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Yes, dosage adjustments for methotrexate are necessary in elderly patients with kidney issues. Methotrexate is primarily excreted by the kidneys, and impaired renal function can lead to increased methotrexate concentrations and toxicity. Therefore, it is recommended to reduce the methotrexate dosage in elderly patients with kidney problems [1].

The recommended dosage adjustments for methotrexate in elderly patients with kidney issues depend on the severity of the renal impairment. For patients with mild renal impairment (creatinine clearance (CrCl) 50-80 mL/min), a 25-50% reduction in the methotrexate dosage is recommended. For patients with moderate renal impairment (CrCl 10-49 mL/min), a 50% reduction in the methotrexate dosage is recommended. For patients with severe renal impairment (CrCl <10 mL/min), methotrexate should be avoided or used with extreme caution [2].

It is important to note that the methotrexate dosage should be individualized based on the patient's renal function, age, body weight, and other factors. Regular monitoring of renal function, methotrexate concentrations, and hematologic parameters is necessary during methotrexate therapy in elderly patients with kidney issues [3].

In summary, dosage adjustments for methotrexate are necessary in elderly patients with kidney issues due to the primary excretion of methotrexate by the kidneys. The recommended dosage adjustments depend on the severity of the renal impairment, and regular monitoring of renal function, methotrexate concentrations, and hematologic parameters is necessary during methotrexate therapy in elderly patients with kidney issues.

Sources:

1. Methotrexate. Lexicomp Online, Hudson, Ohio: Wolters Kluwer Health; 2021.
2. Methotrexate. In: Clinical Pharmacology [database online]. Tampa, FL: Gold Standard, Inc.; 2021.
3. Methotrexate. DrugPatentWatch.com. <https://www.drugpatentwatch.com/drugs/methotrexate>. Accessed February 24, 2023.