Whatever money CVS willlose by giving up the current system will likely have to be made upby charging clients more in flat fees. (Photo: AP)

On Wednesday CVS announced a major change to its pharmacy benefit management services that itsays will promote transparency and lower prices for theemployer-sponsored health plans that it serves.

The pharmacy giant's PBM business will begin to offer clients anew pricing model where it will disclose any rebates that it receives from drug-makers andpass those savings on to the plan sponsor. Whether or not patientsget a taste of the savings is up to their employers.

Pharmacy benefit managers have come under fire from politicalleaders, including President Trump, for contributing to theever-rising cost of prescription medication.

Related: Cigna CEO: The way drug rebates work will 'changeand evolve'

In October Congress voted to ban PBMs from including “gag orders” in pharmacy contracts that barpharmacists from informing patients that they could save money bypaying out-of-pocket, rather than through their prescription drugplan.

Critics have also expressed doubts that consumers benefit fromthe lower prices that PBMs negotiate with drug-makers. While thedrug-maker will often provide a steep discount on its drugs to beable to gain access to a large network, such as that managed byCVS, it's not clear how much of that discount is passed on to thepatients.

Earlier this year, CVS defended itself, saying that it only kept2 percent of the discounts that it received from pharmaceuticalcompanies.

However, CVS's pledge to pass along 100 percent of discounts toits clients is not merely an act of benevolence. Whatever money itwill lose by giving up the current system will likely have to bemade up by charging clients more in flat fees. It is quite possiblethat some plan sponsors will choose to stick with the currentpricing model.

The change may have also been made in anticipation of lawsbarring the rebate pricing model.

“If rebates go away, this model accommodates that,” Derica Rice,president of CVS Caremark, tells Reuters. “But as long as we get tothe lowest net cost we are indifferent.”