The UK approved fewer new medicines in the first year after the end of the transition period than the EU and US, according to researchers at Imperial College London.
In comparison to the EU and the US, only 35 new drugs were approved for use in the UK last year.
There could be negative effects on the UK's role in scientific research and development.
The question was "how do we make that happen in other areas", he said.
The office in Canary Wharf that employed 900 people was closed in March of 2019.
Extra paperwork is needed to get new medicines approved in the EU and UK.
According to James Barlow, a professor of healthcare technology and innovation management at Imperial College Business School, the findings raised questions as to whether the UK would remain attractive to international drugmakers in the long run.
Despite the fact that we have 70 million people, it is still a small market and the EU is larger than the US. He said that they were an "increasingly minor player".
Barlow said that a layer of bureaucracy had been created by the departure of the UK from the EU. It is more time consuming and expensive for a smaller market.
He said it was too early to say if the lower number of drug approvals in the UK was a blip or a trend.
He warned that R&D will shift from the UK. The United Kingdom has a strong life sciences research sector. Drugmakers may be less willing to invest in R&D in the UK if they become less interested in launching drugs in the country.
The analysis only looks at regulatory authorisations of new medicines, according to the MHRA. The work the MHRA does to support innovation in established medicines can save many people's lives.
The approval of the Covid-19 vaccine, made by Pfizer/BioNTech and AstraZeneca, has shown that we are an innovative and Agile Regulator.
A year ago, the UK government set out a 10-year life sciences strategy and said the MHRA would be able to act as an independent, sovereignty regulator with great agility and a focus on getting vaccines, drugs and technologies to patients as safely and quickly as possible.
An £80 billion turnover is generated by the life sciences sector in the UK.