Unlicensed and off-label uses of medicines: definitions and clarification of terminology.

The terms 'licensed', 'unlicensed', and 'off-label', often used in relation to marketing and prescribing medicinal products, may confuse UK prescribers. To market a medicinal product in the UK requires a Marketing Authorization ('product licence') for specified indications under specified conditions, regulated by the Medicines and Healthcare products Regulatory Agency (MHRA). The Marketing Authorization includes the product's agreed terms of use (the 'label'), described in the Summary of Product Characteristics (SmPC). Prescribing a licensed product outside those terms is called 'off-label' prescribing. Products for which no-one holds a UK Marketing Authorization are unlicensed. Prescribers can prescribe authorized products according to the conditions described in the SmPC ('on-label') or outside those conditions ('off-label'). They can also prescribe unauthorized products, even if they are unlicensed in the UK, if they are licensed elsewhere or if they have been manufactured in the UK by a licensed manufacturer as a 'special'. The complexities of this system can be understood by considering the status of the manufacturer of the product, the company that markets it (which may or may not be the same), the product itself, and its modes of use, and by emphasizing the word 'authorized'. If a Marketing Authorization is granted to the supplier of a product, it will specify the authorized modes of use; the product will be prescribable as authorized (i.e. 'on-label') or in other modes of use, which will all be off-label. Unlicensed products with no authorized modes of use can be regarded as 'unauthorized products'. All 'specials' can be regarded as authorized products lacking authorized modes of use.