Dapsone

ACZONE ® (dapsone) Gel, 7.5%, is indicated for the topical treatment of acne vulgaris in patients 9 years of age and older. ACZONE ® Gel, 7.5%, is a sulfone indicated for the topical treatment of acne vulgaris in patients 9 years of age and older ( 1 ).

Gel, 7.5%. Each gram of ACZONE Gel, 7.5% contains 75 mg of dapsone in an off-white to yellow gel with suspended particles. Gel, 7.5% ( 3 ).

None. None ( 4 ).

Methemoglobinemia: Cases of methemoglobinemia have been reported. Discontinue ACZONE Gel if signs of methemoglobinemia occur ( 5.1 ). Hemolysis: Some patients with Glucose-6-phosphate Dehydrogenase (G6PD) deficiency using topical dapsone developed laboratory changes suggestive of hemolysis ( 5.1 )( 8.6 ).

5.1 Hematological Effects Methemoglobinemia Cases of methemoglobinemia, with resultant hospitalization, have been reported postmarketing in association with twice daily dapsone gel, 5%, treatment. Patients with glucose-6-phosphate dehydrogenase deficiency or congenital or idiopathic methemoglobinemia are more susceptible to drug-induced methemoglobinemia. Avoid use of ACZONE Gel, 7.5% in those patients with congenital or idiopathic methemoglobinemia. Signs and symptoms of methemoglobinemia may be delayed some hours after exposure. Initial signs and symptoms of methemoglobinemia are characterized by a slate grey cyanosis seen in e.g., buccal mucous membranes, lips, and nail beds. Advise patients to discontinue ACZONE Gel, 7.5% and seek immediate medical attention in the event of cyanosis. Dapsone can cause elevated methemoglobin levels particularly in conjunction with methemoglobin-inducing agents [see Drug Interactions ( 7.4 )]. Hemolysis Oral dapsone treatment has produced dose-related hemolysis and hemolytic anemia. Individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency are more prone to hemolysis with the use of certain drugs. G6PD deficiency is most prevalent in populations of African, South Asian, Middle Eastern, and Mediterranean ancestry. In clinical trials, there was no evidence of clinically relevant hemolysis or hemolytic anemia in subjects treated with topical dapsone. Some subjects with G6PD deficiency using dapsone gel, 5 %, twice daily developed laboratory changes suggestive of hemolysis [see Use in Specific Populations ( 8.6 )]. Discontinue ACZONE Gel, 7.5%, if signs and symptoms suggestive of hemolytic anemia occur. Avoid use of ACZONE Gel, 7.5% in patients who are taking oral dapsone or antimalarial medications because of the potential for hemolytic reactions. Combination of ACZONE Gel, 7.5%, with trimethoprim/sulfamethoxazole (TMP/SMX) may increase the likelihood of hemolysis in patients with G6PD deficiency [see Drug Interactions ( 7.1 )] .

5.2 Peripheral Neuropathy Peripheral neuropathy (motor loss and muscle weakness) has been reported with oral dapsone treatment. No events of peripheral neuropathy were observed in clinical trials with topical dapsone treatment.

5.3 Skin Reactions Skin reactions (toxic epidermal necrolysis, erythema multiforme, morbilliform and scarlatiniform reactions, bullous and exfoliative dermatitis, erythema nodosum, and urticaria) have been reported with oral dapsone treatment. These types of skin reactions were not observed in clinical trials with topical dapsone treatment.

Most common (incidence ≥ 0.9%) adverse reactions are application site dryness and pruritus ( 6.1 ). To report SUSPECTED ADVERSE REACTIONS, contact Almirall at 1-866-665-2782 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch .

6.1 Clinical Studies 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. A total of 2161 subjects were treated with ACZONE Gel, 7.5%, for 12 weeks in 2 controlled clinical trials. The population ranged in age from 12 to 63 years, was 56% female, and 58% Caucasian. Adverse drug reactions that were reported in at least 0.9% of subjects treated with ACZONE Gel, 7.5% appear in Table 1 below. Table 1. Adverse Reactions Occurring in at Least 0.9% of Subjects with Acne Vulgaris in 12-week Controlled Clinical Trials ACZONE Gel, 7.5% (N=2161) Vehicle (N=2175) Application Site Dryness 24 (1.1%) 21 (1.0%) Application Site Pruritus 20 (0.9%) 11 (0.5%)

6.2 Experience with Oral Use of Dapsone Although not observed in the clinical trials with topical dapsone, serious adverse reactions have been reported with oral use of dapsone, including agranulocytosis, hemolytic anemia, peripheral neuropathy (motor loss and muscle weakness), and skin reactions (toxic epidermal necrolysis, erythema multiforme, morbilliform and scarlatiniform reactions, bullous and exfoliative dermatitis, erythema nodosum, and urticaria).

6.3 Postmarketing Experience 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 adverse reactions have been identified during post-approval use of topical dapsone: methemoglobinemia, rash (including erythematous rash, application site rash) and swelling of face (including lip swelling, eye swelling).

No formal drug-drug interaction studies were conducted with ACZONE Gel, 7.5%. Trimethoprim/sulfamethoxazole (TMP/SMX) increases the systemic level of dapsone and its metabolites ( 7.1 ). Topical benzoyl peroxide used at the same time as ACZONE Gel, 7.5% may result in temporary local yellow or orange skin discoloration ( 7.2 ).

7.1 Trimethoprim-Sulfamethoxazole A drug-drug interaction study evaluated the effect of the use of dapsone gel, 5% in combination with double strength (160 mg/800 mg) trimethoprim-sulfamethoxazole (TMP/SMX). During co-administration, systemic levels of TMP and SMX were essentially unchanged, however, levels of dapsone and its metabolites increased in the presence of TMP/SMX. The systemic exposure from ACZONE Gel, 7.5% is expected to be about 1% of that from the 100 mg oral dose, even when co-administered with TMP/SMX.

7.2 Topical Benzoyl Peroxide Topical application of dapsone gel followed by benzoyl peroxide in patients with acne vulgaris may result in a temporary local yellow or orange discoloration of the skin and facial hair.

7.3 Drug Interactions with Oral Dapsone Certain concomitant medications (such as rifampin, anticonvulsants, St. John’s wort) may increase the formation of dapsone hydroxylamine, a metabolite of dapsone associated with hemolysis. With oral dapsone treatment, folic acid antagonists such as pyrimethamine have been noted to possibly increase the likelihood of hematologic reactions.

7.4 Concomitant Use with Drugs that Induce Methemoglobinemia Concomitant use of ACZONE Gel, 7.5% with drugs that induce methemoglobinemia such as sulfonamides, acetaminophen, acetanilide, aniline dyes, benzocaine, chloroquine, dapsone, naphthalene, nitrates and nitrites, nitrofurantoin, nitroglycerin, nitroprusside, pamaquine, para‐aminosalicylic acid, phenacetin, phenobarbital, phenytoin, primaquine, and quinine may increase the risk for developing methemoglobinemia [see Warnings and Precautions ( 5.1 )] .

8.1 Pregnancy Risk Summary There are no available data on ACZONE Gel, 7.5%, use in pregnant women to inform a drug-associated risk for adverse developmental outcomes. The systemic absorption of ACZONE in humans following topical application is low relative to oral dapsone administration [see Clinical Pharmacology ( 12.3 )] . In animal reproduction studies, oral doses of dapsone administered to pregnant rats and rabbits during organogenesis that resulted in systemic exposures more than 400 times the systemic exposure at the maximum recommended human dose (MRHD) of ACZONE Gel, 7.5%, resulted in embryocidal effects. When orally administered to rats from the onset of organogenesis through the end of lactation at systemic exposures approximately 500 times the exposure at the MRHD, dapsone resulted in increased stillbirths and decreased pup weight [see Data ] . The estimated background risks of major birth defects and miscarriage for the indicated population are unknown. In the U.S. general population, the estimated background risk of major birth defects and miscarriage in clinically recognized pregnancies is 2-4% and 15-20%, respectively. Data Animal Data Dapsone has been shown to have an embryocidal effect in rats and rabbits when administered orally daily to females during organogenesis at dosages of 75 mg/kg/day and 150 mg/kg/day, respectively. These dosages resulted in systemic exposures that represented approximately 1407 times [rats] and 425 times [rabbits] the systemic exposure observed in human females as a result of use of the MRHD of ACZONE Gel, 7.5%, based on AUC comparisons. These effects were probably secondary to maternal toxicity. Dapsone was assessed for effects on perinatal/postnatal pup development and postnatal maternal behavior and function in a study in which dapsone was orally administered to female rats daily beginning on the seventh day of gestation and continuing until the twenty-seventh day postpartum. Maternal toxicity (decreased body weight and food consumption) and developmental effects (increase in stillborn pups and decreased pup weight) were seen at a dapsone dose of 30 mg/kg/day (approximately 563 times the systemic exposure that is associated with the MRHD of ACZONE Gel, 7.5%, based on AUC comparisons). No effects were observed on the viability, physical development, behavior, learning ability, or reproductive function of surviving pups.

8.2 Lactation Risk Summary There is no information regarding the presence of topical dapsone in breastmilk, the effects on the breastfed infant or the effects on milk production. Orally administered dapsone appears in human milk and could result in hemolytic anemia and hyperbilirubinemia especially in infants with G6PD deficiency. Systemic absorption of dapsone following topical application is low relative to oral dapsone administration. The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for ACZONE Gel, 7.5% and any potential adverse effects on the breastfed child from ACZONE Gel, 7.5% or from the underlying maternal condition.

8.4 Pediatric Use The safety and effectiveness of ACZONE Gel, 7.5% for the topical treatment of acne vulgaris have been established in patients 9 years of age and older. Use of ACZONE Gel, 7.5% in patients 9 to 11 years of age for this indication is supported by evidence from adequate and well-controlled clinical trials in 1066 subjects 12 years of age and older and with additional pharmacokinetic and safety data in pediatric subjects 9 to 11 years of age from an open label study of 100 subjects with acne [see Adverse Reactions ( 6.1 ), and Clinical Pharmacology ( 12.3 )] . The safety profile for ACZONE Gel, 7.5% in clinical trials was similar to the vehicle control group. Safety and effectiveness of ACZONE Gel, 7.5%, have not been established in pediatric patients below the age of 9 years.

8.5 Geriatric Use Clinical trials of ACZONE Gel, 7.5% did not include sufficient numbers of subjects aged 65 years and over to determine whether they respond differently from younger subjects.

8.6 Glucose-6-phosphate Dehydrogenase (G6PD) Deficiency Individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency may be more prone to methemoglobinemia and hemolysis [see Warnings and Precautions ( 5.1 )] . ACZONE Gel, 5% and vehicle were evaluated in a randomized, double-blind, cross-over design clinical study of 64 subjects with G6PD deficiency and acne vulgaris. Subjects were Black (88%), Asian (6%), Hispanic (2%) or of other racial origin (5%). Blood samples were taken at Baseline, Week 2, and Week 12 during both vehicle and ACZONE Gel, 5% treatment periods. Some of these subjects developed laboratory changes suggestive of hemolysis, but there was no evidence of clinically significant hemolytic anemia in this study [see Warnings and Precautions ( 5.1 )] .

The mechanism of action of dapsone gel in treating acne vulgaris is not known.