Cyclopentolate

Cyclopentolate is an anticholinergic used in diagnostic tests on the eye to dilate the pupils and paralyze the ciliary muscles of the eye.

Pharmacodynamics and mechanism of action

Cyclopentolate is an antimuscarinic agent and is similar to both atropine and scopolamine. Cyclopentolate blocks certain receptors in the muscles of the eye (muscarinic receptors). These receptors are involved in controlling pupil size and the shape of the lens. Cyclopentolate thus causes relaxation of these muscles of the iris and ciliary muscles. When applied topically to the eye, it produces a rapid, intense cycloplegic and mydriatic effect that reaches its maximum after 15 to 60 minutes; recovery usually occurs within 24 hours. The cycloplegic and mydriatic effects are slower to onset and last longer in patients with darkly pigmented irises.

Pharmacokinetics

The dose is very low due to local application to the eye. For this reason, the substance is absorbed into the systemic circulation only in minute quantities. Therefore, no reliable data on pharmacokinetic parameters are available.

Interactions

Cyclopentolate may interfere with the antihypertensive effects of drugs used in glaucoma therapy. These include the substances carbachol, pilocarpine or the group of ophthalmic cholinesterase inhibitors.

Side effects

Side effects are limited to the eyes due to topical application. These include:

• Increased intraocular pressure
• Burning sensation
• Photophobia
• Blurred vision
• Irritation
• Conjunctivitis
• Punctate keratitis
• Synechiae

Contraindications and precautions

If allergy to the active ingredient is known, do not administer.