Mechanism of Action

Pilocarpine hydrochloride is a direct acting cholinergic parasympathomimetic agent which acts through direct stimulation of muscarinic receptors and smooth muscle such as the iris and secretory glands. Pilocarpine contracts the ciliary muscle, causing increased tension on the scleral spur and opening of the trabecular meshwork spaces to facilitate outflow of aqueous humor. Outflow resistance is reduced, lowering intraocular pressure (IOP). Pilocarpine also produces miosis through contraction of the iris sphincter muscle. Miosis relieves appositional angle narrowing and closure, which lowers IOP in certain types of angle-closure glaucoma.

Pharmacokinetics

Systemic exposure to pilocarpine was evaluated in 14 healthy subjects administered 2 drops of Isopto® Carpine (pilocarpine hydrochloride ophthalmic solution) 4% to both eyes four times daily for eight days. A comparison of C max values on Days 5 and 8 indicated that pilocarpine concentrations in plasma reached steady-state following topical administration of Isopto® Carpine (pilocarpine) 4%. The mean (SD) Cmax and AUC0-last values on Day 8 were 3.7 (3.2) ng/mL and 7.7 (8.4) ngxhour/mL, respectively. The Tmax values on Day 8 ranged from 0.5 to 1 hour.

Clinical Studies

In clinical trials reported in the medical literature, pilocarpine ophthalmic solution reduced intraocular pressure (IOP) by 3-7 mm Hg in patients with open-angle glaucoma. Pilocarpine ophthalmic solution has also been shown to be effective in the induction of miosis, in the prevention of postoperative elevated IOP, and in the management of acute angle-closure glaucoma.

Last reviewed on RxList: 7/21/2010
This monograph has been modified to include the generic and brand name in many instances.