After reviewing the sources provided, there is no information regarding age-related dosage adjustments for Cosentyx. The drug patent watch website [1] and the official Cosentyx website [2] do not provide any information about age-related dosage adjustments. The prescribing information [3] provided by Novartis, the manufacturer of Cosentyx, only mentions dosage adjustments for patients with moderate to severe renal impairment and patients with moderate to severe hepatic impairment. It is important to note that the dosage of Cosentyx should be determined by a healthcare professional based on the patient's medical history, severity of the condition, and other factors. Therefore, it is recommended that patients consult with their healthcare provider regarding dosage adjustments for Cosentyx.

Sources:
[1] https://www.drugpatentwatch.com/p/biologics/tradename/COSENTYX
[2] https://www.cosentyx.com/treatment-cost
[3] https://www.novartis.com/us-en/sites/novartis_us/files/cosentyx.pdf