Oxtriphylline

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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C₁₂H₂₁N₅O₃ 283.33

Ethanaminium, 2-hydroxy-N,N,N-trimethyl-, salt with 3,7-dihydro-1,3-dimethyl-1H-purine-2,6-dione;

Choline salt with Theophylline (1:1) CAS RN^®: 4499-40-5; UNII: 3K045XR58X.

1 DEFINITION

Oxtriphylline contains NLT 61.7% and NMT 65.5% of anhydrous theophylline (C₇H₈N₄O₂), calculated on the dried basis.

2 IDENTIFICATION

A.

Sample solution: 50 mg/mL in water

Analysis: To 10 mL of the Sample solution add 5 mL of mercuric-potassium iodide TS.

Acceptance criteria: A pale yellow precipitate is formed (presence of choline).

B.

Sample solution: 50 mg/mL in water

Analysis: To 10 mL of the Sample solution add 5 drops of 6 N ammonium hydroxide and 5 mL of silver nitrate TS.

Acceptance criteria: A gelatinous precipitate is formed, and it coagulates on heating (presence of theophylline).

3 ASSAY

THEOPHYLLINE

Sample solution: The solution retained in the test for Choline Content

Analysis: Add 35 mL of silver nitrate TS to the Sample solution, and swirl gently to promote complete precipitation. Titrate with 0.1 N sodium hydroxide VS to a green endpoint. Each mL of 0.1 N sodium hydroxide is equivalent to 18.02 mg of theophylline (C₇H₈N₄O₂).

Acceptance criteria: 61.7%-65.5% on the dried basis

4 OTHER COMPONENTS

CHOLINE CONTENT

Indicator solution: Dissolve 30 mg of methyl red in 100 mL of methanol, and add 15 mL of methylene blue solution (1 in 1000).

Sample solution: 900 mg of Oxtriphylline in 50 mL of water

Analysis: Add 4 drops of Indicator solution to the Sample solution, and titrate with 0.1 N sulfuric acid VS to a purple endpoint. Each mL of 0.1 N sulfuric acid is equivalent to 12.12 mg of choline (C₅H₁₅NO₂). Retain the final solution for the Assay for Theophylline.

Acceptance criteria: The content of choline (C₅H₁₅NO₂) is between 652 and 693 mg/g of theophylline (C₇H₈N₄O₂) found in the Assay.

5 IMPURITIES

5.1 RESIDUE ON IGNITION (281)

NMT 0.3%

5.2 CHLORIDE AND SULFATE, Chloride(221)

Standard: 0.15 mL of 0.020 N hydrochloric acid

Sample: 0.50 g

Acceptance criteria: 0.02%; the Sample shows no more chloride than corresponds to the Standard.

5.3 ORDINARY IMPURITIES (466)

Standard solution: Chloroform, alcohol, and formic acid (88:10:2)

Sample solution: Chloroform, alcohol, and formic acid (88:10:2)

Eluant: Chloroform, alcohol, and formic acid (88:10:2)

Visualization: 1

Acceptance criteria: Meets the requirements

6 SPECIFIC TESTS

6.1 MELTING RANGE OR TEMPERATURE, Class I(741)

185°-189°

6.2 LOSS ON DRYING (731)

Analysis: Dry at 80° for 4 h.

Acceptance criteria: NMT 1.0%

7 ADDITIONAL REQUIREMENTS

7.1 PACKAGING AND STORAGE

Preserve in tight containers.

7.2 USP REFERENCE STANDARDS (11)

USP Oxtriphylline RS