Benztropine Mesylate 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

Benztropine Mesylate Tablets contain NLT 90.0% and NMT 110.0% of the labeled amount of benztropine mesylate (C₂₁H₂₅NO · CH₄O₃S).

2 IDENTIFICATION

A.

Standard stock solution: 0.2 mg/mL of USP Benztropine Mesylate RS

Standard solution: In a separator containing the Standard stock solution add 2 mL of 1 N sodium hydroxide. Extract with three 10-ml portions of chloroform, collecting the chloroform extracts to a 50-ml. beaker. Evaporate the chloroform extracts with the aid of gentle heat and a current of air to dryness, and dissolve the residue in 1 mL of chloroform.

Sample stock solution: Dissolve a portion of finely powdered Tablets, equivalent to 10 mg of benztropine mesylate, in 50 ml, of water, shake by mechanical means for 30 min, and filter into a separator (0.2 mg/mL).

Sample solution: In a separator containing the Sample stock solution add 2 mL of 1 N sodium hydroxide. Extract with three 10-mL portions of chloroform, collecting the chloroform extracts to a 50-mL beaker. Evaporate the chloroform extracts with the aid of gentle heat and a current of air to dryness, and dissolve the residue in 1 mL of chloroform.

Chromatographic system

Adsorbent: 0.25-mm layer of chromatographic silica gel

Application volume: 1 µL

Developing solvent system: Chloroform, methanol, and a 1-in-4 solution of ammonium hydroxide (40:10:1)

Analysis

Samples: Standard solution and Sample solution

Allow the applications to dry, and develop the chromatogram in the Developing solvent system until the solvent front has moved about three-fourths of the length of the plate. Remove the plate from the developing chamber, mark the solvent front, and allow the solvent to evaporate. Locate the spots on the plate by lightly spraying with potassium iodoplatinate TS.

Acceptance criteria: The Re value of the principal spot of the Sample solution corresponds to that of the Standard solution.

3 ASSAY

PROCEDURE

Buffer: Transfer 0.83 ml. of octylamine to a 1-L volumetric flask, dilute with water to volume, and adjust with phosphoric acid to a pH of 3.0.

Diluent: Isopropyl alcohol, water, and phosphoric acid (40:60:0.1)

Mobile phase: Acetonitrile and Buffer (45:55)

Standard solution: 0.04 mg/mL of USP Benztropine Mesylate RS in Diluent

Sample solution: Nominally 0.04 mg/mL of benztropine mesylate from a suitable amount of powdered Tablets in Diluent prepared as follows Add a suitable amount of fine powder from NLT 20 Tablets to a portion of Diluent corresponding to 60% of the final volume. Mix by mechanical means for NLT 60 min, and dilute with Diluent to volume. Centrifuge a portion of this mixture, and filter the supernatant layer.

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 259 nm

Column: 4.6-mm x 25-cm; packing L7

Flow rate: 0.7 mL/min

Injection volume: 50 µL

System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 4.0

Relative standard deviation: NMT 2.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of benztropine mesylate (C₂₁H₂₅NO · CH₄O₃S) in the portion of Tablets taken:

Result = (r_u /r_s ) × (C_s /C_u ) × 100

r_u = peak response from the Sample solution

r_s = peak response from the Standard solution

C_s = concentration of USP Benztropine Mesylate RS in the Standard solution (mg/mL)

C_u = nominal concentration of benztropine mesylate in the Sample solution (mg/mL)

Acceptance criteria: 90.0%–110.0%

4 PERFORMANCE TESTS

DISSOLUTION (711)

Medium: 0.1 N hydrochloric acid; 900 mL

Apparatus 2: 50 rpm

Time: 30 min

Determine the amount of benztropine mesylate (C₂₁H₂₅NO · CH₄O₃S) dissolved by using the following method.

Buffer: Transfer 0.83 mL of octylamine to a 1-L volumetric flask, dilute to volume, and adjust with phosphoric acid to a pH of 3.0.

Mobile phase: Acetonitrile and Buffer (65:35)

Standard solution: USP Benztropine Mesylate RS in Medium. Dilute to obtain a solution having a known concentration similar to that of the

Sample solution.

Sample solution: Use a filtered portion of the solution under test from the dissolution vessel.

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 220 nm.

Column: 4.6-mm x 25-cm; packing L7

Flow rate: 2 mL/min

Injection volume: 300 µL

System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 3.0%

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of benztropine mesylate (C₂₁H₂₅NO · CH₄O₃S) dissolved:

Result = (r_u /r_s ) × C_s × V × (1/L) × 100

r_u = peak response from the Sample solution

r_s = peak response from the Standard solution

C_s = concentration of USP Benztropine Mesylate RS in the Standard solution (mg/mL)

V = volume of the Medium, 900 mL

L = label claim (mg/Tablet)

Acceptance criteria: NLT 80% (Q) of the labeled amount of benztropine mesylate (C H NO · CH O S) is dissolved.

Uniformity of Dosage Units 〈905〉: Meet the requirements

5 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in well-closed containers.

USP REFERENCE STANDARDS (11)

USP Benztropine Mesviate RS