Liposomal piroxicam formulations

Details Liposomal piroxicam formulations Liposomal piroxicam formulations

1994-07-26

1996-04-09

Kishore, Gollamudi S.

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Liposomes

A61K 9127

Patent

active

055059600

DESCRIPTION:

BRIEF SUMMARY
CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon PCT Application Serial No. PCT/EP 93/00272, filed Feb. 4, 1993, which claims priority from European patent application Serial No. 92.200.398.3, filed Feb. 12, 1992.
The present invention relates to a topical liposomal formulation comprising piroxicam, a phospholipid, a solvent system for piroxicam and said phospholipid, water and conventional auxiliary formulating agents, and a method of preparing said formulation.
JP-61/172,833 discloses formulations comprising non-steroidal anti-inflammatory drugs such as indomethacin and piroxicam, with phospholipids. Said compositions are not made up of liposomes, however.
EP-0,249,561 and EP-0,260,241 disclose particular liposomal formulations for systemic administration of active ingredients, including piroxicam.
EP-0,253,619 describes a convenient method for preparing single bilayered liposomes containing encapsulated active ingredients.
Piroxicam is an analgesic, anti-inflammatory and antipyretic drug which is sparingly soluble in aqueous and/or alcoholic media. This property considerably hampers the development of effective topical piroxicam formulations. Classic topical formulations usually comprise a rather large amount of piroxicam, mostly dispersed, in order to deliver a sufficient amount of the active ingredient to the area that is treated. The problem has now been solved by using an especially designed organic solvent system.
The present liposomal piroxicam formulation penetrates rapidly and deeply in epithelial tissues and shows excellent retention of the active ingredient therein. The efficacy of the composition is similar to that of classic cream formulations wherein piroxicam is dispersed, although the concentration of piroxicam in the present formulations often is considerably lower than the concentration of piroxicam in said classic cream formulations. The present formulation is stable and in particular does not show the disadvantage of crystallization of the sparingly soluble active ingredient piroxicam.
The present invention provides a topical liposomal formulation comprising piroxicam, a phospholipid, a solvent system for piroxicam and said phospholipid, water and conventional auxiliary formulating agents, characterized in that said composition comprises as a solvent system dimethylisosorbide and tetraglycol. The use of said solvent system in topical liposomal formulations is novel.
The present composition is preferably in the form of single bilayered liposomes, in particular liposomes having a size ranging from 100 to 1000 nm, more in particular from 100 to 500 nm. In general, the stability of the liposomal formulation increases as the size of the single bilayered liposomes decreases. Single bilayered liposomes, also referred to as unilamellar vesicles, consist of a single bilayer of suitable amphophilic molecules such as phospholipids which encapsulate an aqueous phase and which are separated from each other by an aqueous phase.
Hereinafter, the amounts of each of the ingredients in the present composition are expressed as percentages by weight based on the total weight of the formulation. Similarly, ratios are intended to define weight-by-weight ratios.
Suitable phospholipids for use in the present composition are, for example, phosphatidyl cholines, ethanolamines and serines, sphingomyelins, cardiolipins, plasmalogens, phosphatictic acids and cerebrosides, in particular those which are soluble together with piroxicam in non-toxic, pharmaceutically acceptable organic solvents. Preferred phospholipids are, for example, phosphatidyl choline, phosphatidyl ethanolmine, phosphatidyl serine, phosphatidyl inositol, lysophosphatidyl choline, phosphatidyl glycerol and the like, and mixtures thereof especially lecithin, e.g. soya lecithin. The amount of phospholipid used in the present formulation can range from about 10 to about 30%, preferably from about 15 to about 25% and in particular is about 20%.
Lipophilic additives may be employed advantageously to modify selectively the chara

REFERENCES:
patent: 3699230 (1972-10-01), Beauchamp
patent: 4082881 (1978-04-01), Chin
patent: 4963297 (1990-10-01), Madden

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