First, C-V-S drug stores pulled tobacco from its shelves. Now, it plans to make some customers think twice about filling prescriptions at other stores that still sell smokes. C-V-S is developing a new tobacco-free pharmacy network for clients of its Caremark pharmacy benefits management business. The network would slap an extra co-payment on patients who fill their prescriptions at stores that still sell tobacco. That payment won't apply to prescriptions filled in the tobacco-free network, which would include CVS and Target locations nationally, as well as other pharmacies that abstain. CVS' national rival Walgreen still sells tobacco. The tobacco-free network would only be used by the pharmacy-benefit management customers that choose it.