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Pharmacology for Nurses

38.4 Antiglaucoma Drugs

Pharmacology for Nurses38.4 Antiglaucoma Drugs

Learning Outcomes

By the end of this section, you should be able to:

  • 38.4.1 Identify the characteristics of antiglaucoma drugs used to treat glaucoma-related eye disorders.
  • 38.4.2 Explain the indications, actions, adverse reactions, and interactions of antiglaucoma drugs used to treat glaucoma-related eye disorders.
  • 38.4.3 Describe the nursing implications of antiglaucoma drugs used to treat glaucoma-related eye disorders.
  • 38.4.4 Explain the client education related to antiglaucoma drugs used to treat glaucoma-related eye disorders.

There are two common forms of glaucoma: primary open-angle glaucoma (POAG), which is the most common form, and acute angle-closure (narrow-angle) glaucoma. These differ with respect to underlying pathology and treatment. Treatment of POAG focuses on reducing elevated IOP, the only risk factor that can be modified. Although no cure exists, reducing IOP can slow or even cease disease progression. Drugs lower IOP by either promoting aqueous humor drainage or reducing the production of aqueous humor. First-line drugs belong to three classes: beta-adrenergic blockers (beta blockers), alpha-2 adrenergic agonists, and prostaglandin analogs. Carbonic anhydrase inhibitors are considered second-line drugs. All of these medications are available in ophthalmic form, which is the preferred route. Because these classifications lower IOP by different mechanisms, combined therapy is usually more effective than monotherapy. If sufficient amounts of drug enter the circulation, systemic adverse effects may occur (Farkouh et al., 2016).

Angle-closure glaucoma is triggered by displacement of the iris where it covers the trabecular meshwork. The angle between the cornea and the iris is greatly reduced. This prevents aqueous humor from leaving the anterior chamber. IOP levels increase rapidly to dangerous levels. The client will complain of severe ocular pain and headache. Permanent vision loss may occur within 24–48 hours if left untreated. Treatment consists of a combination of drugs to suppress symptoms. Once the IOP is reduced to a safe level, the client will undergo surgery on the iris. This is performed to allow unobstructed outflow of aqueous humor.

Nonadherence is an issue for POAG drugs for multiple reasons. These include the asymptomatic nature of the condition such that clients may feel drug therapy is unnecessary, frequent dosing intervals, multiple drugs to administer, and age-related issues (see the box below). It is essential to emphasize to the client the importance of having regular eye exams to track progress or identify complications (Centers for Disease Control and Prevention, 2020).

Special Considerations

Older Adults

Glaucoma affects older adults more than any other population. Due to the complexity of treatment, older adults may struggle with following the treatment plan. This occurs for various reasons including:

  • Forgetfulness due to mild cognitive impairment (MCI) or dementia
  • Inability to remember in which sequence to administer the multiple drugs
  • High cost
  • Inability to properly instill eye medication
  • Medication causing temporary blurry vision, leading to an increased risk for falls

Concerns related to specific drug classifications include:

  • Beta blockers may exacerbate heart failure in those who have a history of this condition.
  • Alpha-2 agonists can cause orthostatic hypotension, creating a risk for falls.
  • Those with inadequate renal function should avoid carbonic anhydrase inhibitors.

Beta-Adrenergic Blockers

Beta blockers reduce IOP by decreasing the production of aqueous humor. They are mainly used to treat POAG. These drugs are suitable for both initial and maintenance therapy. Beta blockers, in conjunction with other drugs, are also used for emergency management of acute narrow-angle glaucoma. Some ophthalmic beta blockers can be absorbed in sufficient amounts to create systemic adverse effects, including angina, upper respiratory infection, and muscle or joint pain (Haga et al., 2022); therefore, health care personnel and clients should be aware of these. This classification of drugs does not cause miosis like other classes and must be used in combination for angle-closure glaucoma.

In some clients, the lowering of intraocular pressure may require a few weeks to stabilize. More information on systemic administration of this classification can be found in Antihypertensive and Antianginal Drugs.

Betaxolol Hydrochloride (Cardioselective)

Betaxolol is a selective blocker for the beta-1 adrenergic receptors. The onset of this drug generally occurs within 30 minutes, and peak effect is reached in about 2 hours after administration. A single dose has a duration of 12 hours. Studies have shown clients treated with this drug for up to 3 years have maintained lowered IOP levels (DailyMed, Betaxolol, 2023).

Timolol Hydrochloride (Nonselective)

The onset of timolol is 30 minutes. Peak effects occur in 1–2 hours, and the duration of action is 24 hours. This allows the drug to be given once daily. Clients studied over a period of 1 year exhibited well-maintained IOP levels (DailyMed, Timolol, 2023).

Clinical Tip

Identifying Names of Beta Blockers

All beta blockers end in the suffix “olol.” This is useful to know when the nurse does not recognize the drug’s name but can identify it is a beta blocker based on its suffix.

Table 38.14 lists common beta-adrenergic blockers and typical routes and dosing for adult clients.

Drug Routes and Dosage Ranges
Betaxolol hydrochloride
(Betoptic)
Ophthalmic dosage (0.25% suspension): 1 drop in affected eye(s) twice daily; maximum dose: 2 drops/day.
Ophthalmic dosage (0.5% solution): 1–2 drops in affected eye(s) twice daily; maximum dose: 4 drops/day.
Carteolol hydrochloride
(Ocupress)
1 drop 1% solution applied to conjunctiva of affected eye(s) twice daily; maximum dose: 2 drops/day.
Timolol hydrochloride
(Timoptic)
Ophthalmic dosage (solution): 1 drop of 0.25% solution in affected eye(s) twice daily; may increase to 1 drop of 0.5% solution twice daily, if necessary for adequate reduction of intraocular pressure. Dosage may be reduced to 1 drop daily if effective to maintain reduced pressure.
Ophthalmic dosage (Timoptic-XE gel): 1 drop of 0.25% solution in affected eye(s) once daily; may increase to 1 drop of 0.5% solution once daily, if necessary for adequate reduction of intraocular pressure. Doses greater than 1 drop of the 0.5% solution once daily have not been studied.
Table 38.14 Drug Emphasis Table: Beta-Adrenergic Blockers (source: https://dailymed.nlm.nih.gov/dailymed/)

Adverse Effects and Contraindications

Ocular beta-adrenergic blockers are contraindicated in clients who have a known hypersensitivity to any of the ingredients. They also are contraindicated in clients with sinus bradycardia, second- or third-degree AV block, cardiogenic shock, or severe heart failure.

Ocular adverse effects of beta-adrenergic blockers include eye pain, itching or discomfort, corneal sensitivity, eye erythema, keratitis, and photophobia. Although there is less concern about systemic effects when using beta blockers topically, some systemic absorption can occur when direct pressure is not applied to the medial canthus to occlude the nasolacrimal sac. If adequate amounts of drug reach the circulation, the client may experience some systemic adverse effects. These effects may include bradycardia, hypotension, heart block, or worsening of heart failure. Dyspnea and bronchospasm can occur in clients with severe respiratory conditions like chronic obstructive pulmonary diseases (COPD) and asthma who are taking a nonselective beta blocker (timolol) but are less likely to occur with cardioselective agents (betaxolol). Additionally, CNS effects including dizziness, vertigo, lethargy, and headaches have been associated with the use of beta blockers. Because of the potential effect on heart rate, beta blockers may mask the symptoms of hypoglycemia in clients with diabetes (DailyMed, Timolol, 2023).

Table 38.15 is a drug prototype table for beta-adrenergic blockers featuring timolol. It lists drug class, mechanism of action, adult dosage, indications, therapeutic effects, drug and food interactions, adverse effects, and contraindications

Drug Class
Beta-adrenergic blocker

Mechanism of Action
Reduces the production of aqueous humor by blocking the sympathetic nerve endings in the ciliary process
Drug Dosage
Ophthalmic dosage (solution): 1 drop of 0.25% solution in affected eye(s) twice daily; may increase to 1 drop of 0.5% solution twice daily, if necessary for adequate reduction of intraocular pressure. Dosage may be reduced to 1 drop daily if effective to maintain reduced pressure.
Ophthalmic dosage (Timoptic-XE gel): 1 drop of 0.25% solution in affected eye(s) once daily; may increase to 1 drop of 0.5% solution once daily, if necessary for adequate reduction of intraocular pressure. Doses greater than 1 drop of the 0.5% solution once daily have not been studied.
Indications
Primary open-angle glaucoma
Ocular hypertension

Therapeutic Effects
Decreases the amount of aqueous humor in the anterior chamber
Drug Interactions
Other antihypertensives

Food Interactions
No significant interactions
Adverse Effects
Transient ocular stinging
Bradycardia
Second- or third-degree heart block
Hypotension
Bronchospasm
Contraindications
Sinus bradycardia
Atrioventricular block
Heart failure
Cardiogenic shock
COPD
Asthma

Caution:
Diabetes mellitus (due to masking symptoms of hypoglycemia)
COPD
Asthma
Table 38.15 Drug Prototype Table: Timolol (source: https://dailymed.nlm.nih.gov/dailymed/)

Nursing Implications

The nurse should do the following for clients who are taking beta-adrenergic blockers:

  • Review the client’s cardiovascular and respiratory history.
  • Obtain information about the client’s smoking and alcohol use.
  • Monitor the client’s heart rate and rhythm.
  • Periodically assess blood pressure.
  • Assess respiratory status, such as respiratory rate, lung sounds, and difficulty breathing.
  • Monitor for signs of hypoglycemia in clients with diabetes.
  • Emphasize the importance of holding pressure against the lacrimal sac at the medial canthus when administering.
  • Provide client teaching regarding the drug and when to call the health care provider. See below for client teaching guidelines.

Client Teaching Guidelines

The client taking a beta-adrenergic blocker should:

  • Notify their provider if they are pregnant or planning to become pregnant.
  • Notify the health care provider if dizziness, shortness of breath, wheezing, excess fatigue, peripheral edema, or palpitations occur.
  • Be certain they occlude the inner canthus to avoid systemic absorption.
  • Identify signs/symptoms of hypoglycemia and monitor blood glucose levels if they have diabetes because these drugs may mask hypoglycemia.

The client taking a beta-adrenergic blocker should not:

  • Change positions quickly to avoid falls (especially older adults) because this may cause dizziness, which may result in a fall.
  • Wear contact lenses during administration and for 15 minutes afterward.
  • Operate machinery if feeling dizzy or lightheaded.

Carbonic Anhydrase Inhibitors

This classification of drugs reduces IOP by decreasing production of aqueous humor. They are not as effective as others; however, they are very beneficial when used as an adjunct therapy with other drug classes. Carbonic anhydrase is an enzyme found in many tissues of the body, including the eye. It speeds up the reaction of hydrating carbon dioxide and dehydrating carbonic acid.

During chronic use, dorzolamide accumulates in red blood cells (RBCs) as it binds to carbonic anhydrase. When the drug is stopped, it will wash out of the RBCs (DailyMed, Dorzolamide, 2021). Brinzolamide and dorzolamide have the same effects. A combination drug consisting of dorzolamide and timolol exists. The combination provides an additive effect for decreasing the production of aqueous humor. The therapeutic and adverse effects of timolol are discussed in a previous section of this chapter.

Table 38.16 lists common carbonic anhydrase inhibitors and typical routes and dosing for adult clients.

Drug Routes and Dosage Ranges
Brinzolamide 1% solution
(Azopt)
1 drop, 3 times daily.
Dorzolamide 2% solution
(Trusopt)
1 drop, 3 times daily when used alone.
1 drop, twice daily if used in combination with other topical glaucoma treatment.
Table 38.16 Drug Emphasis Table: Carbonic Anhydrase Inhibitors (source: https://dailymed.nlm.nih.gov/dailymed/)

Adverse Effects and Contraindications

Clients with sulfonamide hypersensitivity can experience severe or even fatal reactions, such as Stevens–Johnson syndrome, toxic epidermal necrolysis, hepatic necrosis, aplastic anemia, or agranulocytosis. Sensitivity can occur regardless of the route of administration. If there are any signs of an allergic reaction, the client should notify the provider immediately. Local ocular adverse effects occur with chronic administration (DailyMed, Brinzolamide, 2023). Although acid–base imbalance and electrolyte disturbances primarily occur with the oral form, the potential should be considered with clients receiving this classification via the topical route. The risk of metabolic acidosis is compounded with concurrent use of high-dose salicylic acid. These adverse effects do disappear once the underlying condition is treated (Tang et al., 2023). Other adverse effects include alopecia, chest pain, conjunctivitis, diarrhea, diplopia (double vision), dizziness, dry mouth, dyspnea, dyspepsia, eye fatigue, hypertonia, keratoconjunctivitis, keratopathy, kidney pain, lid margin crusting or a sticky sensation, nausea, pharyngitis, tearing, and urticaria (DailyMed, Dorzolamide, 2021).

Table 38.17 is a drug prototype table for carbonic anhydrase inhibitors featuring dorzolamide. It lists drug class, mechanism of action, adult dosage, indications, therapeutic effects, drug and food interactions, adverse effects, and contraindications.

Drug Class
Carbonic anhydrase inhibitor

Mechanism of Action
Reduces the production of aqueous humor from the ciliary process by slowing the formation of bicarbonate ions with subsequent reduction in sodium and fluid transport
Drug Dosage
1 drop, 3 times daily when used alone.
1 drop, twice daily if used in combination with other topical glaucoma treatment.
Indications
Primary open-angle glaucoma
Ocular hypertension

Therapeutic Effects
Decreases the level of IOP
Drug Interactions
High-dose salicylates
Oral carbonic anhydrase inhibitors

Food Interactions
No significant interactions
Adverse Effects
Ocular burning and stinging
Bitter taste
Superficial punctate keratitis
Ocular allergic reaction (conjunctivitis, eyelid edema)
Eye redness, photophobia, tearing
Metabolic acidosis/hyperkalemia
Contraindications
Allergy to sulfonamides
Hypersensitivity to any component of this product
Table 38.17 Drug Prototype Table: Dorzolamide (sources: https://dailymed.nlm.nih.gov/dailymed/; Hoffmanova & Sanchez, 2018)

Nursing Implications

The nurse should do the following for clients who are taking carbonic anhydrase inhibitors:

  • Monitor potassium levels periodically in clients with impaired renal function.
  • Assess for signs/symptoms of metabolic acidosis, such as rapid breathing in clients with impaired renal function.
  • Teach the client that they may experience a bitter taste and that this is not harmful.
  • Provide client teaching regarding the drug and when to call the health care provider. See below for client teaching guidelines.

Client Teaching Guidelines

The client taking a carbonic anhydrase inhibitor should:

  • Be acclimated to the medication before operating machinery because they may experience fatigue, tiredness, or dizziness.
  • Be aware that they may experience a bitter taste, stinging, burning, or conjunctival irritation.
  • Stop taking the drug and contact their health care provider if they develop conjunctivitis or eyelid edema.
  • Contact the health care provider immediately with any manifestations of ocular or systemic allergic reactions, such as skin rash, jaundice, right upper quadrant (RUQ) pain, or easy bruising (Mayo Clinic, 2023a).

The client taking a carbonic anhydrase inhibitor should not:

  • Wear contact lenses during administration and for 15 minutes afterward because the preservative in the medication will bind to the contacts.

Prostaglandin Analogues

These drugs are as effective as beta blockers without the serious adverse effects. The recommended daily dosage produces the same reduction in IOP as does twice-daily timolol. Prostaglandin analogues are considered first-line agents for glaucoma, especially in clients with cardiac conditions. In contrast to beta blockers, these drugs lower IOP by relaxing the ciliary muscle to facilitate aqueous humor outflow. If the drug is given more frequently or at a higher dose, this action can have the opposite effect and decrease the IOP-lowering effect (DailyMed, Latanoprost, 2023).

Latanoprost

The onset of action for latanoprost occurs in about 3–4 hours, and peak effect is reached in 8–12 hours. This drug has a 24-hour duration of action (DailyMed, Latanoprost, 2023).

Bimatoprost

The actions and adverse effects of bimatoprost are the same as those of latanoprost. When marketed as Latisse, it is used for the specific purpose of increasing eyelash length, darkening lashes, and making the lashes thicker (DailyMed, Bimatoprost, 2022).

Travoprost

The actions and adverse effects of travoprost are the same as those of latanoprost. This drug was found to be more effective in Black clients than in other groups. The reason for this is unknown (DailyMed, Travoprost, 2020).

Clinical Tip

Identifying Names of Prostaglandin Analogues

All prostaglandin analogues end in the suffix “prost.” This is useful to know when the nurse does not recognize the drug’s name but can identify it is a prostaglandin analogue based on its suffix.

Table 38.18 lists common prostaglandin analogues and typical routes and dosing for adult clients.

Drug Routes and Dosage Ranges
Latanaprost 0.005% solution
(Xalatan)
1 drop in the affected eye(s) once daily in the evening.
Bimatoprost 0.01% and 0.03% solution
(Lumigan)
1 drop in the affected eye(s) once daily in the evening.
Travoprost 0.004% solution
(Travatan)
1 drop in the affected eye(s) once daily in the evening; maximum dose: 1 drop per day per affected eye.
Table 38.18 Drug Emphasis Table: Prostaglandin Analogues (source: https://dailymed.nlm.nih.gov/dailymed/)

Adverse Effects and Contraindications

On rare occasions and for reasons unknown, this drug classification can cause migraines. The most common adverse effect is ocular hyperemia, which is engorgement of ocular blood vessels.

There are two main contraindications: hypersensitivity and active intraocular inflammation. Clients with iritis or uveitis should not use this drug because the inflammation may worsen, which could have negative effects on vision (DailyMed, Latanoprost, 2023)

Table 38.19 is a drug prototype table for prostaglandin analogues featuring latanoprost. It lists drug class, mechanism of action, adult dosage, indications, therapeutic effects, drug and food interactions, adverse effects, and contraindications.

Drug Class
Prostaglandin analogue

Mechanism of Action
Reduces IOP by increasing the outflow of aqueous humor through relaxation of the ciliary process and increasing the outflow at both the uveoscleral and trabecular meshwork structures
Drug Dosage
1 drop in the affected eye(s) once daily in the evening.
Indications
Primary open-angle glaucoma
Ocular hypertension
Treatment of hypotrichosis of the eyelashes

Therapeutic Effects
Reduces the amount of IOP
Drug Interactions
No significant interactions

Food Interactions
No significant interactions
Adverse Effects
Ocular hyperemia
Intraocular inflammation (iritis/uveitis)
Foreign body sensation
Local irritation, stinging
Redness
Blurred vision
Heightened brown pigmentation of the iris
Increased pigmentation of the eyelid
Increased length and thickness of the eyelashes
Burning or stinging
Punctate keratopathy
Contraindications
Hypersensitivity to the active and inactive ingredients of the drug
Active intraocular inflammation

Caution:
Herpetic and bacterial keratitis
Table 38.19 Drug Prototype Table: Latanoprost 0.005% Ophthalmic Solution (source: https://dailymed.nlm.nih.gov/dailymed/)

Nursing Implications

The nurse should do the following for clients who are taking prostaglandin analogues:

  • Assess for ocular changes, including hyperemia, pruritus, conjunctivitis, and visual disturbances.
  • Explain the hyperpigmentation changes that can occur so the client is not alarmed. Be certain the client is aware that the hyperpigmentation of the iris is usually permanent, but the darkened skin of the eyelids more than likely will resolve.
  • Assess for hypersensitivity reactions, both locally and systemically, including stinging, painful eyes and blurry vision.
  • Explain that the medication should be administered at bedtime.
  • Provide client teaching regarding the drug and when to call the health care provider. See below for client teaching guidelines.

Client Teaching Guidelines

The client taking a prostaglandin analogue should:

  • Notify the health care provider of ocular redness, swelling, or visual changes.
  • Administer the medication at bedtime as ocular pressure is typically highest in the morning, so usage at night is a timely intervention to address an expected higher ocular pressure by morning.
  • Observe for the hyperpigmentation changes and increase in eyelash length.

The client taking a prostaglandin analogue should not:

  • Wear contact lenses during administration and for 15 minutes afterward because the preservative in the medication will bind to the contacts.
  • Skip follow-up appointments with the ophthalmologist for intraocular pressure measurements.

Rho Kinase Inhibitors

This drug class was approved in 2017. It decreases IOP by increasing aqueous humor outflow through the trabecular meshwork. The exact mechanism is unknown. Clinical trials have shown up to a 5 mm Hg reduction in the baseline IOP (DailyMed, Rhopressa, 2023).

The 0.02% solution of netarsudil (Rhopressa) is used to reduce IOP in clients with POAG. This drug is typically taken in the evening because IOP is elevated in the morning. The solution should not be administered while wearing contact lenses.

Adverse Effects and Contraindications

Conjunctival hyperemia is the most common ocular adverse effect. Clients may experience discomfort and erythema in the early phase of treatment; however, these will subside as the drug is continued. Corneal verticillata (gray-brown opacities) were noted to develop at 4 weeks of therapy. This reaction did not affect visual acuity. Most corneal verticillata will disappear once the medication is discontinued. Besides the physical aspect, conjunctival hemorrhage is harmless and will resolve on its own. Other common adverse reactions include conjunctival hemorrhage, corneal staining, blurred vision, increased lacrimation, and reduced visual acuity. Safety and effectiveness in clients under age 18 have not been established. Hypersensitivity is currently the only major contraindication (DailyMed, Rhopressa, 2023).

Table 38.20 is a drug prototype table for rho kinase inhibitors featuring netarsudil. It lists drug class, mechanism of action, adult dosage, indications, therapeutic effects, drug and food interactions, adverse effects, and contraindications.

Drug Class
Rho kinase inhibitor 0.02% solution

Mechanism of Action
Inhibits the rho kinase enzyme, thus reducing IOP by increasing the outflow of aqueous humor through the trabecular meshwork
Drug Dosage
1 drop of solution in the affected eye(s) every evening.
Indications
Primary open-angle glaucoma
Ocular hypertension

Therapeutic Effects
Reduces elevated IOP
Increased healing of corneal epithelium
Decreases progression of diabetic retinopathy
Drug Interactions
No significant interactions

Food Interactions
No significant interactions
Adverse Effects
Conjunctival hyperemia
Eye discomfort and/or erythema during instillation
Conjunctival hemorrhage
Corneal verticillata
Increased lacrimation
Reduced visual acuity
Contraindications
None
Table 38.20 Drug Prototype Table: Netarsudil 0.02% Ophthalmic Solution (sources: https://dailymed.nlm.nih.gov/dailymed/; Moshirfar et al., 2018)

Nursing Implications

The nurse should do the following for clients who are taking rho kinase inhibitors:

  • Inform the client they may experience discomfort and redness upon instillation during the initial treatment phase, but this will subside.
  • Encourage the client not to discontinue medication based on the adverse effects without contacting the health care provider.
  • Maintain a safe environment to prevent falls.
  • Provide client teaching regarding the drug and when to call the health care provider. See below for client teaching guidelines.

Client Teaching Guidelines

The client taking a rho kinase inhibitor should:

  • Notify the health care provider of eye swelling or changes in vision or if they experience conjunctivitis or eyelid discomfort.
  • Understand the eye changes are mainly harmless and will subside spontaneously or once the drug is stopped.

The client taking a rho kinase inhibitor should not:

  • Double up on a dose if one is missed because this is not well tolerated.
  • Wear contact lenses during administration and for 15 minutes afterward because the preservative in the medication will bind to the contacts.
  • Stop taking the drug without contacting the health care provider.

Alpha-2 Adrenergic Agonists

Alpha-2 adrenergic agonists work by reducing aqueous outflow to lower pressure. Combigan is an alpha-2 adrenergic agonist combined with a beta blocker (timolol). This drug synergistically uses both mechanisms of action to reduce IOP. If an ocular beta blocker is contraindicated, an alpha-2 adrenergic agent can be used alone. Brimonidine (Alphagan P) has a rapid onset of action with a half-life of 2 hours. Brimonidine reduces aqueous humor production and increases uveoscleral outflow in clients with POAG and ocular hypertension. It may have properties in delaying optic nerve degeneration and may protect retinal neurons from dying due to ischemia.

A fixed-dose combination drug consisting of brimonidine and timolol exists. The combination provides an additive effect for decreasing the production of aqueous humor. The therapeutic and adverse effects of each drug class are discussed previously in this chapter.

Adverse Effects and Contraindications

Brimonidine is contraindicated in those under age 2 because they are at a higher risk of CNS depression. Severe cardiovascular disease and vascular and cerebral insufficiency can be aggravated by this drug classification (DailyMed, Brimonidine, 2023). There has been a causal relationship noted between depression and alpha-2 agonists. Because the alpha-2 adrenergic receptors are part of the CNS, dilation of the pupils can occur, which will further impede the outflow of aqueous humor and exaggerate closed-angle glaucoma.

Table 38.21 is a drug prototype table for alpha-2 adrenergic agonists featuring brimonidine. It lists drug class, mechanism of action, adult dosage, indications, therapeutic effects, drug and food interactions, adverse effects, and contraindications.

Drug Class
Alpha-2 adrenergic agonist

Mechanism of Action
Reduces production of aqueous humor and increases uveoscleral outflow
Drug Dosage
1 drop in the affected eye(s) every 8 hours of 0.1% or 0.15% solution.
Indications
For lowering IOP in clients with open-angle glaucoma or ocular hypertension

Therapeutic Effects
Decreases pressure in the anterior chamber of the eye
Drug Interactions
Monoamine oxidase (MAO) inhibitors
Selective serotonin reuptake inhibitors (SSRIs)
CNS depressants
Antihypertensives/cardiac glycosides

Food Interactions
No significant interactions
Adverse Effects
Ocular hypotension
Systemic hypotension
Tachycardia/bradycardia
Fatigue
Headache/dizziness
Reduced attention span and alertness
CNS depression
Cough/dyspnea
Sinusitis/nasal dryness
Blepharitis
Conjunctival edema/hemorrhage
Eye dryness/irritation
Allergic conjunctivitis/hyperemia/pruritus
Contraindications
<2 years of age
Hypersensitivity to the active and inactive ingredients of the drug

Caution:
Vascular insufficiency
Advanced cardiac disease
Cerebral insufficiency
Raynaud’s disease
Thromboangiitis obliterans (Buerger’s disease, where blood vessels are occluded in the hands and feet)
Depression
Table 38.21 Drug Prototype Table: Brimonidine (source: https://dailymed.nlm.nih.gov/dailymed/)

Nursing Implications

The nurse should do the following for clients who are taking alpha-2 adrenergic agonists:

  • Review the client’s past medical history and medications.
  • Monitor the client’s blood pressure and heart rate periodically.
  • Assess the client’s mental status and alertness.
  • Maintain a safe environment and reduce risk of falls.
  • Evaluate the upper respiratory system for cough, sinus pressure, dyspnea, and nasal dryness.
  • Check for hypersensitivity reaction.
  • Emphasize to the client the importance of keeping follow-up appointments with their health care provider.
  • Provide client teaching regarding the drug and when to call the health care provider. See below for client teaching guidelines.

Client Teaching Guidelines

The client taking an alpha-2 adrenergic agonist should:

  • Notify the health care provider of severe headaches, visual disturbance, dizziness, syncope, excessive fatigue, difficulty concentrating, or vision changes.
  • Check their blood pressure and heart rate at least weekly while maintaining a log of readings.

The client taking an alpha-2 adrenergic agonist should not:

  • Wear contact lenses during administration and for 15 minutes afterward because the preservative in the medication will bind to the contacts.
  • Drive or engage in activity that requires attention and concentration until they know how the medications affects them.
  • Get up quickly and ambulate because the drug can cause orthostatic hypotension and dizziness.
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