Tetrahydrozoline Hydrochloride Nasal Solution

This article is compiled based on the United States Pharmacopeia (USP) – 2025 Edition

Issued and maintained by the United States Pharmacopeial Convention (USP)

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Tetrahydrozoline Hydrochloride Nasal Solution is a solution of Tetrahydrozoline Hydrochloride in water adjusted to a suitable tonicity. It contains not less than 90.0 percent and not more than 110.0 percent of the labeled amount of C₁₃H₁₆N₂ · HCl.

Packaging and storage—Preserve in tight containers.

USP REFERENCE STANDARDS 〈11〉—

USP Tetrahydrozoline Hydrochloride RS

Identification—The UV absorption spectrum of the Nasal Solution, diluted with water, if necessary, to a concentration of about 1 in 4000, exhibits maxima and minima at the same wavelengths as that of a similar solution of USP Tetrahy drozoline Hy drochloride RS, concomitantly measured.

MICROBIAL ENUMERATION TESTS 〈61〉 and TESTS FOR SPECIFIED MICROORGANISMS 〈62〉—It meets the requirements of the tests for absence of Staphylococcus aureus and Pseudomonas aeruginosa.

PH 〈791〉: between 5.3 and 6.5.

Assay—

Oxidized nitroprusside reagent—Dissolve 1.0 g of sodium nitroferricyanide in water to make 10.0 mL (Solution A). Dissolve 1.0 g of potassium ferricyanide in water to make 10.0 mL (Solution B). Transfer 1.0 mL each of Solution A and Solution B to a 100-mL volumetric flask, add 1 mL of sodium hydroxide solution (1 in 10), and allow to stand until the solution changes to a light yellow color (about 20 to 30 minutes). Dilute with water to volume, and mix. Store in a refrigerator or keep in an ice bath, and use within 4 hours.

Standard preparation—Dissolve a suitable quantity of USP Tetrahy drozoline Hy drochloride RS, accurately weighed, in water, and dilute

quantitatively with water to obtain a solution having a known concentration of about 100 µg per mL.

Assay preparation—Transfer an accurately measured volume of Nasal Solution, equivalent to about 10 mg of tetrahydrozoline hydrochloride, to a 100-mL volumetric flask, dilute with water to volume, and mix.

Procedure—Transfer 5.0 mL each of the Standard preparation and the Assay preparation to separate glass-stoppered test tubes. Pipet 5 mL of water into a third tube to provide a blank. To each tube add 4.0 mL of Oxidized nitroprusside reagent, mix, and allow to stand at 30° for 15 minutes. Concomitantly determine the absorbances of the solutions in 1-cm cells at the wavelength of maximum absorbance at about 570 nm, with a suitable spectrophotometer, using the blank to set the instrument. Calculate the quantity, in mg, of C H N · HCl in each mL of the

Nasal Solution taken by the formula:

0.1(C/V)(A_u/A_s)

in which C is the concentration, in µg per mL, of USP Tetrahy drozoline Hy drochloride RS in the Standard preparation, V is the volume, in mL, of Nasal Solution taken, and A_u and A_s are the absorbances of the solutions from the Assay preparation and the Standard preparation, respectively.