The purpose was to find solutions for how to handle active and placebo drugs in the production system CATO to ensure they would end up being identical when prepared.

When preparing treatments for blinded clinical trials it is very important to make sure that it is not possible to distinguish between the active and the placebo dose, as this may lead to unblinding of the treatment and thus jeopardise the results of the trial.

Before preparing a drug using CATO the drug must be registered in the system with all of its data. It is not possible to have two different sets of data for one drug. CATO records detailed documentation of what is being done during preparation and it is not possible to pretend to pick one drug and then grab another instead. Also, the label is printed automatically so it will show exactly what was prepared. We decide on a common name for the active/placebo and register both of these in the system under that name so that they will be prepared in exactly the same way and appear identical on the label but are still distinguishable in the batch documentation. We name the drug ‘Protocol name Active substance/placebo’ and register the stock of both active drug and the sodium chloride solution that is used as placebo under that name. We will also stock vials of NaCl for this purpose next to the drug it is being placebo for, and NaCl can be prepared pretending it has the density of the drug. CATO will think they are the same drug but they have been registered with their very different batch numbers, maybe with a NaCl after the number of that, so it is always possible to see what was actually being prepared.

Our doses of active and placebo are indistinguishable. Labels are the same and, for example, withdrawal into a syringe and insertion of a needle into the port of the infusion bag will be done in the same way.

These very simple routines can be used anywhere for the preparation with CATO and possibly also with other systems.