Hot tableting as a new method for obtaining tablets from slow release-coated pellets

BACKGROUND: Coating of pellets poses difficulties in the tableting process, which is attributed to the fact that ethylcellulose is a fragile polymer having low resistance to compression. This property of ethylcellulose is the reason why obtaining a slow release profile from tableted pellets comparable with that of uncompressed pellets is practically impossible when traditional tableting process is employed. METHOD: This work presents a newly developed method of hot tableting of pellets. The pellets used in the process were tramadol hydrochloride (TH) coated with an Aquacoat ECD aqueous dispersion. A physical property of PEG 3000 (one of the components of the tablet formulation) to liquidify at a given temperature was used in the process of hot tableting carried out at about 56 degrees C. RESULTS: During the hot tableting, when a low compression force of about 1 kN was applied, semiliquid granules containing melted PEG 3000 combined with TH pellets. As the temperature decreases to room temperature, a tablet matrix of good physical parameters was created. In the proposed hot tableting method, granulates containing PEG 3000 provide the tableted pellets sufficient protection from being destroyed. An evidence of such protection is confirmed by the fact that the TH slow release profile from the tableted pellets is comparable to that of uncompressed pellets. CONCLUSION: The hot tableting method allows to obtain the tablets containing compressed pellets with a TH slow release profile comparable to that of uncompresed pellets.