ABSTRACT
The advantages of hydrogels include controlled-release characteristics due to adjustable water sorption and sorption rate, along with good compatibility with biological tissues and fluids. Matrix delivery systems based on hydrogel polymers that exhibit zero-order release kinetics have been developed. Controlled release is often used to extend the time the effective therapeutic dose is present at the target from a single administration, and to prevent or minimize concentrations that exceed therapeutic requirements. The periodate activation of dextran and inulin has been reported. Briefly it was observed that in the reaction of sodium periodate with dextran, different types of dialdehyde structure are formed and that the aldehyde content is higher than calculated, assuming each oxidized anhydroglucoside unit consumes two equivalents of periodate. When a starch suspension is reacted with ethylene oxide or propylene oxide in the presence of hydroxides of alkali, hydroxyethyl- or hydroxypropyl-derivatives are obtained.
