Ion-exchange resin as controlled release system of potassium diclofenac from granules prepared in a high shear mixer.

Ion-exchange resins (IER) are crosslinked water insoluble polymers carrying ionizable functional groups, which have different ability to exchange oppositely charged drugs. Based on the competitive nature of the ion exchange process and on the ionic environment in the gastro-intestinal tract, IER may be optimally suitable for the oral route. In practice, drug in a ionic form (usually a solution) is mixed with the selected IER to form a complex, known as resinate, following one of the two standard procedures. Then, the resinate is used to prepare the desidered pharmaceutical form. However, up to date the preparation of resinate and of granules containing the resinate in a single step procedure by means of wet granulation have not been studied. Therefore, the aim of this work was to investigate controlled release granules containing an appropriate IER, prepared by wet granulation in high a shear mixer. Granules were prepared in a high-shear mixer (RotolabÒ, Zanchetta s.r.l., Italy) employing a technique described in details in previous works, based on the use of steam as granulating liquid. These preliminary results show that the complex between the IER and the drug is formed during the granulation process and that the drug release can be modulated varying the drug to resin ratio.