Are gifts given in exchange for discounts on medicine bills permissible or forbidden, and does the ruling differ if the discount is personal?

These gifts are a discount from the price and an effect of the sale. Since the questioner is a partner in the price and a party to the sale, the gifts and the discount are for him and his workplace according to their respective proportions in the cost of the treatment. It is not permissible for the questioner to keep all of these for himself without his workplace, and there is no difference in this regard whether it is due to his kinship with the pharmacy owner or any other reason.