Does the work of a pharmacist as a promotional representative, which requires giving doctors free samples of medications to persuade them to prescribe the drug to the patient, constitute a forbidden bribe that falls under the scope of "Allah has cursed the one who gives and the one who takes a bribe"?

It is permissible to work as a pharmaceutical sales representative, unless the job involves a Shari'ah-prohibited matter, such as the medications having side effects not mentioned in the leaflets, or promoting them with untrue descriptions. As for gifting samples to doctors, if the purpose is to test the medication to ascertain its efficacy, then there is no harm. Otherwise, it is a forbidden bribe that involves deceiving and betraying patients.