By Earl R. Nichols
FORT LAUDERDALE, FL -- May 15, 2007 -- Much of the problem with hyperemia, burning and itching associated with use of ocular bimatoprost drops in patients with open angle glaucoma can be alleviated by switching from daily dosing to dosing every 48 hours, according to research presented here at the Association for Research in Vision and Ophthalmology (ARVO) annual meeting.
The effect of the drug seems to remain consistent, with only a slight and clinically insignificant difference in intraocular pressure between two dosing regimens, said researcher Daniele Doro, MD, department of neurosciences and ophthalmology, University of Padua, Padua, Italy.
Bimatoprost is one of the most common prostaglandin agents used to treat glaucoma, but the hyperemia that results from using this drug can be so pronounced that upward of one third of patients discontinue their treatment for that reason, and switch to another prostaglandin.
In their study, Dr. Doro and colleagues evaluated 10 patients who instilled bimatoprost in each eye at 10:00 PM every evening for four weeks. Intraocular pressure IOP was measured at 9:00 AM, 1:00 PM and 4:00 PM after one and four weeks of treatment. Next, the patients were instructed to use bimatoprost every other day for a further four weeks, and IOP was recorded again at weeks one and four and at the same timepoints each day.
At the 9:00 AM measurement at week one, IOP was decreased by 7.6 mm Hg (30%) when patients administered the drops every 24 hours. When the drug was administered every 48 hours, the decrease in IOP from baseline was 6.4 mm Hg (25.2%). This difference remained relatively constant from week one to week four.
For glaucoma patients using a prostaglandin, the 9:00 AM IOP measurement is the most important one of the day because this is when the effect of the drug, which is usually administered around 8:00 PM the previous day, would have worn off the most.
Of the six patients who developed conjunctival hyperemia on 24-hour dosing, two developed hyperemia when they went to every 48 hour dosing.
Two patients on daily dosing reported stinging and itching, but none of the patients on 48-hour dosing reported these side effects.
These data indicate that based on this small series of patients, IOP can be reduced as well with bimatoprost every 48 hours as with administration every 24 hours.
These results are not unlike what has been seen with other prostaglandin analogs -- travoprost and latanoprost -- both of which show a statistically significant reduction in IOP from baseline more than 24 hours after the last dose. Travoprost, for example, has been shown in some studies to maintain IOP at a fairly low level as much as 44 hours after the last dose, a fact that makes it convenient for patients who forget to take their medications.
These results may offer good news for patients who are bothered by hyperemia, itching and burning when they use bimatoprost, said Dr. Doro.
He concluded that compliance is an ongoing issue for a large percentage of patients with glaucoma. Simply by moving to 48-hour dosing should not put the patient at risk of any clinically relevant fluctuations in IOP, but on the other hand, switching to dosing every 48 hours could also encourage the patient to become even less compliant than before, he said.
[Presentation title: Bimatoprost Every 24 versus 48 hours in Eyes With Ocular Hypertension and/or Primary Open Angle Glaucoma. Poster 5570 B909]
E-Mail this DGDispatch to a colleague
