OVERVIEW

Acetazolamide is a drug that is commonly used as a diuretic and for conditions where it is necessary to reduce fluid buildup. It is also used to treat and prevent symptoms of altitude sickness, glaucoma (to reduce intraocular pressure), and certain types of seizures. It works by inhibiting an enzyme called carbonic anhydrase, which helps reduce the production of bicarbonate and, in turn, reduce the amount of fluid that builds up in tissues and spaces in the body.It’s important to only take acetazolamide under medical supervision, as it can affect electrolyte balance and acid-base levels in the body. It can also interact with certain medications, so a healthcare provider will usually review any other medications you’re taking.

DOSAGE

MECHANISM OF ACTION

Inhibition of carbonic anhydrase (CA):

Acetazolamide inhibits the enzyme carbonic anhydrase, which is responsible for converting carbon dioxide and water into bicarbonate and protons (H⁺) in various tissues, particularly the kidneys, eyes, and central nervous system.

Kidneys – Diuretic Effects:

In the kidneys, acetazolamide’s inhibition of carbonic anhydrase decreases the formation of bicarbonate ions in the proximal tubule. This reduces bicarbonate reabsorption, resulting in increased urinary bicarbonate, sodium, and water excretion. The result is a mild diuresis (increased urine production) and alkalinization of the urine.

Eyes – Decreased Aqueous Fluid Production:

In the eye, carbonic anhydrase is involved in the production of aqueous fluid (the fluid in the front part of the eye). By inhibiting this enzyme, acetazolamide decreases aqueous humor production, leading to a decrease in intraocular pressure, which is beneficial for conditions such as glaucoma.

Central Nervous System – Anticonvulsant Effects:

Alterations in acid-base balance by acetazolamide may help stabilize neuronal membranes, providing anticonvulsant effects. This mechanism is poorly understood but may be useful in the management of certain types of seizures.

Prevention of Altitude Sickness:

By increasing the excretion of bicarbonate and inducing mild metabolic acidosis, acetazolamide stimulates ventilation, which may counteract respiratory alkalosis caused by rapid ascent to high altitude.

SIDE EFFECTS

Common Side Effects

• Tingling in fingers, toes, or face
• Frequent urination (due to diuretic effect)
• Loss of appetite
• Nausea or vomiting
• Fatigue or drowsiness
• Dizziness or lightheadedness
• Altered taste (often a metallic taste)
• Dry mouth

Less Common but Serious Side Effects

• Severe skin reactions (such as Stevens-Johnson syndrome or toxic epidermal necrolysis)
• Kidney stones
• Severe dehydration or electrolyte imbalances (e.g., low potassium or sodium levels)
• Metabolic acidosis (blood becoming too acidic)
• Liver issues (yellowing of the skin or eyes, dark urine)
• Blood cell abnormalities (like low red or white blood cell counts)
• Severe allergic reactions (hives, rash, difficulty breathing)

Rare Side Effects

• Hearing problems (like ringing in the ears or hearing loss)
• Temporary vision changes
• Depression or mood changes

DRUG-DRUG INTERACTIONS

Diuretics and Other Medications that Lower Potassium or Sodium Levels

There may be an increased risk of electrolyte imbalances, such as deficiency of potassium (hypokalemia) or sodium (hyponatremia).

Salicylates

There is an increased risk of serious side effects such as metabolic acidosis, a serious condition in which the blood becomes too acidic. This interaction may also increase the effects of acetazolamide, leading to toxic effects.

Anticonvulsants

Their use together may increase the risk of bone marrow suppression and may also affect the levels of these drugs in the bloodstream.

Lithium

Acetazolamide may decrease its effectiveness by increasing the excretion of lithium through the kidneys, potentially leading to subtherapeutic levels of lithium.

Cyclosporine

The risk of kidney toxicity may increase if used together, as both drugs put additional strain on the kidneys.

Amphetamines and Related Stimulants

Acetazolamide may alter the excretion rate of amphetamines, possibly affecting their efficacy and increasing the risk of toxicity.

Topiramate and Zonisamide

Acetazolamide may affect the metabolism of warfarin, possibly altering its blood-thinning effect, which may increase the risk of bleeding.

Methenamine

Acetazolamide may decrease the effectiveness of methenamine, a medication often used to prevent urinary tract infections, because it increases the alkalinity of the urine, thereby decreasing the effectiveness of methenamine.

USE

Glaucoma

It reduces intraocular pressure in the eye by decreasing the production of aqueous humor, thereby helping to prevent optic nerve damage and vision loss in conditions such as open-angle glaucoma.

Altitude Sickness (Acute Mountain Sickness)

It helps prevent and reduce altitude sickness such as headaches, nausea, and fatigue, thereby speeding up acclimatization. It works by increasing the breathing rate and improving oxygenation.

Epilepsy

It is used as adjunctive therapy for certain types of seizures, especially in cases of absence seizures. It helps reduce abnormal, excessive brain activity.

Congestive Heart Failure

It helps reduce fluid retention and swelling (edema) caused by congestive heart failure. It reduces fluid build-up by promoting diuresis, thereby easing the workload on the heart.

Idiopathic Intracranial Hypertension

It reduces the increased cerebrospinal fluid pressure in the brain, thereby relieving symptoms such as headache and visual disturbances.

Periodic Paralysis

It is sometimes used to manage the symptoms of periodic paralysis, a rare genetic disorder in which potassium levels in muscle cells can temporarily drop, causing muscle weakness.