Drug – bio-affecting and body treating compositions – Effervescent or pressurized fluid containing – Organic pressurized fluid
Patent
1997-02-24
1998-06-02
Page, Thurman K.
Drug, bio-affecting and body treating compositions
Effervescent or pressurized fluid containing
Organic pressurized fluid
424DIG14, 424430, 424434, A61L 904
Patent
active
057595208
DESCRIPTION:
BRIEF SUMMARY
This application is a 371 of PCT/GB95/01725 filed Jul. 21, 1995.
The present invention relates to an aqueous foamable composition suitable for delivery using known aerosol delivery systems. More particularly, the invention relates to foamable compositions which have a delayed foaming action after delivery, and which are especially suitable for rectal or vaginal delivery of pharmaceutically active ingredients.
It is known to use aqueous foams for rectal administration of pharmaceutical substances. Examples of such foams are disclosed in EP-A-0468555 (Giuliani S.p.A.), EP-A-0395329 (Smith Kline & French) and FR-A-2647344 (Physiopharm). The compositions taught in these prior art documents are so formulated that the same substance or mixture of substances (namely one or more chlorofluorocarbons) is used as both a foaming agent and a propellant for expulsion of the composition out of a conventional aerosol can. These known compositions exhibit immediate foaming on expulsion from the aerosol container.
Intravaginal contraceptive compositions are also known in the art. U.S. Pat. No. 4,588,581 (Schmolka) discloses a liquid contraceptive composition for spraying from a pressurized aerosol container, which is said to form a gel on contact with living tissue. The composition comprises in certain proportions water, propellant, a non-propellant volatile solvent, a sperm function inhibitor and a polyoxyethylene-polyoxybutylene copolymer as a surfactant.
It is an object of the present invention to provide an aqueous foamable composition which exhibits a delayed foaming action on expulsion from a pressurised container. Pharmaceutical compositions exhibiting a delayed foaming action are particularly suitable for rectal or vaginal administration. The two principal advantages associated with a foaming action which is delayed rather than immediate are (1) the likelihood of inducing a defecation or rejection reflex on administration of the composition is much lower; and (2) a better spreading effect is obtained, which leads to increased bioavailability of the active substance.
By "immediate foaming" herein is meant expansion of the foam to its final volume in less than one second following expulsion from the container in question. "Delayed foaming" is obtained when the expansion of the foam to its final volume is achieved after more than one second. Delayed foaming may, however, take place over several minutes. The initial foaming action is partial or negligible.
Non-aqueous foamable compositions with a delayed foaming action are known from WO-A-91/11991 (Kabi Pharmacia). This document teaches the skilled man to exclude water from the compositions with a delayed foaming action. Indeed, it suggests that a delayed foaming action cannot be achieved with aqueous foams. The foamable compositions disclosed in this prior art document contain a liquid polar polyol or polyol mixture as a carrier, particularly polyethylene glycols of low molecular weight (300 to 800). These polyethylene glycols are readily adsorbed and rapidly excreted. However, although they are considered of low toxicity (see Donovan et al, Pharmaceutical Research 7(8), 863-868 (1990)), they may contain undesirable residual amounts of monoethylene glycol, diethylene glycol and ethylene oxide. Water is advantageous since it is a safer vehicle, and is also much less expensive. The other essential components of the non-aqueous foamable compositions disclosed in WO-A-91/11991 are at least one foam-stabilizing and emulsifying surfactant, a pharmaceutically active ingredient and a suitable propellant.
We have surprisingly found that by employing an appropriate combination of materials it is possible to produce an aqueous foamable composition having a delayed foaming action.
According to one aspect of the invention, we therefore provide an aqueous foamable composition having a delayed foaming action on expulsion from a pressurised container, the composition comprising: water-immiscible liquefied gas;
As mentioned above, this composition is of particular use for rectal or vag
REFERENCES:
patent: 5352437 (1994-10-01), Nakagawa et al.
patent: 5369131 (1994-11-01), Poli et al.
patent: 5545401 (1996-08-01), Shanbrom
Page Thurman K.
Shelborne Kathryne E.
Tillotts Pharma AG
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