Oxybutynin Chloride Tablets

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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1 DEFINITION

Oxybutynin Chloride Tablets contain NLT 90.0% and NMT 110.0% of the labeled amount of C₂₁H₃₁NO₃ · HCl.

2 IDENTIFICATION

Thin-Layer Chromatographic Identification Test 〈201〉

Sample solution: Add a portion of powdered Tablets, equivalent to about 50 mg of oxybutynin chloride, to 10 mL of chloroform. Mix for two minutes, and centrifuge. Use the supernatant layer.

Developing solvent system: Methanol

Visualization: Iodine vapor

3 ASSAY

Procedure

Solution A: Methanol, water, and triethylamine (800: 3200: 0.9). Adjust with phosphoric acid to a pH of 3.5 ± 0.05.

Mobile phase: Acetonitrile and Solution A (1:4)

Standard solution: 0.05 mg/mL of USP Oxybutynin Chloride RS in Mobile phase

Sample solution: Transfer an amount of powdered Tablets (from NLT 20 Tablets) nominally equivalent to 50 mg of oxybutynin chloride to a 1000-mL volumetric flask. Add about 400 mL of Mobile phase, sonicate for about 10 min, shake by mechanical means for about 45 min, and dilute with Mobile phase to volume.

3.1 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 203 nm

Column: 4-mm × 30-cm; packing L10

Flow rate: 2 mL/min

Injection size: 20 µL

3.2 System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 2.0%

3.3 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of C₂₁H₃₁NO₃ · HCl in the portion of Tablets taken:

Result = (r_U /r_S) × (C /C_U ) × 100

r_U = peak response from the Sample solution

r_S = peak response from the Standard solution

C_S = concentration of USP Oxybutynin Chloride RS in the Standard solution (mg/mL)

C_U = nominal concentration of the Sample solution (mg/mL)

Acceptance criteria: 90.0%–110.0%

3.4 PERFORMANCE TESTS

Change to read:

Dissolution 〈711〉

3.5 Test 1

Medium: Water; 900 mL

Apparatus 2: 50 rpm

Time: 30 min

Sample solution: Pass a portion of the solution under test through a suitable 0.45-µm filter. Dilute with Medium if necessary.

Analysis: Determine the amount of C₂₁H₃₁NO₃ · HCl dissolved using the method set forth in the Assay, making any necessary modifications to the concentration of the Standard solution to correspond to that of the solution under test and injecting 100 µL of both solutions. Tolerances: NLT 80% (Q) of the labeled amount of C₂₁H₃₁NO₃ · HCl is dissolved.

3.6 Test 2

If the product complies with this test, the labeling indicates that it meets USP Dissolution Test 2.

Medium: 0.01 N hydrochloric acid; 900 mL

Apparatus 2: 50 rpm

Time: 30 min

Standard solution: 5 µg/mL of USP Oxybutynin Chloride RS in Medium. This solution is stable for 5 days at ambient conditions. Sample solution: Pass a portion of the solution under test through a suitable 0.45-µm filter, discarding the first few mL. Mobile phase: Water, acetonitrile, and phosphoric acid (760:240:1)

3.6.1 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 203 nm

Column: 4.6-mm × 7.5-cm; 3.5-µm packing L7

Column temperature: 40°

Flow rate: 1.5 mL/min

Injection size: 100 µL

3.6.2 System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 3.0%

3.6.3 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of oxybutynin chloride dissolved:

Result = (r_U /r_S ) × (C_S /L) × V × 100

r_U = peak response from the Sample solution

r_S = peak response from the Standard solution

C_S = concentration of oxybutynin chloride in the Standard solution

L = Tablet label claim (mg)

V = volume of Medium (mL), 900

Tolerances: NLT 80% (Q) of the labeled amount of oxybutynin chloride is dissolved.

3.7 Test 3

If the product complies with this test, the labeling indicates that it meets USP Dissolution Test 3.

Medium: 0.1 N hydrochloric acid; 500 mL, degassed

Apparatus 2: 50 rpm

Time: 30 min

Standard solution: 0.01 mg/mL of USP Oxybutynin Chloride RS in Medium. Sonicate to dissolve, if necessary.

Sample solution: Pass a portion of the solution under test through a suitable filter of 0.45-µm pore size, discarding the first 5 mL of the filtrate.

Solution A: 0.05% Triuoroacetic acid in water

Solution B: 0.05% Triuoroacetic acid in acetonitrile

Mobile phase: Solution A and Solution B (60:40)

3.7.1 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 203 nm

Column: 4.6-mm × 15-cm; 3.5-µm packing L1

Column temperature: 45°

Flow rate: 1 mL/min

Injection volume: 65 µL

Run time: NLT 2.5 times the retention time of oxybutynin

3.7.2 System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 3.0%

3.7.3 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of oxybutynin chloride (C₂₁H₃₁NO₃ · HCl) dissolved:

Result = (r_U /r_S) × C_S × 1/L × V × 100

r_U = peak response of oxybutynin from the Sample solution

r_S = peak response of oxybutynin from the Standard solution

C_S = concentration of USP Oxybutynin Chloride RS in the Standard solution (mg/mL)

L = label claim (mg/Tablet)

V = volume of Medium, 500 mL

Tolerances: NLT 80% (Q) of the labeled amount of oxybutynin chloride (C₂₁H₃₁NO₃ · HCl) is dissolved. (RB 1-Apr-2021)

Uniformity of Dosage Units 〈905〉: Meet the requirements

4 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight, light-resistant containers.

Labeling: When more than one Dissolution test is given, the labeling states the Dissolution test used only if Test 1 is not used.

USP Reference Standards 〈11〉

USP Oxybutynin Chloride RS