SAN ANTONIO Methotrexate appears to be a safe and effective long-term systemic therapy for pediatric atopic dermatitis, according to a poster presented at the annual meeting of the American Academy of Dermatology.
A systemic therapy for this most common of childhood dermatologic conditions has long been needed, noted Dr. Christopher Rouse of St. Louis University, who disclosed no potential conflicts of interest.
Other therapies have been studied, but none has received approval from the Food and Drug Administration for atopic dermatitis (AD). Meanwhile, methotrexate has been used since 1959 for pediatric conditions including rheumatoid arthritis, Crohn's disease, and psoriasis.
Dr. Rouse reviewed the cases of 26 children (14 boys and 12 girls) with severe AD, all of whom had been previously treated with other therapies. Each patient was given 0.5 mg/kg of methotrexate, to a maximum of 15 mg/week, as well as 0.51 mg/day of folic acid on days when methotrexate was not taken.
Each patient was seen monthly for 3 months and every 3 months thereafter and given kidney and liver function tests. The mean age at onset of AD was 9 years. The mean starting dose was 0.49 mg/kg per week; the mean maximum dose was 0.55 mg/kg per week. The mean duration on methotrexate was 9.4 months.
In 50% of the patients, the AD was well controlled on methotrexate alone. In 25%, the disease was controlled but not clear, requiring the addition of topical steroids. In 20% of patients, the AD was controlled with flares. Two children experienced no improvement in their disease, he reported.
Adverse events included transient elevated liver enzymes in seven patients and gastrointestinal symptoms in seven patients. Five children had staphylococcus-associated skin eruptions, two children had pneumonia, and two had urticaria.
Dr. Rouse cautioned that his retrospective study involved a small number of patients and that there was no standardized method of assessing improvement, but he was sanguine about the implications for pediatric AD. Methotrexate tablets are safer and more readily available than liquid methotrexate and are small enough for children to take without difficulty. Moreover, the tablets obviate the risk that a pharmacy will compound the liquid formulation improperly, he noted. Response might take 23 months of treatment.
In a separate presentation, Dr. Alice Gottlieb, professor and chair of dermatology at Tufts University, Boston, noted that care must be taken not to give significant doses of methotrexate with amoxicillin, because the toxicity of this combination is largely unknown in primary care. The combination of methotrexate and Bactrim (trimethoprim-sulfamethoxazole) is also toxic, she said.
In a previously published open-label study of 20 patients, investigators found that methotrexate was safe and effective for adults with atopic dermatitis, although two of those patients discontinued the drug because of nausea and/or elevated liver enzymes (Eur. J. Dermatol. 2006;16:1558).
Care must be taken not togive large doses of methotrexatewith amoxicillin because of unknown toxicity. DR. GOTTLIEB