The invention relates to a process for reconstitution of a solid form of a pharmaceutical composition, comprising the following successive steps: (i) providing the solid form of the pharmaceutical composition in a sealed container, the pressure within the container being an initial pressure (pi) comprised between 0.5 Pa and 1.2×105 Pa; (ii) at a first time point (t0) introducing the solvent into said sealed container and maintaining the resulting pressure (pr) within the container during a controlled time Δt1; and (iii) at a second time point (t2) increasing the pressure within the container to a controlled pressure (p2) higher than said resulting pressure (pr) until complete reconstitution.