Details for Patent: 7,795,316

Title:	Topical ophthalmic compositions containing tobramycin and dexamethasone
Abstract:	Ophthalmic pharmaceutical compositions containing tobramycin, dexamethasone and deacetylated xanthan gum are described. The compositions provide longer ocular retention for enhanced ocular bioavailability of tobramycin and dexamethasone. In a preferred embodiment, the compositions also provide for improved suspension of dexamethasone. The concentration of ionizable species in the compositions is controlled so as to prevent precipitation of the xanthan gum as a result of ionic interactions between tobramycin and xanthan gum, while allowing for a restoration of viscosity upon topical application of the compositions to the eye. The use of deacetylated xanthan gum is disclosed, so as to avoid formulation instability caused by pH drift during storage.
Inventor(s):	Kabra; Bhagwati P. (Euless, TX)
Assignee:	Alcon Research, Ltd. (Fort Worth, TX)
Filing Date:	Dec 19, 2007
Application Number:	11/960,196
Claims:	1. A topical ophthalmic composition, comprising: 0.1 to 0.5 w/v % tobramycin; 0.03 to 0.1 w/v % of dexamethasone; an aqueous, ophthalmically acceptable vehicle containing deacetylated xanthan gum at a concentration of 0.3 to 0.9%; and one or more ionizable species in an amount sufficient to limit ionic interactions between the tobramycin and the deacetylated xanthan gum, such that the in vitro viscosity of the composition is maintained within the range of 10 to 300 cps at a shear rate of 6 sec.sup.-1 and a temperature of 25.degree. C.; wherein the ionizable species has a sodium chloride equivalent ionic concentration range of 134 to 150 mM; said composition has a pH of 5 to 6. 2. A composition according to claim 1, wherein the one or more ionizable species is selected from the group consisting of inorganic electrolytes, organic buffering agents and combinations thereof. 3. A composition according to claim 2, wherein the one or more ionizable species is selected from the group consisting of sodium chloride, potassium chloride, calcium chloride, magnesium chloride, sodium sulfate, sodium citrate, potassium citrate, sodium phosphate, potassium phosphate, sodium acetate, sodium borate, boric acid/mannitol complexes, boric acid/sorbitol complexes and combinations thereof. 4. A composition according to claim 3, wherein the ionizable species is selected from the group consisting of sodium chloride, sodium sulfate, and combinations thereof. 5. A composition according to claim 1, wherein the composition has an initial viscosity of 25 to 175 cps. 6. A composition according to claim 5, wherein the composition has an in vitro/in vivo viscosity ratio of 0.01 to 0.65. 7. A composition according to claim 6, wherein the one or more ionizable species is selected from the group consisting of inorganic electrolytes, organic buffering agents and combinations thereof. 8. A composition according to claim 7, wherein the one or more ionizable species is selected from the group consisting of sodium chloride, potassium chloride, calcium chloride, magnesium chloride, sodium sulfate, sodium citrate, potassium citrate, sodium phosphate, potassium phosphate, sodium acetate, sodium borate, boric acid/mannitol complexes, boric acid/sorbitol complexes and combinations thereof. 9. A composition according to claim 8, wherein the ionizable species is selected from the group consisting of sodium chloride, sodium sulfate, and combinations thereof. 10. A composition according to claim 9, wherein the composition contains tobramycin at a concentration of 0.3 w/v %, xanthan gum at concentration of 0.6 w/v % and dexamethasone at a concentration of 0.05 w/v %. 11. A composition according to claim 10, wherein the pH of the composition is about 5.7. 12. A method of treating ophthalmic inflammatory conditions wherein either an infection or risk of infection exists, which comprises topically applying a therapeutically effective amount of a composition according to claim 1 to the affected eye. 13. A method of treating ophthalmic inflammatory conditions wherein either an infection or risk of infection exists, which comprises applying a therapeutically effective amount of a composition according to claim 10 to the affected eye. 14. A topical ophthalmic composition, comprising: 0.1 to 0.5 w/v % tobramycin; 0.03 to 0.1 w/v % of dexamethasone; an aqueous, ophthalmically acceptable vehicle containing deacetylated xanthan gum at a concentration of 0.3 to 0.9%; and one or more ionizable species in an amount sufficient to limit ionic interactions between the tobramycin and the deacetylated xanthan gum, such that the in vitro viscosity of the composition is maintained within the range of 10 to 300 cps at a shear rate of 6 sec.sup.-1 and a temperature of 25.degree. C.; wherein the ionizable species has a sodium chloride equivalent ionic concentration range of 134 to 150 mM; said composition has a pH of 5 to 6; wherein the composition has an in vitro/in vivo viscosity ratio of 0.01 to 0.65. 15. A composition according to claim 14, wherein the ionizable species is selected from the group consisting of sodium chloride, sodium sulfate, and combinations thereof. 16. A composition according to claim 15, wherein the composition contains tobramycin at a concentration of 0.3 w/v %, xanthan gum at concentration of 0.6 w/v % and dexamethasone at a concentration of 0.05 w/v %. 17. A topical ophthalmic composition, comprising: 0.1 to 0.5 w/v tobramycin; 0.03 to 0.1 w/v % of dexamethasone; an aqueous, ophthalmically acceptable vehicle containing deacetylated xanthan gum at a concentration of 0.3 to 0.9%; and one or more ionizable species in an amount sufficient to limit ionic interactions between the tobramycin and the deacetylated xanthan gum, such that the in vitro viscosity of the composition is maintained within the range of 10 to 300 cps at a shear rate of 6 sec.sup.-1 and a temperature of 25.degree. C.; wherein the ionizable species has a sodium chloride equivalent ionic concentration range of 134 to 150 mM; said composition has a pH of 5 to 6; wherein the one or more ionizable species is selected from the group consisting of sodium chloride, potassium chloride, calcium chloride, magnesium chloride, sodium sulfate, sodium citrate, potassium citrate, sodium phosphate, potassium phosphate, sodium acetate, sodium borate, boric acid/mannitol complexes, boric acid/sorbitol complexes and combinations thereof; wherein the composition has an in vitro/in vivo viscosity ratio of 0.01 to 0.65. 18. A composition according to claim 17, wherein the ionizable species is selected from the group consisting of sodium chloride, sodium sulfate, and combinations thereof. 19. A composition according to claim 18, wherein the composition contains tobramycin at a concentration of 0.3 w/v %, xanthan gum at concentration of 0.6 w/v % and dexamethasone at a concentration of 0.05 w/v %.