While the typical dose of methotrexate (MTX) for inflammatory disease in pediatric patients varies in published studies, the maximum dose is considered to be 1 mg/kg and not to exceed 25 mg/week. In addition, test doses are not necessary for pediatric patients starting low dose (1 mg/kg or less) MTX for inflammatory skin disease, and the onset of efficacy with MTX may take 8-16 weeks.
and in Pediatric Dermatology.
“Methotrexate is a cost-effective, readily accessible, well-tolerated, useful, and time-honored option for children with a spectrum of inflammatory skin diseases,” project cochair, professor of pediatrics and dermatology at Saint Louis University, told this news organization. “Although considered an ‘immune suppressant’ by some, it is more accurately classified as an immune modulator and has been widely used for more than 50 years, and remains the standard of care when administered at very high doses and intrathecally in children with acute lymphoblastic leukemia – a practice that supports safety. But many details that support optimized treatment are not widely appreciated.”
In their guidelines document, Dr. Siegfried and her 22 coauthors noted that Food and Drug Administration labeling does not include approved indications for the use of MTX for many inflammatory skin diseases in pediatric patients, including morphea, psoriasis, atopic dermatitis, and alopecia areata. “Furthermore, some clinicians may be unfamiliar or uncomfortable prescribing medications off label for pediatric patients, causing delayed initiation, premature drug discontinuation, or use of less advantageous alternatives,” they wrote.
To address this unmet need, Dr. Siegfried and the other committee members used a modified Delphi process to reach agreement on recommendations related to five key topic areas: indications and contraindications, dosing, interactions with immunizations and medications, potential for and management of adverse effects, and monitoring needs. Consensus was predefined as at least 70% of participants rating a statement as 7-9 on the Likert scale. The effort to develop 46 recommendations has been a work in progress for almost 5 years, “somewhat delayed by the pandemic,” Dr. Siegfried, past president and director of the American Board of Dermatology, said in an interview. “But it remains relevant, despite the emergence of biologics and JAK inhibitors for treating inflammatory skin conditions in children. Although the mechanism-of-action of low-dose MTX is not clear, it may overlap with the newer small molecules.”
The guidelines contain several pearls to guide optimal dosing, including the following key points:
- MTX can be discontinued abruptly without adverse effects, other than the risk of disease worsening.
- Folic acid supplementation (starting at 1 mg/day, regardless of weight) is an effective approach to minimizing associated gastrointestinal adverse effects.
- Concomitant use of MTX and antibiotics (including trimethoprim-sulfamethoxazole) and NSAIDS are not contraindicated for most pediatric patients treated for inflammatory skin disease.
- Live virus vaccine boosters such as varicella-zoster virus (VZV) and measles, mumps, and rubella (MMR) are not contraindicated in patients taking MTX; there are insufficient data to make recommendations for or against primary immunization with MMR vaccine in patients taking MTX; inactivated vaccines should be given to patients taking MTX.
- Routine surveillance laboratory monitoring (i.e., CBC with differential, alanine transaminase, aspartate aminotransferase, creatinine) is recommended at baseline, after 1 month of treatment, and every 3-4 months thereafter.
- Transient transaminase elevation (≤ 3 upper limit normal for < 3 months) is not uncommon with low-dose MTX and does not usually require interruption of MTX. The most likely causes are concomitant viral infection, MTX dosing within 24 hours prior to phlebotomy, recent administration of other medications (such as acetaminophen), and/or recent alcohol consumption.
- Liver biopsy is not indicated for routine monitoring of pediatric patients taking low-dose MTX.
According to Dr. Siegfried, consensus of the committee members was lowest on the need for a test dose of MTX.
Overall, she said in the interview, helping to craft the guidelines caused her to reflect on how her approach to using MTX has evolved over the past 35 years, after treating “many hundreds” of patients. “I was gratified to confirm similar practice patterns among my colleagues,” she added.
The project’s other cochair was, a dermatologist at Seattle Children’s Hospital. This work was supported by a grant from the (PeDRA), with additional funding from the National Eczema Association and the National Psoriasis Foundation. Dr. Siegfried disclosed ties with AbbVie, Boehringer Ingelheim, Incyte, LEO Pharma, Novan, Novartis, Pierre Fabre, Pfizer, Regeneron, Sanofi Genzyme, UCB, and Verrica. She has participated in contracted research for AI Therapeutics, and has served as principal investigator for Janssen. Many of the guideline coauthors disclosed having received grant support and other funding from pharmaceutical companies.