Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Tablets – lozenges – or pills
Reexamination Certificate
1999-06-08
2001-03-13
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Tablets, lozenges, or pills
C424S465000, C424S434000
Reexamination Certificate
active
06200604
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to pharmaceutical compositions, and more particularly to pharmaceutical compositions for oral administration of a medicament, which contain an effervescent agent for enhancing oral drug absorption across the buccal, sublingual, and gingival mucosa.
2. Description of Prior Art
Effervescents have been shown to be useful and advantageous for oral administration. See Pharmaceutical DosageForms: Tablets Volume I, Second Edition. A. Lieberman. ed. 1989, Marcel Dekker, Inc. As discussed in this text, and as commonly employed, an effervescent tablet is dissolved in water to provide a carbonated or sparkling liquid drink. See also U.S. Pat. Nos. 5,102,665 and 5,468,504 to Schaeffer, herein incorporated by reference. In such a drink, the effervescent helps to mask the taste of medicaments.
Effervescent compositions have also been employed for use as taste masking agents in dosage forms which are not dissolved in water prior to administration. For example, U.S. Pat. No. 4,639,368 describes a chewing gum containing a medicament capable of absorption through the buccal cavity and containing a taste masking amount of an effervescent.
More recently effervescents have been employed to obtain rapid dissolution and/or dispersion of the medicament in the oral cavity. See U.S. Pat. Nos. 5,178,878 and 5,223,264. The effervescent tends to stimulate saliva production thereby providing additional water to aid in further effervescent action. These dosage forms give an agreeable presentation of the drug, particularly for patients who have difficulty in swallowing tablets or capsules. PCT application WO 97/06786 describes pre-gastric absorption of certain drugs using rapidly-disbursing dosage forms.
Various proposals have been advanced for oral mucosal administration of various drugs. When drugs are absorbed from the oral mucosa, they bypass the gastrointestinal and hepatic metabolism process. This can lead to a faster onset of action and/or improved bioavailability of a drug. However, many compounds do not rapidly penetrate the oral mucosa. See, e.g., Christina Graffner,
Clinical Experience with Novel Buccal and Sublingual Administration;
NOVEL DRUG DELIVERY AND ITS THERAPEUTIC APPLICATION, edited by L. F. Prescott and W. S. Nimmo (1989); David Harris & Joseph R. Robinson,
Drug Delivery via the Mucous Membranes of the Oral Cavity;
JOURNAL OF PHARMACEUTICAL SCIENCES, Vol. 81 (January 1992);
Oral Mucosal Delivery,
edited by M. J. Rathbone, which are herein incorporated by reference. The compounds which may be well absorbed per-orally (through the gastrointestinal tract) may not be well absorbed through the mucosa of the mouth because the oral mucosa is less permeable than the intestinal mucosa and it does not offer as big a surface area as the small intestine.
Despite these and other efforts toward increasing the permeation of medicaments across the oral mucosa, there have been unmet needs for improved methods of administrating medicaments across the oral mucosa.
SUMMARY OF THE INVENTION
The pharmaceutical compositions of the present invention comprise an orally administerable medicament in combination with an effervescent agent used as penetration enhancer to influence the permeability of the medicament across the buccal, sublingual, and gingival mucosa.
DETAILED DESCRIPTION OF THE INVENTION
One aspect of this invention is to use effervescent as penetration enhancers for influencing oral drug absorption. Effervescent agents can be used alone or in combination with other penetration enhancers, which leads to an increase in the rate and extent of absorption of an active drug. It is believed that such increase can rise from one or all of the following mechanisms:
1. reducing the mucosal layer thickness and/or viscosity;
2. tight junction alteration;
3. inducing a change in the cell membrane structure; and
4. increasing the hydrophobic environment within the cellular membrane.
The present dosage forms should include an amount of an effervescent agent effective to aid in penetration of the drug across the oral mucosa. Preferably, the effervescent is provided in an amount of between about 5% and about 95% by weight, based on the weight of the finished tablet, and more preferably in an amount of between about 30% and about 80% by weight. It is particularly preferred that sufficient effervescent material be provided such that the evolved gas is more than about 5 cm
3
but less than about 30 cm
3
, upon exposure of the tablet to an aqueous environment. However, the amount of effervescent agent must be optimized for each specific drug.
The term “effervescent agent” includes compounds which evolve gas. The preferred effervescent agents evolve gas by means of a chemical reaction which takes place upon exposure of the effervescent agent (an effervescent couple) to water and/or to saliva in the mouth. This reaction is most often the result of the reaction of a soluble acid source and a source of carbon dioxide such as an alkaline carbonate or bicarbonate. The reaction of these two general compounds produces carbon dioxide gas upon contact with water or saliva. Such water-activated materials must be kept in a generally anhydrous state and with little or no absorbed moisture or in a stable hydrated form, since exposure to water will prematurely disintegrate the tablet. The acid sources may be any which are safe for human consumption and may generally include food acids, acid and hydrite antacids such as, for example: citric, tartaric, amalic, fumeric, adipic, and succinics. Carbonate sources include dry solid carbonate and bicarbonate salt such as, preferably, sodium bicarbonate, sodium carbonate, potassium bicarbonate and potassium carbonate, magnesium carbonate and the like. Reactants which evolve oxygen or other gasses and which are safe for human consumption are also included.
The effervescent agent(s) of the present invention is not always based upon a reaction which forms carbon dioxide. Reactants which evolve oxygen or other gasses which are safe for human consumption are also considered within the scope. Where the effervescent agent includes two mutually reactive components, such as an acid source and a carbonate source, it is preferred that both components react completely. Therefore, an equivalent ratio of components which provides for equal equivalents is preferred. For example, if the acid used is diprotic, then either twice the amount of a mono-reactive carbonate base, or an equal amount of a di-reactive base should be used for complete neutralization to be realized. However, in other embodiments of the present invention, the amount of either acid or carbonate source may exceed the amount of the other component. This may be useful to enhance taste and/or performance of a tablet containing an overage of either component. In this case, it is acceptable that the additional amount of either component may remain unreacted.
The present dosage forms may also include in amounts additional to that required for effervescence a pH adjusting substance. For drugs that are weakly acidic or weakly basic, the pH of the aqueous environment can influence the relative concentrations of the ionized and unionized forms of the drug present in solution according to the Henderson-Hasselbach equation. The pH solutions in which an effervescent couple has dissolved is slightly acidic due to the evolution of carbon dioxide. The pH of the local environment, e.g., saliva in immediate contact with the tablet and any drug that may have dissolved from it, may be adjusted by incorporating in the tablet a pH adjusting substances which permit the relative portions of the ionized and unionized forms of the drug to be controlled. In this way, the present dosage forms can be optimized for each specific drug. If the unionized drug is known or suspected to be absorbed through the cell membrane (transcellular absorption) it would be preferable to alter the pH of the local environment (within the limits tolerable to the subject) to a level that favors the uni
Eichman Jonathan D.
Hontz John
Khankari Rajendra K.
Pather Sathasivan Indiran
Robinson Joseph R.
Cima Labs Inc.
Ghali Isis
Lerner David Littenberg Krumholz & Mentlik LLP
Page Thurman K.
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