Managing kit supplies

bottle containing tablets

A kit is the vial, bottle of pills, or treatment kit containing the investigational product or placebo. Kits are given to patients in double blind trials after randomisation. A patient may be given one kit or multiple kits at different follow-up visits during the trial. This page explains some of the ways this process can be managed to help you choose the most appropriate method for your trial.



Kits are manufactured by specialist clinical trial manufacturing companies in compliance with Good Manufacturing Practice (GMP). These companies can produce matching placebos, package and label the clinical trial supplies, and distribute to the trial sites.



Kits are sent to either a central trial pharmacy or pharmacies at each trial site. The pharmacy can be blinded or unblinded.

If the pharmacy is unblinded the staff have access to the code list, which links kit codes to the true treatment group (often Active or Placebo).

Example code list
Kit code Treatment
AF5 Placebo
GY6 Active
YU1 Active
FT2 Placebo
Mac computer


An investigator uses the Sealed Envelope website to randomise a patient. They receive a kit code which they take to pharmacy.

box full of vials

Kit from bulk supplies

If the pharmacy staff are unblinded, they can hold the active and placebo treatment kits in bulk.

The pharmacist knows which kit to give to the investigator by looking up the kit code obtained from the randomisation system in the code list:

Finding the kit in the code list
Kit code Treatment
AF5 Placebo
GY6 Active
YU1 Active
FT2 Placebo

The pharmacist applies a custom label to the kit taken from the bulk supply and gives it to the investigator.

labelled vials

Pre-labelled kits

If the kits are pre-labelled at the manufacturer, pharmacy staff can remain blinded. All they have to do is find the kit that matches the randomisation kit code.

However, this approach requires more co-ordination of the labelled kits. The randomisation system must know where the kits are located so that it can choose a kit that is available at the patient's site. Administrative users of the randomisation system must use the code list management feature to update the location of kits as they are shipped to sites.

empty box


In either case (bulk supplies or pre-labelled kits) the stock levels held at each site need to be carefully considered. Insufficient stock can result in randomisation failing. However, excess stock can result in costly wastage. Sealed Envelope can provide low stock alerts and reports to help manage stock levels.