indication

Used mainly to produce mydriasis and cycloplegia for diagnostic purposes.

pharmacology

Cyclopentolate is an anti-muscarinic in the same class as atropine and scopolamine. Cyclopentolate blocks the receptors in the muscles of the eye (muscarinic receptors). These receptors are involved controlling the pupil size and the shape of the lens. Cyclopentolate thus induces relaxation of the sphincter of the iris and the ciliary muscles. When applied topically to the eyes, it causes a rapid, intense cycloplegic and mydriatic effect that is maximal in 15 to 60 minutes; recovery usually occurs within 24 hours. The cycloplegic and mydriatic effects are slower in onset and longer in duration in patients who have dark pigmented irises.

mechanism of action

By blocking muscarinic receptors, cyclopentolate produces dilatation of the pupil (mydriasis) and prevents the eye from accommodating for near vision (cycloplegia).

toxicity

Oral LD₅₀ in the rat is 4000 mg/kg and 960 mg/kg in the mouse. Symptoms of overdose include tachycardia, dizziness, dry mouth, behavioral disturbances, uncoordination and drowsiness.

absorption

Absorbed following ophthalmic administration.

drug interactions

Tacrine: The therapeutic effects of the central acetylcholinesterase inhibitor, Tacrine, and/or the anticholinergic, Cyclopentolate, may be reduced due to antagonism. The interaction may be beneficial when the anticholinergic action is a side effect. Monitor for decreased efficacy of both agents.

Triprolidine: Triprolidine and Cyclopentolate, two anticholinergics, may cause additive anticholinergic effects and enhance their adverse/toxic effects. Monitor for enhanced anticholinergic effects.

Trospium: Trospium and Cyclopentolate, two anticholinergics, may cause additive anticholinergic effects and enhanced adverse/toxic effects. Monitor for enhanced anticholinergic effects.