Idoxuridine Ophthalmic Ointment
» Idoxuridine Ophthalmic Ointment is Idoxuridine in a Petrolatum base. It contains not less than 0.45 percent and not more than 0.55 percent of C9H11IN2O5. It is sterile.
Packaging and storage Preserve in collapsible ophthalmic ointment tubes in a cool place.
USP Reference standards 11
Identification The UV absorption spectrum of the solution from the Ophthalmic Ointment employed for measurement of absorbance in the Assay exhibits maxima and minima at the same wavelengths as that of the Standard preparation prepared for the Assay.
Sterility 71: meets the requirements.
Metal particles It meets the requirements of the test for Metal Particles in Ophthalmic Ointments 751.
Chromatographic column Mix 4 g of chromatographic siliceous earth with 4 mL of 0.1 N hydrochloric acid in a glass mortar until the mixture is fluffy. Transfer to a 19- × 250-mm chromatographic tube (see Chromatography 621) that contains a pledget of glass wool and is fitted with a stopcock at the bottom. Tamp gently to compress to a uniform mass.
Standard preparation Transfer about 25 mg of USP Idoxuridine RS, accurately weighed, to a 50-mL volumetric flask, add methanol to volume, and mix. Dilute 5.0 mL of this solution with a mixture of 1 volume of butyl alcohol and 5 volumes of chloroform to 100.0 mL, and mix.
Assay preparation Mix 4 g of chromatographic siliceous earth with 2 mL of 0.1 N hydrochloric acid in a glass mortar until the mixture is fluffy. Add a quantity of Ophthalmic Ointment, equivalent to about 5 mg of idoxuridine and accurately weighed, to the mixture, and mix.
Procedure Transfer the Assay preparation to the prepared Chromatographic column. Transfer 2 g of chromatographic siliceous earth and 2 mL of 0.1 N hydrochloric acid to the glass mortar, and mix until fluffy, using this material to rinse the mortar and pick up any remaining Ophthalmic Ointment. Transfer about half of this mixture to the tube, and tamp gently until the column appears uniform. Transfer the remaining portion to the Chromatographic column, and tamp as before. Wipe the walls of the mortar with a small pledget of glass wool, and insert the pledget in the top of the column. Pass 50 mL of chloroform through the column at a flow rate of approximately 1 mL per minute, and discard the chloroform. Elute with about 200 mL of a mixture of 1 volume of butyl alcohol and 5 volumes of chloroform at the same flow rate, discarding the first 20 mL of the eluate. Collect the remainder of the eluate in a 200-mL volumetric flask, dilute with the eluting solvent to volume, and mix. Concomitantly determine the absorbances of this solution and the Standard preparation in 1-cm cells at 320 nm and at the wavelength of maximum absorbance at about 283 nm, with a suitable spectrophotometer, using a mixture of butyl alcohol and chloroform as the blank. Calculate the quantity, in mg, of C9H11IN2O5 in the Ophthalmic Ointment taken by the formula:
0.2C(A283 A320)U / (A283 A320)Sin which C is the concentration, in µg per mL, of USP Idoxuridine RS in the Standard preparation; and the parenthetic expressions are the differences in the absorbances of the two solutions at the wavelengths indicated by the subscripts, for the solution from the Ophthalmic Ointment (U) and the Standard preparation (S), respectively.
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USP35NF30 Page 3477