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Lack of consensus among ODs in role of combination therapies
Noncompliance may make them a logical choice, but other issues must be considered.
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When treating patients with glaucoma, optometrists can face many decisions on the way to achieving target intraocular pressure; among these is whether a fixed-combination agent is necessary and, if so, which one to choose.
According to the Ocular Hypertension Treatment Study, published in 2002 in Ophthalmology, nearly 40% of participants required two or more medications to achieve a target IOP.
The study was designed to evaluate the safety and efficacy of ocular hypotensive medication for the treatment of primary open-angle glaucoma. Kass and colleagues set treatment goals as a target IOP of 24 mm Hg or less, as well as at least a 20% reduction in IOP from the average of the baseline IOP and qualifying IOP.
“Topical medication was changed and/or added until both of these goals were met or the participant was receiving maximum-tolerated topical medical therapy,” the researchers noted.
Five years from the start of the study, researchers reported that 39.7% of medication participants were taking two or more topical medications, and 9.3% were taking three or more medications to control their IOP.
A 2006 Ophthalmology study, which investigated concerns related to glaucoma medications and their relationship to adherence, found that a simpler medication regimen was more effective for patients.
“We found that patients taking more glaucoma medications were more likely to have several different problems taking their eye drops than patients taking fewer glaucoma medications,” Sleath and colleagues stated. “Patients taking more glaucoma medications were more likely to report having difficulty remembering to take their drops, opening and squeezing the bottle, and getting their refills on time. These findings suggest that, if possible, [eye care practitioners] should attempt to simplify patients’ regimens to fewer glaucoma medications.”
Noncompliance common
Randall Thomas
“The more complex the dosage regimen, the higher the risk of patient noncompliance,” Randall Thomas, OD, FAAO, said in an interview with Primary Care Optometry News. “Human beings are terrible patients. Why do people sleep in their contact lenses when they’ve been told again and again not to? Or they are told to replace them every month and they wear them 3 months. That’s just such a common part of life. So, you try to keep your glaucoma medicines as simple as possible and, basically, once a day is best, twice a day is second best and once you get into three medicines, it’s a rare patient that can consistently take three medicines as directed.”
George Takeda
Due to these types of compliance issues, George Takeda, OD, told PCON that he prefers combination therapies.
Some believe glaucoma progression is tied to diurnal fluctuation and some believe it is tied to compliance, he said.
“I believe they go hand in hand,” he explained. “All of the compliance studies show that if you’re on more than two medications, you’re really going to get about 80% noncompliance. So, combining the medications and putting them in one is just so much easier.”
Other studies have noted issues aside from compliance in taking multiple medications, including increased exposure to preservatives, a diluted or “washout” effect, increased cost and increased ocular allergy.
“Fixed-combination medications are easy for the patient, allow for less exposure to preservatives and passively promote better compliance,” Thomas explained. “But unless the doctor does a therapeutic trial of the individual components, they cannot know if only one of the ingredient drugs would have achieved target IOP range alone. These ingredient drugs are mostly inexpensive generic drugs and, thus, less expensive.”
Murray Fingeret, OD, a PCON Editorial Board member, noted that additional dilemmas exist in combination treatments.
“In prescribing fixed-combination medications, you have the efficiency of starting two medications at once, so it may reduce office visits,” he said. “But if the patient experiences a side effect, it’s not always clear which drug is causing it.”
When to switch?
These doctors each expressed a different protocol for prescribing fixed-combination drugs.
“I add a second medication when either the eye pressure is too high or higher than I would like it to be or I note progression of the glaucoma,” Fingeret explained. “I will often use a topical carbonic anhydrase inhibitor as my second agent. I’ll go to a fixed combination if I need further reduction after that.”
Murray Fingeret
“I switch to a fixed-combination when I get a pressure that is higher than 20 mm Hg and I feel like I need to add something and I need more than a 20% reduction,” Takeda said.
“I would never just add a combination drug; I would add one of the components of that combination drug because that individual component in and of itself has a very good chance of achieving target pressure,” Thomas said. “That way you’re using a single drug that is generic and less expensive.”
None of the doctors noted a preference in which drug they prescribed.
Medication decisions
The doctors all noted that they have observed a significant increase in the use of fixed-combination drugs, but expressed apprehension regarding the role they should have in glaucoma care in the future.
“Combination medicines should be a somewhat minimal player in glaucoma patient care, but they’re not,” Thomas said. “There’s probably about a 10% or 20% chance of the fixed-combination medication being more effective than one of the individual components. We need to be more attentive and more compassionate and give a lot of thought to how we care for our patients and not just throw stuff at them.
“There are marketing forces out there promoting a ‘combination drug’ as the next step if further IOP lowering is required beyond a prostaglandin,” he continued. “This is intellectually deceiving and very much not consumer friendly. If you are lazy, the combination drugs are easy; however, they’re not patient-centric and they’re expensive.”
Takeda stated that his patients have had a substantial influence on his decision making.
“I really don’t see a downside to a fixed-combination drop, especially if the IOP is too high for just an approximate 15% to 20% decrease in pressure,” he said.
“The feedback that I have received from patients is very uplifting, very positive,” Takeda continued. “They want to cut down on the medications, they want to cut down on the copay and they want to take down the number of drops. Splitting up a combination drop just doesn’t make sense to me.” – by Chelsea Frajerman