Membranization, drug release from polymer beads

Highly water soluble drugs, as they are typical for oral administration, can be released from polymer beads with low (< 10%) water- but high ethanolswelling capacity at controlled rates, for up to 8 hours. The release of oxprenolol-HCl (77% water solubility) and diclofenac Na (2.6% water solubility) from drug loaded monoliths is a function of water content and crosslink density. By partial extraction of the drug loaded beads the release can be further slowed down and, in the case of oxprenolol-HCl, delayed for several hours the delay is dependent on water content of the polymer and is the result of the formation of a hydrophobic surface membrane. 

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