These Regulations are made in exercise of the powers conferred by section 8(1) of the European Union (Withdrawal) Act 2018 (c. 16) in order to address failures of retained EU law to operate effectively and other deficiencies (in particular under section 8(2)(a), (b), (c), (d), (f) and (g) and (6)) arising from the withdrawal of the United Kingdom from the European Union. They are also made under paragraphs 1(1) and 7(2) of Schedule 4 to the European Union (Withdrawal) Act 2018, insofar as they make provision in relation to fees.
Link: The Human Medicines (Amendment etc.) (EU Exit) Regulations 2019
Source: Legislation .gov.uk