Some larger pharmaceutical companies have opted to make their own plans to replenish supplies of critical medicines in the event of a "no deal" Brexit, industry groups said on Friday, while others are aiming to book slots in the government's air and ferry freight plan.
But despite repeated and urgent requests to the government for details, medicines suppliers still don't know which ports such shipments will depart from, the timings and lengths of the journeys, or where they will arrive in the UK.
With some cross-channel trips taking as little as an hour, and others taking six or more, this heightens the potential risk for some medicines which may need refrigeration, the groups said, and raises questions about the number of drivers needed and the length of their working shifts.
"The industry doesn't know which ports will be available, which ferries will be available. So we don't known which ferries are coming from where to where," said Steve Bates, chief executive of the UK BioIndustry Association.
"We have been repeatedly asking for this," he said, adding that with fewer than six weeks to go before the current Oct. 31 Brexit deadline "everything is become increasingly urgent".
The Department for Transport said on Friday it had shortlisted eight companies which could bid to bring in drugs, using ports away from areas that are likely to face disruption.
It said the contracts - awarded to ferry companies, Eurotunnel and an aircraft charter company - would provide capacity equivalent to thousands of trucks per week.
Two Brexit deadlines have already been and gone, but Prime Minister Boris Johnson has now vowed to take Britain out of the EU with or without a deal by the end of October - increasing the chance of a sudden departure that will bring trade tariffs and customs checks with the continent for the first time in decades.
The risk is particularly acute for the pharmaceutical industry, which imports 37 million packs of medicines into the UK from the rest of Europe every month.
Briefing reporters on Friday, leaders of drug industry groups and medical research charities said they have been working for three years on contingency plans and are broadly confident that UK doctors, hospitals and patients will not face immediate or dangerous medical shortages.
"This is all about managing risk," said Mike Thompson, chief executive of the Association of the British Pharmaceutical Industry. "The scale of this means that we have to be sensible and prepare for shortages, but the system is well geared up for managing that."