Use of water with different molecular mobilities could affect drug dissolution of a dosage form and such profile of water might be modifiable using microwave. This study investigated the effects of microwave on water and its influences on dissolution of free drugs and drugs in calcium-crosslinked alginate beads using sulphanilamide and sulphamerazine as hydrophilic and hydrophobic model drugs respectively. The water was treated by microwave at 300 W or without pre-treatment. The drug dissolution, pH and molecule mobility profiles of untreated and microwave-treated water were examined. Microwave-treated water had higher pH and water molecule mobility. The latter was characterized by higher conductivity, lower molecular interaction and crystallinity profiles. The dissolution of hydrophilic and hydrophobic free or encapsulated drugs was enhanced using microwave-treated water due to its higher molecular mobility. The untreated water of the same pH as microwave-treated water did not enhance drug dissolution. The drug dissolution from beads was increased by higher water uptake leading to matrix erosion and pore formation using microwave-treated water and was not promoted by the formation of non-crosslinked hydrated alginic acid matrix in untreated water of lower pH. Microwave treatment of water increased water molecule mobility and can promote drug dissolution.
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