In vitro evaluation of two concepts of sustained release floating minitablets according to the model drug used

This work aims to evaluate the influence of an incorporated drug e.g. levodopa and ciprofloxacin on the dissolution and floating properties of two formulation concepts of sustained release floating minitablets e.g. coated and uncoated. Both floating systems contained one active drug, a meltable binder and gas-generating agents. The dissolution profiles and the floating behavior of uncoated floating minitablets, in which the generated gas is trapped by a swellable polymer, were compared to coated floating minitablets, in which a polymeric membrane can control both the release of the drug and the retention of the generated carbon dioxide. It was shown that the release of a drug that is characterized by a relatively large molecular size could be delayed from coated floating minitablets due to a slower permeation rate through the membrane. In contrast, the dissolution profile of an active drug incorporated into uncoated floating minitablets did not depend on its molecular size. The release of a drug characterized by a pH-dependant solubility depended more on the pH than the sustained release capabilities of the dosage form, regardless of the formulation concept used. When the amount of uncoated floating minitablets filled into a capsule was too high, sticking was an important variable in the release profile of the drug. Finally, the floating properties of the uncoated and coated floating minitablets were also found to depend on which active drug was incorporated.