Ophthalmic Ointment with Polymyxin B contains 0.5% oxytetracycline and 10,000 units of Polymyxin B per gram of sterile petrolatum base.
A 1% solution in water is acidic (pH about 2.5). Its potency is reduced in solutions more acidic than pH 2 and it is rapidly destroyed by alkali hydroxides.
Oxytetracycline is chemically designated as as 4-(Dimethylamino)-1,4,4a,5,5a,6,11,12aoctahydro- 3,5,6,10,12,12a-hexahydroxy-6-methyl-1,11-dioxo-2-naphthacenacarboxamide and has a molecular formula of C22H24N2O9.
The molecular weight of oxytetracycline hydrochloride is 496.90. It is an odorless, bitter, yellow crystalline powder soluble in water. It forms a cloudy or turbid solution in water due to liberation of oxytetracycline base.
Polymyxin B Sulfate is a white or buff-coloured, hygroscopic powder, odorless or with a slight odor. It is very soluble in water with a 2% solution producing a pH of 5 to 7.
Excipients/Inactive Ingredients: Mineral oil, white petrolatum.