I'm not sure this answers your, particular, question but maybe you can find your answer here. I've never gotten a discount on my prescriptions through AARP membership, but have gotten it through the Optum RX that is available from AARPs Medicare Plan AND through other plans available.
https://www.aarp.org/benefits-discounts/
HEALTH & WELLNESS
AARPยฎ Prescription Discounts provided by OptumRxยฎ
Prescription Savings
This program offers a free prescription discount card that can be used at over 66,000 pharmacies nationwide for savings on all FDA-approved medications. The program is open to anyone, whether youโre an AARP member or not โ but AARP members receive additional benefits, including deeper discounts on medications, home delivery, coverage for your dependents and more.
If your pharmacy is unable or unwilling to process your discount, please have the pharmacist call 1-877-422-7718.
How to Access
Access your free discount card online and use at any participating pharmacy.
Never Look Down on Anybody...Unless You Are Helping Them Up. ๐