Triple-Layer Tablets for 24-Hour Zero-Order Drug Release
posted on 01/20/2009
The barrier layers swell and erode faster than the middle drug-containing layer, and thus increase the delivery surface area much more substantially as the drug is being depleted from the middle layer. Standard polymers (including HPMC and PEO) are used throughout.
Allows the middle layer to release the drug and the two other layers to give to support to the middle layer for longer lasting drug release overall.
Many different approaches have been used in recent years to devise solid dosage forms capable of zero-order drug release over 24 hours, such as osmotic pump or triple-layer designs. The Geomatrixâ triple-layer tablet technology currently on the market consists of a swellable middle layer containing the drug and two impermeable outer layers that remain in place while the drug is being released. The purpose of the outer barrier layers is to allow drug delivery only through the edge of the middle layer, the surface area of which increases significantly as it swells. Thus, the surface area open for drug release increases as the remaining drug loading decreases with time.
The present technology provides substantial performance advantages over the Geomatrixâ design by making the barrier layers swell and erode faster than the middle drug-containing layer, and thus increase the delivery surface area much more substantially as the drug is being depleted from the middle layer. Added control of the drug release profile is provided by using different thickness and/or polymers for the two barrier layers, so that they erode at different rates. Standard polymers (including HPMC and PEO) are used throughout.
Tablets of this type containing 240 mg of diltiazem hydrochloride have a drug release profile very similar to that of 240 mg Dilacor XRâ capsules (each of which contains four triple-layer tablets).
File Number: 289RF
Web site: http://www.temple.edu/ott
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