Sustained-release microencapsulated delivery system

Abstract

Disclosed is a process for producing sustained-release powders that is fast, efficient, and economical. The process involves melting a naturally derived oil with a melting point above 110° F. in specially designed mixer through either the work energy input of the mixer shaft itself, or a specially fitted plow type mixer equipped with a heating tank, cooling unit, jacket for hot water circulation, and heated lines with nozzles for atomizing the hot oil to be sprayed on. The entire manufacturing process can be completed in about 5-30 minutes, and results in small, sustained-release particles that are free flowing and solid at room temperature. The preferred oil is a hydrogenated soy oil with a melting point range of 145° F. to 160° F. which is applied at about a 1% level by weight in a high shear mixer. Also included are sustained-release compositions for therapeutic agents such as drugs, botanicals, biological agents, fungicides, and fertilizers.

Description

[0001] The present application is a continuation-in-part of U.S. Pat. No. 6,953,593, issuing on Oct. 11, 2005 and filed on Feb. 1, 2000, which is incorporated herein by reference in its entirety.FIELD OF THE INVENTION [0002] The present invention relates to a sustained-release microencapsulated compositions that can be produced efficiently and result in a very high percentage of active substance at the composition core. BACKGROUND OF THE INVENTION [0003] The benefits of producing sustained-release formulations for drugs or other therapeutic agents is now widely recognized in the medical literature and is utilized in many commercial products. It is important to distinguish at the out-set between solid monolithic dosage forms such as tablets and powders, and particles that are loosely packed into capsules. A sustained-release powder is typically made up of microparticles that are microencapsulated using a manufacturing process that enables them to be ingested as, for example, a powder...

AI Technical Summary

Benefits of technology

[0032] In accordance with these and other embodiments, the present invention provides a sustained-release microencapsulation process that can be produced inexpensively and quickly and result in a very high percentage of active substance in the core. One advantage of the instant invention is that it does not necessitate the use of solvents or synthetic polymers, although polymers can be used as an additional means of control if desired. A further advantage of the present invention is that the process does not require extremely high temperatures to produce the microspheres, and can shorten the length of time the materials are processed or exposed to elevated temperatures. In the present invention, the drug particles are processed in a way to yield a high percentage of active component powder that is still small enough to be virtually indistinguishable from the original drug particles themselves. Surprisingly, drug cores having 99.75% of the active agent are possible that release over a prolonged period.

Problems solved by technology

Microencapsulated powders may behave differently when subjected to the high pressures required to form tablets, and may fracture in the process.

In this case, diffusion and solubility issues become significant for sustained-release profiles.

Evaporation of the solvents becomes an environmental concern, and in many states, it is illegal to release these emissions into the atmosphere.

Aqueous or water based polymers are limited mainly to ethyl cellulose and methacrylic acid esters such as poly methacrylate dispersions.

Subjecting drugs and other therapeutic agents to 60° C. temperatures for 2 hours or more is likely to result in a loss of potency or degradation of active principles, and is especially problematic for substances with low melting points.

For example, botanical extracts have many volatile compounds that can be destroyed if kept at high temperatures for long periods.

Wet granulations have the additional draw backs in that they can affect the potency of the therapeutic agent being encapsulated.

For example, wet granulation can cause botanical extracts often lose potency or become less stable as a result of wet granulation techniques.

In addition, when dried at 60° C., many sensitive active principles are lost.

This system results in large particles that are not acceptable in most drink mix applications.

Another drawback is that botanical extracts cannot be sufficiently dissolved to allow for this effective use of the system.

The large particle size also presents a problem when encapsulating or tableting.

None of the oils are solid at room temperatures or have high melting points.

The oils themselves are not providing sustained-release properties.

Castor oil itself cannot be used as a solid coating material because of its low melting point.