Controlled release system
First Claim
1. A device having two controlled release rates of a water soluble active material into an aqueous medium in contact with the device, the device including a water soluble capillary tube having a wall and at least one open end, said tube being filled with a composition comprised wholly or partially of the active material, wherein, when the device is contracted with an aqueous medium, dissolution of the active material takes place at a first diffusion controlled rate with diffusion at least through said at least one open end until dissolution through the wall, thereafter the active material is released at a second rapid release rate, there being a sufficient amount of the composition relative to the first diffusion controlled rate and the time required for dissolution of the wall that a portion of the composition is not released until dissolution through the wall.
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Accused Products
Abstract
A device for the controlled release of an active material into an aqueous medium comprises a water soluble capillary tube (11) the bore (12) of which contains an active material (13). Dissolution of the active material is diffusion limited during a delay period while the capillary is dissolving. When dissolution of the tube is complete rapid dissolution of the remaining active material then takes place.
10 Citations
18 Claims
- 1. A device having two controlled release rates of a water soluble active material into an aqueous medium in contact with the device, the device including a water soluble capillary tube having a wall and at least one open end, said tube being filled with a composition comprised wholly or partially of the active material, wherein, when the device is contracted with an aqueous medium, dissolution of the active material takes place at a first diffusion controlled rate with diffusion at least through said at least one open end until dissolution through the wall, thereafter the active material is released at a second rapid release rate, there being a sufficient amount of the composition relative to the first diffusion controlled rate and the time required for dissolution of the wall that a portion of the composition is not released until dissolution through the wall.
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18. A method for releasing water soluble active material into an aqueous medium at two controlled release rates, the steps comprising:
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making a device having a water soluble capillary tube with a wall and with at least one open end, the tube being filled with a composition comprised wholly or partially of the active material; and placing said device in contact with an aqueous medium such that dissolution of the active material takes place at a first diffusion controlled rate at least through the at least one open end until dissolution through the wall and, upon dissolution of the wall, there is remaining active material which is released at a second rapid release rate.
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Specification