Carbachol is a potent cholinergic (parasympathomimetic) agent which produces constriction of the iris and ciliary body resulting in reduction in intraocular pressure.

Bethanechol is a parasympathomimetic choline carbamate that selectively stimulates muscarinic receptors with little effect on nicotinic receptors. Bethanechol is indicated for the treatment of acute postoperative and postpartum nonobstructive (functional) urinary retention and for neurogenic atony of the urinary bladder with retention.

Pilocarpine is an alkaloid extracted from plants of the genus Pilocarpus. The drug stimulates the muscarinic receptors (especially M3, which is expressed in smooth muscles and glands) and thus induces salivation, hypertension and water intake. Pilocarpine was appoved by FDA for the alleviation of symptoms of xerostomia in patients who have undergone radiation therapy to their head and neck cancer and in patients with Sjogren's Syndrome. Ophthalmic solution of the drug is prescribed for the treatment of glaucoma, ocular hypertension, postoperative elevated intraocular pressure, etc.

Isopilocarpine is a diastereomer of pilocarpine. Isopilocarpine coexists with pilocarpine in nature and is also a degradation product of pilocarpine after oral administration to humans. It can be found in the leaves of some Pilocarpus species. Pilocarpine targets the muscarinic receptors and is approved for treatment of xerostomia. Isopilocarpine is often present in formulations of pilocarpine but has no appreciable effect on muscarinic receptors.

Timolol is the non-selective Beta antagonist used as eye drops to treat increased pressure inside the eye such as in ocular hypertension and glaucoma. Timolol is also used for high blood pressure, chest pain due to insufficient blood flow to the heart, to prevent further complications after a heart attack, and to prevent migraines. Timolol is a beta1 and beta2 (non-selective) adrenergic receptor antagonist that does not have significant intrinsic sympathomimetic, direct myocardial depressant, or local anesthetic (membrane-stabilizing) activity. Timolol, when applied topically on the eye, has the action of reducing elevated, as well as normal intraocular pressure, whether or not accompanied by glaucoma. Elevated intraocular pressure is a major risk factor in the pathogenesis of glaucomatous visual field loss and optic nerve damage. The precise mechanism of the ocular hypotensive action of Timolol is not clearly established at this time. Tonography and fluorophotometry studies of the timolol maleate ophthalmic solution in man suggest that its predominant action may be related to the reduced aqueous formation. However, in some studies, a slight increase in outflow facility was also observed. In a study of plasma drug concentration in six subjects, the systemic exposure to timolol was determined following once daily administration of Timolol Maleate Ophthalmic Gel Forming Solution 0.5% in the morning. The mean peak plasma concentration following this morning dose was 0.28 ng/mL. Side effects, when given in the eye, include burning sensation, eye redness, superficial punctate keratopathy, corneal numbness.

Pilocarpine is an alkaloid extracted from plants of the genus Pilocarpus. The drug stimulates the muscarinic receptors (especially M3, which is expressed in smooth muscles and glands) and thus induces salivation, hypertension and water intake. Pilocarpine was appoved by FDA for the alleviation of symptoms of xerostomia in patients who have undergone radiation therapy to their head and neck cancer and in patients with Sjogren's Syndrome. Ophthalmic solution of the drug is prescribed for the treatment of glaucoma, ocular hypertension, postoperative elevated intraocular pressure, etc.

Isopilocarpine is a diastereomer of pilocarpine. Isopilocarpine coexists with pilocarpine in nature and is also a degradation product of pilocarpine after oral administration to humans. It can be found in the leaves of some Pilocarpus species. Pilocarpine targets the muscarinic receptors and is approved for treatment of xerostomia. Isopilocarpine is often present in formulations of pilocarpine but has no appreciable effect on muscarinic receptors.