Warnings for Dapsone
Included as part of the PRECAUTIONS section.
Precautions for Dapsone
Methemoglobinemia
Cases of methemoglobinemia, with resultant hospitalization, have been reported postmarketing in association with 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 dapsone gel, 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 dapsone gel, 5% and seek immediate medical attention in the event of cyanosis.
Dapsone can cause elevated methemoglobin levels particularly in conjunction with methemoglobin-inducing agents.
Hematologic Effects
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. Some subjects with G6PD deficiency using dapsone gel developed laboratory changes suggestive of hemolysis. There was no evidence of clinically relevant hemolysis or anemia in patients treated with dapsone gel, 5%, including patients who were G6PD deficient.
Discontinue dapsone gel, 5%, if signs and symptoms suggestive of hemolytic anemia occur. Avoid use of dapsone gel, 5% in patients who are taking oral dapsone or antimalarial medications because of the potential for hemolytic reactions. Combination of dapsone gel, 5%, with trimethoprim/sulfamethoxazole (TMP/SMX) may increase the likelihood of hemolysis in patients with G6PD deficiency.
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 gel, 5% treatment.
Skin
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 gel, 5% treatment.
Patient Counseling Information
Advise the patient to read the FDA-approved patient labeling (PATIENT INFORMATION).
Hematological Effects
- Inform patients that methemoglobinemia can occur with topical dapsone treatment. Advise patients to seek immediate medical attention if they develop cyanosis [see WARNINGS AND PRECAUTIONS].
- Inform patients who have G6PD deficiency that hemolytic anemia may occur with topical dapsone treatment. Advise patients to seek medical attention if they develop signs and symptoms suggestive of hemolytic anemia [see WARNINGS AND PRECAUTIONS].
Important Administration Instructions
- Advise patients to apply dapsone gel, 5%, twice daily to the acne affected area [see DOSAGE AND ADMINISTRATION].
- Dapsone gel, 5% is for topical use only.
- Do not apply dapsone gel, 5% to eyes, mouth, or mucous membranes.
Nonclinical Toxicology
Carcinogenesis, Mutagenesis, Impairment Of Fertility
Dapsone was not carcinogenic to rats when orally administered to females for 92 weeks or males for 100 weeks at dose levels up to 15 mg/kg/day (approximately 231 times the systemic exposure observed in humans as a result of use of the MRHD of dapsone gel, 5%, based on AUC comparisons).
No evidence of potential to induce carcinogenesis was observed in a dermal study in which dapsone gel was topically applied to Tg.AC transgenic mice for approximately 26 weeks. Dapsone concentrations of 3%, 5%, and 10% were evaluated; 3% material was judged to be the maximum tolerated dosage.
Dapsone was negative in a bacterial reverse mutation assay (Ames test), and was negative in a micronucleus assay conducted in mice. Dapsone was positive (clastogenic) in a chromosome aberration assay conducted with Chinese hamster ovary (CHO) cells.
The effects of dapsone on fertility and general reproductive performance were assessed in male and female rats following oral dosing. Dapsone reduced sperm motility at dosages of 3 mg/kg/day or greater (approximately 15 times the systemic exposure that is associated with the MRHD of dapsone gel, 5%, based on AUC comparisons) when administered daily beginning 63 days prior to mating and continuing through the mating period. The mean numbers of embryo implantations and viable embryos were significantly reduced in untreated females mated with males that had been dosed at 12 mg/kg/day or greater (approximately 127 times the systemic exposure that is associated with the MRHD of dapsone gel, 5%, based on AUC comparisons), presumably due to reduced numbers or effectiveness of sperm, indicating impairment of fertility. When administered to female rats at a dosage of 75 mg/kg/day (approximately 956 times the systemic exposure that is associated with the MRHD of dapsone gel, 5%, based on AUC comparisons) for 15 days prior to mating and for 17 days thereafter, dapsone reduced the mean number of implantations, increased the mean early resorption rate, and reduced the mean litter size. These effects probably were secondary to maternal toxicity.
Use In Specific Populations
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 [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 956 times [rats] and 289 times [rabbits] 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.
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 minimal relative to oral dapsone administration; however, it is known that dapsone is present in human milk following administration of oral dapsone.
Pediatric Use
Safety and efficacy was evaluated in 1169 children aged 12-17 years old treated with dapsone gel, 5%, in the clinical trials. 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.
Geriatric Use
Clinical trials of dapsone gel, 5% did not include sufficient number of subjects aged 65 and over to determine whether they respond differently from younger subjects.
G6PD Deficiency
Dapsone gel, 5% and vehicle were evaluated in a randomized, double-blind, cross-over design clinical trial 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 dapsone gel, 5% treatment periods. There were 56 out of 64 subjects who had a Week 2 blood draw and applied at least 50% of treatment applications. Table 3 contains results from testing of relevant hematology parameters for these two treatment periods. Dapsone gel was associated with a 0.32 g/dL drop in hemoglobin after two weeks of treatment, but hemoglobin levels generally returned to baseline levels at Week 12.
Table 3 : Mean Hemoglobin, Bilirubin, and Reticulocyte Levels in Acne Subjects with G6PD Deficiency in Dapsone gel, 5%/ Vehicle Cross-Over Study
|
|
Dapsone gel, 5% |
Vehicle |
| N |
Mean |
N |
Mean |
| Hemoglobin (g/dL) |
Pre-treatment |
53 |
13.44 |
56 |
13.36 |
| 2 weeks |
53 |
13.12 |
55 |
13.34 |
| 12 weeks |
50 |
13.42 |
50 |
13.37 |
| Bilirubin (mg/dL) |
Pre-treatment |
54 |
0.58 |
56 |
0.55 |
| 2 weeks |
53 |
0.65 |
55 |
0.56 |
| 12 weeks |
50 |
0.61 |
50 |
0.62 |
| Reticulocytes (%) |
Pre-treatment |
53 |
1.30 |
55 |
1.34 |
| 2 weeks |
53 |
1.51 |
55 |
1.34 |
| 12 weeks |
50 |
1.48 |
50 |
1.41 |
There were no changes from baseline in haptoglobin or lactate dehydrogenase during Dapsone or vehicle treatment at either the 2-week or 12-week time point.
The proportion of subjects who experienced decreases in hemoglobin ≥ 1 g/dL was similar between dapsone gel, 5% and vehicle treatment (8 of 58 subjects had such decreases during Dapsone treatment compared to 7 of 56 subjects during vehicle treatment among subjects with at least one on-treatment hemoglobin assessment). Subgroups based on gender, race, or G6PD enzyme activity did not display any differences in laboratory results from the overall study group. There was no evidence of clinically significant hemolytic anemia in this study. Some of these subjects developed laboratory changes suggestive of hemolysis.