Delivery systems and devices for the controlled release of chemicals, including drugs, comprising a wall, formed in part at least, of a porous material, pores of which contain a hydrogel, said porous wall in contact with at least a portion of a reservoir comprised of a chemical and, if desired, a water-soluble liquid excipient and/or a detergent; process for preparation thereof, and use for the controlled release of chemicals, including drugs, to an aqueous liquid-containing environment. Emphasis is given to said systems and devices in which the porous material is a sintered plastic and gelled cellulose triacetate is the hydrogel, and to their use for controlled release of drugs to animals, especially to ruminants over prolonged periods of time.
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation-in-part of copending application Ser. No. 904,078 filed May 8, 1978 and now abandoned.
A system is disclosed for dispensing an useful agent. The system comprises (1) means for storing an agent, (2) an agent stored in the means, (3) means for releasing agent from the system, (4) means for absorbing fluid into the system surrounding the storing means, and (5) means for admitting fluid into the system. In operation fluid is admitted into the system by the admitting means cooperating with the absorbing means, causing it to increase in dimensions and apply force against the storing means, which force urges the storing means to decrease its dimensions and correspondingly dispense agent through the releasing means from the system. Laminates are disclosed useful for manufacturing the system.
A method for obtaining a measurement of the time integral of concentrations of substances in a biological fluid, without the necessity to collect samples of that fluid, and a device useful in the practice of that method. The concepts accomplish time-integrated measurement of the freely-diffusable fraction of substances of interest by providing conditions under which the rate of accumulation of such substances by a device placed in intimate contact with the biological fluid is at all times proportional to their concentration.
A vaccine composition including an antigen dispersed in an alginate gel is described. The alginate gel is preferably in the form of discrete particles coated with a polymer. Vaccination of vertebrate species can be accomplished by administering the alginate-based vaccine compositions orally.
A device for enabling a measurement of the time integral of concentrations of substances in a biological fluid, without the necessity to collect samples of that fluid, is disclosed for accomplishing time-integrated measurement of the freely-diffusable fraction of substances of interest by providing conditions under which the rate of accumulation of such substances by the device placed in intimate contact with the biological fluid is at all times proportional to their concentration.
A bolus for administering medicament containing the medicament in a bio-erodible polymer having a shape or size so that it is retained in the rumen for at least two weeks, having a fine mesh completely encasing the bolus, which can contain a heavy metal core to give it weight, or can be in two segments connected by a spring, or a flexible polyurethane band, which changes position after being administered to the animal.
