Claims for Patent: 6,031,007

Summary for Patent: 6,031,007

Title:	Pharmaceutical composition with anaesthetic effect
Abstract:	The invention is directed to a novel pharmaceutical composition comprising one or more local anaesthetics in oil form, one or more surfactants, water and optionally a taste masking agent. The novel composition is advantageously used as a local anaesthetic for pain relief within the oral cavity.
Inventor(s):	Brodin; Arne (Sodertalje, SE), Fynes; Raymond (Mississauga, CA), Heijl; Lars (Lerum, SE), Nyqvist-Mayer; Adela (Tullinge, SE), Scherlund; Marie (Bromma, SE)
Assignee:	Astra AB (SE)
Application Number:	08/875,888
Patent Claims:	1. The pharmaceutical composition comprising: (i) one or more local anaesthetics in oil form; (ii) one or more surfactants in an amount effective to produce a homogenous formulation wherein, at least one surfactant has thermoreversible gelling properties; and (iii) water; wherein said composition is in the form of an emulsion or microemulsion and has thermoreversible gelling properties such that said composition is less viscous at room temperature than after introduction onto a mucous membrane of a patient. 2. The pharmaceutical composition according to claim 1, further comprising one or more taste masking agents. 3. The pharmaceutical composition according to claim 1, wherein said one or more local anaesthetics are present in an amount of 0.5-20% by weight based on the total weight of the composition. 4. The pharmaceutical composition according to claim 3, wherein said one or more local anaesthetics are present in an amount of 2-7% by weight based on the total weight of the composition. 5. The pharmaceutical composition according to claim 1, wherein said one or more local anaesthetics is a eutectic mixture of local anaesthetics. 6. The pharmaceutical composition according to claim 5, wherein said one or more local anaesthetics is a eutectic mixture of lidocaine and prilocaine. 7. The pharmaceutical composition according to claim 1, wherein said one or more local anaesthetics comprises ##STR2## 8. The pharmaceutical composition according to any one of claims 1-7, comprising more than one surfactant of which at least one is a surfactant having thermoreversible gelling properties. 9. The pharmaceutical composition according to any one of claims 1-7, wherein the total amount of surfactant is present in an amount of up to 50% by weight based on the total weight of the composition. 10. The pharmaceutical composition according to any one of claims 1-7, wherein the surfactant is a non-ionic surfactant. 11. The pharmaceutical composition according to claim 10, wherein the surfactant is a poloxamer. 12. The pharmaceutical composition according to any one of claims 1-7, comprising the two surfactants Poloxamer 188.RTM. and Poloxamer 407.RTM.. 13. The method of treating a patient for pain associated with periodontal scaling, comprising applying to the periodontal pocket of said patient an effective amount of the pharmaceutical composition according to claim 1. 14. The process for the manufacture of the pharmaceutical composition according to claim 1, wherein said composition has more than one surfactant, comprising: (a) melting together said one or more local anesthetics and the surfactant with the lowest molecular weight; (b) adding water to the melt of step (a) during homogenization to form an emulsion concentrate; (c) dispersing the remaining surfactant or surfactants in water; (d) mixing, the emulsion concentrate of step (b) and the surfactant solution of step (c); (e) adjusting the pH of the mixture of step (d) so that the final pH is greater than or equal to pK.sub.a -1, wherein pK.sub.a is that of the local anesthetic with the lowest pK.sub.a ; and (f) adding water to the final weight of the composition. 15. A process for the manufacture of the pharmaceutical composition according to claim 1, wherein said composition has only one surfactant, comprising: (a) melting together said one or more local anesthetics and said surfactant; (b) addingc water to the melt of step (a) during homogenization to form an emulsion concentrate; (c) adjusting the pH of the mixture of step (b) so that the final pH is greater than or equal to pK.sub.a -1, wherein pK.sub.a is that of the local anesthetic with the lowest pK.sub.a ; and (d) adding water to the final weight of the composition. 16. The composition of claim 1, wherein said one or more local anesthetics comprise 0.5 to 20% of the final weight of said composition, and said one or more surfactants comprise up to 50% of the final weight of said composition. 17. The composition of claim 16 wherein the pH of said composition is greater than or equal to pK.sub.a -1, wherein pK.sub.a is that of the local anesthetic with the lowest pK.sub.a.