Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Implant or insert
Patent
1993-02-01
1994-11-08
Page, Thurman K.
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Implant or insert
514773, 514953, A61F 1302, A61K 4742
Patent
active
053624980
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a bioadhesive pharmaceutical dosage form and to a process for preparing it. It relates, in particular, to a controlled-release pharmaceutical dosage form which can remain attached to all mucosae, buccal, perlingual, nasal, vaginal or rectal, for an extended period.
The therapeutic efficacy of a medicinal product is conditioned by its bioavailability, that is to say the proportion of active principle reaching the general circulation, and according to the relevant kinetic behavior.
One of the aims of pharmaceutical formulations is hence to obtain a dosage form that displays good bio-availability and whose administration is readily accepted by the patient.
The oral route constitutes one of the routes initially favored, on account of its ease of administration and its low cost. The medicinal products thus administered may be absorbed over the whole length of the digestive tract. As a result, they will undergo various degradations under the action of enzymes, of digestive juices and also of pH variations.
In addition, after absorption in the stomach, duodenum or intestine, the active principles will first be transported to the liver, where they may be metabolised, leading, more often than not, to an at least partial inactivation of the compounds. The kinetics of distribution are, furthermore, difficult to control.
Parenteral administration enables this hepatic first-pass effect to be avoided. A rapid but transient effect is obtained, which makes repeated injections mandatory in order to maintain an active concentration. There are hence constraints for the patient, and risks of side effects as a result of the high plasma concentrations which are rapidly attained. In the case of substances capable of giving rise to addiction, such as, for example, opiates, the risk of dependence is enhanced.
An especially advantageous route is hence the administration of products via the buccal mucosa, with a view to local absorption through the epithelium. In effect, conditions favorable to the absorption of medicinal products exist in the buccal cavity: thin, multicellular epithelium, weakly acid pH and rich vascularization permitting a rapid passage through the mucosa to the blood stream. A higher blood concentration than that obtained after absorption at a lower level from the gastrointestinal tract is often observed. This is due to the fact that the efferent blood flows via the maxillary and sublingual pathways into the external jugular vein, thereby preventing the active principle absorbed from undergoing a rapid bioconversion by the liver, as can occur with molecules absorbed in the intestine. However, in addition, the active principle escapes the action of the pH variation of the different levels of the digestive tract, and the action of enzymes and, where appropriate, a complexing with food substances. The route in question is hence one that combines the good bioavailability of the parenteral route with the ease of administration of the oral route.
Administration via the other mucosae, rectal, perlingual, nasal or vaginal, will also display good absorption characteristics by avoiding the hepatic first-pass effect. A local action, such as, for example, an antiseptic, antifungal, anti-inflammatory or astringent action, may also be sought, whence the advantage of a dosage form capable of remaining in place for an extended period.
For oral administration, lyophilized dosage forms have been used. These are, more often than not, tablets for the perlingual route, displaying a rapid disintegration on rehydration by the saliva, providing the active principle with a rapid but short-lived action.
Various problems arise for maintaining the active principle in contact with the mucosa for the longest possible time, and in order to be able to regulate the release of the active principle from this dosage form under the strictest conditions so as not to cause massive absorption and not to interfere with the patient's life by putting, in the case of forms for buccal absorption, an annoying dosage form in h
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Proceed. Intern. Symp. Control. Rel. Biact. Mater., 21 (1994), Controlled Release Society, Inc., Beysac et al, "Development and Pharmacokinetic Evaluation of S2005 Bioadhesive Buccol Tablet".
Proceed. Internal. Symp. Control. Rel. Bioact. Mater., 21 (1994), Controlled Release Society, Inc., Beyssac et al, "Development and Pharmacokinetic Evaluation of S2005 Bioadhesive Buccal Tablet".
Azpuru C.
Page Thurman K.
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