Influence of the type of enteric coating suspension, coating layer and process conditions on dissolution profile and stability of coated pellets of diclofenac sodium

• Temperature and coating suspension affected efficiency and agglomeration index.
• Tests performed with the lowest temperature and Advantia® were more efficient.
• To achieve enteric release, a mass gain of 9.7% of Acryl-Eze® was necessary.
• A mass gain of 8.6% of Advantia® was necessary to achieve enteric release profile.
• Neither the drug content nor the release profiles were affected by stability test.

In this work, diclofenac sodium pellets were produced through an extrusion/spheronization process and subsequently coated in a fluidized bed coater column with a Wurster insert. The aim of this work was to study the coating of pellets with two commercial aqueous enteric polymer suspensions, Advantia® Performance and Acryl-Eze® MP. The coating process was studied with a 23 experimental design. The variables were as follows: inlet air temperature, suspension flow rate and coating polymer. The response variables were as follows: the process efficiency, which generated results above 78.2%, and the agglomeration fraction, which generated results below 8%. The polymer coating type was the variable that influenced the response variables the most. The minimum masses gain needed to achieve enteric release were also determined: Acryl-Eze® MP: 9.7% and Advantia® Performance: 8.6%. The coated pellets were tested for drug content, dissolution and stability. Neither the drug content nor the release profiles were significantly affected by storage at 40 °C and 75%. The suspensions were tested for rheology, contact angle and static wettability to investigate the characteristics of the polymer.

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