Roche, Merck and Lilly are among those calling for regulatory harmonisation and free movement of goods between the EU and the UK once the latter leaves the Union.
Parties negotiating TTIP have discussed measures that would end EMA API and drug manufacturing plant inspections in the US and FDA inspections in Europe.
Ensuring drugs, APIs and excipients are safe will be a focus for the EMA, which says it will explore supplier inspection databases and using trade deals like TTIP to promote GMP standards globally.