A prescription drug may only be sold by a pharmacist when authorised by a written prescription from a medical practitioner. Ethical drug is a synonym for prescription drug that is often favoured by pharmaceutical companies despite being less widely understood.
The law varies from country to country, but a drug that requires prescription in one of the major pharmaceutical markets (the US, Europe and Japan, in order of size) will generally require prescription in all.
The opposite of a prescription drug is an over-the-counter drug.
Selling prescription drugs requires a sales force that can successfully reach the necessary prescribers. The number of prescribers to be reached, and therefore the size of the sales force required, depends on who is expected to prescribe a drug. This can vary from a small number of specialists to any GP.
Because of this only the biggest pharmaceutical companies are able to market a wide range of products globally by themselves. Even fairly substantial companies that are nonetheless not giants may do one, or usually more, of the following:
- Specialise in a range of drugs that sell to particular specialists and develop a sales force big enough to reach only those specialists.
- License out drugs in regions where they do not have a sales fore of their own.
- License out some drugs completely.
- Specialise in over-the-counter or generic drugs that do not require such a large sales force.
Their large sales forces are a key reason why the major pharmaceutical companies are unlikely to lose their dominance even if their research efforts prove to be less effective than those of smaller companies (a very real risk).