The Effects of Cosopt® Vs Xalacom® on Ocular Hemodynamics and Intraocular Pressure (IOP) in Primary Open-angle Glaucoma (POAG)
Information source: Meir Medical Center
ClinicalTrials.gov processed this data on August 23, 2015 Link to the current ClinicalTrials.gov record.
Condition(s) targeted: Open-Angle Glaucoma; Ocular Hypertension
Intervention: Dorzolamide+Timolol Maleate0.5% (Drug); Latanoprost+Timolol Maleate0.5%+Lytears (Drug)
Phase: N/A
Status: Withdrawn
Sponsored by: Meir Medical Center Official(s) and/or principal investigator(s): Adi Abulafia, MD, Principal Investigator, Affiliation: Meir Medical Center, Tel Aviv University
Summary
Both Cosopt® and Xalatan® plus Timoptic® will significantly lower IOP, however only Cosopt®
will demonstrate positive hemodynamic effects. The clinical significance of this will be
investigated by examining the ophthalmic and short posterior ciliary arteries to determine
the blood supply to the optic nerve head, the site of damage in glaucoma
Clinical Details
Official title: A Comparative Analysis of the Effects of Cosopt® Versus Xalacom® on Ocular Hemodynamics and Intraocular Pressure in Patients With Primary Open-angle Glaucoma
Study design: Allocation: Randomized, Intervention Model: Crossover Assignment, Masking: Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor)
Primary outcome: Ocular hemodynamics as measured by Color Doppler imaging
Secondary outcome: Intraocular pressure as measured by Goldmann applanation tonometry
Detailed description:
Background and Rationale
Apoptosis of retinal ganglion cell has been considered as the most plausible pathogenic
mechanism of glaucoma. Apoptosis can be caused by neurotrophic factor withdrawal or
glutamate release and both of them are triggered by elevated intraocular pressure (IOP) and
ischemia simultaneously or separately.
The topical carbonic anhydrase inhibitor, Dorzolamide (Trusopt*), has recently been approved
for chronic use in the treatment of glaucoma. The ocular hypotensive effects of this topical
carbonic anhydrase inhibitor seem likely to produce the same results as *-adrenergic
antagonists. Systemic carbonic anhydrase inhibitors are known to have vasodilatory effects
(Maren,1987). Rassam S. M.B., Patel V. and Kohner E. M. (1993) have concluded that
acetazolamide causes an increase in retinal blood flow in the human retinal circulation. It
has also been demonstrated that Trusopt* increases retinal circulation as measured by
scanning laser ophthalmoscopy (SLO) (Harris, Arend, Martin, 1996). Furthermore, Trusopt
increases arteriovenous passage (AVP) time and improves contrast sensitivity in normal
tension glaucoma patients (Harris, 1999).
Cosopt* (dorzolamide hydrochloride-timolol maleate ophthalmic solution) is combination of a
topical carbonic anhydrase inhibitor and a topical beta-adrenergic receptor blocking agent.
Each of these two components reduces intraocular pressure. The IOP-reducing effect of Cosopt
b. i.d. was greater (1-3 mm Hg) than that of monotherapy with either 2. 0 % dorzolamide t. i.d.
or 0. 5 % timolol b. i.d. The IOP-lowering effect of Cosopt* b. i.d. was approximately 1 mm Hg
less than that of concomitant therapy with 2. 0% dorzolamide t. i.d. and 0. 5 % timolol b. i.d.
A previous study showed that the retinal circulation (AVP time) was significantly
accelerated after replacing Timoptic* with Cosopt* in glaucoma patients (Harris, 1999).
Latanoprost (Xalatan*) is a prostaglandin F2* analogue which is believed to reduce IOP by
increasing the outflow of aqueous humor. The retinal vascular effects of Latanoprost,
however, remain unclear. While some studies have shown PGF2* to induce constriction in
bovine isolated aqueous veins (Nielsen 1996), other studies have been unable to demonstrate
an effect on retrobulbar flow velocities (Drance 1996). It is possible that vasoconstrictive
properties of the drug may produce a negative impact on previously ischemic retinal tissue
or at best no change.
In a recent study comparing Trusopt® with Xalatan® some very encouraging results emerged,
AVP time was significantly reduced with Trusopt®, but not with Xalatan® despite the fact
that Xalatan® increases perfusion pressure (due to IOP) more than Trusopt®. This is the
strongest evidence so far of a pressure independent effect of Trusopt® on ocular blood flow.
Objectives
- To compare the IOP efficacy of Cosopt® and Xalacom® on IOP.
- To determine the perfusion pressure effect of Cosopt® and Xalacom®.
- To determine the blood flow effect of the two drugs on the ophthalmic, central retinal
and short posterior ciliary arteries, using Color Doppler Imaging (CDI).
Eligibility
Minimum age: 18 Years.
Maximum age: N/A.
Gender(s): Both.
Criteria:
Inclusion Criteria:
1. 18 years of age or greater.
2. Patient signed an informed consent agreement.
3. Corrected visual acuity of 6/12 or better:
4. Characteristic glaucomatous visual-field loss and optic nerve head damage in one or
both eyes.
5. Either IOP measurements ≥21 mmHg in the 3 months prior to study entry or IOP ≥ 21
mmHg at the end of the washout period
6. Patient on ≥1 IOP reducing agents. -
Exclusion Criteria:
1. Past history of ocular diseases (other than OAG / Cataract / Refractive error).
2. Past history of orbital/ocular surgery or trauma.
3. Receiving ≥ 3 IOP reducing agents.
4. Receiving agents known to produce significant cardiovascular, respiratory, renal or
hepatic side effects.
5. Personal history of respiratory disease such as asthma, emphysema or other chronic
obstructive pulmonary disease.
6. Personal history of congestive heart failure.
7. Personal history of bradycardia or 2nd and 3rd degree AV block.
8. Known allergy to sulfa.
9. Women who are pregnant or nursing.
10. Women who of child bearing age who are planning to become pregnant within one month
after study completion.
11. Receiving Levitra, Viagra, Cialis or other erectile dysfunction drugs.
Locations and Contacts
Meir Medical Center, Kfar Saba, Israel
Additional Information
Starting date: December 2008
Last updated: March 15, 2012
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