Notwithstanding any other provision of law to the contrary, pharmaceutical programs as defined herein shall obtain drugs through the program established pursuant to this chapter, unless a particular pharmaceutical program can purchase its pharmaceuticals at a special rate, which is lower than the savings and rebates that could be realized under this chapter, through an agreement or federal or state government public health program or a contract currently in place for the purchasing of pharmaceuticals by a pharmaceutical program in this state. In the event a contract is currently in place for the purchasing of pharmaceuticals by a pharmaceutical program in this state, the contract shall not be abrogated and shall remain in place until the occurrence of the earlier of the expiration date or the earliest termination date, as applicable.