Disruption at the ports will cause delays in all sorts of supply chains. Those organisations who don't hold large stocks of drugs (or anything else for that matter) because their business model has been built on the JIT supply chains enabled by the single market and customs union are going to struggle and may not survive
A larger problem is going to be the longer term future of the pharmacutical industry. Faced with diverging regulatory systems, the manufacturers are going to aim at the biggest market and concentrate on getting approval in the EU first.
The regulator has moved, those who visit the regulator (and their expenses which supported local hotels etc) will be moving with them,
If manufacturers start to focus on the EU then it starts to make sense to move manufacturing and research into the EU especially if there is longer term disruption at the port and increasing tariff and non-tariff barriers.