Pharmaceutical formulations in form of thixotropic gel

Abstract: The present invention relates to a topical formulation of gel-like consistency, but nebulizable by a mechanical pump, containing colloidal silices as gelifying agent.

Description: The present invention relates to a topical formulation of gel-like consistency, nebulizable by mechanical pump, containing colloidal silices as gelifying agent. PRIOR ART The preparation of a semi-solid system nebulizable by means of a spray mechanical system seemed up to now to be an unsurmountable problem. In fact, efforts to prepare formulations making use of the conventional, most used gelifying agents lead to the production of gels which, although being highly valid, are absolutely not sprayable. Even making a compromise, namely decreasing the system viscosity, at the most the emission of the product from the mechanical pump is obtained, but not the nebulization. Moreover, decreasing viscosity, the product tends to leak once sprayed on the concerned part. In the cosmetic field, the so-called gel-sprays exist, which however have an exceedingly low viscosity, thereby tending to leak after the emission, therefore they cannot be even defined gels. Moreover they are usually prepared using acrylates such as Carbopols. DISCLOSURE OF THE INVENTION The present invention overcomes the problems of the prior art, by the use of a high viscosity system, which is nearly semisolid, characterized in that it is destructurated by a mechanical stress and in that it can be sprayed by a mechanical pump. The pharmaceutical formulations in form of thixotropic gel of the present invention will contain, besides an active ingredient, a colloidal silica with a surface area from 130 to 300 m 2 /g and an average diameter of 12 nm, in an amount from 2 to 15% by weight, water and optionally excipients. In addition, the thixotropic gel may contain a solvent selected from glycerol, polyoxyethylene glycol, diethylene glycol monoalkyl ether, N-methylpyrrolidone, glycofurol, isopropanol, ethylene glycol, propylene glycol, in amounts from 1 to 10% by weight. Any excipients conventionally used in the pharmaceutical techniques, such as surfactants, preservatives, flavouring agents, co-solvents and lipophilic phases can also be present. Particularly preferred surfactants are those belonging to the following classes: Sorbitan esters (for example Span 20, Span 40, Span 60, Span 65, Span 80, Span 85); Polyoxyethylene sorbitan esters (for example Tween 80, Tween 60, Tween 40, Tween 20); Polyoxyethylene alkyl ethers (for example Cremophor A™, Bryj™, Texofor A) ; Polyoxyethylene stearates (for example Myrj 52, Myrj 53). The pharmaceutical formulations of the invention will preferably contain a colloidal silica having a surface area of 175-225 m 2 /g, in amounts ranging from 2 to 8%, more preferably from 2.5 to 7% by weight. In the pharmaceutical formulations of the invention, water may be present in an amount ranging from 60 to 97% by weight. The present invention provides a system characterized by: Pseudoplasticity: the viscosity decreases with the increase in the intensity of the applied stress; Thixotropy: the viscosity decreases with time, as the applied stress goes on. The system of the present invention uses as gelifying agent colloidal silices, which are excipients widely used in the topical field as thickening and suspending agents, and in the oral solid as lubricants. It should be noted that within the definition "colloidal silica" lie several commercial products used as pharmaceutical excipients, whose characteristics can be summarized as follows: Surface area from 50 to 400 m 2 /g Average diameter from 7 to 40 nm. All of these materials give similar gelification phenomena but, since gelification occurs through adsorption, the surface area characteristics become paramount for the choice of the type and amount of colloidal silica to use. Suitable silices according to the invention have a surface area ranging from 130 to 300 m 2 /g and an average diameter of 12 nm. The present invention uses specifically as colloidal silices Aerosils™, preferably colloidal silices with characteristics similar to Aerosil 200. Aerosil characteristics of pseudoplasticity and thixotropy are well known, however up to now said characteristics have not been made use of in order to spray/nebulize a product in the form of gel by the simple pressure of a finger. In essentially aqueous systems, aerosils (only) at high concentrations (5-15%) cause the structuration of water through adsorption phenomena, until a consistence of gel (or, more correctly, magma). The Aerosil-Water bond is very mild and it can be cleaved by even slight stresses, such as those caused by a mechanical pump. During the stress, and therefore during the spray, the viscosity of the system remarkably decreases, thereby allowing the nebulization. Once applied to the skin, the sprayed product, no longer stressed, quickly returns to its original state, acquiring back a gel-like consistence. It is particularly surprising that, when in the formulation of the invention besides Aerosil and water, a less polar solvent is also present, such as glycerol, polyoxyethylene glycol, diethylene glycol monoalkyl ether (Transcutol™), N-methylpyrrolidone, glycofurol, isopropanol, ethylene glycol, propylene glycol, viscosity falls upon the slightest mechanical stress; in the absence of said solvent, such a phenomenon appears less markedly, but anyhow so as not to affect adversely the thixotropic characteristics according to the invention. The use of the propylene glycol is particularly preferred. The topical gel formulation of the present invention can be administered with a suitable dosage, through doser mechanical pumps which dispense prefixed volumes. The topical formulations of the present invention can be used, besides for the topical administration on the skin, also for the vaginal, nasal, otological administration, wherein the absence of leakage and the in loco persistence are particularly important. The gels of the present invention will preferably be dispensed by means of mechanical pump dispensers. The formulations of the invention can also contain all of the active ingredients whose topical administration is therapeutically effective. Examples of active ingredients which can be used in the formulations of the invention comprise: non-steroidal antiinflammatory agents, such as ketoprofen, ibuprofen (including optical isomers and salts thereof), naproxen, diclofenac, diflunisal, nimesulide, ketorolac, flurbiprofen, indomethacin, acetylsalicylic acid and the like; antifungal drugs such as miconazole, econazole, fluconazole, tyrothricin, antibacterials/antibiotics such as polymyxin, neomycin, kanamycin, gentamycin, tetracycline, meclocycline, clindamycin; antiviral drugs such as acyclovir, cytarabine; corticosteroids; antihistamines; sympathomimetic drugs; antiallergic drugs such as disodium cromoglycate; local anesthetics; cicatrizants; capillary-protective substances; bioflavonoids; retinoids; vitamins; enzymes; growth factors. Some examples of pharmaceutical and para-pharmaceutical formulations containing active ingredients at therapeutical concentrations are reported hereinbelow. a.i. = active ingredient PHARMACEUTICAL FORMULATIONS EXAMPLE 1 a.i. Ketoprofen Lys 15 g colloidal silica 5 g propylene glycol 5 g Tween 80 0.5 g Na nipagin 0.1 g Nerolene lavender 0.1 g demin. water q.s. to 100 g EXAMPLE 2 a.i. miconazole nitrate 2 g propylene glycol 10 g colloidal silica 3 g esterified polyoxyethylene glycols 3 g polysorbate 80 0.5 g sodium methyl-p-hydroxybenzoate 0.15 g malva perfume 0.5 g demin. water q.s. to 100 g EXAMPLE 3 a.i. disodium cromoglycate 4 g propylene glycol 5 g colloidal silica 5.5 g sodium edetate 10 mg polysorbate 80 0.5 g benzalkonium chloride 10 mg menthol 0.3 g eucalyptol 0.1 g demin. water q.s. to 100 g EXAMPLE 4 a.i. oxymetazoline hydrochloride 0.050 g monobasic sodium phosphate 1.020 g dibasic sodium phosphate 1.110 g EDTA 0.010 g propylene glycol 5.0 g colloidal silica 5.0 g Tween 20 0.5 g sodium methyl-p-hydroxybenzoate 0.15 g menthol 0.4 g eucalyptol 0.1 g demin. water q.s. to 100 g EXAMPLE 5 a.i. menthol 0.4 g camphor 0.4 g eucalyptol 0.2 g sodium phosphate monobasic 1.02 g sodium phosphate dibasic 1.11 g EDTA 0.01 g propylene glycol 8,0 g colloidal silica 4,0 g polysorbate 80 1.0 g sodium methyl-p-hydroxybenzoate 0.15 g demin. water q.s. to 100 g EXAMPLE 6 a.i. tyrothricin 0.02 g cethyltrimethylammonium bromide 0.05 g benzocaine 0.05 g PEG 200 4 g colloidal silica 4 g ethyl alcohol 5 g Cremophor A11 0.7 g sodium saccharine 0.02 g sodium methyl-p-hydroxybenzoate 0.15 g peppermint oil 0.5 g demin. water q.s. to 100 g EXAMPLE 7 a.i. polymixin B sulfate 1.000.000 I.U. neomycin sulfate 0.5 g lidocaine chloride 4 g propylene glycol 10 g colloidal silica 3 g polysorbate 80 0.5 g demin. water q.s. to 100 g EXAMPLE 11 a.i. naproxene 10 g colloidal silica 5 g ethyl alcohol 10 g polysorbate 80 0.75 g sodium methyl-p-hydroxybenzoate 0.15 g camphor 0.2 g demin. water q.s. to 100 g EXAMPLE 12 a.i. escin 2 g sodium heparin 5.000 I.U. diethylamine salicylate 5 g transcutol 2 g colloidal silica 6 g ethyl alcohol 10 g polysorbate 80 0.50 g sodium methyl-p-hydroxybenzoate 0.15 g camphor 0.05 g lavender essence 0.05 g demin. water q.s. to 100 g EXAMPLE 13 a.i. capsaicin oleoresin 1 g 2 g (= 0.01 g capsaicin) propylene glycol 1 g colloidal silica 5 g ethyl alcohol 2 g polyoxyethylen glycol 300 5 g polysorbate 80 0.80 g sodium methyl-p-hydroxybenzoate 0.15 g camphor 0.2 g menthol 0.2 g demin. water q.s. to 100 g EXAMPLE 14 a.i. sodium heparin 5.000 U.E.B. ethyl alcohol 10 g propylene glycol 10 g colloidal silica 6 g polysorbate 80 0.50 g sodium methyl-p-hydroxybenzoate 0.15 g camphor 0.6 g demin. water q.s. to 100 g EXAMPLE 15 a.i. sodium heparin 10.000 I.U. escin 1 g phosphatidyl choline 0.8 g isopropyl alcohol 15 g propylene glycol 5 g colloidal silica 6 g polysorbate 80 1 g sodium methyl-p-hydroxybenzoate 0.15 g lavender essence 0.1 g demin. water q.s. to 100 g EXAMPLE 16 a.i. hydrocortisone acetate 0.5 g benzocaine 5 g sodium heparin 5.000 I.U. colloidal silica 5 g propylene glycol 7 g isopropyl myristate 3 g polysorbate 80 1 g sodium methyl-p-hydroxybenzoate 0.15 g menthol 0.25 g demin. water q.s. to 100 g EXAMPLE 17 a.i. Hamamelis hydroalcoholic extract 0.75 g tannic acid 5 g benzalkonium chloride 1 g ethyl alcohol 4 g propylene glycol 5 g colloidal silica 5 g Cetomacrogol 1000 0.5 g sodium methyl-p-hydroxybenzoate 0.15 g bergamot oil 0.1 g demin. water q.s. to 100 g EXAMPLE 18 a.i. chlorhexidine 1 g ethyl alcohol 3 g isopropyl myristate 4 g propylene glycol 2 g colloidal silica 3 g polysorbate 80 0.5 g sodium methyl-p-hydroxybenzoate 0.15 g bergamot oil 0.1 g demin. water q.s. to 100 g EXAMPLE 19 a.i. benzyl alcohol 4 g benzocaine 5 g chloroxylenol 0.5 g ethyl alcohol 5 g propylene glycol 8 g colloidal silica 5 g Bryj 35™ 0.5 g sodium methyl-p-hydroxybenzoate 0.15 g bergamot oil 0.1 g demin. water q.s. to 100 g EXAMPLE 20 a.i. acyclovir 5 g ethyl alcohol 5 g propylene glycol 10 g colloidal silica 5 g polysorbate 80 0.5 g sodium methyl-p-hydroxybenzoate 0.15 g peppermint oil 0.3 g demin. water q.s. to 100 g EXAMPLE 21 a.i. escin 0.3 g levothyroxine 0.05 g ethyl alcohol 10 g propylene glycol 2 g colloidal silica 3,5 g esterified polyeoxyethylene glycols 3 g polysorbate 80 1 g sodium methyl-p-hydroxybenzoate 0.15 g lily of the valley essence 0.3 g demin. water q.s. to 100 g EXAMPLE 22 a.i. vitamin E 550 I.U. propylene glycol 1 g Jojoba oil 1 g colloidal silica 3 g anhydrous lanolin 1 g Labrafil M1944 CS 3 g polyoxyethylene glycol palmitostearate 2 g Tween 20 0.75 g sodium methyl-p-hydroxybenzoate 0.15 g rose perfume 0.5 g demin. water q.s. to 100 g EXAMPLE 23 a.i. beclometasone dipropionate 10 mg propylene glycol 10 g colloidal silica 3.5 g polysorbate 80 0.7 g sodium methyl-p-hydroxybenzoate 0.15 g menthol 0.3 g camphor 0.2 g demin. water q.s. to 100 g EXAMPLE 24 a.i. 2,4-dichlorobenzyl alcohol 600 mg propylene glycol 6 g colloidal silica 3 g ethyl alcohol 10 g polysorbate 80 0.5 g sodium saccharine 0.03 g sodium methyl-p-hydroxybenzoate 0.15 g mint essence 0.3 g menthol 100 mg balsamic flavor 1 g demin. water q.s. to 100 g EXAMPLE 25 a.i. thiocolchicoside 0.25 g propylene glycol 7 g colloidal silica 3.5 g 70% sorbitol 5.0 g polysorbate 80 0.5 g sodium methyl-p-hydroxybenzoate 0.15 g lavender essence 0.5 g demin. water q.s. to 100 g EXAMPLE 26 a.i. ketoprofene lysine salts 15 g propylene glycol 5.5 g colloidal silica 2.5 g polysorbate 80 0.5 g methyl-p-hydroxybenzoate 0.15 g camphor 0.1 g lavender essence 0.1 g demin. water q.s. to 100 g EXAMPLE 27 a.i. sodium heparin 10000 I.U. propylene glycol 5 g colloidal silica 3.5 g 70% sorbitol 8 g polysorbate 80 0.5 g methyl-p-hydroxybenzoate 0.15 g nerolene lavender 0.2 g demin. water q.s. to 100 g EXAMPLE 28 a.i. benzalkonium chloride 1 g propylene glycol 5 g colloidal silica 3.5 g polysorbate 80 0.5 g methyl-p-hydroxybenzoate 0.15 g lavender essence 0.2 g lemon essence 0.4 g demin. water q.s. to 100 g EXAMPLE 29 a.i. deschlorpheniramine maleate 1 g ethyl alcohol 3 g propylene glycol 5 g gliceryl monostearate self-emulsifier 5 g 70% sorbitol 5 g colloidal silica 3.5 g polysorbate 80 0.7 g methyl-p-hydroxybenzoate 0.15 g rose essence 0.1 g demin. water q.s. to 100 g EXAMPLE 30 a.i. metronidazole 1 g ethyl alcohol 5 g propylene glycol 10 g colloidal silica 3.0 g polysorbate 80 1 g methyl-p-hydroxybenzoate 0.15 g lily of the valley essence 0.5 g demin. water. q.s. to 100 g PARA-PHARMACEUTICAL FORMULATIONS EXAMPLE 31 Facial astringent masque a.i. Hamamelis hydroalcoholic extract 5 g nettle oily extract 2 g propylene glycol 5 g colloidal silica 5 g polysorbate 60 1 g sodium methyl-p-hydroxybenzoate 0.15 g lemon essence 0.07 g demin. water q.s. to 100 g EXAMPLE 32 Sun shield gel a.i. β carotene solution in vegetable oil 3 g Hypericum oily extract 2 g propylene glycol 2 g colloidal silica 5 g polysorbate 80 1 g sodium methyl-p-hydroxybenzoate 0.15 g sandalwood essence 0.1 g demin. water q.s. to 100 g EXAMPLE 33 Astringent facial masque a.i. Burdock hydroalcoholic extract 1 g Cornflower hydroalcoholic extract 1 g propylene glycol 4 g colloidal silica 3.5 g polysorbate 80 0.5 g methyl-p-hydroxybenzoate 0.15 g apricot flavour 0.2 g demin. water q.s. to 100 g EXAMPLE 34 Face detergent a.i. Ruscus hydroalcoholic extract 1 g Asparagus hydroalcoholic extract 1 g propylene glycol 5 g colloidal silica 3 g polysorbate 80 0.5 g methyl-p-hydroxybenzoate 0.15 g rose essence 0.3 g demin. water q.s. to 100 g

Claims: Use of a thixotropic gel containing an active ingredient, from 2 to 15% by weight of a colloidal silica with a surface area from 130 to 300 m 2 /g and an average diameter of 12 nm, water and optionally excipients, for the preparation of a pharmaceutical or para-pharmaceutical composition to be sprayed by means of a mechanical pump. Use of a thixotropic gel according to claim 1, wherein the colloidal silica has surface area comprised in the interval 175-225 m 2 /g. Use of a thixotropic gel according to claims 1-2, containing from 2 to 8% by weight of colloidal silica. Use of a thixotropic gel according to claims 1-3, further comprising a solvent selected from glycerol, polyoxyethylene glycol, diethylene glycol monoalkylether, N-methylpyrrolidone, glycofurol, isopropanol, ethylene glycol, propylene glycol in an amount from 1 to 10% by weight. Use of a thixotropic gel according to claim 4, wherein the solvent is propylene glycol. Use of a thixotropic gel according to claims 1-5, wherein the excipients are selected from surfactants, preservatives, flavouring agents, co-solvents and lipophilic phases. Use of a thixotropic gel according to claims 1-6, wherein water is present in amount ranging from 60 to 97% by weight. Use of a thixotropic gel according to claims 1-7, further comprising a surfactant selected from sorbitan esters, polyoxyethylene sorbitan esters, polyoxyethylene alkyl ethers, polyoxyethylene stearates. Use according to any of the preceding claims, wherein the pharmaceutical or para-pharmaceutical composition is for the topical administration on the skin or for vaginal, nasal, otological administration. Spray-dosage container provided with mechanical pump containing a thixotropic gel according to claims 1-8.

Inventors: BOLTRI LUIGI, CLAVENNA GAETANO, COPPOLA ANTONIETTA, GENTILE MARCO, BOLTRI, LUIGI, CLAVENNA, GAETANO, COPPOLA, ANTONIETTA, GENTILE, MARCO
Applicants: DOMPE SPA, DOMPE S.P.A.
Application year: 1996
Main classification: A61K9
IPC codes: A61K8, A61K47, A61K9, A61Q19