Antiglaucoma medications: Nursing pharmacology

Antiglaucoma medications are used to treat glaucoma, which refers to a group of eye conditions in which drainage of aqueous humor out of the eye is restricted, causing an increased intraocular pressure.

Now, antiglaucoma medications can be divided based on their mechanism of action into two classes: those that decrease aqueous humor production, and those that increase aqueous outflow.

Medications to decrease aqueous humor production include beta-adrenergic blockers, like timolol, levobunolol, and betaxolol; and carbonic anhydrase inhibitors, like brinzolamide and acetazolamide.

On the other hand, medications to improve aqueous outflow include prostaglandin analogs, like latanoprost and bimatoprost; and cholinergic agents, like pilocarpine.

Additionally, some medications can work by both decreasing the production and increasing the outflow of aqueous humor, including alpha-adrenergic agonists like brimonidine and apraclonidine. Finally, acute cases can be treated with osmotic diuretics, like mannitol.

After administration, osmotic diuretics act as hyperosmotic agents by creating an osmotic gradient that attracts water out of the eyes and into the blood, to rapidly decrease intraocular pressure.

Almost all medications are administered as eye drops, with the exception of acetazolamide and mannitol, which can be administered orally and intravenously.

Alright, now the most common side effects of antiglaucoma eye drops include blurred vision, eye redness, stinging, and itching following application.

In particular, beta-adrenergic blockers cause neurological side effects like headache, depression, hallucination, and sleep problems, like insomnia and nightmares.

Other side effects include hypotension, decreased cardiac output, and bradycardia, as well as bronchospasm leading to cough or dyspnea.

On the other hand, carbonic anhydrase inhibitors may cause neurologic side effects, such as dizziness, drowsiness, and fatigue.

Carbonic anhydrase inhibitors can also cause gastrointestinal side effects, such as nausea, vomiting, and diarrhea or constipation.

Now, acetazolamide in particular can also often cause electrolyte abnormalities, such as hypokalemia and hyperchloremia; as well as altered blood glucose levels, which can lead to hypo- or hyperglycemia.

This can manifest as neurological side effects like headache, seizures, mental status changes, and paresthesia.

Finally, acetazolamide can cause serious side effects like hepatotoxicity, and has a boxed warning for blood dyscrasias, like pancytopenia, as well as for hypersensitivity reactions, such as Stevens-Johnson syndrome and toxic epidermal necrolysis.

On the other hand, prostaglandin analogs are most often associated with side effects involving the eye itself, including darkening of the iris and eyelids, as well as eyelash growth.

Cholinergic agents can cause miosis, increased lacrimation, and decreased night vision. Systemic side effects may include sweating, drooling, and gastrointestinal problems, among others.

Alpha-adrenergic agonists may cause side effects like eye burning and tearing, photophobia, and blurred vision. In addition, some clients may experience headache, dizziness, and somnolence, as well as dry nose or mouth, coughing, and dyspnea.

Finally, the most common side effect of osmotic diuretics is frequent urination. In addition, these medications can also pull water from cells into the extracellular space, which could worsen edematous conditions like heart failure and pulmonary edema.

As more water gets pulled into the blood vessels, the concentration of sodium will go down, causing dilutional hyponatremia. Other side effects include dehydration, hypotension, confusion, headache, nausea, and vomiting, which occur due to the rapid fluid shift.

Now, antiglaucoma medications should be used with caution during pregnancy and breastfeeding, while contraindications depend on the specific medication.

Beta-adrenergic blockers and alpha-adrenergic agonists should be avoided in clients with cardiovascular conditions like hypotension, severe bradycardia, second or third degree atrioventricular block, and decompensated heart failure.

In addition, beta-blockers should be used with caution in clients with respiratory disorders, such as asthma and chronic obstructive pulmonary disease or COPD; as well as in those with diabetes mellitus.

On the other hand, alpha-adrenergic agonists should be used with caution in clients with cerebrovascular disease or Raynaud phenomenon.

Next, carbonic anhydrase inhibitors are contraindicated in clients with severe renal or hepatic disease, severe renal or hepatic failure, sickle cell anemia, or Addison’s disease; and should be used with caution in clients with COPD.

Finally, osmotic diuretics are contraindicated in clients with severe hypovolemia or dehydration, severe renal impairment and anuria; and should be used with caution in clients with edematous conditions, such as heart failure and pulmonary edema.