A comparison of the ocular hypotensive effect of 0.025% bromocriptine and 0.25% timolol eye drops in normal human volunteers

Natural Ergot Alkaloids in Ocular Pharmacotherapy: Known Molecules for Novel Nanoparticle-Based Delivery Systems

Several pharmacological properties are attributed to ergot alkaloids as a result of their antibacterial, antiproliferative, and antioxidant effects. Although known for their biomedical applications (e.g., for the treatment of glaucoma), most ergot alkaloids exhibit high toxicological risk and may even be lethal to humans and animals. Their pharmacological profile results from the structural similarity between lysergic acid-derived compounds and noradrenalin, dopamine, and serotonin neurotransmitters. To reduce their toxicological risk, while increasing their bioavailability, improved delivery systems were proposed. This review discusses the safety aspects of using ergot alkaloids in ocular pharmacology and proposes the development of lipid and polymeric nanoparticles for the topical administration of these drugs to enhance their therapeutic efficacy for the treatment of glaucoma.

Fluctuations of the Intraocular Pressure in One Eye Influence the Intraocular Pressure in the Fellow Eye

PURPOSE

To investigate the ophthalmotonic consensual reaction (OCR) in healthy individuals.

METHODS

This was a cohort study of 59 pairs of eyes of patients who underwent cataract surgery in one eye and had no other ocular pathology than cataract. Main outcome measure was change of intraocular pressure (IOP) in the untreated fellow eye. The IOP was measured 1 hour before, 1 hour after, and 1 day after surgery.

RESULTS

One hour after surgery, IOP decreased in 24 (41%) operated eyes (group A). In the corresponding untreated fellow eyes (group Af), the mean IOP (±standard deviation [SD]) did not change (14.1 ± 3.0 mmHg preoperatively to 14.2 ± 3.1 mmHg postoperatively, p = 0.8). Only two operated eyes showed unchanged IOP (group B). In 33 (56%) operated eyes, the IOP increased (group C). In the untreated fellow eyes (group Cf), the mean IOP decreased significantly from 15.1 ± 2.9 to 13.7 ± 2.6 mmHg (p = 0.0012). One day after surgery, the mean IOP of group Af decreased significantly from 14.2 ± 3.1 (postoperative IOP) to 12.7 ± 3.2 mmHg (p = 0.007). In group Cf, the mean IOP revealed no changes from 13.7 ± 2.6 to 13.5 ± 2.4 mmHg (p = 0.69).

CONCLUSIONS

Our results showed some evidence for the existence of the OCR in healthy individuals. Significant IOP elevation in one eye resulted in IOP reduction in the fellow eye. Interestingly, this phenomenon did not exist vice versa.

The effect of trabeculectomy on intraocular pressure of the untreated fellow eye in the collaborative initial glaucoma treatment study

PURPOSE

To describe the intraocular pressure (IOP) of the untreated fellow eye after unilateral trabeculectomy in the Collaborative Initial Glaucoma Treatment Study (CIGTS).

DESIGN

Data collected from a prospective, multicenter, randomized clinical trial.

PARTICIPANTS

Three hundred patients with newly diagnosed open-angle glaucoma enrolled at 14 centers in the United States who were randomized to initial trabeculectomy.

METHODS

After baseline evaluation and randomization to initial trabeculectomy in the study eye, patients were evaluated at 3 and 6 months and at 6-month intervals thereafter. The IOP was measured by Goldmann applanation tonometry. All eyes included in the analysis were untreated fellow eyes, and the data were censored for potential IOP-lowering events in the fellow eye, including trabeculectomy, argon laser trabeculoplasty, or cataract extraction. Predictive factors for IOP response in the fellow eye to initial trabeculectomy in the study eye were analyzed using a linear mixed model.

MAIN OUTCOME MEASURES

Intraocular pressure in the untreated fellow eye during follow-up.

RESULTS

Although the IOP in the fellow eye was lower than baseline at 3, 6, 12, 18, and 24 months after trabeculectomy in the study eye, this decrease was statistically significant only at month 12 (mean decrease from baseline, 0.73 ± 3.37 mmHg; P = 0.0134). Predictive associations with higher IOP in the fellow eye during follow-up included higher baseline IOP (P < 0.0001), lower level of education (P = 0.0129), time (P = 0.0005), and the presence of other vascular disease (P = 0.0069). Patients who ultimately required fellow eye trabeculectomy (P < 0.0001) or argon laser trabeculoplasty (P<0.0001), but not cataract extraction (P = 0.4597) in the fellow eye, had lower IOPs during follow-up after these procedures.

CONCLUSIONS

There was no evidence of a substantial effect of trabeculectomy on the IOP of the untreated fellow eye during follow-up. Trabeculectomy does not seem to decrease the mean IOP of the fellow eye, as suggested by some previous studies.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Contralateral effect of topical beta-adrenergic antagonists in initial one-eyed trials in the ocular hypertension treatment study

PURPOSE

To evaluate the magnitude of the contralateral effect of topically administered beta-blockers on intraocular pressure.

METHODS

The Ocular Hypertension Treatment Study enrolled 1,636 subjects. Of these, 817 subjects were randomized to receive topical ocular hypotensive medication and 819 subjects were randomized to close observation (i.e., no topical medication). We compared the intraocular pressure of the contralateral eye of subjects at the baseline visit and after an initial one-eyed therapeutic trial of topical beta-blockers. We examined differences between baseline and follow-up intraocular pressure in untreated eyes of subjects randomized to close observation.

RESULTS

The mean reduction in intraocular pressure in the beta-blocker-treated eyes was -5.9 +/- 3. 4 mm Hg (-22% +/- 12%; Student t test, P <.0001). In the contralateral eyes, mean intraocular pressure reduction was -1.5 +/- 3.0 mm Hg (-5.8% +/- 12%; P <.0001). Of the contralateral eyes, 35% showed a reduction of 3 mm Hg or more, and 10% showed a reduction of 6 mm Hg or more. The contralateral effect of the relatively selective beta-blocker betaxolol did not differ from that of any of the nonselective beta-blockers. Factors associated with the magnitude of the contralateral effect were the degree of intraocular pressure reduction in the treated eye and baseline intraocular pressure of the contralateral eye. In the close observation group, no significant reduction in intraocular pressure was noted between the baseline and follow-up visit.

CONCLUSIONS

The contralateral effect is important in clinical practice and in clinical trials when the hypotensive effect of a topical beta-blocker is evaluated by means of a one-eyed therapeutic trial.

Effect of intravenous fenoldopam on intraocular pressure in ocular hypertension

Intravenous fenoldopam, a selective dopamine-1 receptor agonist, was compared with placebo in this randomized, double-blind, two-period crossover study to evaluate its effects on intraocular pressure, aqueous dynamics, and macular blood flow in patients with elevated intraocular pressure or primary open-angle glaucoma. Doses of fenoldopam were titrated up to a maximum of 0.5 microgram/kg/min. Intraocular pressure, measured by pneumotonometry, was the primary outcome variable. Other outcomes included macular blood flow assessed by blue field examination, visual field examined by automated perimetry, aqueous outflow facility measured by tonography, and aqueous humor production determined by fluorophotometry. During infusions of fenoldopam, intraocular pressure increased from a mean baseline level of 29.2 mmHg to a mean maximum level of 35.7 mmHg. During the placebo infusions, pressure increased from a mean baseline of 28.4 mmHg to a mean of 29.0 mmHg at the time point that corresponded to the mean maximum intraocular pressure on the day intravenous fenoldopam was administered, to yield a mean difference in pressure between study days of 6.7 mmHg (P < 0.05). There were no apparent changes in macular blood flow, visual fields, or production or outflow of aqueous humor associated with fenoldopam infusion. The increase in intraocular pressure seen in this population of patients with ocular hypertension during infusions of fenoldopam is consistent with fenoldopam-associated increases in intraocular pressure reported in previous studies of healthy volunteers and of patients with accelerated systemic hypertension. These results further suggest that dopamine-1 receptors play a role in the regulation of intraocular pressure.

The determination of additive effect and intraocular pressure lowering effects of 0.05% bromocriptine and 0.25% timolol

It has been confirmed that topically applied bromocriptine has a satisfactory intraocular pressure (IOP) lowering effect without serious ocular or systemic side effects. We compared the IOP lowering effects of 0.05% bromocriptine and 0.25% timolol and determined whether they have an additive effect in lowering IOP in normal volunteers. In a double-blind, randomised, prospective, single-dose study, we measured IOP in 24 ocular normotensive subjects before (baseline) and 2, 4 and 6 hours after topical instillation of the following drugs: timolol and bromocriptine alone (n: 14), timolol+bromocriptine, timolol+placebo, bromocriptine+placebo (n: 10). Both bromocriptine and timolol have a significant IOP lowering effect (p < 0.01) compared with the baseline value during the study period. There were no significant differences in IOP lowering effect between timolol and bromocriptine at 2 and 4 hours (p > 0.05), but timolol was more efficacious than bromocriptine at 6 hours (p < 0.05). An additive effect in lowering IOP was not found. Although timolol and bromocriptine have no additive effect in lowering IOP, topically applied bromocriptine may be used in the treatment of glaucoma.

The effects of dopamine, haloperidol and bromocriptine on intraocular pressure

In a double-blind randomised, prospective single dose study, we measured intraocular pressure (IOP), pupil diameter, systemic blood pressure and heart rate in 43 ocular normotensive subjects before (baseline) and 2, 4, and 6 hours after topical instillation of the following drugs: dopamine 2% (n = 11), a dopamine receptor blocking drug, haloperidol 0.5% (n = 11), a dopamine receptor stimulating drug, bromocriptine 0.05% (n = 11) and 0.1% (n = 10). In the groups receiving dopamine or haloperidol, there were no significant differences in IOP compared with baseline values (p > 0.01). But, a significant decrease in IOP compared with the baseline values was found in both bromocriptine groups (p < 0.001). With the 0.05% and 0.1% concentrations, maximum reductions in intraocular pressure were 22.0% +/- 5.8% and 28.4% +/- 9.8%, respectively. No significant differences in mean pupil diameter, systemic blood pressure and heart rate were detected in all of these groups. In addition, in the group receiving bromocriptine 0.1%, there was no change in serum prolactin levels. These results suggest that topically administered bromocriptine has satisfactory intraocular pressure lowering capacity without serious ocular or systemic side effects. Consequently we conclude that, an ophthalmic formulation of bromocriptine may have substantial clinical potential for the treatment of glaucoma.

Ocular hypotensive effects of medifoxamine

Medifoxamine is a novel monoamine re-uptake inhibiting antidepressive drug which preferentially inhibits dopamine reuptake. In human volunteer studies it has been found to reduce significantly intraocular pressure after single oral doses of 300-1000 mg, and to produce a small but statistically significant miosis. Its maximal ocular hypotensive action was less than that of oral timolol 20 mg.

Antagonism by domperidone of the ocular hypotensive effect of pergolide

1. The effect of pre-dosing with 15 mg domperidone, a relatively selective dopamine 2-receptor antagonist, on the ocular hypotensive action of a single oral dose of 25 micrograms pergolide, a dopamine 2-receptor agonist, was studied in 9 normal human volunteers, using a non-invasive method. 2. Compared with domperidone followed after 1 h by placebo, placebo followed after 1 h by pergolide had an ocular hypotensive effect in both eyes. Domperidone followed after 1 h by pergolide had no effect on intraocular pressure in both eyes. 3. The results of this study showed that domperidone inhibited the ocular hypotensive action of pergolide, suggesting that pergolide reduces intraocular pressure by the stimulation of the peripheral dopamine 2-receptors.