Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Food or edible as carrier for pharmaceutical
Reexamination Certificate
1999-12-30
2002-01-22
Spear, James M. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Food or edible as carrier for pharmaceutical
C424S441000, C424S464000, C424S465000, C424S490000, C424S498000, C514S783000, C514S778000, C514S784000, C514S951000
Reexamination Certificate
active
06340471
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a method for producing an oral drug delivery system that can be provided in a chewable oral dosage form for both human and animal use.
It is always a challenge to administer pharmaceuticals to animals, not only in getting the animal to accept the drug, but also in administering the correct dosage. Clearly, animals are often unwilling to accept the more direct and invasive means of delivery, such as hypodermic needle injections, forced oral delivery of large boluses, or even topical applications of salves. These methods usually are met with limited cooperation by the animal. During administration of a drug, the relative uncooperativeness of the animal affects the degree to which the complete dosage is able to be delivered. Ideally, a drug delivery system should be one in which the animal is unaware that it is even being administered a drug. Some methods, accordingly, employ a drug supplement which can be added to an animal's food so that it will voluntarily, albeit unknowingly, ingest the drug along with the food. However, animals generally have a keen sense of taste and smell and can often detect the rather strong taste and smell of most pharmaceuticals. Animals are reluctant to consume anything that has a taste foreign to their standard diet. Thus, drug-supplemented food is frequently ineffective for delivery of drugs to animals as the animal may regurgitate, spit out, or even refuse to eat the food.
To address the problem of animals' high sensitivity to the taste of the pharmaceuticals, various taste masking methods have been employed in the prior art. One method is to add flavorings to help offset the taste of the drug chemical. This, however, does not remove the drug taste, per se, but rather, creates a relative diminished taste; the drug taste is nonetheless still present. To help suppress the taste of the drug, microencapsulation of the drug active may be used which places a coating around minute drug particles to seal off the taste emanating from the drug. The microencapsulating coating, however, is relatively fragile and, if disrupted, becomes ineffective in containing the taste of the drug. The relative fragility of the microencapsulation therefore leads to problems in preparing delivery vehicles for the drug. Tablets are a common source for delivering drugs. However, the compression inherent in the tableting process will disrupt the protective coating of the encapsulation, rendering its taste masking properties ineffective. While excessive microencapsulation coating can be employed to compensate for the damage attendant with tableting, such a process would significantly increase the cost of manufacturing the drug tablet. The microencapsulated drug actives might alternately be dry-filled into a gelatin capsule; however, this is also a costly procedure in that there is an inefficient use of space within the gelatin capsule, thus decreasing the amount of active drug present within the dose. Further, the gelatin capsule does not lend itself to being a potential chewable product, which is a desirable characteristic for getting the animal to ingest the drug.
Another concern in producing drug delivery systems is for the drug to have certain controlled release properties such as immediate release and sustained release for controlling the concentration and rate of drug available for action on the animal's physiological system. Drugs can be targeted for release in terms of time (i.e., rapid or slow) and/or location (i.e., mouth or intestinal tract). Controlled release characteristics are imparted to drug actives by forming them into a pellet for sustained release or in tiny particles for immediate release. The rate of release is affected by the degree of surface area exposed in relation to the mass of the drug active particle; the rate of release is greatest when the particles have a large surface area in relation to their overall mass. Controlled release characteristics are adversely and unpredictably affected by compressing the drug actives into a tablet, as it distorts the actives' surface area to mass ratio. There have been attempts to solve the tableting problem relative to sustained release pellets by complicated formulations that take into account the breakage of pellets that will occur during the tableting process. However, this breakage issue is not reproducible. Therefore, many batches produced by this method will likely be rejected for not meeting final release specifications. Tablets can, however, be designed in themselves to have controlled release properties without the need for adding preprocessed pellets. It is also possible to produce tablets that have taste masking properties as a result of flavorings and other materials. However, using tableting processes to mask tastes requires extensive use of flavors and is minimally successful relative to very negative tasting compounds.
Accordingly, there is a need for a drug delivery system that is capable of providing taste masking qualities and preserving controlled release characteristics. It is further desirable that such a drug delivery system be provided in a form that is both chewable and palatable to the animal.
SUMMARY OF THE INVENTION
By means of the instant invention there is provided a method for producing a drug delivery system for transporting pharmaceuticals in a chewable and palatable form for ingestion by an animal that provides taste masking properties to minimize the subject animal's ability to detect the drug's presence, and which also preserves the intended controlled release characteristics of the drug active. The delivery system produced by this method comprises a lipid source in which drug actives and other particles are homogeneously suspended to form a high solids suspension which can be solidified and molded into an oral dosage form, such as a pill or tablet, for swallowing and/or chewing. The lipid source is hydrophobic (lipophilic) and provides an external phase comprising the carrier for the suspension and also provides a hydrophobic film which continuously coats the hydrophilic drug actives and other materials. The lipid source can be comprised of petroleum based and/or food based lipophilic materials such as petroleum wax, vegetable or animal stearines or a high solids sharp melting point vegetable fat. The lipid source can consist of a single source “hard butter”, which refers to a lipid system that has characteristics and/or a solid fat melting index similar to cocoa butter, and is similar in meltdown characteristics. The lipid source is selected to have a melting range of between 90°-160° F. that allows a sufficiently high melting point such that the final product will not melt while in transport or storage. The lipid system could also consist of combinations of hard butters and stearines in order to ensure a high melting point along with rapid meltdown. The melting point of the lipid may also be selected based upon the chewing texture preferences of the subject recipient. A melting point in the 90° range, for instance, will allow for melting in the mouth, which is preferable for humans, who may have an aversion to the waxy texture of a higher melting point lipid.
To prepare the suspension, the lipids are melted to the appropriate temperature, ranging from approximately 100° F. to 160° F. depending on the melting point. A surfactant, such as lecithen, is added to the melted lipid mixture to ensure optimum coating of hydrophilic particles comprising drug actives and other materials to be added later. Prior to being mixed in with the melted lipid base, the hydrophilic particles are first separately micro-encapsulated using standard pharmaceutical coating techniques. The type of encapsulation produced can vary depending on whether taste masking is desired or controlled released characteristics are desired, or both. After the hydrophilic particles are thusly prepared and encapsulated, they are added and mixed into the melted lipid base where a continuous phase lipid coating will take place within the lipi
Kershman Alvin
Shear Jeff L.
Greensfelder Hemker & Gale, P.C.
Lewis Linda L.
Robbins, II Glenn K.
Spear James M.
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