Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Tablets – lozenges – or pills
Patent
1995-05-04
1997-11-25
Page, Thurman K.
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Tablets, lozenges, or pills
424461, 424470, 424489, A61K 924
Patent
active
056909594
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
This invention relates to a thermal infusion process for preparing controlled release solid dosage forms of medicaments for oral administration and controlled release solid dosage forms of medicaments prepared thereby. More specifically, controlled release solid dosage forms of amoxicillin, clavulanate and mixtures thereof are prepared according to this invention.
BACKGROUND OF THE INVENTION
It is desirable to provide pharmaceutical formulations for oral administration in a form in which a delayed or controlled release of the active materials within the formulation is achieved, so that complete release of the active materials into solution in the body of the patient from the formulation occurs over a prolonged period after oral administration, so that for example the formulation need only be taken twice or even only once a day.
Various methods of formulating pharmaceutically active compounds for oral administration so that the release of the active compound(s) in the formulation takes place over a prolonged period after ingestion are known. For example, tablets maybe made which are coated with a controlled release material, such as a polymer or a wax. Encasing tablets is useful in delaying the initial release of the active compound but generally contributes little toward controlling the release of the medicament subsequent to in vivo removal of the coating.
Pharmaceutically active compounds may be incorporated into a matrix with a relatively impermeable polymer. Compounds which are moisture sensitive, however, are considered inappropriate candidates for matrixed polymeric controlled release formulations because of the degradation which occurs in the time taken to diffuse out of the matrix after dissolution. Additionally, the dissolution profile of matrixed polymeric controlled release formulations generally relies on dissolution followed by diffusion to liberate the medicament from the matrix thereby subjecting moisture sensitive compounds to aqueous degradation prior to in vivo release.
Solvent based mediums used in the preparation of matrixed polymeric formulations and other controlled release formulations are either environmentally unsound due to the release of solvent into the atmosphere or expensive due to the cost of maintaining solvent recovery systems for such process. Further, solvent based mediums of hydrophobic waxy material used in the preparation of controlled release formulations generally require a large surface area and significant time (often a week or more) to provide for proper annealing of the coating material in order to achieve proper control of the release of medicament from the solid dosage form.
Additionally, melt granulation methods have been employed in formulating controlled release dosage forms of pharmaceutically active compounds. Conventional melt granulation processes are characterized by the melting of a controlled release wax and then dispersing the medicament throughout the melt. The melted material is allowed to congeal and the solidified mass is sized and compressed into tablets. It is apparent that there are disadvantages associated with this method of preparing a sustained release tablet. First, heat labile compounds will decompose in the molten wax. Further, it is expensive and hazardous to adopt this molten wax technique to mass production. Aside from the hazard of working with large quantities of molten wax, there is the difficulty of working with the hard congealed-medicament mixture which must be removed from the mixing vessel and sized. Additionally, the sizing of the hard congealed-medicament mixture exposes the previously encased medicament thereby detracting from its controlled release profile in subsequent dosage forms. A further outstanding disadvantage of the known art method of preparing sustained release tablets, in particular by the molten wax process, is that a high dosage drug cannot be easily prepared with satisfactory release characteristics.
Some of the above described disadvantages are overcome by spraying the molten wax
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Palepu Nageswara R.
Venkatesh Gopadi M.
Benston, Jr. William E.
Dustman Wayne J.
Kinzig Charles M.
Lentz Edward T.
Page Thurman K.
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