The present invention relates to novel particles comprising polyelectrolyte polymers which are transporters of active principle (AP), in particular protein and peptide active principle, and to novel modified-release pharmaceutical formulations comprising said AP microparticles.These novel particles loaded with AP release the AP over a prolonged period of time of several days, or even several weeks.The invention relates, in a first aspect, to particles comprising:a) a first polyelectrolyte polymer (PE1) in a charged state, carrying side hydrophobic groups (GH), wherein said first polyelectrolyte polymer (PE1) can spontaneously form, in water, a colloidal solution of particles at least one pHm value of the pH of between 3 and 8b) a second polyelectrolyte polymer (PE2) of opposite polarity to the first polyelectrolyte polymer (PE1), wherein said second polyelectrolyte polymer (PE2) forms, in water, a solution or a colloidal solution at said pHm value of the pH andc) at least one active principle (AP) associated noncovalently with the particles of the colloidal solution of the first polyelectrolyte polymer (PE1)wherein said particles are obtained by mixing, at a pH equal to pHm, the first polyelectrolyte polymer (PE1), in the form of a colloidal solution of particles associated with the active principle (AP), with the second polyelectrolyte polymer (PE2), in the form of a solution or colloidal solution.The invention also relates to the process for the preparation of these particles, to a pharmaceutical formulation comprising such particles and to a process for the preparation of medicaments.
