Intercalation of drugs in layered double hydroxides and their controlled release: A review

The intercalation of different drugs in layered double hydroxides with the hydrotalcite-like structure is reviewed. The intercalation processes are carried out following different routes (direct synthesis, coprecipitation, anion exchange) and the advantages and disadvantages of these methods are described for the specific drug/LDH system studied. Characterisation of the intercalation compounds is also studied, to determine the way the guest molecules are intercalated between the layers of the layered double hydroxide. The controlled release (in some cases also the kinetics analysis) is also studied. We conclude that layered double hydroxides are very suitable materials to host different families of drugs and in the controlled release they show benefitial properties, on comparing with the effect of the bulk drug. It should be also stressed that these are almost the unique materials (in addition to layered hydroxy salts) able to host drugs in the anionic form, so nicely completing the studies carried out so far on the suitability of cationic clays to host cationic or neutral drugs.