Drugs Used To Treat Glaucoma - Epinephrine and
Apraclonidine
Epinephrine: Epinephrine is an agonist drug used to
control glaucoma. Some of the brand names it is sold under include Epifrin, Epinal, Epitrate, Eppy, and Glaucon. It is a nonselective
medication because it acts on more than one area in the eye; it
affects aqueous flow, trabecular outflow, and uveascleral outflow.
Chemically, epinephrine is identical to the hormone adrenaline,
which is secreted by the adrenal gland and is known to control
glaucoma. Secretions of this fluid are extremely complex, and the
mystery of its manufacture and diffusion still remain to be
unraveled.
|
|
Epinephrine medications work well at reducing
IOP, but may create one or two problems. After a period of
use, or at times immediately after you instill the drop,
your eye may become red. This is because epinephrine dilates
the blood vessels in the eye. The redness is harmless, but
most people object to walking around with a red eye. If your
eye begins to itch and/or hurt, you may be having an
allergic reaction to the medication.
Scientists have found that if epinephrine is combined with
another drug, dipivefrin, better results can be obtained.
This combination is sold under the brand name Propine.
Because Propine penetrates the cornea and reaches the
interior of the eye more rapidly, some of the troublesome
effects of epinephrine are averted. But not for long. The
body catches on and the reactions against the drug begin to
reappear. |
Unlike the miotics, Propine dilates the pupil,
which helps to counteract somewhat the pupil-constricting
properties of the miotics such as pilocarpine and carbachol.
It also constricts the blood vessels on the surface of the
eye, which enhances the whiteness of your sclera, giving
your eye a beautiful appearance.
Epinephrine can cause blurred vision if you wear
soft contact lenses, because it stains the lenses. Propine is
said to avert this problem, possibly because of its rapid
penetration into the eye. People with heart problems and/or high
blood pressure should use any drugs in the epinephrine family
with caution, for systemic side effects can include acute
hypertension (high blood pressure), arrhythmia (irregular
heartbeat), and angina (chest pains). If you already have any of
these problems, the drug can worsen them.
|
Apraclonidine: Apraclonidine (lopidine) is
another agonist drug used in the treatment of glaucoma. The
mechanism of how it works is not completely established, but
researchers believe it predominantly reduces the formation
of aqueous humor. Originally, apraclonidine was used to
counteract the temporary spikes in IOP that can occur
directly following laser treatment. Heartened by its effect
on intraocular pressure, ophthalmologists lobbied the U.S.
Food and Drug Administration (FDA) to approve its use in the
general treatment of glaucoma, and 1995, apraclonidine
joined the list of medications prescribed for lowering IOP.
As with any medication, there can be side effects. Possible
side effects of apraclonidine include dilation of the pupil,
burning, discomfort, a foreign-body sensation, dryness,
itching, blurred or dimmed vision, a generalized allergic
response, and tiny hemorrhages in the conjunctiva. |
|
|
|
Systemically, it can cause abdominal pain, diarrhea, stomach
discomfort, and vomiting. People with some forms of severe
cardiovascular disease are advised against taking this medication
because it lowers blood pressure. Some patients have complained of
insomnia, dream disturbances, irritability, and decreased libido.
Others have cited dry mouth, nasal burning or dryness, headache,
heaviness or burning in the chest, clammy or sweaty palms, body
heat, shortness of breath, fatigue, and pain in the extremities. In
some patients, this drug apparently loses its effectiveness after
several months' use. |
