Patient history, use of other medications dictate medical management of glaucoma

Issue: October 1997

ByBobby Christensen, OD FAAO

Because this issue of Primary Care Optometry News spotlights glaucoma care, I am changing the primary focus of this column from therapeutic pharmaceutical drops and ointments most often used to an overview of glaucoma drops used in our practice.

This column will not try to tell you how to make the diagnosis or which drops you should use as your first choice of treatment. I want to cover some of the most important patient management tips, history, considerations when prescribing specific drops and common side effects associated with these medications.

Beta-blockers

Points to consider when using beta-blockers:

Does the patient have a history of congestive heart failure, bradycardia (slow pulse), asthma, lung disease or pulmonary dysfunction?
Does the patient have a history of difficulty with other beta-blockers?
Tell patients to discontinue the beta-blocker 5 to 7 days before general anesthesia.
For best results, use the drop in the early morning and a few hours before bedtime.

Timoptic (timolol maleate, Merck), introduced in 1978, was our first beta-blocker and was a welcomed addition to a very limited arsenal of glaucoma medications. Since that time, Betagan (levobunolol HCl, Allergan), Betoptic and Betoptic S (betaxolol HCl, Alcon), Ocupress (carteolol HCl, Otsuka America), Betimol (timolol hemihydrate, Ciba Vision) and Timoptic XE (timolol maleate, Merck) have been approved for glaucoma therapy. Here are a few considerations regarding each of these drops.

Betagan has been approved to use one time per day. It is now available in generic form (contains 0.004% benzalkonium chloride [BAK]), which reduces the cost for patients.
The dosage for Betoptic is twice per day, and it tends to sting on instillation, which is one of the reasons Betoptic S was formulated.
Betoptic S (contains .01% BAK) produces only mild stinging on instillation. It and Betoptic are the only selective beta-1 blockers which reduce the possibility of side effects as compared with nonselective beta-blockers. Betoptic S does not lower the intraocular pressure (IOP) as much as the other beta blockers, but patients may have less field loss due to improved perfusion of the optic nerve head.
Ocupress (contains .005% BAK) has "intrinsic sympathomimetic activity," according to the package insert, which tends to produce less bradycardia. It may also be a better choice for patients with high serum lipid imbalances. Dosage is usually twice per day.
Betimol (contains .01% BAK) is produced with a different salt of timolol. It uses hemihydrate instead of maleate and seems to demonstrate the same potency and side effects as Timoptic. This drop is less expensive than Timoptic. Dosage is usually twice per day.
Timoptic XE (contains .015% BAK) is timolol combined with a gel called Gelrite. It is approved for once-a-day usage, which increases compliance. The gel increases contact time with the cornea, but some patients do complain of blur after the drop is instilled.

Trusopt 2%

Points to consider when using Trusopt:

Do not use if the patient is taking oral CAIs (Diamox, Neptazane).
Adjunctive therapy often increases the effectiveness of Trusopt.
A bitter taste is often reported.
Use with caution if patients have renal impairment or hepatic disease.
Do not use if the patient has a history of sulfonamide reaction.

Oral carbonic anhydrase inhibitors (CAIs) such as Diamox (acetazolamide, Storz) and Neptazane (methazolamide, Storz) have proven to be excellent medications to reduce IOP. The side effects of these oral CAIs often required that the use of these medications be discontinued. After years of development, Trusopt 2% (dorzolamide, Merck) — with an orange cap — reached the market for topical glaucoma treatment. Systemic side effects encountered with oral CAIs have not been noted with topical CAI therapy.

If the patient has a history of allergic reaction to sulfonamide drugs, a different drop for glaucoma treatment should be selected. For monotherapy, Trusopt (contains .0075% BAK) is prescribed three times per day. When used as adjunctive therapy, it is prescribed two or three times per day.

Xalatan

Points to consider when using Xalatan:

It enhances uveoscleral outflow.
Use it in the evening one time per day (27% to 35% IOP reduction).
It may change eye color in eyes with a hazel-green and blue-green iris; this is a special concern if unilateral treatment is needed.
Do not use as additive therapy with pilocarpine.
Mild conjunctival hyperemia has been reported in 10% to 35% of the patients.
Tell the patient the bottle is small and only half full.
The soft bottle requires a gentle touch to prevent waste.

Xalatan (latanoprost, Pharmacia & Upjohn) — a small, clear bottle — is an exciting new glaucoma therapy that has received good reviews during clinical trials and by most practitioners who have used the drop since it became available in 1996. It is a prostaglandin analog, which is effective in a low concentration (0.005%).

Xalatan (contains .02% BAK) enhances uveoscleral outflow. This gives us another mechanism in addition to trabecular outflow to reduce IOP. Because of this unique mechanism, latanoprost should produce an additive effect when used with Trusopt, Alphagan (brimonidine tartrate, Allergan), beta-blockers and Propine (dipivefrin, Allergan). Pilocarpine may decrease the effectiveness of Xalatan by tightening the ciliary muscle, which would decrease the uveoscleral outflow.

Alphagan

Points to consider when using Alphagan:

Can be used twice daily or three times daily; provides approximately 4 mm to 6 mm of IOP decrease.
It may reduce blood pressure.
Possible additive effect for patients on central nervous system depressants.
Side effects can include hyperemia, dry mouth, headache or burning/
stinging.
Monitor for allergic reaction with long-term use.

Alphagan — with a purple cap — is an alpha-2 agonist that has recently been approved for three times per day dosage. Some of the clinical studies indicated there was no advantage of three times daily dosage compared with twice daily dosage. Alphagan (contains .05% BAK) appears to lower IOP by suppressing aqueous production and increasing uveoscleral outflow. Possible systemic side effects could be a decrease in systolic blood pressure, dry mouth and fatigue. Changes in heart rate appear to be minimal. Allergic reactions are less than with Iopidine (apraclonidine, Alcon), but are still a factor and need to be monitored over time.

Pilocarpine

Points to consider when using pilocarpine:

The patient may experience a brow ache for a few days after starting treatment.
Due to accommodative spasm, it is best to use on patients older than 50 years.
Vision will be reduced for patients with central cataracts.
It increases difficulty with night driving.
Some patients complain of throat irritation.
Check the peripheral retina before starting treatment because there is a higher risk of detachment.

Pilocarpine (green cap), once the mainstay, is not used as often since the advent of the newer glaucoma medications. The dosage is four times per day, which can decrease compliance. The miotic pupil makes it difficult to drive at night for older patients who often have sclerotic lenses that further decrease illumination to the retina.

Despite all of the negatives with this drug, it still commands consideration for some patients. It is inexpensive and does reduce the IOP for most patients. For a patient with congestive heart failure and a history of allergic reaction to sulfonamide, pilocarpine may be considered for initial therapy.

Starting the patient on drops

Written instructions help the patient establish a routine. These instructions are a helpful checklist for the prescribing doctor to make sure that all points have been discussed.

Each glaucoma medication has the potential for side effects. Explain to the patient such things as brow ache with pilocarpine, stinging with Betoptic, bitter taste with Trusopt and dry mouth with Alphagan. Long-term side effects, such as the potential for iris color change with Xalatan, need to be explained and documented in the record. Patients need to be made aware of what to expect and be educated on how to respond to abnormal reactions.

This overview of glaucoma medications highlights the major considerations and side effects of the commonly used glaucoma medications in primary care practice. Potential interactions with systemic medications, the treatment of different types of glaucoma and considerations of age, gender and race are many of the other factors that need to be considered when selecting a treatment plan for the glaucoma patient.

Explaining to the Patient How to Instill Drops

Have the patient wash his or her hands before instilling drops.
Give the patient a handout on how to instill drops, then demonstrate to the patient how to pull down the lower lid, look up, and instill the drop.
Have the patient wait 5 minutes between instillation of drops.
Explain that the bottle can be placed in the refrigerator; when the drop is cold, they can tell when it hits the eye surface.
Tell the patient to close his or her eyes for 20 seconds after drop instillation.
While the eyes are closed, have the patient apply punctal occlusion for 20 seconds.
Demonstrate how much pressure to apply and where to place the finger and thumb for punctal occlusion.
If the dropper accidentally hits the lashes on instillation, recommend that they rinse the dropper tip with warm water before replacing the cap.
When using multiple drops, identify each drop by the color of the cap during the explanation (example: orange cap — Trusopt; blue cap — Betoptic S).