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PubMed1996

Clinical experience with brimonidine 0.2% and timolol 0.5% in glaucoma and ocular hypertension.

The ocular hypotensive efficacy and safety of brimonidine tartrate 0.2%, a highly selective alpha 2-adrenergic agonist, was compared with that of timolol 0.5%, a nonselective beta-blocker in two multicenter, randomized, double-masked studies. Combined data from a 12-month completed study and 6-month interim data from an ongoing study are reported. Efficacy and safety were evaluated at baseline, weeks 1 and 2, and months 1, 2, 3, 6, 9, and 12. Intraocular pressure (IOP) was measured at peak (2 hours after the morning dose) and trough (12 hours after the evening dose). Patients (n = 926) instilled either brimonidine tartrate 0.2% or timolol maleate 0.5% twice daily. At peak, the mean decreases from baseline IOP ranged from 5.9 +/- 3.2 mm Hg to 7.6 +/- 3.6 mm Hg for brimonidine and 6.0 +/- 3.4 mm Hg to 6.6 +/- 3.6 mm Hg for timolol (p < 0.001 within groups compared with baseline). No significant between-group differences were seen at peak except for weeks 1 and 2 and month 3 (p < or = 0.04), when brimonidine had lower mean IOP. At trough the mean decreases from baseline ranged from 3.7 +/- 4.0 mm Hg to 5.0 +/- 3.0 mm Hg for brimonidine and 5.9 +/- 3.4 to 6.6 +/- 3.0 for timolol. A significant between-group difference was seen at trough at all visits (< 0.001), when timolol had a lower mean IOP. Brimonidine and timolol showed sustained efficacy. Both drugs were well-tolerated. The brimonidine group had more ocular allergy, oral dryness and conjunctival follicles. The timolol group had more burning and stinging. In the brimonidine group, 38/513 (7.4%) discontinued treatment due to ocular allergy. The timolol group had significantly lower mean heart rate compared to baseline. The effect on blood pressure was minimal for both drugs. Brimonidine showed efficacy similar to timolol and a relatively low rate of ocular allergy. Brimonidine 0.2% administered twice daily is an effective and safe ocular hypotensive agent that maintains IOP-lowering in chronic use.

Adrenergic alpha-Agonists↗
PubMed2001

Comparison of once- or twice-daily bimatoprost with twice-daily timolol in patients with elevated IOP : a 3-month clinical trial.

OBJECTIVE: To compare the safety, tolerability, and efficacy of bimatoprost 0.03% instilled once daily or twice daily with timolol 0.5% twice daily. DESIGN: Multicenter, 3-month, randomized, double-masked, interventional comparison trial. PARTICIPANTS: Patients diagnosed with ocular hypertension or glaucoma (n = 596). INTERVENTION: Patients received bimatoprost 0.03% ophthalmic solution once daily (8 PM, with vehicle control at 8 AM), bimatoprost 0.03% twice daily (8 AM; 8 PM), or timolol 0.5% twice daily (8 AM; 8 PM) in an uneven 2:2:1 randomization. Scheduled visits were at prestudy, baseline (day 0), weeks 2 and 6, and month 3. Intraocular pressure (IOP) was measured at 8 AM (predose), 10 AM, and 4 PM. MAIN OUTCOME MEASURES: The primary outcome measure was reduction in IOP in the eye with higher IOP at baseline. Secondary outcome measures included safety variables (adverse events, ophthalmoscopy, biomicroscopy, iris pigmentation, laser-flare meter, visual acuity, visual fields, heart rate, blood pressure, blood chemistry, hematology, and urinalysis). RESULTS: At month 3, the mean reduction in IOP from baseline at 8 AM was 9.16 mmHg (35.2%) with bimatoprost once daily, 7.78 mmHg (30.4%) with bimatoprost twice daily, and 6.74 mmHg (26.2%) with timolol twice daily. At all follow-up visits, mean IOP reductions were significantly greater in the bimatoprost once daily group than in the timolol group at each time point (8 AM, 10 AM, and 4 PM; P < 0.001). Twice-daily dosing of bimatoprost also provided significantly greater mean reductions in IOP than timolol at most time points but was not as effective as once-daily dosing. Bimatoprost was associated with significantly more hyperemia and eyelash growth than timolol, whereas timolol was associated with significantly more burning and stinging sensation in eyes. Overall, bimatoprost was well tolerated with few discontinuations because of adverse events. CONCLUSIONS: Bimatoprost 0.03% once daily was safe and statistically superior to timolol 0.5% twice daily in lowering IOP in patients with ocular hypertension or glaucoma. Bimatoprost given once daily consistently provided IOP reductions approximately 2 to 3 mmHg greater than those provided by timolol. Once-daily dosing of bimatoprost, 0.03%, demonstrated greater IOP-lowering effect and better ocular tolerability than twice-daily dosing.

Adult↗
PubMed2003

A 3-month randomized controlled trial of bimatoprost (LUMIGAN) versus combined timolol and dorzolamide (Cosopt) in patients with glaucoma or ocular hypertension.

PURPOSE: To compare the efficacy and safety of topical bimatoprost (LUMIGAN; Allergan, Inc., Irvine, CA) once daily with that of topical combined timolol and dorzolamide (Cosopt; Merck and Co, Inc., Whitehouse Station, NJ) twice daily. DESIGN: Prospective, randomized, double-masked, multicenter clinical trial. PARTICIPANTS: One hundred seventy-seven patients with a diagnosis of glaucoma or ocular hypertension and inadequate control of intraocular pressure (IOP) after at least 2 weeks of topical timolol maleate 0.5% monotherapy. METHODS: Patients were randomized to receive bimatoprost 0.03% once daily (n = 90) or combined timolol 0.5% and dorzolamide 2% twice daily (n = 87) over a 3-month period. MAIN OUTCOME MEASURES: Intraocular pressure, the primary end point, was measured at 8 AM and 10 AM at baseline, week 1, and months 1, 2, and 3, and also at 4 PM and 8 PM at baseline and month 3. RESULTS: Bimatoprost provided significantly greater IOP lowering compared with combined timolol and dorzolamide. At the 8 AM measurements, bimatoprost lowered mean IOP 6.8 mmHg to 7.6 mmHg from baseline, whereas combined timolol and dorzolamide lowered mean IOP 4.4 to 5.0 mmHg from baseline (P<0.001). At the last follow-up, patients had better diurnal IOP control with bimatoprost than combined timolol and dorzolamide. At 8 AM at the 3-month visit, the percentages of patients achieving IOPs of <or =13 mmHg, < or =14 mmHg, < or =15 mmHg, or < or =16 mmHg were more than twice as high for bimatoprost than for combined timolol and dorzolamide (all P< or =0.008). Taste perversion, ocular burning, and stinging with instillation were more common with combined timolol and dorzolamide, whereas conjunctival hyperemia was more common with bimatoprost. CONCLUSIONS: In individuals with glaucoma or ocular hypertension, uncontrolled on a topical beta-blocker alone, bimatoprost lowered IOP more consistently than did combined timolol and dorzolamide.

Administration, Topical↗
PubMed1984

Plasma timolol in glaucoma patients.

Plasma timolol levels were measured in our timolol-treated glaucoma patients employing three protocols: (1) measurements in ten patients over age 60 on chronic timolol therapy before, one hour, and three hours after receiving one drop of 0.5% timolol, (2) measurements in nine adult patients, with and without punctal occlusion, and (3) random measurement of plasma timolol in children on chronic timolol therapy while under general anesthesia. In the ten patients over age 60 years, baseline mean plasma timolol was 0.34 ng/ml, increasing to a mean of 1.34 ng/ml one hour after receiving drops. When punctal occlusion was applied, the mean one-hour plasma timolol diminished to 0.9 ng/ml, approximately 40% less than that observed without punctal occlusion. The plasma timolol levels examined in nine determinations in five children ranged from a low 3.5 ng/ml in a five-year-old child to 34 ng/ml in a three-week-old infant.

Absorption↗
PubMed1991

Additivity of prostaglandin F2 alpha-1-isopropyl ester to timolol in glaucoma patients.

The effect on intraocular pressure (IOP) of adding prostaglandin F2 alpha-1-isopropyl ester (PGF2 alpha-IE) to timolol was studied in 21 eyes of 13 patients with newly diagnosed primary open-angle glaucoma that was inadequately controlled with timolol alone. After at least 2 weeks of twice daily timolol 0.5% therapy, PGF2 alpha-IE, 0.5 microgram in 30 microliters, was topically applied twice daily at 8 AM and 8 PM, 5 minutes before each timolol dose, for 7 days. Intraocular pressures were measured before timolol treatment, and at 8 AM, 8:30 AM, 12 PM, 2 PM, and 4 PM on the day before the addition of PGF2 alpha-IE, and on day 1 and on day 7 of combined therapy. Mean IOP was 39 +/- 2 mmHg (+/- standard error) before timolol therapy and 31 +/- 2 mmHg after at least 2 weeks of treatment with timolol alone. A significant (P = 0.004) further reduction of IOP was first observed 4 hours after the first dose of PGF2 alpha-IE, which was maintained throughout the duration of combined therapy. During the last day of combined treatment and at 12 hours after the final dose, IOP was reduced a mean of 6 to 9 mmHg (mean, 9.0 +/- 1.5 mmHg at 12 hours) below baseline values obtained with timolol alone. These results indicate that adding PGF2 alpha-IE in patients treated with timolol causes a further reduction of IOP that may prove to be clinically useful in glaucoma therapy.

Adult↗
PubMed1982

Timolol and propranolol: bioavailability, plasma concentrations, and beta blockade.

Timolol, like propranolol, is a nonselective beta-adrenergic blocker, but it is much less lipid soluble and is formulated as a single enantiomer rather than a racemic mixture. We examined the effects of such differences on bioavailability, systemic clearance, and pharmacologic response. Ten healthy subjects received placebo, 0.2 mg/kg IV propranolol, 3.2 mg/kg oral propranolol, 0.025 mg/kg IV timolol, and 0.4 mg/kg oral timolol in double-blind, randomized crossover fashion. Plasma concentrations of total drug were monitored up to 8 hr, while responses to submaximal exercise were measured at 0, 2, and 6 hr. Timolol had greater bioavailability (F = 0.61 +/- 0.06(SEM) and 0.32 +/- 0.04) and lower systemic clearance (463 +/- 74 ml kg-1 hr-1 and 1040 +/- 120 ml kg-1 hr-1) than propranolol. Half-lifes were of the same order (2.7 and 2.9 hr). There was a marginal correlation between areas under the intravenous and oral plasma concentration-time curves for timolol (r = 0.66, P = 0.054), but none for propranolol (r = 0.48, P NS). There were also correlations of the response (percent reduction in heart rate) to oral and intravenous timolol at 2 hr (r = 0.72, P less than 0.05) and 6 hr (r = 0.84, P less than 0.01) hr, but none between responses to oral and intravenous propranolol. Finally, the response to oral timolol was related to the area under its plasma concentration-time curve, whereas that to propranolol was not. We conclude that the physicochemical properties of timolol lead to greater bioavailability. Pharmacologic response to an oral dose of timolol, unlike that to propranolol, can be predicted from the response to an intravenous dose and reflects its plasma concentration.

Administration, Oral↗
PubMed1991

Beta-blocking effects of timolol at low plasma concentrations.

The concentration-effect relationship of 0.25 mg intravenous timolol with and without pretreatment with 100 mg quinidine was studied in six healthy young volunteers with a randomized, double-blind, crossover study design. Blockade of cardiac beta-adrenoceptors was assessed by determining the dose ratios (DR) of isoproterenol infusions required to increase heart rate by 25 beats/min before and after timolol infusion. The logarithm of timolol concentration in plasma was linearly related to the logarithm (DR-1) of isoproterenol infusion, with a mean Pearson correlation coefficient of 0.89 +/- 0.11 (+/- SD; n = 24) at timolol concentrations well below 1 ng/ml. The increases in cyclic adenosine monophosphate (cAMP) and norepinephrine plasma levels caused by isoproterenol infusions were attenuated after timolol. Quinidine administration increased timolol plasma levels and cardiac beta-blocking effects by 10% to 40%. It was concluded that timolol at concentrations below 1 ng/ml in plasma competitively antagonizes cardiac and noncardiac effects of isoproterenol infusions. Timolol effects are augmented after quinidine administration. The beta-blockade occurring at low plasma levels can explain side effects and actions of ocularly applied timolol.

Adult↗
PubMed1992

Sezolamide: additivity to timolol twice daily.

Sezolamide, a potent topical carbonic anhydrase inhibitor previously known as MK-417, was studied to determine its ocular hypotensive activity in patients with elevated intraocular pressure while on continuing therapy with topical timolol. This was a three-centre, double-masked, randomised, placebo-controlled, parallel study in 36 patients with bilateral primary open angle glaucoma or ocular hypertension on therapy receiving 0.5% timolol twice daily, with a morning intraocular pressure greater than or equal to 22 mmHg in both eyes 2-4 hours following an 8 a.m. dose of timolol. Sezolamide 1.8% or placebo twice daily was added to treatment with timolol on the evening of day 1 and continued for 2 weeks. Twelve-hour diurnal curves were performed before the study on day 1 (timolol alone) and on day 15. Intraocular pressure measurements were also taken on days 2 and 8 at 8 a.m. and 9 a.m. Patients who received timolol and sezolamide showed additional intraocular pressure reductions from day 1 (timolol alone) of 8.0 to 15.5%, which were significant at all times. At hours 1, 2, 4 and 8 the reductions in intraocular pressure observed in the group receiving sezolamide and timolol were significantly greater than those in the group receiving timolol and placebo.

Aged↗
PubMed2002

A comparison of the efficacy and tolerability of 0.5% timolol maleate ophthalmic gel-forming solution QD and 0.5% levobunolol hydrochloride BID in patients with ocular hypertension or open-angle glaucoma.

The purpose of this study was to compare the ocular hypotensive efficacy and tolerability of 0.5% timolol maleate ophthalmic gel-forming solution (timolol gel) and 0.5% levobunolol hydrochloride (levobunolol). This was a randomized, double-masked, multi-center, active-controlled, 2-period, crossover study. After a 3-week, single-masked placebo run-in phase, patients with ocular hypertension or open-angle glaucoma and an intraocular pressure (IOP) > or = 22 mmHg were randomized to receive timolol gel QD or levobunolol BID for 6 weeks followed by a 3-week, placebo washout period. Patients were then crossed over to the alternate treatment for 6 weeks. IOP and heart rate (HR) were measured at 3 and 6 weeks after the start of therapy with either timolol gel or levobunolol. Of 133 patients randomized, 116 received both treatments. Timolol gel QD was comparable to levobunolol BID in reducing trough and peak IOP. At trough, HR was marginally increased with timolol gel and was decreased with levobunolol (p = < 0.001). At peak, HR was decreased with both treatments, but the decrease was significantly less with timolol gel than with levobunolol (p = 0.049). Significantly more patients experienced at least one adverse event (p = 0.024), adverse events related to special senses (p = 0.002), and burning and stinging (p < 0.001) with levobunolol compared to timolol gel. The study demonstrates that timolol gel QD has IOP-lowering effects comparable to those of levobunolol BID with fewer adverse experiences and less effect on HR.

Adrenergic beta-Antagonists↗
PubMed1989

Binding of timolol to iris-ciliary body and melanin: an in vitro model for assessing the kinetics and efficacy of long-acting antiglaucoma drugs.

Topical beta blockers are used to treat glaucoma patients. These drugs inhibit aqueous production for prolonged periods of time. The purpose of this study was to determine whether timolol maleate (a non-specific beta blocker) binds to human iris-ciliary body (CB) melanin and to elucidate the binding characteristics of the drug to melanin. Timolol bound to bovine iris and ciliary body by two possible mechanisms. The binding kinetics indicate that the binding is probably of a nonspecific nature. There was no statistically significant differences between the melanotic tissues (CB, iris) and the nonmelanotic tissues (lens, cornea, liver, kidney) regarding the amount of timolol bound. However significantly more timolol was bound to the isolated melanins than the whole tissues. Timolol was released from the nonmelanotic tissues at a much faster rate than from the melanotic tissues. The amount of timolol bound to iris-CB from albino and pigmented rabbits showed that the amount of timolol bound to these tissues diminished in the following order: black or gray greater than brown greater than albino. It was also found that the rate of timolol release decreased in the following order: albino greater than gray greater than brown or black. Our results demonstrate the binding of beta blocker to human, bovine and rabbit iris-CB and consequent slow release of timolol from these tissues.

Adrenergic beta-Antagonists↗
PubMed1992

Effects of D- and L-isomers of timolol on retinal and choroidal blood flow in ocular hypertensive rabbit eyes.

An ocular hypertensive rabbit eye model was used to study the effect of L- and D-timolol on retinal and choroidal blood flow. Ocular hypertension was induced artificially by raising the intraocular pressure to 40 mmHg which reduced the ocular blood flow to 1/3 that of the normal blood flow. The effects of L- and D-isomers of timolol on the ocular blood flow of ocular hypertensive eyes were then determined using the colored microspheres technique over a range of 0-180 min after eyedrop instillation. It was found that L-timolol produced biphasic action on the blood flow in the iris, ciliary body and choroid by significantly reducing it initially at 30 min, then markedly increasing it later at 90 min and thereafter. Although L-timolol produced a tendency to reduce the blood flow in the retina, it was not statistically significant. At 90 min and thereafter, the blood flow in all ocular tissues was markedly increased by L-timolol. D-timolol did not reduce the blood flow of ocular tissues initially. There was a tendency to increase the blood flow in all ocular tissues from the very beginning by D-timolol. The increase of blood flow became significant at 90 min and thereafter, up to 3 hrs. D-timolol was less potent than L-timolol in increasing the blood flow in ocular tissues.

Animals↗
PubMed2000

Long-term topical timolol and blood lipids: the Blue Mountains Eye Study.

OBJECTIVES: To examine whether an association exists between long-term use of topical timolol and blood lipids, including high-density lipoprotein cholesterol (HDL-C), cholesterol, and triglycerides, among participants of the Blue Mountains Eye Study. METHODS: From 1992 through 1994, a detailed medical and eye examination was performed in 3,654 people aged 49 years or older, representing 82% of permanent residents in two postcode areas west of Sydney. Glaucoma and ocular hypertension were diagnosed, and an ophthalmic history was taken, including use of topical timolol. Fasting blood tests were performed in 89% of subjects. Lipid levels were compared in subjects using topical timolol for at least 1 year with those not using timolol, after excluding people using oral beta-blockers, topical beta1-selective agents, or oral lipid-lowering medications. RESULTS: Analyses compared blood lipids of 63 people who had used topical timolol for at least 1 year with 2,597 nonusers. No statistically significant differences were found in any blood lipid mean levels between treated and untreated people, after multivariate adjustment. However, subgroup analyses of men and women separately showed that male timolol users had a mean value of HDL-C 0.13 mmol/L (11%) lower then the mean value of male nonusers, while female timolol users had a mean value of HDL-C 0.09 mmol/L (5%) higher than the mean for female nonusers. There were no statistically significant associations between timolol treatment duration and HDL-C or other lipid levels. Previously reported adverse effects of oral beta-blockers on blood lipid levels were confirmed. CONCLUSIONS: These population-based data suggest that long-term administration of topical timolol for glaucoma or ocular hypertension can cause adverse effects on HDL-C in men, but not in women. The magnitude of the effect in men was similar to that previously described in a number of short-term studies.

Adrenergic beta-Antagonists↗
PubMed2001

Effect of timolol 0.5% gel and solution on pulmonary function in older glaucoma patients.

PURPOSE: To evaluate the effect of timolol maleate solution or gel forming solution versus placebo on pulmonary function in patients with primary open-angle glaucoma or ocular hypertension without reactive airway disease. METHODS: After a screening visit, each patient was randomized by a Latin square technique to receive placebo twice daily, 0.5% timolol solution twice daily, or 0.5% timolol gel once a day (placebo given as second dose) to each eye for 2 weeks. Subjects then were crossed over to the two other treatments for 2-week treatment intervals. At each visit, patients were received a dose 15 minutes before pulmonary function testing. RESULTS: This study began with 25 patients, and 20 finished the trial. There was no difference between treatment groups for the forced expiratory volume at one second (FEV1), forced vital capacity (FVC), FEV1/FVC ratio (P > 0.1). The mean FEV1 for timolol solution, timolol gel, and placebo was 2.42 L, 2.45 L, and 2.50 L, respectively. The mean FVC for timolol solution, timolol gel, and placebo was 3.33 L, 3.38 L, and 3.44 L, respectively. No difference in intraocular pressure was observed between the timolol solution (17.1 +/- 3.3 mm Hg) and timolol gel (17.1 +/- 3.6 mm Hg) between the treatment periods (P > 0.1). No difference in side effects was observed between treatment groups (P > 0.05). CONCLUSIONS: In older patients with primary open-angle glaucoma or ocular hypertension without reactive airway disease, nonselective beta-blockers should not worsen pulmonary function.

Adrenergic beta-Antagonists↗
PubMed1985

Bronchial beta-adrenoceptor blockade following eyedrops of timolol and its isomer L-714,465 in normal subjects.

The R-enantiomer of timolol, L-714,465, is considerably less potent as a beta 1- and beta 2-adrenoceptor antagonist in animals than timolol, whilst only slightly less potent in reducing intraocular pressure. If the same was true in man L-714,465 would have potential benefits over timolol in the treatment of glaucoma. The extent of bronchial beta-adrenoceptor blockade following one eyedrop in each eye of timolol 1% and L-714,465 1% was compared in six normal subjects, by measuring the displacement of the bronchodilator dose-response curve to isoprenaline following each drug compared to the isoprenaline dose-response curve after placebo eyedrops (methyl-cellulose). There was no significant difference between the dose-response curves to L-714,465 and placebo, but a significant displacement of the dose-response curve following timolol. The geometric mean dose ratio following timolol (21) differed significantly from that following L-714,465 (1.6). Heart rate at the end of the isoprenaline dose-response study was lower after timolol, despite the fact that subjects had received higher doses of isoprenaline. The trend was in the same direction after L-714,465 when compared with placebo though less marked. L-714,465 clearly causes less beta-adrenoceptor blockade than timolol when given as 1% eyedrops. The effects of L-714,465 1% on the airways and heart rate did not differ significantly from placebo in these six subjects but the pattern of response would be most consistent with L-714,465 having some beta-adrenoceptor blocking activity though considerably less than timolol.

Adrenergic beta-Antagonists↗
PubMed1987

Comparison of the airway response to eye drops of timolol and its isomer L-714,465 in asthmatic subjects.

1. The inadvertent administration of timolol to asthmatic patients continues to cause occasional severe and even fatal attacks of asthma. The (R)-enantiomer of timolol, L-714,465, is four times less potent than timolol in reducing intraocular pressure in man. It is 49 times less potent than timolol on beta 2-adrenoceptors in animals and 13 times less potent on the airways of normal subjects. These findings suggested that L-714,465 might be a safer alternative for the treatment of glaucoma. 2. Ten subjects with mild asthma who bronchoconstricted to timolol eye drops (0.25 or 0.5%) were studied. Airway dose-response curves to timolol (0-2%), L-714,465 (0-4%), and placebo (methyl cellulose) eye drops were performed in a double-blind randomised study in which airway response was measured as change in FEV1 and specific airway conductance (sGaw). 3. L-714,465 and timolol caused dose dependent falls in sGaw and FEV1 with L-714,465 being approximately four times less potent than timolol. The geometric mean dose ratio was 3.89 for FEV1 (95% confidence interval (CI) 1.7-8.7) and 3.93 (95% CI 2-7.8) for sGaw. Since the difference in potency is similar to the reported difference in potency of the two drugs on intraocular pressure we conclude that L-714,465 would not have a greater safety margin than timolol. 4. After completion of the dose-response study eight subjects inhaled ipratropium bromide (72 micrograms) and this caused an increase in FEV1 from 74% to 80% of baseline.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2004

Optic nerve oxygen tension: the effects of timolol and dorzolamide.

BACKGROUND/AIMS: The authors have previously reported that carbonic anhydrase inhibitors such as acetazolamide and dorzolamide raise optic nerve oxygen tension (ONPO(2)) in pigs. The purpose of the present study was to investigate whether timolol, which belongs to another group of glaucoma drugs called beta blockers, has a similar effect. In addition, the effect of dorzolamide and timolol in combination was studied. METHODS: Polarographic oxygen electrodes were placed transvitreally over the optic disc in anaesthetised pigs and ONPO(2) was recorded continually. Drugs were administered intravenously either as 100 mg timolol followed by 500 mg dorzolamide (n = 5), 500 mg dorzolamide followed by 100 mg timolol (n = 5), or 100 mg timolol and 500 mg dorzolamide given simultaneously (n = 5). Arterial blood pressure, blood gasses, and heart rate were recorded. RESULTS: ONPO(2) was unaffected by administration of 100 mg timolol as an intravenous injection (n = 5). Administration of 500 mg dorzolamide by itself significantly increased ONPO(2) from 2.96 (SD 0.62) kPa to 3.69 (SD 0.88) kPa (n = 4, p = 0.035). The dorzolamide induced ONPO(2) increase was not significantly different from the ONPO(2) increases were seen when dorzolamide was administered simultaneous with (n = 5) or 35 minutes (n = 5) after 100 mg timolol. CONCLUSION: Systemic administration of timolol does not affect the optic nerve oxygen tension despite its lowering effect on the intraocular pressure. Additionally, timolol does not affect the ONPO(2) increasing effect of dorzolamide.

Adrenergic beta-Antagonists↗
PubMed2005

Effect of dorzolamide and timolol on ocular blood flow in patients with primary open angle glaucoma and ocular hypertension.

BACKGROUND: There is evidence that perfusion abnormalities of the optic nerve head are involved in the pathogenesis of glaucoma. There is therefore considerable interest in the effects of topical antiglaucoma drugs on ocular blood flow. A study was undertaken to compare the ocular haemodynamic effects of dorzolamide and timolol in patients with primary open angle glaucoma (POAG) or ocular hypertension (OHT). METHODS: One hundred and forty patients with POAG or OHT were included in a controlled, randomised, double blind study in two parallel groups; 70 were randomised to receive timolol and 70 to receive dorzolamide for a period of 6 months. Subjects whose intraocular pressure (IOP) did not respond to either of the two drugs were switched to the alternative treatment after 2 weeks. Scanning laser Doppler flowmetry was used to measure blood flow in the temporal neuroretinal rim and the cup of the optic nerve head. Pulsatile choroidal blood flow was assessed using laser interferometric measurement of fundus pulsation amplitude. RESULTS: Five patients did not respond to timolol and were changed to the dorzolamide group, and 18 patients changed from dorzolamide treatment to timolol. The effects of both drugs on IOP and ocular perfusion pressure were comparable. Dorzolamide, but not timolol, increased blood flow in the temporal neuroretinal rim (8.5 (1.6)%, p<0.001 versus timolol) and the cup of the optic nerve head (13.5 (2.5)%, p<0.001 versus timolol), and fundus pulsation amplitude (8.9 (1.3)%, p<0.001 versus timolol). CONCLUSIONS: This study indicates augmented blood flow in the optic nerve head and choroid after 6 months of treatment with dorzolamide, but not with timolol. It remains to be established whether this effect can help to reduce visual field loss in patients with glaucoma.

Aged↗
PubMed1995

Effect of timolol with and without preservative on the basal tear turnover in glaucoma.

AIMS: The purpose of this study was to assess whether the preservative benzalkonium chloride (BAC 0.01%) present in timolol induced a decrease in basal tear turnover and a deterioration of precorneal tear film in patients with glaucoma and ocular hypertension using topical timolol. METHODS: The basal tear turnover of 20 patients with open angle glaucoma or ocular hypertension was measured by computerised objective fluorophotometry when using topical timolol preserved with BAC and 2 weeks after changing to topical timolol containing no preservative. Evaluation of the precorneal tear film was done by measuring the break up time (BUT) before and 2 weeks after changing medication. RESULTS: The tear turnover of the patients before the change was 32% lower than that of healthy controls (mean tear turnover values (SD) (%/min): 10.7 (3.0) and 15.6 (5.4), respectively, p < 0.0001). A mean increase of 28% (47%) in the individual tear turnover values was found after the change to the preservative-free timolol (p = 0.04). The BUT values before the change of medication did not differ significantly from those after the change (p = 0.5) but both values were significantly lower than the values of healthy controls (p = 0.009 and p = 0.003, respectively). CONCLUSION: Preservative-free timolol solution has a favourable effect on the tear turnover of patients with glaucoma and ocular hypertension in comparison with timolol containing BAC. The integrity of the precorneal tear film persisted to be affected when using timolol without BAC. Timolol without preservative can be recommended in those patients who have keratoconjunctivitis sicca or a borderline tear production since BAC may exacerbate a dry eye state.

Benzalkonium Compounds↗