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PubMed1983

Stimulation of calcium pump activity in heart sarcolemma by timolol.

The effects of beta-adrenergic blocking agents, timolol and atenolol (1-1000 microM), were studied on rat heart sarcolemmal ATPase and Ca2+ binding activities. Timolol, unlike atenolol, increased both Ca2+-stimulated ATPase and ATP-dependent Ca2+ binding; the maximal effects were seen at 1 microM concentration of timolol. Both timolol and atenolol did not alter the sarcolemmal Mg2+ ATPase and nonspecific Ca2+ binding activities. Sarcolemmal Ca2+-stimulated ATPase was also activated by concanavalin A (6-66 micrograms/mL) which is known to alter membrane fluidity; however, Mg2+ ATPase was unaffected by this agent. These results indicate that timolol may stimulate Ca2+ pump activity in heart sarcolemma by changing membrane fluidity in a manner similar to that of concanavalin A.

Animals↗
PubMed1999

A comparison of the intraocular pressure-lowering effect of 0.5% timolol maleate and the docosanoid derivative of a PGF2 alpha metabolite, 0.12% unoprostone, in subjects with chronic open-angle glaucoma or ocular hypertension.

The efficacy of 0.5% timolol was compared with that of the prostaglandin derivative unoprostone in maintaining control of intraocular pressure (IOP) in subjects with chronic open angle glaucoma (COAG) or ocular hypertension (OH) already responding satisfactorily to beta-blocker monotherapy. In a two-centre, double-masked, randomised parallel group study, 40 subjects were placed on 0.5% timolol eyedrops twice daily for two weeks. They were then randomised either to continue with 0.5% timolol or to switch to 0.12% unoprostone, applied twice daily for six weeks. IOP was measured at two-weekly intervals. The status of the conjunctiva, iris, cornea and anterior chamber was kept under observation. Ocular safety was monitored by measurements of visual acuity, and any systemic adverse events were recorded. After six weeks' treatment, there were no statistically significant differences in mean change from baseline IOP within or between treatment groups. For the subjects treated with unoprostone, mean IOP increased by 0.69 mm Hg (p = 0.368) while that of the timolol-treated subjects fell by 0.47 mm Hg (p = 0.287). The difference in mean IOP between groups was 1.16 mm Hg (p = 0.211, 95% confidence interval [CI] -0.69 to 3.02). The most common complaint was a mild and transient burning sensation on instillation which occurred more frequently in the unoprostone group. In conclusion, an aqueous solution of 0.12% unoprostone isopropyl, applied topically to the eye twice daily for six weeks, was as effective as 0.5% timolol in maintaining control of IOP in subjects with chronic open angle glaucoma or ocular hypertension. Both treatments were safe and well tolerated.

Adrenergic beta-Antagonists↗
PubMed1979

Comparison of effectiveness of timolol administered once a day and twice a day in the control of blood pressure in essential hypertension.

The effects of a single dose and of two equally divided doses of timolol were compared in a double-blind trial in 15 patients with essential hypertension. The amount of timolol per day remained constant for each patient, but individual patients received different amounts (from 10 mg to 30 mg/day). Timolol combined with a diuretic produced similar lowering of blood pressure in patients who required 10 mg, 20 mg or 30 mg of timolol per day when given either as one dose or in two equal doses. Plasma concentrations of timolol were high enough to be a major contributing factor to the long duration of the hypotensive response.

Adult↗
PubMedDate not supplied

Efficacy and side effects of latanoprost monotherapy compared to adding dorzolamide to timolol in patients with glaucoma and ocular hypertension--a three-month randomised study. Spanish Latanoprost Study Group.

PURPOSE: To compare the efficacy and safety of latanoprost monotherapy or dorzolamide and timolol in glaucoma patients inadequately controlled on adrenergic beta-receptor antagonist therapy. METHODS: A total of 164 patients with primary open-angle glaucoma, capsular glaucoma or ocular hypertension were included in a three-month, open-label, randomised multicentre study. Patients with open-angle glaucoma were required to have IOP at least 22 mmHg and patients with ocular hypertension were required to have IOP at least 27 mmHg, on treatment with one or two ocular hypotensive drugs of which at least one had to be a beta-blocker. All patients were treated with timolol, 5 mg/ml twice daily, for a 2-4 week run-in period. They were then randomised to latanoprost, 50 microg/ml once daily, or timolol 5 mg/ml plus dorzolamide, 20 mg/ml twice daily. The difference in mean diurnal IOP change from baseline to month 3 was compared in the two groups. RESULTS: When patients were switched to latanoprost, mean diurnal IOP was reduced by 5.2 mmHg (23%) compared to 4.0 mmHg (17%) in the group in which dorzolamide was added to timolol. The difference of 1.2 mmHg was statistically significant (p = 0.005). The majority of adverse events during both treatments were judged as mild. CONCLUSIONS: The results suggest that a switch to latanoprost monotherapy is an alternative to combined treatment with timolol and dorzolamide in patients inadequately controlled on a topical adrenergic beta-receptor antagonist alone.

Adrenergic beta-Antagonists↗
PubMed2002

[Study on hypotensive effect of latanoprost vs timolol-dorzolamide association].

PURPOSE: To compare hypotensive effect of latanoprost versus timolol-dorzolamide association on patients with glaucoma. MATERIAL AND METHOD: We studied 102 eyes in 52 patients with intraocular pressure (IOP) higher than 21 mmHg, previously treated with a betablocker. Patients were divided in two groups. Treatment was changed on group 1 (51 eyes in 27 patients) to a timolol-dorzolamide association. Group 2 (51 eyes in 27 patients) changed treatment to latanoprost. After determination of previous IOP, readings were taken at 1, 3 and 8 months later. RESULTS: Both groups showed a decrease in IOP levels: Group 1, 5.6 mmHg and Group 2, 8.5 mmHg. Association between timolol and dorzolamide reached the highest hypotensive effect after the first month of treatment and remained constant during the rest of the study period. Latanoprost showed a maximal effect after the third month of treatment and maintained its effect all through the study as well. Latanoprost behaved similar to associated timolol-dorzolamide not showing significant differences during the first month of treatment. Significant differences appeared at third and eighth month favoring latanoprost (p<0.005 and p<0.001 respectively). CONCLUSION: There was a similarity in efficacy of both treatments. However, after the third month latanoprost became more effective than the timolol-dorzolamide association.

Antihypertensive Agents↗
PubMed2002

Projected impact of travoprost versus both timolol and latanoprost on visual field deficit progression and costs among black glaucoma subjects.

PURPOSE: We compared differences associated with use of travoprost and latanoprost on both progression of perimetric loss over time and associated costs among black patients. METHODS: Patients with primary open-angle glaucome or ocular hypertension were randomly assigned to one of four arms in a 12-month, double-masked study: travoprost (0.004% or 0.0015%), latanoprost (0.005%), or timolol (0.5%). Forty-nine patients received 0.004% travoprost, 43 received latanoprost, and 40 received timolol. We applied algorithms found in published studies that link intraocular pressure (IOP) control to visual field progression and calculated the likelihood of visual field deterioration based on IOP data. This was used to estimate differences in medical care costs. RESULTS: The average IOP was lower for patients receiving travoprost than for patients receiving latanoprost or timolol (17.3 versus 18.7 versus 20.5 mm Hg respectively, P < .05). Travoprost-treated patients had a smaller predicted change in visual field defect score (VFDS) than latanoprost-treated patients and timolol-treated patients, and significantly fewer were expected to demonstrate visual field progression. Medical care costs would be higher for latanoprost-treated and timolol-treated patients. CONCLUSIONS: Recent studies have provided algorithms linking IOP control to changes in visual fields. We found that treatment with travoprost was associated with less visual field progression and potential cost savings.

Aged↗
PubMed2003

[Efficacy and safety of substituting a twice-daily regimen of timolol with a single daily instillation of nonpreserved beta-blocker in patients with chronic glaucoma or ocular hypertension].

AIM: To evaluate the efficacy and safety of a single daily instillation of nonpreserved timolol in patients with chronic glaucoma or ocular hypertension previously treated with a twice-daily regimen of timolol 0.25% or 0.50%. PATIENTS AND METHODS: A prospective open clinical trial was undertaken by 220 ophthalmologists in 435 patients with chronic glaucoma or ocular hypertension controlled with twice-daily instillations of timolol 0.25% or 0.50%. In this population, the previous regimen was substituted with a single daily instillation of preservative-free timolol 0.25% or 0.50% for 3 months. The changes in intraocular pressure (IOP) were recorded as well as local and systemic tolerance and patient compliance. RESULTS: It was found that 398 patients (93.6%) maintained stable IOP: in 92%, IOP increased no more than 2 mmHg. The mean IOP was 17.0 +/- 2.2 mmHg at D0, 16.5 +/- 2.4 mmHg at D28/42 and 16.6 +/- 2.4 mmHg at D84. The proportion of patients with at least one ocular symptom upon instillation or at another time decreased (p<0.0001 and p=0.03, respectively). The proportion of conjunctival hyperemia reduced from 24.4% to 14.6% (p=0.0002). The rate of folliculopapillar reactions and superficial punctate keratitis was halved (p=0.005 and p=0.02, respectively). CONCLUSION: During this study in daily practice, the switch from a twice-daily regimen of timolol to a once-daily application maintained stable intraocular pressure with a notable improvement in tolerance.

Adrenergic beta-Antagonists↗
PubMed1992

The efficacy of hydrochlorothiazide, timolol and enalapril in Ethiopians with essential hypertension.

A double-blind trial of hydrochlorothiazide, timolol and enalapril was carried out in Ethiopians with essential hypertension at the Tikur Anbessa Hospital, Addis Abeba, between 1987 and 1990. Patients with a supine diastolic blood pleasure of 95-120 mmHg after a washout period of 2 weeks were randomized to receive hydrochlorothiazide 25 mg daily, timolol 10 mg daily or enalapril 10 mg daily. Doses were doubled at 4 weeks if the diastolic blood pressure remained above 95 mmHg. At the end of 8 weeks of treatment, there were 9 patients taking hydrochlorothiazide, 10 patients taking timolol and 7 patients taking enalapril. Hydrochlorothiazide significantly lowered both systolic and diastolic blood pressure at 4 and 8 weeks compared with pre-treatment levels. Timolol and enalapril did not significantly lower the systolic blood pressure, but each lowered the diastolic blood pressure at 4 weeks and 8 weeks respectively. More patients on hydrochlorothiazide attained a diastolic blood pressure of less than 90 mmHg while less patients required doubling of dosage compared to timolol and enalapril. It is concluded that Ethiopian hypertensives may respond better to diuretics than to beta-blockers or angiotensin converting enzyme inhibitors, as found in other black populations.

Adult↗
PubMed1992

[Topical timolol and blood-aqueous barrier permeability to protein in human eyes].

The effect of topical 0.5% timolol on the permeability of the blood-aqueous barrier to plasma protein was studied in ten young normal volunteers. Before and after instillation of timolol in one eye, simultaneous measurements of aqueous flow rate, f(t), by fluorophotometry and protein concentration in the anterior chamber, Ca(t), with a laser flare-cell meter were made in both eyes at hourly intervals. The coefficient of protein entry into the anterior chamber was calculated using an equation formulating protein dynamics in the anterior chamber from the changes in f(t), Ca(t), and plasma protein concentration. The Ca(t) in the treated eye showed a maximum increase of 37 +/- 4% (mean +/- SEM) as compared with that in the fellow eye 5 hours after instillation, while the f(t) in the treated eye showed a maximum reduction of 30 +/- 4% 2 hours after instillation. The intraocular pressure in the treated eye showed a maximum reduction of 3.0 +/- 0.3 mmHg 2 hours after instillation. No significant changes were found in the coefficient of protein entry in the anterior chamber between before and after timolol instillation or between timolol-treated and fellow untreated eyes. These results indicated that topical 0.5% timolol does not affect the permeability of the blood-aqueous barrier to plasma protein significantly.

Administration, Topical↗
PubMed2004

[Short and long-term hypotensive effect of timolol-gel and latanoprost instillation in normal-tension glaucoma].

PURPOSE: To confirm the predictive value of the results of a 4-week trial of latanoprost alone, timolol-gel alone, or a combination of the two in normal-tension glaucoma (NTG) patients, when compared with the hypotensive response after a 6-month trial using the same combination of eye drops for the same patients. METHODS: One eye each of 45 NTG patients was used in a prospective 4-week trial of latanoprost alone, timolol-gel alone, or a combination of the two. Patients continued using the eye drops for 6 months, according to the results of the trial. The correlation of the results of the 6-moth use and the baseline data, and the baseline data and the results of the 4-week trial were evaluated by the paired-t test. RESULTS: The intraocular pressure(IOP)s of patients using timolol-gel alone were 13.9 mmHg at the base line, 9.7 mmHg after the trial, and 12.0 mmHg after 6-month use(baseline, trial: p < 0.05). IOPs when using latanoprost alone were 15.3 mmHg at baseline, 11.7 mmHg after the trial, and 11.5 mmHg after 6-month use(baseline: p < 0.05, trial: p = 0.33). IOPs using timolol-gel and latanoprost in combination were 14.8 mmHg at baseline, 11.4 mmHg after the trial, and 12.0 mmHg after 6-month use (baseline: p < 0:05, trial: p = 0.14). CONCLUSION: The result of the 4-weeks trial of latanoprost alone or in combination with timolol-gel can be indicative of the IOP after 6-month use.

Adult↗
PubMed1978

[Results of a double-blind medium-term study comparing effects of timolol maleate and epinephrine in 120 patients with chronic open-angle glaucoma].

A double-blind medium term study of the activity of timolol in chronic open-angle glaucoma was conducted in four French ophthalmological centers, using the same protocol. A total of 119 patients were treated: --60 with timolol; --59 with épinéphrine, for comparison. Results showed a significantly superior efficacy for timolol over épinéphrine, after in weeks of treatment. Good tonometric control was obtained in 81.6% of the patients treated with timolol, against 52.5% of those receiving épinéphrine. In 68% of the glaucomatons patients treated with timolol, good tonometric control was obtained with the lowest dose preparation containing 0.1%. No side-effects were noted during the study, either locally or generally (particularly blood pressure changes).

Chronic Disease↗
PubMed2005

Polymorphism of the beta-2 adrenoceptor and IOP lowering potency of topical timolol in healthy subjects.

PURPOSE: Beta-2 adrenoceptor antagonists such as timolol have been used in the treatment of glaucoma for more than 30 years. Several functionally important polymorphisms for the beta-2 receptor have been described. In the present study we hypothesized that a relation between the intraocular pressure (IOP) lowering effect of timolol and beta-2 adrenoceptor polymorphisms may exist. METHODS: A total of 270 healthy nonsmoking subjects were screened and individuals homozygous for the wild beta-2 Adrenoceptor (Arg16/Gln27) and two polymorphisms (Gly16/Gln27 or Gly16/Glu27) were included. In these subjects the IOP lowering effect of timolol was compared. RESULTS: Twenty-four subjects were included in the group Arg16/Gln27, 18 subjects in the group Gly16/Gln27, and 47 subjects in the group Gly16/Glu27. The ocular hypotensive effect of timolol was between 40 and 45% in all groups, but not significantly different between the three study groups (p=0.979). CONCLUSIONS: The present study indicates that the beta-2 adrenoceptor polymorphism does not influence the ocular hypotensive effects of topical beta adrenoceptor antagonists. Accordingly, other factors appear to be responsible for the intersubject variability seen with timolol in glaucoma subjects.

Administration, Topical↗
PubMed1991

[Influence of topical administration of diclofenac on the reduction of intraocular pressure induced by timolol in healthy subjects].

The presence or absence of an interaction between topical diclofenac (nonsteroidal antiinflammatory agent) and topical timolol (beta-blocker) was studied in 37 eyes. We instilled one drop of diclofenac several times into the patient's right eye and one drop of timolol into the same eye. We measured intraocular pressure in both eyes twice and compared the results in both eyes with the baseline intraocular pressure and with the pressure after administration of diclofenac alone and timolol alone. The joint use of both drugs did not modify the decrease in the ocular pressure induced by timolol. We can therefore use timolol and diclofenac together when a combination of antiinflammatory and beta-blocker agents is required.

Administration, Topical↗
PubMed1990

Transdermal timolol: beta blockade and plasma concentrations after application for 48 hours and 7 days.

An effective and well-tolerated transdermal beta-adrenergic blocker that could be applied once weekly would facilitate compliance. The pharmacokinetics and pharmacodynamics of a once-weekly formulation of transdermal timolol, a beta-blocker, were evaluated in healthy males. One (n = 6), two (n = 5), and three (n = 5) patches (97.5 mg base/12.58 cm2 patch) were applied at weekly intervals to the subjects' inner arm for 48 hours (part A) and two patches were applied for 7 days (part B). In part A, mean exercise (bicycle ergometry) heart rate (beats/min, bpm) was suppressed from baseline at 48 hours after the patch (p less than 0.05) in each case (1 patch 167 vs 131 bpm; 2 patches 165 vs 120 bpm; 3 patches 159 vs 120 bpm). Mean plasma timolol concentrations at 48 hours after the patch for one, two, and three patches were 5, 11, and 14 ng/ml, respectively. For part B, mean exercise heart rate at baseline, 24, and 168 hours was 161, 113, and 130 bpm (p less than 0.05), and mean plasma timolol concentrations at these times were 0, 23, and 4 ng/ml. The relationship between suppression of exercise heart rate and plasma timolol concentrations within subjects was well described by an inhibitory EMAX model, where EMAX ranged from a suppression of 42-65 bpm associated with a 50% inhibitory (IC50) concentration that ranged from 2-4 ng/ml. Transdermal timolol was associated with significant beta blockade for up to 7 days, and caused only minimal skin irritation.

Adult↗
PubMed1987

The effects of naloxone and timolol on plasma catecholamine levels during short-term dynamic exercise.

In order to study the role of opioid- and betareceptors on exercise-induced catecholamine responses, the effects of acute intravenous administration of 1 and 4 mg naloxone and of the non-selective betablocker timolol 2 mg of on circulating concentrations of adrenalin, noradrenaline and dopamine during exercise to exhaustion were examined in eight normal, healthy young men, using a double-blind, randomized, placebo-controlled design. During maximal exercise, adrenalin levels increased from 71 +/- 17 to 821 +/- 235 pg/ml (p less than 0.05), noradrenaline from 355 +/- 58 to 4235 +/- 1031 pg/ml (p less than 0.05), and dopamine from 72 +/- 20 to 178 +/- 44 pg/ml (p less than 0.05). Naloxone did not influence basal or exercise-induced noradrenaline responses. Timolol clearly augmented peak adrenalin concentration at maximal exercise capacity (1543 +/- 510 pg/ml, p less than 0.05). Basal noradrenaline level was increased (546 +/- 86 pg/ml, p less than 0.05), while exercise-induced noradrenaline level was reduced (2954 +/- 594 pg/ml, p less than 0.05) in proportion to the reduction in maximal exercise capacity during timolol treatment. Neither naloxone nor timolol affected dopamine levels. No additive effect was seen with the combination of naloxone and timolol. It is concluded that the opioid peptides are probably not involved in noradrenaline and dopamine responses, whereas betablockers change the catecholamine response to short-term maximal exercise.

Adrenergic beta-Antagonists↗
PubMed1986

Effect of topical timolol on the human retinal circulation.

The effect of topical timolol maleate 0.5% on the retinal circulation was investigated in 14 normal subjects using laser Doppler velocimetry and monochromatic fundus photography. In a double masked, randomized design, one eye received two drops of timolol maleate 0.5% and the fellow eye received two drops of placebo. Vessel diameter, maximum velocity of red blood cells, and volumetric blood flow rate were determined in a major temporal vein of each eye just prior to the instillation of drops, and then 90 min later. In comparison to the baseline value, there was a significantly larger average percentage increase in maximum velocity of red blood cells and volumetric blood flow rate in the timolol-treated eyes (11.0% and 13.2%, respectively) than in the control eyes (2.2% and 1.5%, respectively, paired t-test, P less than 0.05). No significant change in venous diameter was detected. No significant linear correlations were found between the percentage change in maximum velocity of red blood cells and mean brachial artery blood pressure, and between the percentage change in volumetric blood flow rate and mean brachial artery pressure in the placebo-treated eyes, whereas significant correlations were present between these quantities in the timolol-treated eyes (P less than 0.01 and P less than 0.05, respectively). The lack of such correlations in the control eyes is probably due to autoregulation of the retinal circulation. The presence of correlations in the timolol-treated eyes suggests that the drug may affect the capacity of the retina to autoregulate.

Administration, Topical↗
PubMed1988

[Modification in amplitude of nycthemeral changes in intraocular pressure under timolol].

Diurnal variations of intraocular pressure are probably related to indolamines, prostaglandins, and the sensory nervous system. Because timolol maleate is able to block beta-1, beta-2, and dopaminergic receptors, as well as to act like an antagonist of serotonin, we evaluated its effect on diurnal variations of intraocular pressure. Eighty-eight intraocular pressure curves were established in 22 normal young volunteers. Intraocular pressures were measured in both eyes before and one week after the beginning of monolateral treatment with timolol 0.5% twice daily. The results showed a decrease in amplitude of diurnal variations of 24% (P = 0.07 in paired t-test) in timolol-treated eyes and no significant change in the contralateral eyes. The difference between both eyes was statistically significant in paired t-test (P = 0.01). Knowing the type of receptors on which timolol is susceptible to act, and furthermore, the type of neuro-transmitter which may be involved in the regulatory mechanisms of diurnal variations of intraocular pressure, we suggest that timolol could reduce the amplitude of these variations by means of interactions with indolamines.

Adult↗
PubMed1988

Aqueous humor flow measured with fluorophotometry in timolol-treated primates.

Anterior chamber aqueous humor flow rate was measured in unanesthetized owl monkeys using fluorophotometry and anterior chamber photogrammetry. The mean anterior chamber turnover constant (ko) was 0.01, the mean aqueous humor flow rate was 2.75 microliters min-1, and the mean anterior chamber volume was 317 microliters in 16 eyes of eight monkeys. A significantly lower (11%, P less than 0.002) flow rate was measured in the afternoon compared to flow rates measured in the morning. This diurnal cycle is analogous to the fluctuations in flow in humans and supports the hypothesis that aqueous humor formation in primates is regulated by endogenous mechanisms. To investigate the role of adrenergic mechanisms in regulating flow, the dose-response effect of topical timolol (0.5-100 micrograms) was measured. Five microliters drops were used to minimize systemic absorption. Lower concentrations (0.01% and 0.05%) caused sporadic changes in flow. Topical 0.1% timolol (5 micrograms) significantly decreased aqueous humor flow in the treated eye compared to baseline flow while flow in the contralateral eye was not significantly different from baseline flow. Higher concentrations of timolol (0.5% and 1%) caused a dose-related bilateral decrease in flow. These results indicate that even with small topical volumes systemic absorption of the higher concentrations of timolol occurs. Significant local inhibition of flow occurred following 5 micrograms of topical timolol whereas an equal bilateral decrease in flow occurred following a 100 microgram dose. These results suggest that the standard clinical dose (approximately equal to 100 micrograms) is supramaximal for decreasing aqueous flow.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Topical↗