https://sps.nhs.uk/articles/procurement-of-medicines-and-services-for-nhs-secondary-care/

And more importantly

https://www.nice.org.uk/implementing-nice-guidance/medicines-and-prescribing

TLDR: you got to prove your medication actually works (rather than just having a catchy jingle) and it need to offer ‘value for money’ (this is where politics gets involved)

Still find it weird you guys have adverts on tv for medication.