See this example properly formatted in the QUT Cite tool.
Standard in-text citation examples are in Getting started - In-text citation.
Author, A. A. (Year, Month DD). Title. Source/Database. Retrieved Month DD, Year, from http://www.xxxxxxxx
Ali, A., Qaseem, A., & Rae-Grant, A. (Eds.). (2018, November 30). Delirium in hospitalized patients. DynaMed. Retrieved January 14, 2019, from http://www.dynamed.com/topics/dmp~AN~T116623/Delirium-in-hospitalized-patients
As the information is continuously updated, include the full date and the date of retrieval.
If no author, you can use the editors (Eds.) or use Dynamed Plus as author.
As this information is unique to DynaMed, include the name of the database.
As the URL is stable, the URL of the article is acceptable.