From the Guidelines
Acetazolamide works in acute congestive (angle-closure) glaucoma by reducing intraocular pressure through inhibition of carbonic anhydrase, which decreases aqueous humor production in the ciliary body of the eye. This mechanism of action is crucial in the management of acute congestive glaucoma, as it helps to lower fluid volume and pressure within the eye. The typical dosage for acute treatment is 500 mg intravenously or orally, followed by 250 mg every 4 hours until pressure is controlled, as noted in the study 1. For maintenance therapy, 250 mg orally 2-4 times daily may be used. Acetazolamide also creates a mild metabolic acidosis which further reduces aqueous humor formation. Additionally, it alters ion transport across cell membranes in the eye, facilitating fluid drainage. This medication works relatively quickly, with pressure reduction beginning within 1-2 hours of administration, making it valuable in emergency situations where rapid pressure reduction is needed before definitive treatment (usually laser or surgical iridotomy) can be performed, as discussed in the study 1. Some key points to consider when using acetazolamide include:
- Monitoring for side effects such as paresthesias, fatigue, and electrolyte disturbances, particularly in those with kidney disease or sulfa allergies, as highlighted in the study 1.
- Being aware of potential contraindications, including sulfonamide allergy, kidney stones, aplastic anemia, and sickle cell disease, as noted in the study 1.
- Understanding that acetazolamide is classified as a category C drug in terms of FDA pregnancy safety, meaning that animal reproduction studies have shown an adverse effect on the fetus, but potential benefits may warrant use of the drug in pregnant women despite potential risks, as discussed in the study 1. Overall, acetazolamide is a valuable medication in the management of acute congestive glaucoma, and its use should be guided by the most recent and highest quality evidence, such as the study 1, which provides an overview of the preferred practice pattern for primary angle-closure disease.
From the Research
Mechanism of Action
- Acetazolamide is a carbonic anhydrase inhibitor that reduces intraocular pressure (IOP) in patients with glaucoma by inhibiting the enzyme carbonic anhydrase in the ciliary processes of the eye 2, 3.
- This inhibition leads to a reduction in the production of aqueous humor, which in turn decreases IOP 3.
Treatment of Acute Congestive Glaucoma
- Acetazolamide is used in the initial management of primary acute angle-closure glaucoma (PACG) to reduce IOP 4.
- Intravenous administration of acetazolamide can cause a rapid fall in IOP within 30 minutes 4.
- Acetazolamide can be used in combination with other medications, such as pilocarpine, to treat PACG 4.
Administration and Bioavailability
- Acetazolamide is typically administered orally or intravenously, as there is no topical formulation available 2.
- The development of a topical formulation of acetazolamide has been explored, with studies showing promising results using niosomal formulations 2.
- The bioavailability of acetazolamide can be enhanced through the use of bioadhesive coatings, such as Carbopol, which can improve corneal permeability 2.
Clinical Use and Safety
- Acetazolamide is a useful drug in emergency medicine and critical care, with applications in the treatment of acute heart failure, acute mountain sickness, and idiopathic intracranial hypertension, among others 5.
- The safety profile of acetazolamide is generally favorable, with serious side effects being rare and avoidable with careful patient selection 5.