Pharmaceutical solution and methods for preparation thereof

A method of preparing a stable liquid pharmaceutical solution, the method comprising:

• combining in any order about 3 to about 50 mg trimethoprim per ml liquid pharmaceutical solution, about 42 to about 645 mg N-methylpyrrolidone per ml liquid pharmaceutical solution, about 16 to about 250 mg sulfadiazine per ml liquid pharmaceutical solution, and a remainder of an acidic or basic aqueous medium to form a stable liquid pharmaceutical solution.

A method for treating a bacterial infection in an animal comprising:

• (a) administering to the animal a stable liquid pharmaceutical solution in an amount effective to treat the bacterial infection;
• wherein the stable liquid pharmaceutical solution comprises:
• about 3 to about 50 mg trimethoprim per ml liquid pharmaceutical solution, about 16 to about 250 mg sulfadiazine per ml liquid pharmaceutical solution, about 42 to about 645 mg N-methylpyrrolidone per ml liquid pharmaceutical solution, and a remainder of an acidic or basic aqueous medium.

A method of preparing a stable liquid pharmaceutical solution, the method comprising:

• combining in any order about 3 to about 50 mg trimethoprim per ml liquid pharmaceutical solution, about 42 to about 645 mg N-methylpyrrolidone per ml liquid pharmaceutical solution, about 16 to about 250 mg sodium sulfadiazine per ml liquid pharmaceutical solution, and a remainder of water to form a stable liquid pharmaceutical solution.