issuer offering group health insurance coverage shall— (1) not restrict, directly or indirectly, any pharmacy that dispenses a prescription drug to a participant of beneficiary in the plan or coverage from informing (or penalize such pharmacy for informing) a participant or beneficiary of any differential between the participant’s or beneficiary’s out-of-pocket cost under the plan or coverage with respect to acquisition of the drug and the amount an individual would pay for acquisition of the drug without using any health plan or health insurance coverage