With the aim of obtaining carbamazepine (CBZ) prolonged release dosage forms, cellulose acetate butyrate (CAB70) microspheres have been prepared by the emulsion/solvent evaporation method. In order to modulate the CBZ release, the addition of polyethylene glycols (PEG) in the internal phase of the emulsion was carried out. When compared with microspheres prepared only from CAB70, the encapsulation efficiency and the CBZ content were drastically reduced by the PEG 4000 addition. On the other hand, the incorporation of 10% (w/w) of PEG1500 did not affect the drug content in the microspheres. Most porous particles werw observed by SEM when PEG 1500 or 4000 was added to the formulations, however the lost of the spherical shape of the particles was verified when an ABC70:PEG 4000 1:1 mixture was used to prepare the microspheres. The addition of PEGs did not appear to affect the mean diameter of the particles. The decrease of the CBZ content was related to the PEG extraction during the solvent evaporation step and to its ability to dissolve the CBZ in the external phase of the emulsion. The porosity development control, by adjusting the amount or the molecular weight of PEG, can be useful in the drug release from microparticles.
Carbamazepine; Microspheres; Cellulose acetate butyrate; Polyethylene glycol 1500; Polyethylene glycol 4000; Emulsion/solvent evaporation method
