Pyridostigmine Bromide 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 

Pyridostigmine Bromide Tablets contain NLT 95.0% and NMT 105.0% of the labeled amount of pyridostigmine bromide (C₉H₁₃BrN₂O₂).  

2 IDENTIFICATION 

A. The retention time of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay. B. Identification Tests—General 〈191〉, Chemical Identification Tests, Bromide 

Sample solution: Shake a quantity of finely powdered Tablets, equivalent to 100 mg of pyridostigmine bromide, with 20 mL of water for 5 min, and filter the mixture. Use the filtrate. 

Acceptance criteria: Meet the requirements 

3 ASSAY 

Procedure 

Mobile phase: Dissolve 1 g of sodium 1-heptanesulfonate in 500 mL of water in a 1000-mL volumetric flask, and add 5.0 mL of triethylamine and 100 mL of acetonitrile. Dilute with water to volume, and mix. Adjust with phosphoric acid to a pH of 3.0. Diluent: Mix 11.2 g of phosphoric acid with 500 mL of water, and adjust with a 50% sodium hydroxide solution to a pH of 7.0. Dilute with water to 1000 mL. 

Standard solution: 0.25 mg/mL of USP Pyridostigmine Bromide RS in Diluent 

Sample solution: Nominally 0.25 mg/mL of pyridostigmine bromide prepared as follows. Finely powder NLT 20 Tablets and transfer a portion of the powder, equivalent to about 50 mg of pyridostigmine bromide, to a suitable volumetric flask. Add about 50% of the flask volume of Diluent, and shake for 30 min. Dilute with Diluent to volume, mix, and centrifuge. Use the supernatant. 

Chromatographic system 

(See Chromatography 〈621〉, System Suitability.) 

Mode: LC 

Detector: UV 270 nm 

Column: 4-mm × 30-cm; packing L1 

Flow rate: 2 mL/min 

Injection volume: 20 µL 

System suitability 

Sample: Standard solution 

Suitability requirements 

Tailing factor: NMT 1.5 

Relative standard deviation: NMT 1.0% 

Analysis 

Samples: Standard solution and Sample solution 

Calculate the percentage of the labeled amount of pyridostigmine bromide (C₉H₁₃BrN₂O₂) 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 Pyridostigmine Bromide RS in the Standard solution (mg/mL) 

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

Acceptance criteria: 95.0%–105.0% 

4 PERFORMANCE TESTS 

Dissolution 〈711〉 

Medium: Water; 900 mL 

Apparatus 2: 50 rpm 

Time: 60 min 

Standard solution: USP Pyridostigmine Bromide RS in Medium at a known concentration approximately the same as that of the Sample solution 

Sample solution: Dilute with Medium and filter to obtain a concentration that is similar to that of the Standard solution. Instrumental conditions 

Mode: UV 

Analytical wavelength: 270 nm 

Analysis 

Samples: Standard solution and Sample solution 

Calculate the percentage of the labeled amount of pyridostigmine bromide (C₉H₁₃BrN₂O₂) dissolved: 

Result = (A_U/A_S) × C_S × V × (1/L) × 100 

A_U = absorbance of the Sample solution 

A_S = absorbance of the Standard solution 

C_S = concentration of USP Pyridostigmine Bromide RS in the Standard solution (mg/mL) 

V = volume of Medium, 900 mL 

L = label claim of pyridostigmine bromide (mg/Tablet) 

Tolerances: NLT 80% (Q) of the labeled amount of pyridostigmine bromide (C₉H₁₃BrN₂O₂) is dissolved. 

Uniformity of Dosage Units 〈905〉: Meet the requirements 

5 IMPURITIES 

Organic Impurities 

Solution A: 4.3 g/L of sodium dodecyl sulfate in water. Adjust with phosphoric acid to a pH of 2.0. 

Mobile phase: Acetonitrile and Solution A (30:70) 

System suitability solution: 5 µg/mL each of USP Pyridostigmine Bromide RS and USP Pyridostigmine Related Compound A RS in Mobile phase 

Sensitivity solution: 0.4 µg/mL of USP Pyridostigmine Bromide RS in Mobile phase 

Standard solution 1: 0.005 mg/mL of USP Pyridostigmine Bromide RS in Mobile phase 

Standard solution 2: 0.06 mg/mL of USP Pyridostigmine Bromide RS in Mobile phase 

Sample solution: Nominally 1 mg/mL of pyridostigmine bromide prepared as follows. Transfer a portion of powdered Tablets equivalent to 100 mg of pyridostigmine bromide to a suitable volumetric flask with 100 mL of Mobile phase. Shake for 30 min, and pass a portion of the solution through a glass ber filter. 

Chromatographic system 

(See Chromatography 〈621〉, System Suitability.) 

Mode: LC 

Detector: UV 220 nm 

Column: 4.6-mm × 25-cm; 5-µm packing L1 

Flow rate: 1.1 mL/min 

Injection volume: 20 µL 

Run time: NLT 2 times the retention time of pyridostigmine 

System suitability 

Samples: System suitability solution, Sensitivity solution, and Standard solution 1 

[Note—See Table 1 for the relative retention times.] 

System suitability requirements 

Resolution: NLT 1.5 between pyridostigmine and pyridostigmine related compound A, System suitability solution 

Relative standard deviation: NMT 5.0%, Standard solution 1 

Signal-to-noise ratio: NLT 10, Sensitivity solution 

Analysis 

Samples: Standard solution 1, Standard solution 2, and Sample solution 

Calculate the percentage of pyridostigmine related compound A and any individual unspecified degradation product in the portion of Tablets taken: 

Result = (r_U/r_S) × (C_S/C_U) × 100 

r_U = peak response of pyridostigmine related compound A or any individual unspecified degradation product from the Sample solution 

r_S = peak response of pyridostigmine from Standard solution 1  

C_S = concentration of USP Pyridostigmine Bromide RS in Standard solution 1 (mg/mL) 

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

Calculate the percentage of pyridostigmine related compound B in the portion of Tablets taken: 

Result = (r_U/r_S) × (C_S/C_U) × 100 

r_U = peak response of pyridostigmine related compound B from the Sample solution 

r_S = peak response of pyridostigmine from Standard solution 2 

C_S = concentration of USP Pyridostigmine Bromide RS in Standard solution 2 (mg/mL) 

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

Acceptance criteria: See Table 1. Disregard any peak below 0.04%. 

Table 1 

^a 3-Hydroxy-1-methylpyridin-1-ium bromide. 

6 ADDITIONAL REQUIREMENTS 

Packaging and Storage: Preserve in tight, light-resistant containers. Store at controlled room temperature. 

USP Reference Standards 〈11〉 

USP Pyridostigmine Bromide RS 

USP Pyridostigmine Related Compound A RS 

Pyridin-3-yl dimethylcarbamate. 

C₈H₁₀N₂O₂ 166.18