dichlorphenamide 50 MG Oral Tablet [Keveyis]

INDICATIONS AND USAGE Dichlorphenamide tablets are indicated for the treatment of primary hyperkalemic periodic paralysis, primary hypokalemic periodic paralysis, and related variants. Dichlorphenamide tablets are an oral carbonic anhydrase inhibitor indicated for the treatment of primary hyperkalemic periodic paralysis, primary hypokalemic periodic paralysis, and related variants ( 1 )

DOSAGE AND ADMINISTRATION • Initiate dosing at 50 mg by mouth once or twice daily ( 2.1 ) • Titrate up or down dose based on individual response ( 2.1 ) • The minimum recommended dosage is 50 mg daily, and the maximum recommended dosage is 200 mg daily ( 2.1 ) • Evaluate response to dichlorphenamide tablets after 2 months of treatment ( 2.2 ) 2.1 Dosage Information Initiate dosing at 50 mg by mouth once or twice daily. The dosage may be increased or decreased based on individual response, at weekly intervals (or sooner in case of adverse reaction). The minimum recommended total daily dosage is 50 mg, and the maximum recommended total daily dosage is 200 mg. 2.2 Monitoring to Assess Effectiveness Primary hyperkalemic periodic paralysis, primary hypokalemic periodic paralysis, and related variants are a heterogeneous group of conditions, for which the response to dichlorphenamide may vary. Therefore, prescribers should evaluate the patient's response to dichlorphenamide after 2 months of treatment to decide whether dichlorphenamide tablets should be continued. 2.3 Monitoring to Assess Safety Baseline and periodic measurements of serum potassium and sodium bicarbonate during dichlorphenamide treatment is recommended [see Warnings and Precautions ( 5.3 , 5.4 )] .

WARNINGS AND PRECAUTIONS Hypersensitivity and Other Life-Threatening Reactions: discontinue dichlorphenamide at the first appearance of skin rash or any sign of immune- mediated or idiosyncratic adverse reaction ( 5.1 ) Hypokalemia: baseline and periodic measurements of serum potassium are recommended; if hypokalemia develops or persists, consider reducing the dose or discontinuing dichlorphenamide and correcting potassium levels ( 5.3 ) Metabolic acidosis: baseline and periodic measurements of serum bicarbonate are recommended; if metabolic acidosis develops or persists, consider reducing the dose or discontinuing dichlorphenamide ( 5.4 ) Falls: consider reducing the dose or discontinuing dichlorphenamide in patients who experience falls ( 5.5 ) 5.1 Hypersensitivity and Other Life-Threatening Reactions Fatalities associated with the administration of sulfonamides have occurred because of adverse reactions including Stevens-Johnson syndrome, toxic epidermal necrolysis, fulminant hepatic necrosis, agranulocytosis, aplastic anemia, and other blood dyscrasias. Pulmonary involvement can occur in isolation or as part of a systemic reaction. Dichlorphenamide should be discontinued at the first appearance of skin rash or any sign of immune- mediated or other life-threatening adverse reaction. 5.2 Concomitant Use of Aspirin or Other Salicylates Carbonic anhydrase inhibitors, including dichlorphenamide, can cause metabolic acidosis [see Warnings and Precautions ( 5.4 )] , which can increase the risk of salicylate toxicity. Anorexia, tachypnea, lethargy, and coma have been reported with concomitant use of dichlorphenamide and high-dose aspirin. Therefore, the concomitant use of dichlorphenamide and high-dose aspirin is contraindicated. Patients with concomitant use of dichlorphenamide and low-dose aspirin should be carefully monitored. 5.3 Hypokalemia Dichlorphenamide increases potassium excretion and can cause hypokalemia. The risk of hypokalemia is greater when dichlorphenamide is used in patients with conditions associated with hypokalemia (e.g., adrenocortical excess, renal tubular acidosis type 1 and 2), and in patients receiving other drugs that may cause hypokalemia [see Drug Interactions ( 7.3 ] . Baseline and periodic measurements of serum potassium during dichlorphenamide treatment is recommended. If hypokalemia develops or persists, consideration should be given to reducing the dose or discontinuing dichlorphenamide and correction of potassium levels. 5.4 Metabolic Acidosis Dichlorphenamide can cause hyperchloremic non-anion gap metabolic acidosis. Concomitant use of dichlorphenamide with other drugs that cause metabolic acidosis may increase the severity of acidosis. Concomitant use of dichlorphenamide in compensated patients with respiratory acidosis, such as in advanced lung diseases, may lead to respiratory decompensation. Baseline and periodic measurements of serum bicarbonate during dichlorphenamide treatment are recommended. If metabolic acidosis develops or persists, consideration should be given to reducing the dose or discontinuing dichlorphenamide [see Drug Interactions ( 7.4) ]. 5.5 Falls Dichlorphenamide increases the risk of falls. The risk of falls is greater in the elderly and with higher doses of dichlorphenamide. Consider dose reduction or discontinuation of dichlorphenamide in patients who experience falls while treated with dichlorphenamide.

CONTRAINDICATIONS Dichlorphenamide is contraindicated in the following circumstances: Hypersensitivity to dichlorphenamide or other sulfonamides [see Warnings and Precautions ( 5.1 )] Concomitant use of dichlorphenamide and high dose aspirin [see Warnings and Precautions ( 5.2 ) and Drug Interactions ( 7.1 )] Severe pulmonary disease, limiting compensation to metabolic acidosis caused by dichlorphenamide [see Warnings and Precautions ( 5.4 )] Hepatic insufficiency: dichlorphenamide may aggravate hepatic encephalopathy. Hepatic insufficiency ( 4 ) Severe pulmonary obstruction ( 4 ) Hypersensitivity to dichlorphenamide or other sulfonamides ( 4 ) Concomitant use with high dose aspirin ( 4 )

Mechanism of Action Dichlorphenamide is a carbonic anhydrase inhibitor. However, the precise mechanism by which dichlorphenamide exerts its therapeutic effects in patients with primary periodic paralysis is unknown.