ExpressScripts.com accepts the Five Back Visa card.

When refilling prescriptions on ExpressScripts.com, just add a Gene Grawe Fund Five Back Visa to your account during checkout and then select it as your payment method for this one purchase. Leave your regular credit/debit card as your default payment method.

UPDATE: For six years now, I’ve kept a new, REGISTERED, $250 Gene Grawe Fund Five Back Visa on my Express Scripts account and set it as my default payment method. The refills process fine and charges my co-pays to the Visa without a problem. I keep a close watch on the card balance and when it gets low I replace it before the balance reaches $0.