Dapsone Drug Information

Dapsone Gel, 5%, is indicated for the topical treatment of acne vulgaris.

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, 5%, in a thin layer to the acne affected areas twice daily.

Rub in dapsone gel, 5%, gently and completely. Dapsone gel, 5%, is gritty with visible drug substance particles. Wash hands after application of dapsone gel, 5%.

If there is no improvement after 12 weeks, treatment with dapsone gel, 5%, should be reassessed. Apply twice daily. For topical use only.

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. Serious adverse reactions reported in subjects treated with dapsone gel, 5%, during clinical trials included but were not limited to the following: Nervous system/Psychiatric – Suicide attempt, tonic clonic movements. Gastrointestinal – Abdominal pain, severe vomiting, pancreatitis.

Combined contact sensitization/irritation studies with dapsone gel, 5%, in 253 healthy subjects resulted in at least 3 subjects with moderate erythema. Dapsone gel, 5%, did not induce phototoxicity or photoallergy in human dermal safety studies. Dapsone gel, 5%, was evaluated for 12 weeks in four controlled trials for local cutaneous events in 1819 subjects.

The most common events reported from these studies include oiliness/peeling, dryness, and erythema. These data are shown by severity in Table 1 below. Table 1 – Application Site Adverse Reactions by Maximum Severity The adverse reactions occurring in at least 1% of subjects in either arm in the four vehicle controlled trials are presented in Table 2.

Table 2 – Adverse Reactions Occurring in at Least NOS = Not otherwise specified One subjects treated with dapsone gel in the clinical trials had facial swelling which led to discontinuation of medication. In addition, 486 subjects were evaluated in a 12 month safety trial. The adverse event profile in this trial was consistent with that observed in the vehicle-controlled trials.

Experience with Oral Use of Dapsone

Although not observed in the clinical trials with dapsone gel (topical) 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).

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).

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.

Notably, systemic exposure (AUC 0 to 12 ) of dapsone hydroxylamine (DHA) was more than doubled in the presence of TMP/SMX. Exposure from the proposed topical dose is about 1% of that from the 100 mg oral dose, even when co-administered with TMP/SMX.

Topical Benzoyl Peroxide

Topical application of dapsone gel followed by benzoyl peroxide in subjects with acne vulgaris resulted in a temporary local yellow or orange discoloration of the skin and facial hair (reported by 7 out of 95 subjects in a clinical study) with resolution in 4 to 57 days.

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.

Concomitant Use with Drugs that Induce Methemoglobinemia

Concomitant use of dapsone gel 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.

Pregnancy Risk Summary There are no available data on dapsone gel, 5%, use in pregnant women to inform a drug-associated risk for adverse developmental outcomes. In animal reproduction studies, oral doses of dapsone administered to pregnant rats and rabbits during organogenesis that resulted in systemic exposures more than 250 times the systemic exposure at the maximum recommended human dose (MRHD) of dapsone gel, 5%, resulted in embryocidal effects. When orally administered to rats from the onset of organogenesis through the end of lactation at systemic exposures approximately 400 times the exposure at the MRHD, dapsone resulted in increased stillbirths and decreased pup weight.

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 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 956 times and 289 times the systemic exposure observed in human females as a result of use of the MRHD of dapsone gel, 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 382 times the systemic exposure that is associated with the MRHD of dapsone gel, 5%, based on AUC comparisons). No effects were observed on the viability, physical development, behavior, learning ability, or reproductive function of surviving pups.

The adverse event rate for dapsone gel, 5%, was similar to the vehicle control group. Safety and efficacy was not studied in pediatric patients less than 12 years of age, therefore dapsone gel, 5%, is not recommended for use in this age group.