Topical Anti-Inflammatory Composition and Method of Use

1. Field of the Invention

The invention relates generally to novel anti-inflammatory compositions. More particularly, the present invention relates to novel topical anti-inflammatory compositions useful in temporarily alleviating the symptoms of inflammation in humans and animals.

2. Background of the Prior Art

Theophylline is a xanthine compound which has heretofore been used therapeutically as a smooth muscle relaxant. It is typically administered systemically by oral or intravenous or intramuscular injection.

It has now been unexpectedly discovered that the novel compositions of the present invention, utilizing theophylline as an active ingredient, provide effective, therapeutically useful topical anti-inflammatory activity.

The invention described herein generally relates to novel topical anti-inflammatory compositions comprising about 0.1 to about 1% theophylline and about 5 to about 99% of 2-pyrrolidone or an N-lower alkyl-2-pyrrolidone, and their method of use in the treatment of inflammation, i.e. in the temporary alleviation of the signs and symptoms of inflammation.

The amount of theophylline to be used in the present invention is that amount of theophylline which is effective therapeutically in the temporary alleviation of the signs and symptoms of inflammation. Typical therapeutic amounts are somewhat dependent on the type and severity of the inflammation and its location, but these amounts generally range from about 0.1 to about 1% and preferably about 0.3 percent by weight of the composition. Theophylline may be dissolved in a vehicle of this invention and topically applied to affected areas of the skin in any convenient form, e.g. cream, lotion, spray, solution, etc.

2-Pyrrolidone and N-lower alkyl-2-pyrrolidones are available commercially and are made by a number of methods known to those of skill in the art as exemplified by U.S. Pat. Nos. 2,555,353 and 2,267,757. N-lower alkyl-2-pyrrolidones include the straight and branch chain lower alkyl groups having 1-4 carbon atoms. N-methyl-2-pyrrolidone is preferred.

The amount of 2-pyrrolidone or N-lower alkyl-2-pyrrolidone which may be used in the present invention ranges from about 5 to about 99.9 percent and preferably about 10 to about 50 percent and especially about 20 percent by weight of the composition.

An effective amount of the composition, as the term is used herein, refers to that amount of composition which is effective therapeutically in the treatment of inflammation. Typical inflammations in which the present compositions are useful include conventional inflammations, such as, for example, contact dermatitis, eczema, psoriasis, sunburn, etc. The composition is generally applied about one to three times daily in conventional amounts, that is, amounts sufficient to thinly spread over the affected areas. The treatment is continued until or sometime after all of the manifestations of the inflammation have disappeared.

Ingredients which may be used in these formulations include conventional formulating ingredients, such as, for example, Freons, ethyl alcohol, isopropyl alcohol, acetone, polyvinyl pyrrolidone, fragrances, gel-producing materials, mineral oil, vegetable oil, water, stearyl alcohol, stearic acid, spermaceti, sorbitan monooleate, Polysorbate 80, Tween 60, sorbital solutions, methylcellulose, etc.

Following are specific examples which demonstrate the effectiveness of various forms of this invention.

A number of tests were performed comparing the topical anti-inflammatory activity of theophylline alone or in combination with effective amounts of N-methyl-2-pyrrolidone. The tests were performed on guinea pigs using a known animal inflammation model, namely the guinea pig UV-erythema test. In this test, a large area on the back of each guinea pig used in the test was shaved and depilitated. 18-24 hours after depilitation, each animal received a constant amount of irradiation by fixing the distance from the back of the animal to the light source (11 cm), the area of the surface to be irradiated (2 rings, 2 cm in diameter), the duration of the irradiation (30 seconds) and the intensity of irradiation emitted from the source (360 watt mercury vapor lamp with vycor glass heat filter). (Welhelmi and Domingez, Arch. Internat. Pharmcodyn. 85, 129, 1951).

The weight of the animals was monitored closely and the guinea pigs were randomized before each experiment.

After the exposure to radiation, each guinea pig was painted (using a Q-tip) with about 0.75 ml of the appropriate test solution. The solution was uniformly spread over the entire shaved area. Three or four animals were used for each test solution and/or concentration.

The development of the erythema was recorded at hourly intervals for six hours using a subjective grading system in which each irradiated spot was given a number (0,1,2,3) depending upon the severity of the reaction. The reaction corresponding to each number was defined as follows:

0 -- no redness

1 -- reddish tint without distinct outline

2 -- definite outline of reddish tint

3 -- bright red

The percent decrease of erythema in drug-treated animals compared to control animals treated with the same composition less the drug was calculated. The results are shown in Table 1.

The results indicate that theophylline in the range of about 0.1 to about 1 percent and preferably about 0.3 percent is an effective anti-inflammatory in the presence of N-methyl-2-pyrrolidone but is ineffective in the absence of N-methyl-2-pyrrolidone.

The following are examples of suitable solution formulations:

An aerosol form of formulation B of EXAMPLE 5 is prepared by preparing the following mixture:

The following are examples of suitable gel formulations:

The following are examples of suitable cream formulations:

Example I is repeated utilizing 2-pyrrolidone, N-ethyl-2-pyrrolidone, N-propyl-2-pyrrolidone and N-butyl-2-pyrrolidone. Comparable results are obtained.