used provided the formulation remains shakable. In other certain limited embodiments the upper limit for foamable formulations may be determined by flowability such that any effective amount can be used provided the formulation is sufficiently flowable to be able to flow through an actuator valve and be released and still expand to form a good quality foam. This may be due without being bound by any theory to one or more of a number of factors such as the viscosity, the softness, the lack of crystals, the pseudoplastic or semi pseudo plastic nature of the composition and the dissolution of the propellant into the composition. 

In certain embodiments the amount of surfactant or com› bination of surfactants is between about 0.05% to about 20%; between about 0.05% to about 15%. or between about 0.05% to about 10%. In a preferred embodiment the concentration of surface active agent is between about 0.2% and about 8%. In a more preferred embodiments the concentration of surface active agent is between about 1 % and about 6% or between about 1 % and about 4%. 

In some embodiments, it is desirable that the surface active agent does not contain a polyoxyethylene (POE) moiety, such as polysorbate surfactants, POE fatty acid esters, and POE alkyl ethers, because the active agent is incompatible with such surface active agents. For example, the active agent pimecrolimus is not stable the presence of POE moieties, yet benefits greatly from the use of dicarboxylic esters as pen› etration enhancers. In such cases, alternative surface active agents are employed. In an exemplary manner, POE-free surfactants include non-ethoxylated sorbitan esters, such as sorbitan monopalmitate, sorbitan monostearate, sorbitan tristearate, sorbitan monooleate, sorbitan trioleate, sorbitan monolaurate and sorbitan sesquioleate; glycerol fatty acid esters, such as glycerol monostearate and glycerol monooleate; mono-, di- and tri-esters of sucrose with fatty acids ( sucrose esters), sucrose stearate, sucrose distearate sucrose palmitate and sucrose laurate; and alkyl polyglyco› sides, such as lauryl diglucoside. 

In one or more embodiments, the surface-active agent includes mono-, di- and tri-esters of sucrose with fatty acids (sucrose esters), prepared from sucrose and esters of fatty 40 acids or by extraction from sucro-glycerides. Suitable sucrose esters include those having high monoester content, which have higher HLB values. 

In one or more preferred embodiments of the present invention the surfactant includes at least one surfactant selected from a polyoxyethylene fatty ether, a polyoxyethyl› ene fatty ester, a carbohydrate ester and a sucrose ester. 

In one or more embodiments non limiting examples of non-ionic surfactants include steareth-2, steareth-20, ste› areth-21, ceteareth 2, PEG-100 stearyl ether, cetearyl gluco- side, methyl glucose sesquistearate, sorbitan monostearate, GMS NE and span 20. 

In one or more embodiments non limiting other examples of surfactant combinations are glyceryl stearate and PEG 100 stearate and laureth4; steareth 2, PEG 100 searate and !au- reth4; and cetearyl glucoside and cetearyl alcohol. 

In an embodiment the surfactant containing formulations are further boosted by a foam adjuvant for example stearyl alcohol. 

A non limiting example of a combination of surfactants having a weighted average of their HLB values of 11 is Glyceryl Stearate and PEG-100 Stearate (for example trade name "simulsol 165" from Sepic ). 

## Hydrophobic Solvent 

Optionally, the foamable carrier further contains at least one hydrophobic solvent. The identification of a "hydropho› bic solvent", as used herein, is not intended to characterize the 

solubilization capabilities of the solvent for any specific active agent or any other component of the foamable compo› sition. Rather, such information is provided to aid in the identification of materials suitable for use as a part in the foamable compositions described herein. 

A "hydrophobic solvent" as used herein refers to a material having solubility in distilled water at ambient temperature of less than about 1 gm per 100 mL, more preferable less than about 0.5 gm per 100 mL, and most preferably less than about 0.lgmperl00mL. 

In one or more embodiments, the hydrophobic organic carrier is an oil, such as mineral oil, isopropyl palmitate, isopropyl isostearate, diisopropyl adipate, diisopropyl dime› rate, maleated soybean oil, octyl palmitate, cetyl lactate, cetyl ricinoleate, tocopheryl acetate, acetylated lanolin alcohol, cetyl acetate, phenyl trimethicone, glyceryl oleate, toco› pheryl linoleate, wheat germ glycerides, arachidyl propi› onate, myristyl lactate, decyl oleate, propylene glycol ricino› leate, isopropyl lanolate, pentaerythrityl tetrastearate, neopentylglycol dicaprylate/dicaprate, isononyl isononanoate, isotridecyl isononanoate, myristyl myristate, triisocetyl citrate, octyl dodecanol, unsaturated or polyun› saturated oils, such as olive oil, corn oil, soybean oil, canola oil, cottonseed oil, coconut oil, sesame oil, sunflower oil, borage seed oil, syzigium aromaticum oil, hempseed oil, herring oil, cod-liver oil, salmon oil, flaxseed oil, wheat germ oil, evening primrose oils; essential oils; and silicone oils, such as dimethicone, cyclomethicone, polyalkyl siloxanes, polyaryl siloxanes, polyalkylaryl siloxanes and polyether siloxane copolymers, polydimethylsiloxanes ( dimethicones) and poly( dimethylsiloxane )-( diphenyl-siloxane) copoly› mers. In one or more further embodiments the hydrophobic organic carrier is petrolatum. 

## Humectant 

A humectant, is a substance that helps retain moisture and also prevents rapid evaporation. Non limiting examples of suitable heumectants are propylene glycol, propylene glycol derivatives, and glycerin. Other examples ofhumectants and moisturizers may be found in the Handbook of Pharmaceuti› cal Additives published by Gower. Suitable ones for use with and soluble in the waterless compositions of the present invention may be selected as will be appreciated by a person skilled in the art. 

## Moisturizers 

A moisturizer, is a substance that helps retain moisture or add back moisture to the skin. Examples are allantoin, petro› latum, urea, lactic acid, sodium PCV, glycerin, shea butter, caprylic/capric/stearic triglyceride, candelilla wax, propy› lene glycol, lanolin, hydrogenated oils, squalene, sodium hyaluronate and lysine PCA. Glycerine and sodium pCA work in combination. Other examples may be found in the Handbook of Pharmaceutical Additives published by Gower. 

Pharmaceutical compositions of the present invention may in one or more embodiments usefully comprise in addition a humectant or a moisturizer or combinations thereof. 

## FoamAdjuvant 

Optionally, a foam adjuvant is included in the foamable carriers of the present invention to increase the foaming capacity of surfactants and/or to stabilize the foam. In one or more embodiments of the present invention, the foam adju› vant agent includes fatty alcohols having 15 or more carbons in their carbon chain, such as cetyl alcohol and stearyl alcohol ( or mixtures thereof). Other examples of fatty alcohols are arachidyl alcohol (C20), behenyl alcohol (C22), l-triacon- tanol (C30), as well as alcohols with longer carbon chains (up to C50). Fatty alcohols, derived from beeswax and including a mixture of alcohols, a majority of which has at least 20 

