Diagram of hypothetical mixing process (The Solution Process).

The solution process involves three sub-processes,

1. Drug fusion process: in a hypothetical process, the drug changes phase, transforming into a super-cooled liquid. Technically, this process requires energy supply, which is why it is unfavorable for the solution process.
2. Cavity formation: although the solvent does not present a phase change, the solvent molecules must disintegrate, forming a cavity to house the solute molecule. This process also requires the investment of energy (endothermic process) and is therefore unfavorable for the solution process.
3. Mixing process: Once the drug is in a liquid state, and the cavity has been formed in the solvent, the solute molecule is housed in the solvent cavity, forming the solution. This process is exothermic, which is why it favors the solution process.