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University of Wyoming

UW Technologies Available for Licensing


LICENSED - Technology Disclosure: 02-019 Method for the Controlled Release of Drugs - LICENSED


Background

There are many circumstances in which it is desirable to deliver drugs to an individual at a controlled rate, so as to extend the action of the drug over a convenient time span. The most common examples of this are decongestants and allergy medicines, in which it is very convenient for individuals to take a single pill every twelve hours, as opposed to taking a pill every two to four hours. Another example is the use of pain relievers. Timed release formulations of pain medication allow a convenient way for sufferers of chronic pain, such as arthritis or back pain, to lead more normal lives without the necessity of taking pills on a frequent basis.
Probably the most common method of releasing drugs in a controlled fashion utilizes coatings. Generally, with this method the drug is coated with polymers or inorganic materials that have varying resistance to breakdown by the body’s digestive system. Upon biodegradation of these coatings, the drug is gradually released to the body. Release rates can be controlled by varying the thickness of the coating, use of multiple coatings, utilization of multiple layering of drug and coatings, dissolution rates, and/or pH responsiveness of the coating. Problems with this approach (beside the sizable intellectual property considerations) include the fact that the rate of release generally occurs most rapidly where you don’t want it to (the stomach) and the ease with which the timed-release nature of the technology can be circumvented (purposefully or not). In the case of common drugs of abuse, such as opiates and other alkaloids, simply grinding or chewing the pill up thoroughly before it is swallowed or dissolving the pill in acid and the extracting the drug will by-pass current controlled release protections and may result in overdose, addiction, or ineffectiveness of the prescribed medication.


Summary of the Present Invention

Researchers in the University of Wyoming’s Department of Chemistry have developed and filed a patent application on a novel method for the controlled release of drugs that addresses these problems. With this technology, the drug is attached to a polymer by means of a covalent bond that is not readily cleaved by the ordinary conditions found in the digestive tract (mouth, stomach, intestines). While attached to this polymer, the drug is not bioavailable; that is, it cannot be utilized by the body, and is effectively inert, having no physiological action. Since it is chemically attached to the polymer, the use of any conventional physical means to break down the drug-delivery molecule (e.g., grinding, chewing, heating, extracting with aqueous or organic solvents) will have no effect in releasing the drug. When the drug delivery composition reaches the stomach, an acid-mediated unmasking reaction occurs that changes an important functional group (the triggering group) from its masked, inactive form, into its active form. In its active form, this triggering group is capable of rupturing the covalent bond by which the drug is attached to the polymer in a controllable fashion, thereby releasing the drug to the body in its physiologically-active form. This rupture (the release reaction) may occur by way of a unimolecular reaction or may occur by means of an intramolecular reaction involving the triggering functional group itself.
The rate at which drugs are released may be controlled by the rate of the unmasking reaction, by the rate of the release reaction, or by a combination of these rates. In most circumstances it will be desirable to have a rapid unmasking reaction that is followed by a slower release reaction, the rate of which can be varied in a predictable fashion. This is desirable because it allows for the drug delivery composition to be “unmasked” as soon as it reaches the stomach where pH conditions of about 1-3 prevail, and for the actual drug delivery to take place in the environment of the intestinal tract, where adsorption is more effective.

If you would like to learn more about this technology and how your company may apply it in commercial situations, please contact the director of the University of Wyoming Research Products Center, Davona Douglass. We would be pleased to further discuss details of the invention. The disclosure is also available from the patent office in document WO2003051113 A1.