Name of the Carbonic anhydrase inhibitors Diuretics Drugs
- Acetazolamide
- Methazolamide
- Azopt(Brinzolamide)
- Trusopt(Dorzolamide)
- Cosopt
- Simbrinza
1.Acetazolamide
| Acetazolamide |
| Availability Tablet 125mg ,250mg powder for injection 500mg capsule, extended-release 500mg |
| Indications and Dosages To treat chronic simple (open angle) glaucoma Adults. 250 to 1,000 mg daily (divided for doses exceeding 250 mg). As short-term therapy to treat secondary glaucoma and preoperatively to treat acute congestive (closed angle) glaucoma Adults. 250 mg b.i.d. or every 4 hr; or 1 S.R. capsule (500 mg) b.i.d.; or 500 mg initially, followed by 125 to 250 mg every 4 to 6 hr for severe acute glaucoma. To initially lower intraocular pressure rapidly, 500 mg I.V.; may repeat in 2 to 4 hr in acute cases, depending on patient response. Oral therapy usually started after initial Children. 10 to 15 mg/kg daily in divided doses every 6 to 8 hr. Children. 5 to 10 mg/kg/dose every 6 hr. To induce diuresis in heart failure Adults. Initial: 250 to 375 mg or 5 mg/kg daily in morning. Maintenance: 250 to 375 mg or 5 mg/kg on alternate days or for 2 days followed by a drug-free day To treat drug-induced edema Adults. 250 to 375 mg daily for 1 to 2 days. Children. 5 mg/kg/dose daily in morning. To treat seizures, including generalized tonic-clonic, absence, and mixed seizures, and myoclonic jerk patterns Adults and children. 8 to 30 mg/kg daily in divided doses. Optimal: 375 to 1,000 mg daily. When used with other anticonvulsants, 250 mg daily. To prevent or relieve symptoms of acute mountain sickness Adults. 500 to 1,000 mg daily in divided doses, given 24 to 48 hr before ascent and continued for 48 hr or longer while at high altitude p.r.n. to control symptoms. |
Mechanism of Action
Inhibits the enyzme carbonic anhydrase, which normally appears in the eyes’ ciliary processes, brain’s choroid plexes, and kidneys’ proximal tubule cells. In the eyes, enzyme inhibition decreases aqueous humor secretion, which lowers intraocular pressure. In the brain, inhibition may delay abnormal, intermittent, and excessive discharge from neurons that cause seizures. In the kidneys, it increases bicarbonate excretion, which carries out water, potassium, and sodium, thus inducing diuresis and metabolic acidosis. This acidosis counteracts respiratory alkalosis and reduces symptoms of mountain sickness, including headache, dizziness, nausea, and dyspnea.
Pharmacokinetics
- Bioavailability: Rapidly absorbed orally
- Protein bound: 70-90%
- Metabolism: None
- Half-life: 2-4 hr (tablet)
- Dialyzable: Yes (hemodialysis)
- Excretion: Urine 90%
Contraindications
Chronic noncongestive closed-angle glaucoma; cirrhosis; hyperchloremic acidosis; hypersensitivity to acetazolamide; hypokalemia; hyponatremia; severe pulmonary obstruction; severe renal, hepatic, or adrenocortical impairment
Adverse Reactions
- CNS: Ataxia, confusion, depression, disorientation, dizziness, drowsiness, fatigue, fever, flaccid paralysis, headache, lassitude, malaise, nervousness, paresthesia, seizures, tremor, weakness
- EENT: Altered taste, tinnitus, transient myopia
- GI: Anorexia, constipation, diarrhea, hepatic dysfunction, melena, nausea, vomiting
- GU: Crystalluria, decreased libido, glycosuria, hematuria, impotence, nephrotoxicity, phosphaturia, polyuria, renal calculi, renal colic, urinary frequency
- HEME: Agranulocytosis, hemolytic anemia, leukopenia, pancytopenia, thrombocytopenia, thrombocytopenic purpura
- SKIN: Photosensitivity, pruritus, rash, Stevens-Johnson syndrome, urticaria
- Other: Acidosis, hyperuricemia, hypokalemia, weight loss
Nursing Considerations
- Use acetazolamide cautiously in patients with calcium-based renal calculi, diabetes mellitus, gout, or respiratory impairment.
- Know that acetazolamide may increase risk of hepatic encephalopathy in patients with hepatic cirrhosis.
- To avoid painful I.M. injections (caused by alkaline solution), give acetazolamide by mouth or I.V. injection if possible.
- Reconstitute each 500-mg vial with at least 5 ml sterile water for injection. Use within 24 hours because drug has no preservative.
- Monitor blood tests during acetazolamide therapy to detect electrolyte imbalances.
- Monitor fluid intake and output every 8 hours and body weight daily to detect excessive fluid and weight loss.
Patient Teaching
- Inform patient that acetazolamide tablets may be crushed and suspended in chocolate or another sweet syrup. Or, one tablet may be dissolved in 10 ml hot water and added to 10 ml honey or syrup.
- Advise patient to avoid hazardous activities if dizziness or drowsiness occurs.
- Instruct patient who takes high doses of salicylates to notify prescriber immediately about evidence of salicylate toxicity, such as anorexia, tachypnea, and lethargy.
- If patient plans to mountain climb, urge her to descend mountain gradually and to seek immediate medical care if symptoms of mountain sickness occur.
2.Methazolamide
| Methazolamide |
| Availability Tablet 25mg,50mg |
| Indications and Dosages To treat open-angle glaucoma Adults. 50 to 100 mg b.i.d. or t.i.d |
Mechanism of Action
Inhibits the enyzme carbonic anhydrase, which normally appears in renal proximal tubule cells, choroid plexus of the brain, and ciliary processes of the eye. By inhibiting this enzyme in the eyes, methazolamide decreases aqueous humor secretion, which reduces intraocular pressure.
Pharmacokinetics
- Half-life: 14 d
- Onset: 2-4 hr
- Max Effect: 6-8 hr
- Duration: 10-18 hr
- Bioavailability: absorbed more slowly than acetazolamide
- Excretion: urine 15%
Contraindications
Cirrhosis; hyperchloremic acidosis; hypersensitivity to methazolamide, other carbonic anhydrase inhibitors, or their components; hypokalemia; hyponatremia; severe adrenocortical, hepatic, or renal impairment
Adverse Reactions
- CNS: Confusion, depression, drowsiness, fatigue, fever, malaise, paresthesia, seizures, weakness
- EENT: Hearing loss, myopia (transient), taste perversion, tinnitus
- GI: Anorexia, diarrhea, nausea, vomiting
- GU: Crystalluria, nephrotoxicity, renal calculi
- SKIN: Photosensitivity, pruritus, rash, Stevens-Johnson syndrome, urticaria
- Other: Metabolic acidosis
Nursing Considerations
- Use methazolamide cautiously in patients with obstructive pulmonary disease.
- Monitor fluid intake and output, weight, and serum electrolyte levels during methazolamide therapy
Patient Teaching
- Direct patient to take methazolamide exactly as prescribed because increasing dosage may lead to metabolic acidosis. •Advise patient to take drug with food if GI distress occurs.
- Instruct patient to report if rash develops.
- Caution patient to avoid hazardous activities until drug’s CNS effects are known.
- Emphasize need to have regular eye examinations during methazolamide therapy.
3.Azopt (Brinzolamide)
| Azopt (Brinzolamide) |
| Availability ophthalmic suspension 1% |
Mechanism of Action
Inhibits carbonic anhydrase, which in turn causes aqueous humor secretion to decrease. This effect reduces intraocular pressure.
Pharmacokinetics
- Half-Life: 3.5-4 months
- Absorption: Some systemic
- Distribution: to RBCs
- Protein binding: 60%
- Excretion: Urine
Contraindications
- Hypersensitivity
- Known hypersensitivity to sulphonamides
- Severe renal impairment.
- Hyperchloraemic acidosis
Administration
May be used concomitantly with other topical ophthalmic drug products to lower intraocular pressure; if more than one topical ophthalmic drug being used, administer at least ten min apart
Warnings and precautions
- Like other topically applied ophthalmic agents, brinzolamide is absorbed systemically. Systemic absorption can be minimised by nasolacrimal occlusion (see section 4.2 Method of administration).
- AZOPT is a sulphonamide and, although administered topically, it is absorbed systemically. Therefore, the same types of undesirable effects that are attributable to sulphonamides may occur with topical administration. Hypersensitivity reaction including Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) can occur. At the time of prescription, patients should be advised of the signs and symptoms and monitored closely for skin reactions. If signs of serious reactions or hypersensitivity occur, use of this product should be discontinued immediately.
- There is limited experience with AZOPT eye drops in the treatment of patients with pseudoexfoliative glaucoma or pigmentaryglaucoma.
- AZOPT eye drops was primarily evaluated in concomitant administration with timolol during adjunctive glaucoma therapy. Therefore, there are limited data regarding the administration of brinzolamide with other antiglaucomatous agents
- AZOPT eye drops has not been studied in patients wearing contactlenses.
- Benzalkonium chloride may cause eye irritation and is known to discolour soft contact lenses. Patients should avoid contact with soft contact lenses. Patients must be instructed to remove contact lens prior to application of AZOPT eye drops and to wait at least 15 minutes before reinsertion.
- Potential rebound effects following cessation of treatment with AZOPT eye drops have not been studied; the IOP-lowering effect is expected to last for 5-7days.
- Oral carbonic anhydrase inhibitors may impair the ability to perform tasks requiring mental alertness and/or physical coordination. AZOPT eye drops is absorbed systemically and therefore this may occur with topical administration.
4.Trusopt (Dorzolamide)
| Trusopt (Dorzolamide) |
| Availability ophthalmic solution 2% (generic) |
| Indications and Dosages Ocular Hypertension Instill 1 gtt in affected eye(s) q8hr |
Mechanism of Action
Sulfonamide and carbonic anhydrase inhibitor that reduces the secretion of hydrogen ion at renal tubule and increases excretion of bicarbonate, potassium, sodium, and water, which in turn decreases aqueous humor secretion
Pharmacokinetics
- Absorption: Yes
- Half-life: 120 days
- Peak Plasma: 24 mcg/g (cornea); 27 mcg/g (iris/ciliary body), 7.8 mcg/mL (aqueous humor)
- Protein bound: 33% (to plasma proteins)
- Metabolism: Liver, by cytochrome P450 isozymes to N-desethyldorzolamide
- Excretion: Urine (80%)
Contraindications
Hypersensitivity
Severe renal impairment (CrCl<30 mL/min)
5.Acetazolamide
| Acetazolamide |
| Availability Tablet 125mg ,250mg powder for injection 500mg capsule, extended-release 500mg |
| Indications and Dosages Glaucoma Closed angle (acute congestive) glaucoma 500 mg PO/IV, followed by 125-250 mg PO q4hr Sustained release: 500 mg PO q12hr Open-angle (chronic simple) glaucoma 250 mg-1 g PO/IV qDay or divided q6-12hr Sustained release: 500 mg PO q12hr Secondary glaucoma 500 mg PO/IV, followed by 125-250 mg PO q4hr Sustained release: 500 mg PO q12hr Acute Altitude Sickness Immediate release: 500-1000 mg/day PO divided q8-12hr Extended release: 500-1000 mg PO q12-24hr Congestive Heart Failure CHF-associated edema 250-375 mg (5 mg/kg) PO qAM Seizure 8-30 mg/kg/day PO qDay or divided q12hr Drug-induced Edema 250-375 mg PO/IV qDay Epilepsy Tablet: 8-30 mg/kg/day PO qDay, OR divided q6-12 hr; not to exceed 30 mg/kg/day or 1 g/day |
Mechanism of Action
Carbonic anhydrase inhibitor that decreases rate of aqueous humor formation, in that way decreasing intraocular pressure
Inhibits H+ ion excretion in renal tubule, increasing sodium, potassium, bicarbonate, and water excretion and producing alkaline diuresis
Inhibits carbonic anhydrase in CNS, which in turn decreases abnormal and excessive discharge from the CNS neurons
Pharmacokinetics
- Bioavailability: Rapidly absorbed orally
- Protein bound: 70-90%
- Metabolism: None
- Half-life: 2-4 hr (tablet)
- Dialyzable: Yes (hemodialysis)
- Excretion: Urine 90%
Contraindications
- Hypokalemia
- Hyponatremia
- Hyperchloremic acidosis
- Hypersensitivity to acetazolamide or sulfa
- Liver disease
- Severe renal disease or dysfunction
- Long term use in noncongestive angle-closure glaucoma
- Cirrhosis
- Long-term administration in patients with chronic, noncongestive angle-closure glaucoma
6.Cosopt(timolol-dorzolamide)
| Cosopt(timolol-dorzolamide) |
| Availability Ophthalmic gel: 0.25%, 0.5% Ophthalmic solution: 0.25%, 0.5% Tablets: 5 mg, 10 mg, 20 mg |
| Indications and dosages ➣ Hypertension Adults: Initially, 10 mg P.O. b.i.d., given alone or with a diuretic; may increase at 7-day intervals as needed. Usual maintenance dosage is 10 to 20 mg daily in two divided doses, up to 60 mg/day. ➣ Acute MI Adults: 10 mg P.O. b.i.d. starting 1 to 4 weeks after MI ➣ To prevent vascular headaches Adults: Initially, 10 mg P.O. b.i.d. For maintenance, 20 mg may be given as a single daily dose. Total daily dosage may be increased to a maximum of 30 mg in divided doses or decreased to 10 mg/day, depending on response and tolerance. Withdraw drug if satisfactory response doesn’t occur after 6 to 8 weeks at maximum dosage. ➣ Elevated IOP in patients with ocular hypertension or open-angle glaucoma Adults: One drop of 0.25% to 0.5% ophthalmic solution in affected eye b.i.d., or 0.25% to 0.5% ophthalmic gel in affected eye once daily |
Mechanism of Action
Selectively blocks alpha1 and beta2 receptors in vascular smooth muscle and beta1 receptors in the heart. This reduces peripheral vascular resistance and blood pressure and relieves migraine headaches. Timolol’s potent beta blockade prevents the reflex tachycardia that typically occurs with most alpha blockers, and decreases cardiac excitability, cardiac output, and myocardial oxygen demand, thus preventing MI.
Administration
- Measure apical pulse before giving. If patient has significant bradycardia or tachycardia, withhold dose and consult prescriber.
Adverse reactions
- CNS: fatigue, dizziness, asthenia, insomnia, headache, vertigo, nervousness, depression, paresthesia, hallucinations, memory loss, disorientation, emotional lability, clouded sensorium
- CV: hypotension, angina pectoris exacerbation, bradycardia, atrioventricular or sinoatrial block, arrhythmias, heart failure EENT: visual disturbances, dry eyes, tinnitus, nasal congestion
- GI: nausea, constipation, diarrhea, abdominal discomfort
- GU: erectile dysfunction, decreased libido
- Metabolic: hyperuricemia, hypoglycemia, hyperkalemia
- Musculoskeletal: joint pain
- Respiratory: dyspnea, crackles, bronchospasm, pulmonary edema
- Skin: itching, rash
Contraindications
- Hypersensitivity to drug or other beta-adrenergic blockers
- Uncompensated heart failure
- Bradycardia or heart block
- Cardiogenic shock
- Bronchial asthma (current or previous), severe chronic obstructive pulmonary disease
Precautions:
- Renal or hepatic impairment, diabetes mellitus, thyrotoxicosis
- Elderly patients
- Pregnant or breastfeeding patients
- Children (safety not established).
Patient monitoring
- Closely monitor vital signs, blood pressure, cardiovascular status, and ECG.
- Assess respiratory status. Check breath sounds for wheezing and bronchospasm.
- Monitor blood glucose level in patient with diabetes mellitus.
Patient teaching
- Teach patient how to measure pulse before each dose. Instruct him to contact prescriber if pulse is outside established safe range.
- Caution patient not to stop taking drug abruptly. Dosage must be tapered.
- Teach patient how to administer eye drops. Instruct him to use drops only as prescribed, because they are absorbed systemically. Caution him not to touch dropper tip to eye or any other surface.
- Teach patient to recognize and immediately report significant adverse respiratory, cardiac, and neurologic reactions.
- Inform patient that many over-thecounter drugs and herbs may decrease the efficacy of timolol. Advise him to consult prescriber before using these products.
- Advise diabetic patient that drug may lower blood glucose level. Encourage regular blood glucose monitoring.
- As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, and herbs mentioned above.
Nursing Considerations
- Be aware that timolol may prolong hypoglycemia by interfering with glycogenolysis or may promote hyperglycemia by decreasing tissue sensitivity to insulin.
- Monitor blood pressure and cardiac output, as appropriate, for patient with a history of systolic heart failure or left ventricular dysfunction because timolol’s negative inotropic effect can depress cardiac output
- Expect varied drug effectiveness in elderly patients; they may be less sensitive to drug’s antihypertensive effect or more sensitive because of reduced drug clearance.
- Monitor for impaired circulation in elderly patients with age-related peripheral vascular disease or patients with Raynaud’s phenomenon. Such patients may experience exacerbated symptoms from increased alpha stimulation. Elderly patients also are at increased risk for beta blocker–induced hypothermia.
- If timolol worsens skin condition, such as psoriasis, notify prescriber.
7.Simbrinza (Brinzolamide)
| Simbrinza (Brinzolamide) |
| Availability ophthalmic suspension 1%/0.2% |
| Indications and dosages Open-Angle-Glaucoma Indicated for reduction of elevated intraocular pressure in patients with primary open-angle glaucoma Instill 1 gtt in affected eye(s) TID Ocular Hypertension Indicated for reduction of elevated intraocular pressure in patients with ocular hypertension Instill 1 gtt in affected eye(s) TID Ocular Hypertension Indicated for reduction of elevated intraocular pressure in patients with ocular hypertension Instill 1 gtt in affected eye(s) TID |
Mechanism of Action
Brinzolamide: Carbonic anhydrase inhibitor; inhibition of carbonic anhydrase in ciliary processes of the eye decreases aqueous humor secretion, presumably by slowing the formation of bicarbonate ions with subsequent reduction in sodium and fluid transport
Brimonidine: Alpha2 adrenergic receptor agonist; decreases aqueous humor secretion and increases uveoscleral outflow
Pharmacokinetics
- Peak plasma time: 1-4 hr (brimonidine)
- Peak plasma concentration: <10 ng/mL (brinzolamide)
- Protein bound: ~60% (brinzolamide)
- Metabolized by liver (brimonidine)
- Half-life: 111 days (brinzolamide); 3 hr (brimonidine)
- Excretion: Predominantly in urine (brinzolamide); 87% urine (brimonidine)
Administration
Shake well before use
If more than 1 ophthalmic drop is administered, the drugs should be administered at least 5 minutes apart
Contraindications
- Hypersensitivity
- Neonates and infants (younger than 2 yr)
REFERENCES
- Robert Kizior, Keith Hodgson, Saunders Nursing Drug handbook,1st edition 2024, Elsevier Publications. ISBN-9780443116070
- McGraw Hill- Drug Handbook, Seventh Edition, 2013, McGraw Hill Education Publications,9780071799430.
- April Hazard, Cynthia Sanoski, Davi’s Drug Guide for Nurses -Sixteenth Edition 2019, FA Davis Company Publications,9780803669451.
- Jones and Bartlet, Pharmacology for Nurses, Second Edition, 2020, Jones and Bartlet Learning Publications, ISBN 9781284141986.
- Nursebro.com, Search – Nursebro
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