Résumé
Essential medicines are intended to be available within the context of functioning health systems at all times in adequate amounts, in the appropriate dosage forms, with assured quality, and at a price the individual and the community can afford. The WHO Model List is a guide for the development of national and institutional essential medicine lists. The WHO Model List is updated and revised every 2 years by the WHO Expert Committee on selection and use of medicines. The 19th WHO Expert Committee on Selection and Use met in April 2013 to produce the following lists: 18th WHO Model List of Essential Medicines (2013) and 4th WHO Model List of Medicines for Children (2013). The concept of essential medicines is present in more than 150 countries which have their national list based on WHO Model List.