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Discoidal niosome based controlled ocular delivery of timolol maleate.

Non-ionic surface active agents based discoidal vesicles (discomes) bearing timolol maleate were prepared. Niosomes were incorporated with Solulan C24 in order to effect vesicle to discome transition. The discomes were relatively large in size, 12-60 microm. They were found to entrap a relatively high quantity of timolol maleate. The prepared system characterized for size, shape and drug release profile in vitro. They were found to release the contents following biphasic profile particularly in the case where the drug was loaded using a pH gradient technique. The prepared system could produce or sustain a suitable activity profile upon administration into the ocular cavity; however, systemic absorption was minimized to a negliable level. The discomes were found to be promising and of potential for controlled ocular administration of water-soluble drugs.

Administration, Topical↗

Two-year safety study of dorzolamide as monotherapy and with timolol and pilocarpine. Dorzolamide Safety Study Group.

PURPOSE: To evaluate the safety of open-label 2.0% dorzolamide as monotherapy and when used with timolol and/or pilocarpine for as long as 2 years. METHODS: The safety of dorzolamide was evaluated in patients with open-angle glaucoma or ocular hypertension over a 2-year period. The incidence of the most common drug-related adverse experiences in the first year was compared with that in the second year using McNemar's test. The ocular hypotensive effect of dorzolamide as monotherapy and with adjunctive therapy was assessed using percent change in intraocular pressure (IOP) from baseline. RESULTS: Of the 304 patients enrolled, 164 (53.9%) continued to receive dorzolamide as monotherapy for 2 years and 140 (46.1%) required add-on therapy. Add-on therapy was initiated by month 6 in 112 of these 140 patients (80%). Of the 304 patients, 202 (66.4%) completed 2 years of therapy. Of the patients who received dorzolamide as monotherapy, drug-related adverse events occurred more frequently during the first year (29.7%) than the second year (13.8%), and the most common ocular drug-related adverse events included conjunctivitis, burning/stinging eye, follicular conjunctivitis, and eyelid edema. After 2 years of therapy, the mean percent decrease in peak IOP was 22.8% for patients receiving dorzolamide monotherapy and 31.2% to 36.0% for patients receiving add-on therapy. CONCLUSION: Dorzolamide was generally well tolerated for up to 2 years as monotherapy and when used with timolol and/or pilocarpine. Drug-related adverse events were less frequent during the second year of monotherapy than during the first year. Most patients who required add-on therapy did so within the first 6 months of initiating dorzolamide therapy.

Adult↗

Betaxolol and timolol. A comparison of efficacy and side effects.

Betaxolol hydrochloride, 0.5%, and timolol maleate, 0.5%, were compared in a 26-week randomized, double-masked study involving 46 patients with primary open-angle glaucoma. The two drugs were comparable with regard to both intraocular pressure-lowering efficacy and side effects. Since betaxolol is a selective beta 1-adrenergic antagonist, it may be advantageous for patients in whom beta 2-blockade could be harmful.

Aged↗

Bronchial and cardiovascular effects of ocular topical B-antagonists in asthmatic subjects: comparison of timolol, carteolol, and metipranolol.

B antagonists eye drops are most effective for the treatment of chronic open angle glaucoma. By this way of administration they have a very good systemic bioavailability. Bronchial, and cardiovascular effects of three of these topicals: timolol, carteolol and metipranolol have been evaluated in three parallel groups of asthmatic patients. The three topics induce bronchoconstriction without significant difference between them, and lower heart rate (sometimes very intensely) whatever the B antagonist studied. From these data, it is recommended to practitioners to follow carefully the rules of administration of B blockers, even in eye drops.

Adrenergic beta-Antagonists↗

Delivery of timolol through artificial membranes and pig stratum corneum.

The in vitro passive and iontophoretic (applied current density: 0.5 mA/cm(2)) timolol (TM) permeability from a liquid solution through pig stratum corneum (SC) is found to be 0.9 +/- 0.5 x 10(-6) and 3.9 +/- 0.9 x 10(-6) cm/s, respectively. The in vitro iontophoretic TM delivery through the combination of artificial porous membranes with pig SC is investigated as well. When the meso-porous PES-30 membrane is applied, the SC mainly controls the TM delivery. When the microporous NF-PES-10 membrane is applied, both the membrane and the SC contribute to controlling the delivery of TM. When the microporous LFC 1 membrane is applied, the TM delivery is membrane controlled. In all cases, however, the efficiency of the TM delivery is low and would need to be improved for the development of a commercially viable product.

Administration, Cutaneous↗

Application of substrate depletion assay for early prediction of nonlinear pharmacokinetics in drug discovery: assessment of nonlinearity of metoprolol, timolol, and propranolol.

The purpose of this study was to investigate the advantages of the substrate depletion assay for evaluating linearity of pharmacokinetics compared with the metabolite formation assay. For propranolol, metoprolol, and nisoldipine with multiple and/or sequential metabolisms, the Michaelis constant (Km) and maximum metabolic intrinsic clearance obtained from the depletion assay using rat and human liver microsomes showed a good correlation with relevant parameters with the formation assay. In vitro kinetics and in vivo pharmacokinetic profiles after oral administration of timolol, metoprolol, and propranolol, were investigated in rats using the depletion assay. The same rank order was found between nonlinearities based on dose-normalized areas under the plasma concentration curve (AUC/Dose) and Km values. Using the kinetic parameters of these compounds, AUC was predicted based on a physiological based pharmacokinetic model incorporated saturable metabolism. The AUCs predicted for propranolol and metoprolol had a good relationship with those observed in the in vivo studies, implying that the depletion assay could be useful for assessing linearity of pharmacokinetics.

Adrenergic beta-Antagonists↗

A novel differentiation method of vehicle models for topically applied drugs: application to a therapeutic timolol patch.

A novel method to differentiate basic vehicle models for topically applied drugs is proposed. In this method, the rate of drug release as a function of time, obtained by using a flow-through cell, is plotted on both semilogarithmic and logarithmic scales. In the Solution Case, where all of the drug is dissolved in the vehicle, the profiles become linear on the semilogarithmic scale. However, in the Suspension Case, where the initial drug amount per vehicle volume is greater than the solubility of the drug and the vehicle contains finely dispersed drug, the profiles are linear on the logarithmic scale with a slope of -0.5. They abruptly depart from this pattern upon depletion of the suspended phase. The different attributes of the profiles for the drug release rate-time curves in these two cases can be visualized more clearly when vehicle thickness and drug concentration are varied. The theoretical principles are illustrated in profiles for the drug release-rate time plots of therapeutic patches containing the beta blocker timolol. This was formulated at different concentrations in an acryl copolymer with varied thickness. The release profiles were best fitted to the Solution Case treatment of the data.

Administration, Topical↗

Timolol and intra-ocular pressure elevation following neodymium: YAG laser surgery.

The intra-ocular pressure in 76 patients, undergoing Neodymium: YAG laser surgery was measured just before treatment, and one and two hours afterwards. The fellow eye served as a control. Serious elevation of the intra-ocular pressure was demonstrated, especially in capsulotomy in the aphakic eye, to a lesser extent in pseudophakic eyes. Intra-ocular pressure elevation of more than 20 mm was seen in iridectomies. Timolol 1/2% eyedrops given before Neodymium: YAG laser treatment minimized the elevation of the intra-ocular pressure. Prolonged follow-up of the intra-ocular pressure is recommended.

Aphakia, Postcataract↗

Effect of timolol on the amplitude and dynamics of accommodation.

There is still debate about whether the ciliary muscle is innervated by the sympathetic nervous system. We investigated the amplitude and the dynamics of accommodation under influence of the non-selective beta-blocker timolol. For this purpose the variations in thickness of the human lens during step-like changes in accommodation were measured with high-resolution A-scan echography. Results showed that the dynamics of accommodation, expressed in the time constants of the response, were affected as well as the amplitude.

Accommodation, Ocular↗

A 3-month comparison of 1% and 2% carteolol and 0.5% timolol in open-angle glaucoma.

Carteolol, a nonselective beta-adrenergic antagonist with intrinsic sympathomimetic activity, was compared in 1% and 2% topical solutions with 0.5% timolol in 105 patients with primary open-angle glaucoma. In this double-masked, randomized 3-month trial, all three preparations significantly lowered intraocular pressure throughout the study, with no significant differences being observed. There were also no significant differences among the three preparations with regard to ocular or systemic adverse reactions, including heart rate and blood pressure.

Administration, Topical↗

Pressure lowering effect of timolol with reference to its topical vascular action.

The hemodynamic effect of timolol maleate in open angle glaucoma was studied rheo-oculographically. Increase in the ocular pulse which reaches maximal amplification 2 h after the instillation of the drug was observed. The maximal pressure lowering effect appeared 3 h after instillation, as if the hemodynamic effect were the trigger for the pressure lowering effect.

Administration, Topical↗

Timolol and bendrofluazide in the management of hypertension in general practice.

The beta-adrenergic blocking drug, timolol, was combined with bendrofluazide in a comparative trial between once and twice daily dosage, conducted on 51 patients suffering from hypertension seen in general practice. During the initial control period seven of these patients became normotensive, leaving 44 who entered the trial. Using a crossover design, treatment was continued for a total period of up to 16 weeks. With both dose regimes, systolic and diastolic pressures were rendered normotensive in over three-quarters of the patients, significant reductions occurring within the first two to four weeks of treatment.

Bendroflumethiazide↗

Effects of timolol on visual-field mean retinal sensitivity in normal subjects.

This single-blind, randomized study investigated the effects of unilateral instillation of 0.5% maleate timolol twice a day for 7 days on visual-field parameters of both eyes. Twelve normal, young subjects (30.6 +/- 4.2 years) participated in this study. Using program G1 of the Octopus 500 automated perimeter, the visual fields were measured one week and one day before therapy and a third time one week after beginning therapy. The paired T-test was used for statistical analysis, where a P-value < or = 0.05 indicated significance. Whereas nothing statistically significant was found in the treated eyes, the contralateral, untreated eyes showed a statistically significant decrease of mean sensitivity between the first visual fields and the third ones (P < 0.01) This diminution of mean sensitivity in the untreated contralateral eyes may be due to statistically significant lowering of blood pressure (P < 0.01) and slowing of cardiac frequency, which were not compensated by a local decrease of intraocular pressure. If confirmed, these findings could be of clinical importance in the management of glaucoma patients, since some authors have, in some cases, recommended a unilateral therapy.

Adult↗

Ocular hypotensive effect of topical ketanserin in timolol users.

BACKGROUND: Ketanserin is a specific antagonist of 5-HT2 and 5-HT1c receptors. These receptors are linked to the stimulation of phosphoinositide metabolism and are involved in IOP controls. Orally and topically administered ketanserin reduces IOP in normotensive and glaucomatous eyes. METHODS: Ketanserin 0.5% eye drops were administered to 20 patients with primary open-angle glaucoma in a randomised, crossover, double-masked fashion to evaluate the effect of ketanserin in glaucomatous patients already receiving timolol who did not have controlled IOP (> 21 mmHg). Mean and range of IOP curve (8.00 a.m.-8.00 p.m.), pupil diameter, Schirmer I, basal secretion test and BUT values were recorded at baseline and after 2 weeks of topical administration of ketanserin or placebo twice daily. The alternative treatment was given 2 weeks later and the same protocol was repeated. RESULTS: When patients received placebo no significant variations were found in the analysed parameters. Ketanserin significantly reduced mean IOP (19.5%) and was effective for up to 12 h without inducing variations of tear secretion or pupil diameter. No systemic side effects were observed, and no significant variations in ocular symptoms and signs were reported. CONCLUSION: These results indicate that topical administration of ketanserin may be useful to reduce IOP in patients not controlled with beta-blockers.

Administration, Topical↗

Pharmacokinetics of intravenous timolol in patients with acute myocardial infarction and in healthy volunteers.

Disappearance pharmacokinetics, pharmacodynamics and general tolerance of i.v. timolol were compared in 12 healthy volunteers and 10 patients with a definite or proven acute myocardial infarction. The drug was administered to the patients immediately on arrival at the hospital after a median delay time of 4 h. Tolerance to the injections was good in both volunteers and patients. The study revealed disappearance pharmacokinetics that were similar in volunteers and patients.

Adult↗

Brimonidine Purite and bimatoprost compared with timolol and latanoprost in patients with glaucoma and ocular hypertension.

This 3-month multicenter, investigator-masked, parallel-group study compared brimonidine Purite and bimatoprost (brimP/bim) with timolol gel-forming solution and latanoprost (tim/latan) in 28 patients with open-angle glaucoma or ocular hypertension. IOP was measured at baseline and 2 hours after morning instillation at weeks 2, 4, and 12. The primary outcome measure was the mean IOP reduction from baseline. Secondary measures were the percentage of patients in each group who achieved specific low target pressures and the incidence of adverse events. Mean IOP at baseline was 24.8 mm Hg in each group. At follow-up visits, mean reductions from baseline ranged from 8.5 to 9.0 mm Hg with brimP/bim and from 7.5 to 7.7 mm Hg with tim/latan. More patients achieved low target pressures with brimP/bim. At week 12, 69.2% of brimP/bim patients and 27.3% of tim/latan patients had IOPs of 16 mm Hg or lower (P = .024). Both regimens were well tolerated, and adverse events were infrequent. The combination of brimonidine Purite and bimatoprost was well tolerated and at least as effective as Timoptic-XE and latanoprost in reducing IOP. More patients achieved low target IOPs with brimonidine Purite and bimatoprost than with Timoptic-XE and latanoprost. A larger study is needed to confirm these results.

Administration, Topical↗

A clinical evaluation of the effects of topically applied levobunolol and timolol on increased intraocular pressure.

Data from two short-term double-masked studies using 24 and 16 subjects suggest that topically applied levobunolol safely and effectively treats open-angle glaucoma and ocular hypertension. The onset of effect of a single drop of 0.5% levobunolol occurred within the first hour, producing a maximal hypotensive effect of more than 8 mm Hg after two hours. An intraocular pressure deceased of greater than or equal to 2 mm Hg was still observed after 24 hours for both concentrations of levobunolol tested (0.5% and 1%). Intraocular pressure decreases of more than 9 mm Hg persisted during a one-month trial in which patients were treated twice daily, confirming the results obtained in the 24-hour study. Systemic effects of both timolol (0.5%) and levobunolol (0.5% and 1%) included a consensual intraocular pressure-decreasing effect in the untreated eye and clinically significant reductions in heart rate. Diastolic blood pressure was decreased at two and four hours after administration of 0.5% levobunolol.

Administration, Topical↗

Bilateral effects of long-term monocular timolol therapy.

We studied the bilateral intraocular pressure lowering effect of long-term unilateral timolol maleate 0.5% in 30 patients in whom early primary open-angle glaucoma had recently been diagnosed. A significant intraocular pressure reduction was found in the untreated fellow eyes (21.9 mm Hg from 26.4 mm Hg at baseline) (P less than .001), as well as in the treated eyes (21.0 mm Hg from 28.5 mm Hg at baseline) (P less than .001). Fourteen patients (47%) showed a significant bilateral intraocular pressure reduction (P less than .001), with little difference between the treated (8.2 mm Hg) and the untreated eyes (7.7 mm Hg) (P greater than .8).

Adult↗