Why Every Optometry Student Should Know This About Miotics and Combination Drugs

It is important to note that we sometimes can combine these medications together to increase patient compliance and convenience.

In efforts to wrap up our comprehensive outline of common glaucoma medications, today we will discuss a group of less widely used glaucoma medications, miotics, as well as review the combination drugs that are popular and available today!

Miotics

Mechanism of Action:

Primary open angle glaucoma: stimulation of muscarinic receptors on pupillary sphincter muscle and ciliary body, thus reducing intraocular pressure by increasing outflow through the trabecular meshwork route.

Angle closure glaucoma: contraction of the pupillary sphincter muscle, resulting in miosis and subsequent pulling of the peripheral iris away from the trabecular meshwork, thus opening the anterior chamber angle.

Dosage: Four times daily (QID) as monotherapy; twice daily (BID) as adjunctive treatment.

Side effects:

• Ocular
• Accommodative spasm
• Miosis
• Pupillary block
• Increased chance of vitreoretinal traction
• Systemic
• Headache
• Nausea
• Vomiting
• Diarrhea
• Salivation
• Weakness

Preparations:

• Pilocarpine: This medication is available in concentrations from 0.25% to 10%. Pilocarpine gel (Pilogel®) is also available to use at night.
• Carbachol and Echothiophate: These medications are very rarely used to treat IOP in patients with glaucoma due their significant side effect profiles.

Combination Medications

 Mechanism of action, dosage and side effects vary depending on class of drugs that are present in the combination.

Preparations:

• Cosopt®: Timolol and dorzolamide (beta-blocker and carbonic anhydrase inhibitor). Cosopt® is typically dosed BID. 
• Combigan®: Timolol and brimonidine (beta-blocker and alpha-2 agonist). Combigan® is usually dosed BID.
• Simbrinza®: Combination of brinzolamide and brimonidine (carbonic anhydrase inhibitor and alpha-2 agonist). Recommended dosage for Simbrinza® is TID. Simbrinza® does not contain a beta-blocker (useful in patients in which beta-blockers are contraindicated).
• Rocklatan®: Combination of netarsudil and latanoprost (rho kinase inhibitor and prostaglandin analog). Recommended dosage for Rocklatan® is QHS. Rocklatan® was FDA approved in 2019 for use in open angle glaucoma or ocular hypertension.

Knowing and understanding how to apply the different classes of glaucoma medications can be intimidating. With this comprehensive outline of the most common medications, you have a starting point in treating your mild to most complicated glaucoma cases.

When you’re stuck and don’t know what to do, remember to review the patient’s current medications and systemic conditions and be sure to exclude treatments that are contraindicated, then brush up on dosing schedules and you’ll be good to go!

-   Dr. Amadian