Age impacts Methotrexate dosage recommendations due to the potential for increased toxicity in certain populations, such as the elderly and children [1][2]. The U.S. Food and Drug Administration (FDA) has approved Methotrexate for various indications, including certain types of cancer, severe psoriasis, and rheumatoid arthritis [1]. However, the dosage must be carefully adjusted based on age and other factors to minimize the risk of adverse effects [2].
In the case of children, the dosage is typically based on body surface area (BSA) rather than body weight to account for individual differences in drug metabolism and excretion [2]. For example, the recommended dosage for children with acute lymphoblastic leukemia (ALL) is 15 mg/m2 once a week [2].
In contrast, elderly patients may require lower doses of Methotrexate due to age-related changes in drug pharmacokinetics, including decreased renal function and decreased drug clearance [2]. The National Comprehensive Cancer Network (NCCN) guidelines recommend a starting dose of 2.5-5 mg/week for elderly patients with rheumatoid arthritis, with careful monitoring of renal function and toxicity [2].
It is important to note that Methotrexate has a narrow therapeutic index, meaning that the difference between an effective dose and a toxic dose is small [3]. Therefore, healthcare providers must carefully monitor patients receiving Methotrexate for signs of toxicity, such as bone marrow suppression, liver toxicity, and gastrointestinal side effects [3].
In summary, age is an important factor in Methotrexate dosage recommendations due to the potential for increased toxicity in certain populations. Children typically receive doses based on BSA, while elderly patients may require lower doses due to age-related changes in drug metabolism. Healthcare providers must carefully monitor patients receiving Methotrexate for signs of toxicity.
Sources:
[1] <https://www.drugpatentwatch.com/p/tradename/METHOTREXATE>
[2] <https://www.ncbi.nlm.nih.gov/books/NBK556114/>
[3] <https://pubmed.ncbi.nlm.nih.gov/27590039/>