UK MHRA will not act as ‘leading authority’ for medicines during the Brexit transaction period as per Article 123 of the draft Withdrawal Agreement. In which UK MHRA will not act as leading authority for risk assessments, examinations, approvals and authorisations at the level of the Union or of Member States.

A “leading authority” conducts assessments on behalf of specific EU agencies. The UK and EU are still discussing the scope of activity that this article will cover with respect to medicines. It does not cover medical devices.

No matter, the MHRA’s role will change immediately and the UK will no longer have voting rights in the European Medicines Agency (EMA) and EU committees. MHRA will remain available to provide expert advice during this period, and UK businesses will have the same rights during the implementation period as EU-based businesses to have their cases accepted and processed by EU agencies and EU-based leading authorities.

As per the withdrawal agreement, the UK can continue to participate in the decentralized and mutual recognition licensing procedures, MHRA excluded from acting as a Reference Member State (RMS) in procedures related to the approval of marketing authorizations. Applicants can use the national procedure if they want to market a medicine only in the UK

For more detail please refer below link:

https://www.gov.uk/guidance/apply-for-a-licence-to-market-a-medicine-in-the-uk#history