Does a pharmacist have the right to recover the price difference for a medicine he sold at an old price, which then increased in price?

The seller does not have the right to reclaim the price difference after selling the medicine at the old price by his own choice and consent, due to the Almighty’s saying: "O you who have believed, do not consume one another's wealth unjustly but only [in lawful] trade by mutual consent," and due to the Prophet's (peace be upon him) saying: "Indeed, selling is by mutual consent."