A method of handling of a liquid drug formulation, comprising a step of providing a first primary container and coating the inner surface of the first primary container to be exposed to the formulation with a barrier layer to prevent or at least limiting any escape of material from the inner surface of the first primary container, a step of providing a second primary container and coating the inner surface of the second primary container to be exposed to the formulation with a barrier layer to prevent or at least limit any escape of material from the inner surface of the second primary container, wherein the barrier layer coating the inner surface of the second primary container has the same material composition as the barrier layer coating the inner surface of the first primary container, and a step of transition from handling the formulation filled in the first primary container at a first handling phase to handling the formulation filled in the second primary container at a subsequent handling phase so as the formulation exhibits with the second primary container the same kind of interaction as with the first primary container.
