Although the web version is hosted by NICE, the content is still compiled by the Joint Formulary Committee.
You will need:
Format:
Joint Formulary Committee (Year of publication) Title. Available from: www.webaddress.com [Accessed day month year].
Example:
Joint Formulary Committee (2017) Abatacept. Available from: https://bnf.nice.org.uk/drug/abatacept.html [Accessed 10 February 2021].
In-text citation: (Joint Formulary Committee, 2017)