Pharmaceutical compositions for topical use containing a chelating agent, a tocopheral and an antimicrobial agent

Abstract: Pharmaceutical compositions containing as active principles: a) a chelating agent b) a tocopherol c) an antimicrobial agent are particularly effective as healing agents.

Description: The present invention refers to pharmaceutical compositions for topical use useful for the therapy of skin ulcers, wounds, dermatoses, cutaneous infections and similar conditions. It is known that the pharmacological treatment of certain dermatological pathologies, such as those mentioned above, is usually difficult and problematic and there is an urgent need for new and improved drugs able to induce or assist the healing process. It has now been found that pharmaceutically compositions containing as active principles: a) a chelating agent, b) a tocopherol which could be vitamin E (α-tocopherol), c) an aminoglycoside antibiotic selected from gentamicin in concentration from 0.1 to 1% w/w or netilmicine or amikacine in concentrations from 0.5 to 8%, , when topically administered, are particularly effective for the treatment of pathological conditions in which a radical-scavenging activity, combined with antibacterial and antiinflammatory activity, is required. The free oxygen-radicals, by means of peroxidation reactions, turn out to be particularly aggressive towards the cell membranes. The radicals are formed in vivo both during the usual cellular process and mainly by the action of phagocytes which are always present in any inflammatory condition, acute or chronic. The compositions of the invention are characterized by the combination of an antioxidant, radical scavenging compound belonging to the class of tocopherols, with a chelating agents and an antimicrobial agent. These components have unexpected synergistic effects. The tocopherols may be selected from α-tocopherol or mixed tocopherols. As a chelating agent, ethylenediaminotetraacetic acid (EDTA) or pharmaceutically acceptable salts thereof, dimercaprole disodium, deferoxamine, may be used. The antimicrobial agent is selected from aminoglycoside antibiotics (amikacine, gentamicine, kanamycine, netilmicine). The use of amikacine is particularly preferred. As a chelating agent, the use of EDTA or salts thereof is particularly preferred. The chelating agent may be present in the compositions of the invention in concentrations ranging from 0.05 to 1% w/w; the tocopherols in concentrations ranging from 0.5 to 15% w/w whereas the amount of antibacterial agent will depend on the potency of the same. For instance, gentamicin may be present in concentrations from 0.1 to 1% w/w whereas metilmicine or amikacine may be present in concentrations from 0.5 to 8%. The composition may of course comprise the usual excipients or carriers suited for the topical use, such as buffers, stabilizers (e.g. sulfites, bisulfites), thickening agents, preserving agents and the like. Typical pharmaceutical forms include powders, ointments, creams, lotions, gels. Powders are particularly advantageous in view of their drying action-hindering the maceration. The invention is further illustrated by the following examples. EXAMPLE 1 100 g of cream contain: Sodium edetate g 0.200 Mixed concentrated tocopherols g 1.500 Amikacine sulfate corresponding to amikacine base g 5.000 Glycine g 0.100 Cysteine hydrochloride g 0.100 Methyl p-hydroxybenzoate g 0.090 Propyl p-hydroxybenzoate g 0.010 Hydroxypropylcellulose g 2.500 Sorbitan monopalmitate g 1.430 Polysorbate 80 g 0.570 Purified water q.s. to g 100 EXAMPLE 2 100 g of powder contain: Sodium edetate g 0.200 Mixed concentrated tocopherols g 1.500 Amikacine sulfate corresponding to amikacine base g 5.000 Precipitated silica g 3.000 Zinc oxide g 5.000 Magnesium carbonate g 7.000 Cysteine g 0.100 Talc q.s. to g 100 EXAMPLE 3 Clinical evaluation of the composition of Example 1 The composition of example 1 was clinically tested in several dermatological disease. Table 1 shows the results, wherein the microbiological controls are also reported Dermatological affection Observation (n.) Recovery (%) Healing time (weeks) Culture inhibition Side effects Varicose ulcer -- -- -- -- none Dermatological -- -- -- -- none lesion (dry) Eschars -- -- -- -- none Burns -- -- -- -- 1 doubtful The above results prove that the pharmaceutical composition is effective, particularly for a fast epidermalization, an effective asepsys, an exiccative activity that avoid maceration, without causing side effects. Sensitization The sensitizing properties of the composition according to example 1 were determined by the Magnusson and Klingmans's test, which is the most accurate and sensitive for this kind of investigations. The test was carried out on guinea pigs. Table 2 shows that no potential risk of sensitization occurred when the above composition was used. Concentrations Results Induction phase Rising phase Treated animals Controls Subcutaneous Epicutaneous 0.2% 0.5% 1% 0/20 0/20 0.4% 1% 1% 0/20 0/20

Claims: Topical pharmaceutical compositions containing as active principles: a) a chelating agent b) a tocopherol c) an aminoglycoside antibiotic selected from gentamicin in concentration from 0.1 to 1% w/w or netilmicine or amikacine in concentrations from 0.5 to 8%. Topical pharmaceutical compositions according to claim 1 characterized in that the chelating agent is selected from edetic acid or salts thereof, deferoxamine and dimercaprole (BAL). Topical pharmaceutical compositions according to claim 1 or 2 wherein the chelating agent is present in concentrations ranging from 0.05 to 1% w/w. Topical pharmaceutical compositions according to any one of the previous claims characterized in that the tocopherol is selected from Vitamine E (α-tocopherol) or mixed tocopherols. Topical pharmaceutical compositions according to claim 4 wherein the tocopherols are present in concentrations ranging from 0.5 to 15%.

Inventors: BERTONE EVARISTO, BERTONE, EVARISTO
Applicants: BONISCONTRO E GAZZONE S R L, BONISCONTRO E GAZZONE S.R.L.
Application year: 1992
Main classification: A61K31
IPC codes: A61K31