See the DrugPatentWatch profile for methotrexate

Methotrexate is a commonly used disease-modifying antirheumatic drug (DMARD) for the treatment of juvenile idiopathic arthritis (JIA) and other rheumatic diseases in children [1]. The relative infrequency of alternatives to methotrexate for pediatric patients can be attributed to several factors, including the drug's efficacy, safety profile, and the patent landscape.

Firstly, methotrexate has demonstrated long-term efficacy in managing JIA and other rheumatic conditions in children [1]. Its ability to control inflammation, prevent joint damage, and improve physical function makes it a preferred first-line treatment for many pediatric rheumatologists [1].

Secondly, the safety profile of methotrexate is generally well-established in the pediatric population [1]. Although it can have side effects, such as gastrointestinal symptoms and liver function abnormalities, these are typically manageable and reversible [1]. Moreover, the long-term safety data for methotrexate in children with JIA are reassuring, with no increased risk of malignancy or infertility observed in long-term studies [1].

Lastly, the patent landscape plays a role in the limited availability of alternatives to methotrexate for children. Methotrexate has been available for several decades and is now off-patent, making it a cost-effective option for treating pediatric rheumatic diseases [2]. In contrast, many of the newer biologic DMARDs, such as tumor necrosis factor inhibitors and interleukin-1 inhibitors, remain under patent protection [2]. Consequently, these drugs can be significantly more expensive than methotrexate, which may limit their use in some pediatric patients [2].

In summary, the widespread use of methotrexate in children with rheumatic diseases can be attributed to its established efficacy, favorable safety profile, and cost-effectiveness compared to many newer biologic DMARDs, which are still under patent protection.

Sources:
[1] Lovell, D. J., & Reiff, A. (2016). Methotrexate in juvenile idiopathic arthritis. Rheumatic diseases clinics of North America, 42(3), 455-472.
[2] DrugPatentWatch.com. (n.d.). Methotrexate. Retrieved from https://www.drugpatentwatch.com/drugs/methotrexate