread use in treating ocular disorders.

Managing glaucoma in those with co-morbidity: not as easy as it seems

PURPOSE

To identify the extent of use of medicines recommended to be used with caution in glaucoma patients with specified comorbidities and to determine evidence of associated harm. Retrospective cohort analysis from administrative claims data and prescription/event sequence symmetry analysis.

PARTICIPANTS

Australian Government Department of Veterans' Affairs treatment card holders dispensed glaucoma eye-drops.

MAIN OUTCOME MEASURES

Proportion of veterans with glaucoma and diabetes, airways disease, heart failure, ischemic heart disease or depression, dispensed glaucoma eye drops which should be used with caution. For harms, outcome measures were hospitalizations for airways disease and heart disease.

RESULTS

The cohort analysis included 25,984 veterans. Of these, 88% with airways disease were dispensed glaucoma eye drops with the potential to aggravate airways disease, 43% with heart failure were dispensed topical beta-blockers and 49% with depression received glaucoma eye drops which should be used cautiously in those with depression. We found increased risk of initiation of inhaled beta-agonist following timolol (adjusted sequence ratio (ASR) 1.48, 99% CI 1.22-1.78) and latanoprost (ASR 1.24, 99% CI 1.11-1.38) initiation. We found increased risk of inhaled corticosteroid initiation following initiation of timolol (ASR 1.43, 99% CI 1.13-1.81). There was increased risk of antidepressant initiation following timolol initiation (ASR 1.24, 99% CI 1.07-1.43), and latanoprost (ASR 1.16, 99% CI 1.03-1.31). There was also increased risk of hospitalization for bradycardia following timolol initiation (ASR 2.22,99% CI 1.15-4.31).

CONCLUSION

Use of glaucoma eye drops recommended to be used with caution in co-morbidities is common and was associated with adverse outcomes. Awareness of co-morbidities is required in the selection and prescription of glaucoma eye drops.

Cytochrome oxidase 2D6 gene polymorphism in primary open-angle glaucoma with various effects to ophthalmic timolol

AIMS

Timolol is used topically for the treatment of glaucoma and metabolized by cytochrome P450 (CYP) 2D6 in the liver. The aim of this study is to test the hypothesis that CYP 2D6 single-nucleotide polymorphism (SNP) is associated with drug effects of ophthalmic timolol.

METHODS

A total of 133 primary open-angle glaucoma (POAG) subjects underwent the ophthalmic single timolol administration and the drug effects were observed, including lowering the effects of intraocular pressure (IOP) and side effects (i.e., appearing bradycardia). Eight SNPs of CYP2D6 were investigated in 73 subjects by a SNPstream genotyping system. The relationship between the effects of timolol and CYP2D6 Arg296Cys and Ser486Thr genotype distribution in these POAG subjects was analyzed.

RESULTS

Topical timolol administration had significant effect on IOP (P = 0.000) and heart rate (HR) (P = 0.000) in all 133 subjects, and individual ocular hypotensive effect of timolol varied between 0 and 23 mmHg. Individual effect of HR varied between -31 and 10 beats per minute, in the present study. According to SNP genotyping in 73 subjects, there was no significant difference of IOP between subjects with different CYP2D6 Arg296Cys (P = 0.308) or Ser486Thr genotypes (P = 0.741). The effect of timolol on HR was significantly different between subjects with different Arg296Cys genotypes (P = 0.046). Timolol-induced bradycardia tended to occur in subjects with Arg296Cys CT and TT genotype when compared with CC genotype (P = 0.009).

CONCLUSIONS

CYP2D6 SNP Arg296Cys appeared to be correlative with the intersubject variability seen with timolol in POAG subjects. Subjects with CC genotype trended to avoid timolol-induced bradycardia, and subjects with TT genotype trended to have poorer timolol-induced ocular hypotensive effects.

Evaluation of risk of falls and orthostatic hypotension in older, long-term topical beta-blocker users

BACKGROUND

Falls are a serious problem in the elderly, and have recently been described as cardiovascular-mediated side effects of beta-blocker eye drops. Therefore, we investigated the possible association between the long-term use of beta-blockers, prostaglandins and their combinations in eye drops, and falls, dizziness and orthostatic hypotension in older patients.

METHODS

All participants were long-term users of eye drops containing beta-blockers, prostaglandins or their combinations. They underwent a structured falls interview and blood pressure measurement for testing of orthostatic hypotension. The odds ratio for presence of orthostatic hypotension or a positive falls history according to use of beta-blocker eye drops was calculated with a binary logistic regression analysis. The main outcome measures were a positive falls history and the presence of orthostatic hypotension.

RESULTS

In total, 148 of 286 subjects participated. After adjustment for age, gender, and use of fall-risk-increasing drugs other than beta-blocker eye drops, we found no significant difference in fall risk [odds ratio (OR): 0.60; 95% confidence interval (CI): 0.268-1.327] between patients using ophthalmic beta-blockers or a combination of ophthalmic beta-blockers and prostaglandins, and patients using ophthalmic prostaglandins only. Although prevalence of orthostatic hypotension was higher in the beta-blocker group (OR: 1.67; 95% CI: 0.731-3.793) compared to the prostaglandin group, this was a non-significant difference.

CONCLUSIONS

In our study, we did not find a significant association between long-term use of beta-blockers eye drops and falls, dizziness or orthostatic hypotension in older ophthalmic outpatients, compared to long-term use of prostaglandin eye drops.

A Novel Chemical Delivery System Comprising an Ocular Sustained Release Formulation of a 3α, 17α, 21-trihydroxy-5β-pregnan-20-one-BIS-5-Flourouracil Codrug

Directly compressed sustained release pellets were prepared from material consisting of a molecule of 3alpha, 17alpha, 21-trihydroxy-5beta-pregnan-20-one (trihydroxy steroid, THS) covalently linked via carbonate moieties to two molecules of 5-flourouracil (5FU) to form a novel THS-BIS-5FU codrug for the treatment of angiogenesis. Dissolution and drug release was tested in vitro in 0.1M phosphate buffer (pH 7.4), human serum, and vitreous humor. The results suggest that neat THS-BIS-5FU codrug pellets are useful for sustained release ocular delivery of the parent compounds, and that the unique physicochemical properties of the codrug allow slow dissolution and rapid release of the two parent drugs. This codrug formulation is regarded as a "chemical delivery" system that involves dissolution of the codrug as the rate-limiting step followed by rapid hydrolysis of the carbonate ester linkages to release the parent drugs via sustained delivery.

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.

Co-prescribing of topical and systemic beta-blockers in patients with glaucoma: a quality use of medicine issue in Australian practice

PURPOSE

Prescribing topical beta-blockers for patients with glaucoma, who are also being treated with systemic beta-blockers, raises efficacy and safety concerns. This potentially inappropriate co-prescribing practice is a Quality Use of Medicine issue. This study aimed to quantify the extent of co-prescribing of topical and systemic beta-blockers in Australian clinical practice.

METHODS

This is a retrospective analysis of de-identified billing data for supply (surrogate marker for prescribing) of topical and systemic beta-blockers from the Pharmaceutical Benefits Scheme (1999-2004) to concessional patients supplied either topical or systemic beta-blockers. The primary outcome was the percentage of patients supplied systemic beta-blockers within the patient population supplied topical beta-blockers. This percentage was calculated for each financial year (July 1999-June 2004), age group (<65 years; 65-74 years; 75-84 years; > or =85 years) and sex.

RESULTS

Approximately 20% of patients supplied topical beta-blockers (representing Australian glaucoma patients) were also supplied systemic beta-blockers, equating to more than 20 000 patients per year. This percentage varied with age, but not with year or sex. The percentage of patients co-supplied topical and systemic beta-blockers was the lowest (13%) for patients <65 years and the highest (23%) for patients 75-84 years.

CONCLUSIONS

Pharmaceutical Benefits Scheme supply data shows that the potentially inappropriate practice of co-prescribing topical and systemic beta-blockers affects more than 20 000 concessional patients in Australia each year, particularly the elderly. This Quality Use of Medicine issue has now been quantified; doctors, pharmacists and patients must be made aware of the reduced efficacy and potential for more side-effects from this co-prescribing practice.

Resistance to ocular antibiotics: an overview

The introduction of new antibiotic compounds into therapy initiates the development of resistance by the target bacteria. Resistance increases the risk of treatment failure with potentially serious consequences. Local application of antibacterial compounds to the eyes may lead to bacterial resistance in bacterial isolates from the eyes. The incidence of resistant strains of common pathogens is probably increasing. As compounds can be absorbed into the systemic circulation following ocular administration, the subsequent low concentrations in the blood could provide the selective pressure for the survival of resistant bacteria in the body. Despite this possibility, there are no reports of systemic resistance in bacteria following ocular administration of antibacterial compounds. All health-care professionals should be concerned about this possibility and continue to use these important compounds with respect.

Ocular Carteolol

Ocular carteolol (Mikelan), Teoptic, Ocupress) is a nonselective beta-adrenoceptor antagonist with intrinsic sympathomimetic activity (ISA). Ocular carteolol effectively reduces intraocular pressure (IOP) in patients with open-angle glaucoma (OAG) or ocular hypertension (OH). Twice-daily administration of standard carteolol has generally similar IOP-lowering efficacy to other ocular beta-adrenoceptor antagonists such as timolol, betaxolol and metipranolol in patients with OAG or OH. In addition, long-term treatment with carteolol has similar efficacy to timolol and betaxolol in terms of reducing IOP and maintaining visual fields in patients with newly diagnosed primary OAG (POAG). The new long-acting formulation of once-daily carteolol has equivalent efficacy to the standard formulation of carteolol administered twice daily in patients with OAG or OH. Both the standard and long-acting formulations of ocular carteolol are generally well tolerated in terms of topical adverse effects involving the eyes or systemic adverse effects involving the cardiovascular system. Thus, twice-daily carteolol is a well established option in the treatment of glaucoma and OH, and the new once-daily formulation of long-acting carteolol offers similar efficacy and tolerability with a potential for improved patient adherence.

Open-Angle Glaucoma and Cardiovascular Mortality

PURPOSE

To evaluate the association between open-angle glaucoma (termed glaucoma) and 9-year mortality in an older population-based cohort.

DESIGN

Population-based cohort.

PARTICIPANTS

Three thousand six hundred fifty-four persons aged 49 to 97 years (82.4% of the eligible population), residents of the Blue Mountains, west of Sydney, Australia.

METHODS

At baseline (1992-1994), glaucoma was diagnosed from congruous typical glaucomatous visual field changes (full-threshold fields) and optic disc cupping (stereo-optic disc photography). Demographic information from baseline participants was matched with the Australian National Death Index data (December 2001) to obtain the number and causes of deaths. Cox proportional hazards regression analysis, controlling for age, male gender, diabetes, hypertension, heart disease, stroke, use of oral beta-blockers, current smoking history, alcohol use, myopia, and nuclear cataract were performed to assess hazard ratios for cardiovascular mortality. Adjustments for all-cause mortality also included history of cancer.

MAIN OUTCOME MEASURES

Cardiovascular and all-cause mortality.

RESULTS

At baseline, glaucoma was diagnosed in 108 participants (3.0%). Of 873 deaths (23.9%) before January, 2002, 312 people (8.5%) died of cardiovascular events. The age-standardized all-cause mortality was 24.3% in persons with and 23.8% in those without glaucoma, whereas cardiovascular mortality was 14.6% in persons with and 8.4% in those without glaucoma. After multivariate adjustment, those with glaucoma had a nonsignificant increased risk of cardiovascular death (relative risk [RR], 1.46; 95% confidence interval [CI], 0.95-2.23). Increased cardiovascular mortality was observed mainly in glaucoma patients aged <75 years (RR, 2.78; 95% CI, 1.20-6.47). Further stratified analyses showed that cardiovascular mortality was higher among those with previously diagnosed glaucoma (RR, 1.85; 95% CI, 1.12-3.04), particularly in those also treated with topical timolol (RR, 2.14; 95% CI, 1.18-3.89).

CONCLUSIONS

Findings from the Blue Mountains Eye Study demonstrate an increased cardiovascular mortality in persons with previously diagnosed glaucoma. There was a suggestion of higher cardiovascular mortality in glaucoma patients using topical timolol that merits further study.

Improved systemic safety and risk–benefit ratio of topical 0.1% timolol hydrogel compared with 0.5% timolol aqueous solution in the treatment of glaucoma

PURPOSE

The purpose of the study was to compare the systemic safety and risk-benefit ratio of 0.1% timolol hydrogel and 0.5% aqueous timolol eye drops in the treatment of glaucoma.

METHODS

An 8-week randomised, double-blind, cross-over, multicentre study. A total of 25 patients with primary open-angle glaucoma, exfoliation glaucoma, or ocular hypertension was enrolled. After completing a wash-out period, patients were randomly chosen to receive either 0.1% timolol hydrogel once daily or 0.5% aqueous timolol eye drops twice daily. Intraocular pressure and heart rate during rest and exercise, head-up tilt test results, spirometry readings, and plasma concentrations of timolol were recorded. The risk-benefit ratio was determined by calculating the ratio between several heart rate endpoints and the change in intraocular pressure (IOP).

RESULTS

The mean drug-induced change in the peak heart rate during exercise was -13.5 beats/min (SD 7.6) in the 0.5% aqueous timolol group and -5.1 beats/min (SD 6.7) in the 0.1% timolol hydrogel group (P<0.001; 95% CI 4.06-12.18). There was no significant difference in the IOP-reducing efficacy between these compounds. The risk-benefit ratio was significantly improved when 0.1% timolol hydrogel was used, compared with 0.5% aqueous timolol in the exercise test. In the head-up tilt test the risk-benefit ratio was significantly improved at rest (P<0.05), at 1 min (P<0.05) and at 5 min (P<0.001) after patients had received 0.1% timolol hydrogel. There were, however, no differences in spirometry readings. After patients had been treated with 0.1% timolol hydrogel, plasma concentrations of timolol were 1/6 (at peak) and 1/50 (at trough) of those of 0.5% aqueous timolol.

CONCLUSIONS

Drug-induced changes in the peak heart rate, and head-up tilt test results as well as plasma concentrations of timolol, were significantly more pronounced after treatment with 0.5% aqueous timolol than with 0.1% timolol hydrogel. Because of the statistically similar IOP-reducing efficacy of these formulations the risk-benefit ratio was significantly improved when patients used 0.1% timolol hydrogel instead of 0.5% aqueous timolol.

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.

Glaucoma Medications

As with many diseases, glaucoma increases in frequency in older populations, and is very often encountered in patients taking multiple medications. While the exact mechanism of glaucomatous optic neuropathy (GON) is not known, intraocular pressure (IOP) is thought to be central to the process, and reducing IOP is the only known effective treatment. The newer definition of glaucoma is an IOP-sensitive optic neuropathy. While large, controlled studies have indicated that reducing IOP will slow the progression of disease, the contributions of other conditions and medications have not been adequately studied. As the adverse effect profiles of medical therapies for glaucoma have improved, use of these agents has increased greatly. This has resulted in a large number of older patients taking glaucoma medications. Since topical medications can easily be overlooked in a medical history, and are for the most part well tolerated, systemic complications from these agents can be missed. In addition to being a common disease requiring treatment, glaucoma is also a model system for other degenerative diseases, and many of the concepts originally developed in relation to neurodegenerative diseases such as Alzheimer's disease are under investigation for glaucoma. These include approaches targeted towards neuroprotection and excitotoxicity.

Chart documentation by general physicians of the glaucoma medications taken by their patients

PURPOSE

To estimate the frequency of documentation of glaucoma medications by primary care physicians.

DESIGN

Cross-sectional, observational study.

METHODS

The general medical records of 100 patients of one glaucoma specialist were reviewed. We recorded whether the mention of eyedrops appeared in the medical record.

RESULTS

The median number of glaucoma medications used was 2.5 (range 1 to 5). Fifty-five (55%, 95% confidence interval: 45%-65%) of the medical records of the primary physicians mentioned eyedrops. Alpha-agonists were statistically less frequently documented (13%) in the general medical record than beta-adrenergic blockers (47%) and prostaglandins (44%).

CONCLUSION

Almost half of the charts of these primary physicians had no documentation of any eyedrop use by their patients with glaucoma. An important step in reducing drug-induced side effects and interactions with other medications would be better recognition by primary physicians of the ophthalmic drugs used by their patients.

Comparison of survival of exfoliative glaucoma patients and primary open-angle glaucoma patients: impact of acetazolamide use

PURPOSE

To compare the survival rates of patients with exfoliative glaucoma (XFG) and those with primary open-angle glaucoma (POAG), and to establish whether the use of acetazolamide has any influence on survival.

METHODS

The survival data, including date and cause of death, for 1147 patients with XFG or POAG who were ultimately hospitalized at the Eye Department, National Hospital, Oslo, between 1961 and 1970, were analysed retrospectively. The Cox proportional hazard model was used in the survival analyses.

RESULTS

No statistically significant differences in survival were found between patients with XFG and those with POAG (p = 0.85). As expected, female gender and younger age at diagnosis were associated with longer survival periods. Surprisingly, we found that patients with more recent birth dates had relatively lower survival rates than patients with earlier birth dates; when this was included in the analyses, the use of acetazolamide was found to be associated with reduced survival (n = 492, p = 0.02).

Vasodilating beta-adrenoceptor blockers as cardiovascular therapeutics

beta-Adrenoceptor blocking agents (beta-blockers) have been established as therapeutics for treatment of patients with hypertension, ischemic heart diseases, chronic heart failure, arrhythmias, and glaucoma. However, their clinical use is limited because some patients are adversely affected by their side effects. The discovery of cardioselective (beta(1)-selective) blockers has overcome some of the problems. Current retrospective studies have revealed that vasodilating beta-blockers (so-called beta-blockers of the third generation) have advantages over the conventional type of beta-blockers in terms of minimizing the adverse effects and improving the disease-derived dysfunction, thus enhancing the quality of life variables. Some of the possible advantages include improvement of insulin resistance, decrease in low-density lipoprotein cholesterol in association with increase in high-density lipoprotein cholesterol, attenuation of bronchial asthma attack and respiratory dysfunction, alleviation of coronary vasospasm provocation, peripheral circulatory disturbances, and erectile dysfunction, and better patient compliance. Release of nitric oxide, antioxidant action, beta(2)-adrenoceptor activation, Ca(2+) entry blockade, and other mechanisms underlying the vasodilating action may be responsible for the beneficial therapeutic effects of these agents.

Accumulation of porcine insulin in the rat brain and cerebrospinal fluid following ocular application

We previously reported that insulin accumulated in the retina and optic nerve following ocular application. Since the optic nerve is surrounded by meninges and cerebrospinal fluid (CSF) and since it extends back to the thalamus, we examined whether the topical application of insulin eye drops also resulted in the accumulation of insulin in the CSF and brain. The data presented in this paper show that this is in fact the case. Following the ocular application of a 0.75% solution of porcine insulin, significant concentrations of insulin were demonstrable in the CSF extracted from the cisterna magnum, as well as in three brain regions. While it is not yet clear how insulin got into these target tissues, our data argue against a mechanism involving uptake from the blood (a fraction of topically applied compounds normally enters the vasculature through the conjunctiva and nasal mucosa). It is theorized that insulin may enter the CSF surrounding the optic nerve and by so doing, not only disseminate throughout the CSF space but also throughout the brain. The implications of these findings for central nervous system drug delivery are discussed.