Orodispersible tablets containing fexofenadine

Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Particulate form

Reexamination Certificate

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C424S465000, C424S458000, C424S489000, C424S495000, C424S497000

Reexamination Certificate

active

06723348

ABSTRACT:

FIELD OF THE INVENTION
The present invention concerns orodispersible tablets comprising coated granules of fexofenadine. The invention also concerns said coated granules of fexofenadine, a process for the preparation thereof and the use of said orodispersible tablets.
In the context of the present invention, the term “orodispersible tablets” means tablets which are able to disintegrate in the buccal cavity in less than 60 seconds, preferably in less than 40 seconds, upon contact with saliva by formation of an easy-to-swallow suspension.
The disintegration time corresponds to the time between the moment when the tablet is placed in the buccal cavity in contact with saliva and the moment when the suspension (resulting from the disintegration without chewing of the tablet) is swallowed.
BACKGROUND OF THE INVENTION
Fexofenadine is a well known synthetic antiallergenic with the chemical name (±)-4-[1-hydroxy-4-[4(hydroxydiphenylmethyl)-1-piperidinyl]-butyl]-&agr;,&agr;-dimethyl benzeneacetic acid.
Fexofenadine, a metabolite of terfenadine, is an antihistamine with selective peripheral H1-receptor antagonist activity.
Fexofenadine is known from e.g. U.S. Pat. No. 4,254,129. It is acknowledged in the art and is commercially available, in particular as an oral tablet or capsule, under the trade name Allegra®.
The tablets, commercially available under the trade name Allegra® contain 30, 60, or 180 mg fexofenadine hydrochloride (depending on the dosage) and, as excipients, croscarmellose sodium, magnesium stearate, microcrystalline cellulose and pregelatinized starch. Said tablets are coated with a film coating based on hydroxypropyl methylcellulose, mixture of iron oxides, polyethylene glycol, povidone, silicone dioxide, and titanium dioxide.
Fexofenadine is highly active via oral administration. While numerous pharmaceutical compositions for oral administration have been proposed, there still exists a need for commercially acceptable fexofenadine formulations for oral administration with good patient convenience and acceptance, especially for children or the elderly.
One particular difficulty in the formulation of fexofenadine in oral pharmaceutical compositions is its unpleasant, strong bitter taste and aftertaste.
Another difficulty in the formulation of fexofenadine in oral pharmaceutical compositions is the low solubility of fexofenadine, especially in gastric conditions (solubility of 0.2 mg of fexofenadine HCl per ml of pH 1.2 aqueous buffer solution).
It is therefore highly desirable to develop coated granules, containing fexofenadine, which have taste-masking properties while permitting rapid release of the active substance from the granules and allowing rapid absorption in the body after oral administration.
Furthermore, some patients, especially children and the elderly, experience difficulties swallowing the tablets, even with liquids.
It is estimated that 50% of the population have problems swallowing the tablets. This leads to poor, or even noncompliance, with the treatment and thus has a negative impact on the efficiency of the treatment (H. Seager, 1998, J. Pharm. Pharmacol 50, 375-382).
Oral disintegrable multiparticulate tablets have already been described in U.S. Pat. Nos. 5,464,632, 6,106,861, WO 00/27357 and WO00/51568, the contents of which are hereby incorporated by reference. The active ingredient is in the form of coated microcrystals or coated microgranules.
Up to now, no oral formulations of fexofenadine exist which are specifically suitable for patients having difficulties when swallowing or for patients taking the drugs with no liquids.
It is thus highly desirable to remedy this situation and to develop an orodispersible tablet, containing fexofenadine, which has taste-masking properties and presents a pleasant palatability such that the administration of the tablet is not unpleasant for the patient and which allows the obtaining of pharmacokinetic parameters at least bioequivalent to those which are obtained with conventional oral formulations of fexofenadine, for example tablets such as those available under the trademark Allegra®.
The Applicant has now surprisingly found that these characteristics can be obtained by formulating a tablet containing fexofenadine as active ingredient in the form of coated granules, and a mixture of excipients containing at least one disintegrating agent, a soluble diluent agent and a lubricant, and optionally a swelling agent, an antistatic agent, a permeabilising agent, sweeteners, flavoring agents and colors.
The present invention relates to orodispersible tablets which are able to disintegrate in the buccal cavity upon contact with saliva by formation of an easy-to-swallow suspension, in less than 60 seconds, preferably in less than 40 seconds, such tablets containing fexofenadine as active ingredient in the form of coated granules, and a mixture of excipients comprising at least one disintegrating agent, a soluble diluent agent, a lubricant and optionally a swelling agent, an antistatic agent, a permeabilising agent, sweeteners, flavoring agents and colors.
Surprisingly, although the tablets according to the invention disintegrate in the buccal cavity and present a release of the active ingredient which is equivalent to the conventional formulation, they nevertheless have a pleasant taste.
Furthermore, the orodispersible tablets of the invention are found to show high stability and physical integrity, e.g. during storage, handling, packaging and the like, while maintaining very good disintegration performance.
Fexofenadine may be used in the form of its racemate or a single enantiomer, in free base form or in acid addition salt form of the racemate or one of its single enantiomers. An acid addition salt form may be prepared from the free base form in a conventional manner and vice-versa. Examples of suitable acid addition salt forms include hydrochloride, lactate and ascorbate, preferably hydrochloride. Fexofenadine in the form of a hydrochloride salt is preferred.
In a preferred embodiment, fexofenadine particles present a particle size such that 100% of the particles have an average size of less than 20 &mgr;m.
In the tablets according to the invention, fexofenadine in anyone of said forms is present as coated granules.
In the present patent application, the term “fexofenadine” is employed for designating anyone of its specific forms.
According to an advantageous embodiment, the tablet according to the invention, has a hardness of not less than 15 N, when measured with the test method of the European Pharmacopeia (2.9.8).
According to an advantageous embodiment, the tablet according to the invention contains coated granules of fexofenadine, or one of its pharmaceutically acceptable salts, and a mixture of excipients, the ratio of the mixture of excipients to the coated granules is 0.4 to 9, preferably 1.5 to 5 and even more preferably 2 to 3 parts by weight, the mixture of excipients comprising:
at least one disintegrating agent,
a soluble diluent agent,
a lubricant,
and optionally a permeabilising agent, a swelling agent, an antistatic agent, sweeteners, flavoring agents and colors.
The disintegrating agent is selected from the group consisting of croscarmellose, available as e.g. Ac-di-sol®, crospovidone available as e.g. Kollidon CL®, and mixtures thereof.
According to an advantageous embodiment of the invention, the soluble diluent agent used in the tablets presents binding properties. The soluble diluent agent with binding properties consists of a polyol having less than 13 carbon atoms and being either in the form of a directly compressible product with an average particle size of 100 to 500 &mgr;m, or in the form of a powder with an average particle size of less than 100 &mgr;m, this polyol preferably being selected from the group comprising mannitol, xylitol, sorbitol and maltitol, it being understood that sorbitol cannot be used alone and that, in the case where there is only one soluble diluent agent with binding properties, it is used in the form of the directly compressible prod

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