Dichlorphenamide

KEVEYIS is indicated for the treatment of primary hyperkalemic periodic paralysis, primary hypokalemic periodic paralysis, and related variants. KEVEYIS is an oral carbonic anhydrase inhibitor indicated for the treatment of primary hyperkalemic periodic paralysis, primary hypokalemic periodic paralysis, and related variants ( 1 )

Round, white tablets, scored on one side, engraved with "D" above the score and "50" below the score, the other side is plain, 50 mg each. Tablets: 50 mg ( 3 )

KEVEYIS is contraindicated in the following circumstances: Hypersensitivity to dichlorphenamide or other sulfonamides [see Warnings and Precautions (5.1) ] Concomitant use of KEVEYIS 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 KEVEYIS [see Warnings and Precautions (5.4) ] Hepatic insufficiency: KEVEYIS 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 )

Hypersensitivity and Other Life-Threatening Reactions: discontinue KEVEYIS 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 KEVEYIS 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 KEVEYIS ( 5.4 ) Falls: consider reducing the dose or discontinuing KEVEYIS 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. KEVEYIS 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 KEVEYIS, 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 KEVEYIS and high-dose aspirin is contraindicated. Patients with concomitant use of KEVEYIS and low-dose aspirin should be carefully monitored.

5.3 Hypokalemia KEVEYIS increases potassium excretion and can cause hypokalemia. The risk of hypokalemia is greater when KEVEYIS 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 KEVEYIS treatment is recommended. If hypokalemia develops or persists, consideration should be given to reducing the dose or discontinuing KEVEYIS and correction of potassium levels.

5.4 Metabolic Acidosis KEVEYIS can cause hyperchloremic non-anion gap metabolic acidosis. Concomitant use of KEVEYIS with other drugs that cause metabolic acidosis may increase the severity of acidosis. Concomitant use of KEVEYIS 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 KEVEYIS treatment are recommended. If metabolic acidosis develops or persists, consideration should be given to reducing the dose or discontinuing KEVEYIS [see Drug Interactions (7.4) ] .

5.5 Falls KEVEYIS increases the risk of falls. The risk of falls is greater in the elderly and with higher doses of KEVEYIS. Consider dose reduction or discontinuation of KEVEYIS in patients who experience falls while treated with KEVEYIS.

The following serious adverse reactions are described elsewhere in labeling: Hypersensitivity and Other Life-Threatening Reactions [see Warnings and Precautions (5.1) ] Hypokalemia [see Warnings and Precautions (5.3) ] Metabolic Acidosis [see Warnings and Precautions (5.4) ] Falls [see Warnings and Precautions (5.5) ] Most common adverse reactions (incidence at least 10% and greater than placebo) include paresthesias, cognitive disorder, dysgeusia, and confusional state ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Xeris Pharmaceuticals, Inc. at 1-855-324-8912, or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch .

6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice. In a 9-week randomized controlled trial in adults with hyperkalemic or hypokalemic periodic paralysis (Study 1), the most common adverse reactions in patients treated with KEVEYIS, with rates greater than placebo, were paresthesia, cognitive disorder, dysgeusia, and confusional state. The mean dose of KEVEYIS was 94 mg/day in patients with hypokalemic periodic paralysis and 82 mg/day in patients with hyperkalemic periodic paralysis. Table 1 lists the incidence of adverse reactions that occurred in ≥ 5% of patients treated with KEVEYIS and more commonly than in patients treated with placebo in Study 1. Table 1: Adverse Reactions in Patients Treated with KEVEYIS with Incidence ≥ 5% and more common than in Patients Treated with Placebo in Study 1 Adverse Reaction KEVEYIS N = 36 (%) Placebo N = 29 (%) Nervous system disorders Paresthesia 44 14 Cognitive disorder Cognitive disorder combined cases with the preferred terms of cognitive disorder, disturbance in attention, and mental impairment. 14 7 Dysgeusia 14 0 Confusional state 11 0 Headache 8 7 Hypoesthesia 8 0 Lethargy 8 0 Dizziness 6 0 Gastrointestinal disorders Diarrhea 6 3 Nausea 6 0 General disorders and administration site conditions Fatigue 8 0 Malaise 6 0 Investigations Weight decreased 6 0 Musculoskeletal and connective tissue disorders Muscle spasms 8 0 Arthralgia 6 3 Muscle twitching 6 0 Respiratory Dyspnea 6 0 Pharyngolaryngeal pain 6 0 Skin Rash 8 0 Pruritus 6 0

6.2 Postmarketing Experience Adverse reactions have been identified during postapproval use of dichlorphenamide. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. The following are adverse reactions which have been reported during postapproval use of dichlorphenamide and were serious or are not reported in the previous section of labeling [see Clinical Trials Experience (6.1) ] : amnesia, cardiac failure, condition aggravated, convulsion, hallucination, nephrolithiasis, pancytopenia, psychotic disorder, renal tubular necrosis, stupor, syncope, tremor.

Aspirin: anorexia, tachypnea, lethargy, and coma have been reported with concomitant use of dichlorphenamide and high-dose aspirin. The concomitant use of KEVEYIS and high-dose aspirin is contraindicated. KEVEYIS should be used with caution in patients receiving lower doses of aspirin ( 4 , 5.2 , 7.1 )

7.1 Aspirin and Other Salicylates Carbonic anhydrase inhibitors, including KEVEYIS, can cause metabolic acidosis [see Warnings and Precautions ( 5.2 , 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, concomitant use of KEVEYIS and high-dose aspirin is contraindicated. Patients with concomitant use of KEVEYIS and low-dose aspirin should be carefully monitored [see Contraindications (4) and Warnings and Precautions (5.2) ].

7.2 Drugs that are Substrates of Organic Anion Transporter1 (OAT1) In vitro , dichlorphenamide is an inhibitor of OAT1 transporters. The concomitant administration of KEVEYIS may increase the plasma exposures of OAT1 substrates. Use of KEVEYIS with drugs that are sensitive to OAT1 inhibition (e.g., methotrexate, famotidine, oseltamivir) is not recommended [see Clinical Pharmacology (12.3) ].

7.3 Drugs that Cause Hypokalemia The risk of hypokalemia is greater with coadministration of KEVEYIS and other drugs that can cause hypokalemia (e.g., loop diuretics, thiazide diuretics, laxatives, antifungals, penicillins, and theophylline) [see Warnings and Precautions (5.3) ] .

7.4 Drugs that Cause Metabolic Acidosis Coadministration of KEVEYIS and other drugs that can cause metabolic acidosis may increase the severity of the acidosis [see Warnings and Precautions (5.4) ].

7.5 Drugs that are Inhibitors of OAT1 or OAT3 An in vitro transporter study indicated that dichlorphenamide is a substrate of human transporters OAT1 and OAT3 [see Clinical Pharmacology (12.3) ] . Therefore, signs of dichlorphenamide toxicity should be monitored when administered with OAT1 or OAT3 inhibitors.

Pregnancy: Based on animal data, may cause fetal harm ( 8.1 )

8.1 Pregnancy Risk Summary There are no adequate data on the developmental risk associated with the use of KEVEYIS in pregnant women. A no-effect dose has not been established. Dichlorphenamide was teratogenic when administered orally to pregnant rats. The background risk of major birth defects and miscarriage for the indicated population is unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2% to 4%, and 15% to 20%, respectively. Clinical Considerations Fetal/Neonatal adverse reactions KEVEYIS treatment can cause metabolic acidosis [see Warnings and Precautions (5.4) ]. The effect of dichlorphenamide-induced metabolic acidosis has not been studied in pregnancy; however, metabolic acidosis in pregnancy (due to other causes) can cause decreased fetal growth, decreased fetal oxygenation, and fetal death, and may affect the fetus’ ability to tolerate labor. Pregnant patients should be monitored for metabolic acidosis and treated as in the nonpregnant state. Newborns of mothers treated with KEVEYIS should be monitored for metabolic acidosis because of possible occurrence of transient metabolic acidosis following birth. Labor or Delivery Although the effect of KEVEYIS on labor and delivery in humans has not been established, the development of dichlorphenamide-induced metabolic acidosis in the mother and/or in the fetus might affect the fetus’ ability to tolerate labor. Data Animal Data Teratogenic effects (fetal limb reduction defects) were reported following oral administration of dichlorphenamide to pregnant rats during organogenesis at 350 mg/kg, or 17 times the maximum recommended human dose (200 mg/day) on a body surface area (mg/m 2 ) basis. A no-effect dose for adverse effects on embryofetal development has not been established.

8.2 Lactation Risk Summary There are no data on the presence of dichlorphenamide in human milk, the effects on the breastfed infant, or the effects on milk production. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for KEVEYIS and any potential adverse effects on the breastfed infant from KEVEYIS or from the underlying maternal condition.

8.4 Pediatric Use Safety and effectiveness of KEVEYIS in pediatric patients have not been established.

8.5 Geriatric Use The risk of falls and of metabolic acidosis are greater in elderly patients [see Warnings and Precautions (5.4 , 5.5) ] ​.

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.