Pharmaceutical formulations

Details Pharmaceutical formulations Pharmaceutical formulations

1991-12-11

1995-04-25

Page, Thurman K.

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Particulate form

424458, 424461, 424462, 424464, 424465, 424468, 424494, 424496, 424497, 5147723, 514784, 514785, 514951, 514970, 514974, A61K 920, A61K 954, A61K 956

Patent

active

054097118

DESCRIPTION:

BRIEF SUMMARY
This invention relates to pharmaceutical formulations, particularly formulations in which the taste of orally administered drugs is masked, to the preparation of such formulations and to a method for masking the taste of orally administered drugs.
The oral administration of solid forms, for example tablets, often presents ingestion problems for the patient, especially in the case of children or old people. In order to get around this problem other forms of pharmaceutical formulations are resorted to, for example chewable tablets, tablets which disgregate rapidly in the mouth or in a spoonful of water and monodose sachets, the contents of which are dissolved or suspended in a glass of water.
Unfortunately however many drugs have an unpleasant, bitter or irritating taste and therefore it is necessary to mask the taste. In order to mask the taste, particles of the drug may be coated with a membrane which prevents the release of the drug in water (if taken with water before ingestion) and in the oropharyngeal cavity during ingestion but liberates the drug after ingestion.
The most suitable membranes for this purpose are impermeable to water and saliva but dissolve as a function of the gastrointestinal pH. Among the most common membranes are those constituted by polymers which are insoluble in water or in acid environments but are soluble at pH greater than 5 as found in the intestine. However the pH of saliva is also greater than this value and so the partial dissolution of the membrane with consequent release of the unpleasant taste of the drug can begin in the oropharyngeal cavity.
It has now been found that this difficulty can be avoided or minimized by adding acidic substances to the orally administered pharmaceutical forms such that the acidic substances dissolve to create a microenvironment around the coated particles, which prevents the dissolution of the polymers making up the membrane. Thus the taste masking is maintained in the oral cavity by the coating on the drug.
Accordingly the present invention provides a pharmaceutical formulation for oral administration comprising
a core comprising a drug, said core being coated with a polymeric membrane which is soluble only at a pH of 5 or greater
and an acidic compound for reducing or preventing the dissolution of the membrane in the oral cavity.
The core may, for example, be the drug itself eg in crystalline form or it may be a granulate containing the drug.
The formulation may be prepared by coating the core with a polymer which forms the polymeric membrane and adding the acidic compound to the formulation.
The invention also provides a method for masking the taste of drugs contained in pharmaceutical formulations, in which the taste of the drug is masked by coating with a polymeric membrane which is soluble only at a pH of 5 or greater characterised in that an acidic compound is added to the formulation in order to reduce or prevent the dissolution of the membrane in the environment of the oral cavity.
According to the invention the drug will be released only when the coated cores (ie particles) have passed through the stomach and reached the intestine where there is a pH equal to or greater than 5 (this occurs rapidly especially if the stomach is empty, and when dealing with particles of small dimensions).
Another proposal suggests that a taste masking action may be obtained with a membrane which is insoluble at a high pH (greater than 5) and soluble at a low pH (1.2-1.5) such as for example Eudragit E; this would be insoluble in the oral cavity (thus having a favourable effect on masking the taste) and soluble in the gastric tract. However if the passage of the product is particularly rapid, as can happen with particles of small dimensions and on an empty stomach, there is a risk of having an incomplete dissolution of the membrane and so an incomplete absorption of the drug.
The present invention also differs from that described in patent EP-A-0101418 where substances, e.g. carbohydrates and polysaccharides, are added to formulations containing drugs

REFERENCES:
patent: 4675175 (1987-06-01), Autant et al.
patent: 4762702 (1988-08-01), Gergely et al.
patent: 4894240 (1990-01-01), Geoghegan et al.
patent: 5051262 (1991-09-01), Panoz et al.
4 Page Rohm Pharma Technical Data Sheet dated Sep. 1982 entitled "Rapidly disintegrating, taste masking coatings with EUDRACIT.TM. L 30 D produced in an Immersion Sword System".

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