|
Medical Health Encyclopedia
Glaucoma - Medications
(Page 5)
Demecarium (Humorsol), isoflurophate (Floropryl), and echothiophate (Phospholine) are a group of long-acting drugs known as anticholinesterase miotics. Because of their potential for serious side effects, however, some authorities even prefer surgery to their use.
Epinephrine and its derivatives are the older anticholinergics. Epinephrine is now rarely prescribed because of side effects. Dipivefrin (Dipivefrin), a newer form of epinephrine, remains inactive until it reacts with enzymes in the cornea. It is effective in low doses and causes few systemic side effects.
Side Effects. Side effects include:
- Teary eyes, brow-aches, eye pain, and allergic reactions.
- A miotic narrows the pupil and so can cause nearsightedness. Vision can also become dim and it may difficult to see in darkened rooms or at night, when driving could be hazardous. A gel form administered once a day or wafer placed under the lid once a week may help reduce these side effects.
- The anticholinesterase miotics increase the risk of cataract development and are therefore used mostly in patients in whom cataracts have already been removed. Retinal detachment is an uncommon but dangerous side effect in susceptible individuals. Excessive use of these miotics may cause toxic reactions, including convulsions, muscular paralysis, and even death from respiratory failure.
- Epinephrine can produce burning in the eyes, enlarged pupils, and allergic reactions. Occasionally it can cause anxiety and headaches. Rare side effects include high blood pressure and disturbances in heart rhythm. It is rarely prescribed now. Although dipivefrin, the newer form of epinephrine, has fewer systemic side effects, it still causes problems in the eyes similar to those of epinephrine.
Experimental Therapies
Cannabinoids. Cannabinoids, compounds in marijuana (cannabis), are being studied for their effects on glaucoma. For example, oral or inhaled tetrahydrocannabinol (THC), the active ingredient in marijuana, has been shown to reduce IOP in 60 - 65% of patients. The effects of smoking marijuana on IOP last only 3 hours, however. THC also increases the release of glutamate -- a nerve-protecting chemical. Experts are hoping that topical use of THC or other cannabinoids may help prevent optic nerve damage without the widespread effects of oral or inhaled administration.
Managing Drug Regimens
Reasons for Noncompliance
Studies indicate that more than 40% of patients miss 10% of their doses, and 15% of patients miss more than 50% of their doses. Noncompliance is very high for many reasons:
- People with chronic glaucoma who are on medication must use eye drops or take pills one or more times a day, usually for the rest of their lives.
- Many people require a multi-drug regimen, two or more different kinds of medications that can be used in various combinations, such as eye drops, ointments, or time-release wafers inserted under the eyelid. Such regimens can be very confusing.
- The side effects of the drugs are more unpleasant than the disease itself, which has no symptoms until vision is lost. Because the treatment does not usually produce any noticeable improvement, the consequence of not taking the drugs (blindness) may seem far in the future.
- Skipping even a few doses can greatly increase the risk of visual loss. It is essential that patients tell their doctor if they are not regularly taking their medication. Otherwise, the doctor may increase the dosage, thereby causing unwelcome side effects.
Patients who do not regularly take their glaucoma medication are at high risk for blindness. If you have problems taking your medications or sticking to the dosing regimen, talk with your doctor.
Hints for Managing a Regimen
- Pharmaceutical manufacturers use colored tops, yellow for timolol, for example, and green for pilocarpine, to help prevent mix-ups. Creating a chart scheduling each drug by color can be helpful.
- Small electronic timers are available that will signal times for taking the medications. The timing of these combinations is important. For example, the combination of pilocarpine with latanoprost is most effective when pilocarpine is taken four times a day and when the bedtime dose is administered an hour after latanoprost.
- Some patients may be candidates for single medications that combine two drugs, such as Cosopt, which contains both dorzolamide and timolol. This medication requires only one drop twice per day. Patients who need additional glaucoma drugs, however, will need to take these two drugs separately.
- When using any drug for a long period of time, side effects are a potential problem. If they become intolerable, patients should discuss with the doctor reducing the dosage or trying other drugs.
Administering Eye Drops
A common reason that medicine does not work is that patients do not take it correctly. Patients should ask the ophthalmologist to watch while they place the drops in their own eyes to make sure the procedure is being done correctly. The following are some recommended steps:
- If you use both ointments and eye drops, take the eye drops first.
- Wash your hands before applying eye drops.
- Hold the bottle upside down.
- Tilt your head back and, with one hand, pull the lower eyelid down to form a pocket.
- With your other hand, hold the bottle as close as possible to your eye. Don’t let the bottle directly touch your eye or eyelid.
- After you have placed the drop, close your eye or press your index finger against the corner of the eye near your nose. Gently move the lower lid upward until the eye is closed. Keep your eye closed for at least 1 minute. This prevents the drop from draining out.
- Wait at least 5 minutes before applying another drop or a different medication
|
Drug Therapy for Acute Closed-Angle Glaucoma
In this emergency situation, ophthalmologists may administer a combination of two or more anti-glaucoma medications to reduce eye pressure quickly before it can damage the optic nerve and cause visual loss. Apraclonidine (Iopidine) is a powerful drug used before and after laser surgery to prevent an increase in fluid pressure and is more effective than other medications. In addition to standard drugs, doctors may also administer glycerin (Glyrol, Osmoglyn) by mouth or mannitol or acetazolamide intravenously. Surgery is almost always performed once the pressure is reduced.
Therapies for Less Common Glaucomas
Most rare forms of glaucoma respond to the same medications and surgery used for open angle glaucoma. Irido corneal endothelial syndrome (ICE) is difficult to treat and if surgery is required, filtering surgery is the best choice. Neovascular glaucoma is also very hard to treat; researchers are investigating drainage implants for this disorder.
Review Date: 03/03/2007
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine,
Harvard Medical School; Physician, Massachusetts General Hospital.
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).
| |
.gif)
Get our free newsletter
