Co-Insurance (the beneficiary pays a percentage of the drug costs -- for instance, 25% paid by the beneficiary and 75% paid by the plan provider)?
Co-Payment (the beneficiary pays a fee per prescriptions and the prescription drugs are organized into cost tiers -- for instance, a copay schedule could look like $5/$25/$65 for tier 1/2/3 drugs)?
A combination of copayment or coinsurance?
See the Link below to how Coinsurance and Copayment actually function with a few examples