LYNOX

One of the carbonic anhydrase inhibitors that is sometimes effective against absence seizures.

It is sometimes useful also as an adjunct in the treatment of tonic-clonic, myoclonic, and atonic seizures, particularly in women whose seizures occur or are exacerbated at specific times in the menstrual cycle.

However, its usefulness is transient often because of rapid development of tolerance.

Its antiepileptic effect may be due to its inhibitory effect on brain carbonic anhydrase, which leads to an increased transneuronal chloride gradient, increased chloride current, and increased inhibition. (From Smith and Reynard, Textbook of Pharmacology, 1991, p337).

For adjunctive treatment of: edema due to congestive heart failure; drug-induced edema; centrencephalic epilepsies; chronic simple (open-angle) glaucoma

Acetazolamide is a potent carbonic anhydrase inhibitor, effective in the control of fluid secretion, in the treatment of certain convulsive disorders and in the promotion of diuresis in instances of abnormal fluid retention.

Acetazolamide is not a mercurial diuretic.

Rather, it is a nonbacteriostatic sulfonamide possessing a chemical structure and pharmacological activity distinctly different from the bacteriostatic sulfonamides.

Carbonic anhydrase 1 Inhibitor Carbonic anhydrase 2 Inhibitor Carbonic anhydrase 4 Inhibitor + 4 more targets.

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No specific antidote is known.

Treatment should be symptomatic and supportive.

Electrolyte imbalance, development of an acidotic state, and central nervous effects might be expected to occur.

Serum electrolyte levels (particularly potassium) and blood pH levels should be monitored.

Supportive measures are required to restore electrolyte and pH balance.

The acidotic state can usually be corrected by the administration of bicarbonate.

Despite its high intraerythrocytic distribution and plasma protein binding properties, acetazolamide is dialyzable.

This may be particularly important in the management of acetazolamide overdosage when complicated by the presence of renal failure.

Fatalities have occurred, although rarely, due to severe reactions to sulfonamides including Stevens-Johnson syndrome, toxic epidermal necrolysis, fulminant hepatic necrosis, agranulocytosis, aplastic anemia, and other blood dyscrasias, and anaphylaxis.

Sensitizations may recur when a sulfonamide is readministered irrespective of the route of administration.

If signs of hypersensitivity or other serious reactions occur, discontinue use of this drug.

Caution is advised for patients receiving concomitant high-dose aspirin and acetazolamide, as anorexia, tachypnea, lethargy, metabolic acidosis, coma, and death have been reported.

Hypersensitivity to acetazolamide or any excipients in the formulation.

Since acetazolamide is a sulfonamide derivative, cross sensitivity between acetazolamide, sulfonamides and other sulfonamide derivatives is possible.

Acetazolamide therapy is contraindicated in situations in which sodium and/or potassium blood serum levels are depressed, in cases of marked kidney and liver disease or dysfunction, in suprarenal gland failure, and in hyperchloremic acidosis.

It is contraindicated in patients with cirrhosis because of the risk of development of hepatic encephalopathy.

Long-term administration of acetazolamide is contraindicated in patients with chronic noncongestive angle-closure glaucoma since it may permit organic closure of the angle to occur while the worsening glaucoma is masked by lowered intraocular pressure.

Acetazolamide should be used as an adjunct to the usual therapy.

The dosage employed in the treatment of chronic simple (open-angle) glaucoma ranges from 250 mg to 1 g of acetazolamide per 24 hours, usually in divided doses for amounts over 250 mg. It has usually been found that a dosage in excess of 1 g per 24 hours does not produce an increased effect.

In all cases, the dosage should be adjusted with careful individual attention both to symptomatology and ocular tension.

Continuous supervision by a physician is advisable.

In treatment of secondary glaucoma and in the preoperative treatment of some cases of acute congestive (closed-angle) glaucoma, the preferred dosage is 250 mg every four hours, although some cases have responded to 250 mg twice daily on short-term therapy.

In some acute cases, it may be more satisfactory to administer an initial dose of 500 mg followed by 125 or 250 mg every four hours depending on the individual case.

A complementary effect has been noted when acetazolamide has been used in conjunction with miotics or mydriatics as the case demanded.

It is not clearly known whether the beneficial effects observed in epilepsy are due to direct inhibition of carbonic anhydrase in the central nervous system or whether they are due to the slight degree of acidosis produced by the divided dosage.

The best results to date have been seen in petit mal in pediatric patients.

Good results, however, have been seen in patients, both pediatric patients and adult, in other types of seizures such as grand mal, mixed seizure patterns, myoclonic jerk patterns, etc.

The suggested total daily dose is to 30 mg per kg in divided doses.

Although some patients respond to a low dose, the optimum range appears to be from to 1,000 mg daily.

However, some investigators feel that daily doses in excess of 1 g do not produce any better results than a 1 g dose.

When acetazolamide tablets are given in combination with other anticonvulsants, it is suggested that the starting dose should be 250 mg once daily in addition to the existing medications.

This can be increased to levels as indicated above.

The change from other medications to acetazolamide should be gradual and in accordance with usual practice in epilepsy therapy.

For diuresis in congestive heart failure, the starting dose is usually to 375 mg once daily in the morning (5 mg/kg).

If, after an initial response, the patient fails to continue to lose edema fluid, do not increase the dose but allow for kidney recovery by skipping medication for a day. Acetazolamide tablets yields best diuretic results when given on alternate days, or for two days alternating with a day of rest.

Failures in therapy may be due to overdosage or too frequent dosage.

The use of acetazolamide does not eliminate the need for other therapy such as digitalis, bed rest, and salt restriction.

Recommended dosage is to 375 mg of acetazolamide once a day for one or two days, alternating with a day of rest.

Dosage is 500 mg to 1,000 mg daily, in divided doses using tablets or sustained-release capsules as appropriate.

In circumstances of rapid ascent, such as in rescue or military operations, the higher dose level of 1,000 mg is recommended.

It is preferable to initiate dosing to 48 hours before ascent and to continue for 48 hours while at high altitude, or longer as necessary to control symptoms.

The dosage recommendations for glaucoma and epilepsy differ considerably from those for congestive heart failure, since the first two conditions are not dependent upon carbonic anhydrase inhibition in the kidney which requires intermittent dosage if it is to recover from the inhibitory effect of the therapeutic agent.

Sulfonamides may give false negative or decreased values for urinary phenolsulfonphthalein and phenol red elimination values for urinary protein, serum non-protein and for serum uric acid.

Acetazolamide may produce an increased level of crystals in the urine.

Acetazolamide interferes with the

HPLC method of assay for theophylline.

Interference with the theophylline assay by acetazolamide depends on the solvent used in the extraction; acetazolamide may not interfere with other assay methods for theophylline.

USP, 125 mg are available for oral administration as white to off white, round tablet, debossed HP on one side and scored on other side.

They are supplied as follows

Bottles of 100 Tablets NDC 23155-287-01 Bottles of 1,000 Tablets NDC 23155-287-10 Acetazolamide Tablets USP, 250 mg are available for oral administration as white to off white, round tablet, debossed HP on one side and scored in quarters on other side.

Bottles of 100 Tablets NDC 23155-288-01 Bottles of 1,000 Tablets NDC 23155-288-10 Store at 20° to 25°C (68° to 77°F); excursions permitted between 15° to 30°C (59° to 86°F). .

Dispense in a tight, light-resistant container as defined in the USP using a child-resistant closure.

Keep container tightly closed.

KEEP THIS AND ALL MEDICATIONS OUT OF THE REACH OF CHILDREN.

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Teratogenic effects

Acetazolamide, administered orally or parenterally, has been shown to be teratogenic (defects of the limbs) in mice, rats, hamsters, and rabbits.

There are no adequate and well-controlled studies in pregnant women.

Acetazolamide should be used in pregnancy only if the potential benefit justifies the potential risk to the fetus.

Because of the potential for serious adverse reactions in nursing infants from acetazolamide, a decision should be made whether to discontinue nursing or to discontinue the drug taking into account the importance of the drug to the mother.

Acetazolamide should only be used by nursing women if the potential benefit justifies the potential risk to the child.

The safety and effectiveness of acetazolamide in pediatric patients have not been established.

Growth retardation has been reported in children receiving long-term therapy, believed secondary to chronic acidosis.