What is atropine, and how does it work (mechanism of action)?
Atropine occurs naturally and is extracted from
belladonna alkaloids contained in plants. Atropine blocks the action of
acetylcholine, a neurotransmitter that causes the contraction of two types of
muscle, smooth and cardiac muscles. It also has other neurological effects.
Ophthalmic atropine is used during eye examinations to dilate the pupil.
Atropine is also used to weaken the contraction of the muscles within the eyes,
both the muscles that operate the iris and the lens. Paralysis of the lens,
called cycloplegia, results in the loss of the ability to focus vision.
Paralysis of the iris (mydriasis) prevents the iris from adjusting to the
brightness of incoming light and affects the ability to see clearly. In
clinical studies, use of a single topical administration of atropine 1%
ophthalmic solution (eye drops) resulted in maximal mydriasis (pupil dilation or
widening) in approximately 40 minutes and maximal cycloplegia in approximately
60 to 90 minutes. In most cases, full recovery occurred in approximately one
week but can take a couple of weeks. The FDA approved atropine in 1938.
What brand names are available for atropine?
N/A
Is atropine available as a generic drug?
Yes
Do I need a prescription for atropine?
Yes
What are the side effects of atropine?
The most common side effects reported include
- eye pain,
- stinging on administration,
- blurred vision,
- sensitivity to light,
- decreased tear
production, - eyelid swelling, and
- increased heart rate and blood pressure if the
atropine is absorbed from the eye.
What is the dosage for atropine?
- For inducing mydriasis (pupil dilation) or cycloplegia in adults:
Instill 1-2 drops of 1% ophthalmic solution in eye 1 hour before procedure. - For the treatment of inflammatory conditions of the eye (iritis or uveitis)
in adults: Instill 1-2 drops of 1% solution in eye up to 4 times per day.
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Which drugs or supplements interact with atropine?
:
Use of atropine with
monoamine oxidase inhibitors (MAOI) is not recommended
due to the risk of causing severely elevated blood pressure (hypertensive
crisis). Examples of MAO inhibitors include
- linezolid (Zyvox),
- methylene blue,
- phenelzine (Nardil),
- procarbazine (Matulane),
- rasagiline (Azilect),
- selegiline (Eldepryl,
Zelapar, Carbex), - tranylcypromine (Parnate) and others.
Patients should ask their doctor or pharmacist before using atropine eye
products if they are taking certain drugs such as
- antiarrhythmic drugs, for example,
quinidine,
procainamide (Procanbid), antihistamines such as
meclizine (Antivert) or
diphenhydramine (Benadryl), - antispasmodics such as
dicyclomine (Bentyl), - certain
medications used to treat
Parkinson’s disease such as benztropine (Cogentin) or
trihexyphenidyl (Artane), and -
antidepressants, for example
amitriptyline (Endep, Elavil).
Is atropine safe to take if I’m pregnant or breastfeeding?
There are no adequate and well-controlled studies of atropine
sulfate in pregnant women
Small amounts of atropine were detected in human milk
following administration of injectable atropine. Ophthalmic preparations of
atropine are compatible with breastfeeding.
What else should I know about atropine?
What preparations of atropine are available?
Ophthalmic solution: 1%
How should I keep atropine stored?
Atropine ophthalmic solution can be stored in the refrigerator or at
room temperature away from heat and light.