DAPSONE

Dapsone gel, 7.5%, contains dapsone, a sulfone, in an aqueous gel base for topical dermatologic use. Dapsone gel, 7.5% is an off-white to yellow homogeneous gel with suspended particles. Chemically, dapsone has an empirical formula of C 12 H 12 N 2 O 2 S. It is a white to creamy white, crystalline powder that has a molecular weight of 248.30. Dapsone's chemical name is 4-[(4-aminobenzene) sulfonyl] aniline and its structural formula is: Each gram of dapsone gel, 7.5%, contains 75 mg of dapsone, USP, in a gel of diethylene glycol monoethyl ether, methylparaben, acrylamide/sodium acryloyldimethyl taurate copolymer, isohexadecane, polysorbate 80, and purified water. Image

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

For topical use only. Not for oral, ophthalmic, or intravaginal use. After the skin is gently washed and patted dry, apply approximately a pea-sized amount of dapsone gel, 7.5%, in a thin layer to the entire face once daily. In addition, a thin layer may be applied to other affected areas once daily. Rub in dapsone gel, 7.5%, gently and completely. If there is no improvement after 12 weeks, treatment with dapsone gel, 7.5% should be reassessed. Apply once daily ( 2 ). Apply approximately a pea-sized amount of dapsone gel, 7.5%, in a thin layer to the entire face. A thin layer can also be applied to other affected areas ( 2 ). If there is no improvement after 12 weeks, treatment with dapsone gel, 7.5% should be reassessed ( 2 ). For topical use only. Not for oral, ophthalmic, or intravaginal use ( 2 ).

None. None ( 4 ).

Most common (incidence ≥ 0.9%) adverse reactions are application site dryness and pruritus ( 6.1 ). To report SUSPECTED ADVERSE REACTIONS, contact 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 dapsone 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 dapsone 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 Dapsone 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 dapsone 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 dapsone 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 dapsone 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 dapsone 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 )].