Transdermal testosterone formulation for minimizing skin residues

1. A transdermal or transmucosal non-occlusive pharmaceutical formulation that contains testosterone as active ingredient; and a solvent system present in an amount sufficient to solubilise the active ingredient, wherein the solvent system consists essentially of:

(i) a pharmaceutically acceptable monoalkyl ether of diethylene glycol present in an amount of between about 1.36% and 7.5% by weight of the solvent system;

(ii) a pharmaceutically acceptable glycol present in an amount of between about 13.64% and 30% by weight of the solvent system, provided that the monoalkyl ether of diethylene glycol and the glycol are present in a weight ratio of 1:4 to 1:10; and

(iii) a mixture of a C2 to C4 alcohol and water which mixture is present in an amount of between about 40% and 98% of the solvent system, wherein the C2 to C4 alcohol is present in an amount of about 5% to 80% of the mixture, and the water is present in an amount of about 20% to 95% of the mixture;

wherein the formulation does not include additional permeation enhancers, and provided that the monoalkyl ether of diethylene glycol and the glycol in combination are present in amount of at least 15% and no more than 37.5% of the solvent system, so that, compared to formulations containing the same components but in different amounts and ratios, the present solvent system (a) inhibits crystallization of the at least one active ingredient on a skin or mucosal surface of a mammal, (b) reduces or prevents transfer of the formulation to clothing or to another being, (c) modulates biodistribution of the at least one active ingredient within different layers of skin, (d) facilitates absorption of the at least one active ingredient by a skin or a mucosal surface of a mammal or (e) provides a combination of one or more of (a) through (d).

2. The pharmaceutical formulation of claim 1 , wherein the monoalkyl ether of diethylene glycol is selected from the group consisting of diethylene glycol monomethyl ether and diethylene glycol monoethyl ether and mixtures thereof.

3. The pharmaceutical formulation of claim 1 , wherein the glycol is selected from the group consisting of propylene glycol, dipropylene glycol and mixtures thereof.

4. The pharmaceutical formulation of claim 1 , wherein the C2 to C4 alcohol is selected from the group consisting of ethanol, propanol, isopropanol, 1-butanol, 2-butanol and mixtures thereof.

5. The pharmaceutical formulation according to claim 1 which includes an agent selected form the group consisting of gelling agents, preservatives, antioxidants, buffers, humectants, sequestering agents, moisturizers, surfactants, emollients and any combination thereof.

6. The pharmaceutical formulation of claim 1 , wherein the testosterone is present in the formulation in an amount of about 1% by weight.

7. The pharmaceutical formulation of claim 1 , wherein the pharmaceutically acceptable monoalkyl ether of diethylene glycol is diethylene glycol monoethyl ether and is present in an amount of at least about 5% by weight of the solvent system; the pharmaceutically acceptable glycol is propylene glycol and is present in an amount of at least about 20% by weight of the solvent system; and the monoethyl ether of diethylene glycol and the propylene glycol in combination are present in amount of at least 25% by weight of the solvent system.

8. The pharmaceutical formulation of claim 7 , wherein the C2 to C4 alcohol is ethanol and is present in an amount of between about 15% and 65% by weight of the solvent system.

9. A transdermal or transmucosal non-occlusive pharmaceutical formulation consisting of:

testosterone as active ingredient;

an agent selected form the group consisting of gelling agents, preservatives, antioxidants, buffers, humectants, sequestering agents, moisturizers, surfactants, emollients and any combination thereof; and

a solvent system present in an amount sufficient to solubilise the active ingredient, wherein the solvent system consists of:

(i) a pharmaceutically acceptable monoalkyl ether of diethylene glycol present in an amount of 5% to 7.5% by weight of the solvent system;

(ii) a pharmaceutically acceptable glycol of propylene glycol present in an amount of 20% to 30% by weight of the solvent system, provided that the monoalkyl ether of diethylene glycol and the glycol are present in a weight ratio of 1:4 to 1:6; and

(iii) a mixture of a C2 to C4 alcohol and water which mixture is present in an amount of between about 40% and 98% of the solvent system, wherein the C2 to C4 alcohol is present in an amount of about 5% to 80% of the mixture, and the water is present in an amount of about 20% to 95% of the mixture;

wherein the formulation does not include fatty alcohols, fatty esters or fatty acids, and the monoalkyl ether of diethylene glycol and the glycol in combination are present in amount of at least 25% and no more than 37.5% of the solvent system, so that, compared to formulations containing the same components but in different amounts and ratios, the present solvent system (a) inhibits crystallization of the at least one active ingredient on a skin or mucosal surface of a mammal, (b) reduces or prevents transfer of the formulation to clothing or to another being, (c) modulates biodistribution of the at least one active ingredient within different layers of skin, (d) facilitates absorption of the at least one active ingredient by a skin or a mucosal surface of a mammal or (e) provides a combination of one or more of (a) through (d).

10. The pharmaceutical formulation of claim 9 , wherein the C2 to C4 alcohol is ethanol and is present in an amount of between about 15% and 65% by weight of the solvent system.

11. The pharmaceutical formulation of claim 9 , wherein the testosterone is present in the formulation in an amount of about 1% by weight.