What is the ruling on a doctor taking money in exchange for prescribing a specific medication to patients, given that the medication is effective, suitable for their condition, and inexpensive, especially since there are fatwas describing this act as deceit and betrayal? If the money is unlawful, what should the female doctor do to repent, and what is the ruling on money acquired through bribery after repentance?

What you mentioned about prohibiting a doctor from taking a commission from pharmaceutical companies in exchange for referring patients to them, absolutely, is what the fatwa on the website has settled upon, as a way of blocking the means to corruption. The patient is harmed by the increased price and the prescription of lower-quality medication. Thus, the prohibition is general, even if some doctors are righteous, and the complete prohibition, as a way of blocking the means, considers the prevalent situation. What was acquired from that act, while ignorant of its prohibition, there is no blame upon the acquirer in benefiting from it, according to the preponderant opinion, based on the Almighty's saying: "So whoever receives an admonition from his Lord and desists, he may have what has already passed, and his affair is to Allah." As for whoever acquired it knowing of its prohibition, he must dispose of its equivalent in charitable causes and for the benefit of Muslims, and he is not required to sell the things he bought with it.