Thermogelling anaesthetic compositions
View Patent ↗The present invention relates to a thermogelling pharmaceutical composition comprising local anaesthetics in base form and which is suitable for topical administration. The compositions further comprise a polyoxyethylene castor oil and one or more surfactants to obtain thermogelling characteristics.
1. A pharmaceutical composition comprising:
(a) 1 to 10% by weight of lidocaine in base form, which is solubilized in 10 to 30% by weight of a polyoxyethylene castor oil;
(b) 15 to 30% by weight of one or more non-ionic block copolymers of poly(oxyethylene) and poly(oxypropylene) type; and
(c) water,
wherein the pH of the composition is at least the value of the pKa of said lidocaine.
2. The pharmaceutical composition according to claim 1 , further comprising an additional solubilizer in an amount of 1 to 5% by weight.
3. The pharmaceutical composition according to claim 1 , wherein the amount of lidocaine is 1 to 7% weight.
4. The pharmaceutical composition according to claim 1 , wherein the amount of lidocaine present is 3 to 5% by weight.
5. The pharmaceutical composition according to claim 1 , wherein the polyoxyethylene castor oil is a polyoxyethylene 35 castor oil.
6. The pharmaceutical composition according to claim 1 , wherein the block copolymers comprise a higher molecular weight poloxamer and a lower molecular weight poloxamer, and wherein the higher molecular weight poloxamer and the lower molecular weight poloxamer are present in about equal amounts.
7. The pharmaceutical composition according to claim 1 , wherein the block copolymers are a mixture of poloxamer 188 and poloxamer 407.
8. The pharmaceutical composition according to claim 2 , wherein the additional solubilizer is a lower alcohol.
9. The pharmaceutical composition according to claim 8 , wherein the lower alcohol is selected from the group consisting of ethanol, propanol, isopropanol, propylene glycol and benzyl alcohol.
10. The pharmaceutical composition according to claim 2 , wherein the additional solubilizer is selected from the group consisting of glycerol formal, glycofural, polysorbate 80 and ethyl acetate.
11. The pharmaceutical composition according to claim 1 with thermogelling characteristics, having an elasticity modulus (G′) below 20 Pa at room temperature and an elasticity modulus (G′) in the range of 50 to 10000 Pa at body temperature.