Pilocarpine Hydrochloride 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

Pilocarpine Hydrochloride Tablets contain NLT 90.0% and NMT 110.0% of the labeled amount of pilocarpine hydrochloride (C₁₁H₁₆N₂O₂ · HCl). 

2 IDENTIFICATION

A. The retention time of the major peak of the Sample solution corresponds to the major peak of the Standard solution, as obtained in the Assay.

B. The UV spectrum of the major peak of the Sample solution corresponds to that of the Standard solution, as obtained in the Assay.

3 ASSAY

Procedure

Solution A: 10 N sodium hydroxide, 85% phosphoric acid, triethylamine, and water (7:6:1:500). Adjust with 10 N sodium hydroxide to a pH of 3.0.

Mobile phase: Methanol and Solution A (3:100)

Standard solution: 50 µg/mL of USP Pilocarpine Hydrochloride RS

System suitability solution: Transfer 10 mL of the Standard solution to a test tube. Add 100 µL of 2 N sodium hydroxide, mix well, and allow it to stand for 5 min. Add 100 µL of 2 N hydrochloric acid and mix well. [Note—This preparation contains pilocarpine, isopilocarpine, and two unidentified compounds.]

Sample stock solution: Nominally 0.1 mg/mL of pilocarpine hydrochloride in water prepared as follows. Place Tablets, equivalent to 50 mg of pilocarpine hydrochloride, in a 500-mL volumetric flask. Fill the flask 75% full with water. Stir for at least 30 min or more if necessary, until the Tablets are completely disintegrated and the powder is finely dispersed. Dilute with water to volume.

Sample solution: Nominally 50 µg/mL of pilocarpine hydrochloride in water from Sample stock solution. Pass a suitable amount of solution through a PVDF filter of 0.45-µm pore size, and discard the first 5 mL of the filtrate.

3.1 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 215 nm. For Identification B, use a diode array detector in the range of 190–400 nm.

Column: 4.6-mm × 15-cm; 5-µm packing L1

Flow rate: 1.5 mL/min

Injection volume: 20 µL

3.2 System suitability

Samples: Standard solution and System suitability solution

[Note—The relative retention times for isopilocarpine, pilocarpine, and two unidentified peaks are 0.9, 1.0, 1.2, and 1.5, respectively.]

Suitability requirements

Resolution: NLT 1.2 between isopilocarpine and pilocarpine; NLT 1.2 between pilocarpine and the peak at a relative retention time of 1.2; NLT 1.2 between the peaks at relative retention times of 1.2 and 1.5, System suitability solution

Tailing factor: NMT 1.5, Standard solution

Relative standard deviation: NMT 2.0%, Standard solution

3.3 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of pilocarpine hydrochloride (C₁₁H₁₆N₂O₂ · HCl) in the portion of Tablets taken: 

Result = (r_U /r_S) × (C_S /C_U ) × 100

r_U = peak response of pilocarpine hydrochloride from the Sample solution

r_S = peak response of pilocarpine hydrochloride from the Standard solution

C_S = concentration of USP Pilocarpine Hydrochloride RS in the Standard solution (mg/mL)

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

Acceptance criteria: 90.0%–110.0%

4 PERFORMANCE TESTS

4.1 Dissolution 〈711〉

Medium: 0.1 N hydrochloric acid; 500 mL

Apparatus 2: 50 rpm

Time: 45 min

Buffer solution: 13.5 mL of phosphoric acid and 3.0 mL of triethylamine in 1000 mL of water. Adjust with phosphoric acid or 10 N sodium hydroxide to a pH of 3.

Mobile phase: Methanol and Buffer solution (3:17)

Standard stock solution: 0.1 mg/mL of USP Pilocarpine Hydrochloride RS in Medium

Standard solution

For Tablets labeled to contain 7.5 mg: Transfer 15.0 mL of the Standard stock solution to a 100-mL volumetric flask, and dilute with Medium to volume.

For Tablets labeled to contain 5 mg: Transfer 5.0 mL of the Standard stock solution to a 50-mL volumetric flask, and dilute with Medium to volume.

Sample solution: Pass the solution under test through a suitable polyethylene filter of 45-µm pore size.

4.1.1 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 215 nm

Column: 4.6-mm × 15-cm; packing L1

Flow rate: 1 mL/min

Injection volume: 20 µL

4.1.2 System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 2.0%

4.1.3 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of pilocarpine hydrochloride (C₁₁H₁₆N₂O₂ · HCl) 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 the Standard solution (mg/mL)

L = label claim (mg/Tablet)

V = volume of Medium, 500 mL

Tolerances: NLT 75% (Q) of the labeled amount of pilocarpine hydrochloride (C₁₁H₁₆N₂O₂ · HCl) is dissolved.

Change to read:

4.2 Uniformity of Dosage Units 〈905〉

Meet the requirements (CN 1-Aug-2023)

Procedure for content uniformity

Mobile phase, Standard solution, System suitability solution, Chromatographic system, and System suitability: Proceed as directed in the Assay.

Sample solution: Place 1 Tablet in a suitable volumetric flask, ll the flask about 75% full with water, and vigorously stir for NLT 30 min to ensure complete disintegration. Dilute with water to volume to obtain a nal concentration of 0.05 mg/mL of pilocarpine hydrochloride. Pass the solution through a PVDF filter of 0.45-µm pore size.

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of pilocarpine hydrochloride (C₁₁H₁₆N₂O₂ · HCl) in the portion of Tablets taken: 

Result = (r_U /r_S )) × (C_S /C_U ) × 100

r_U = peak response of pilocarpine hydrochloride from the Sample solution

r_S = peak response of pilocarpine hydrochloride from the Standard solution

C_S = concentration of USP Pilocarpine Hydrochloride RS in the Standard solution (mg/mL)

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

(CN 1-Aug-2023)

5 IMPURITIES

Organic Impurities

Procedure

Mobile phase, System suitability solution, Sample stock solution, and System suitability: Proceed as directed in the Assay. Standard solution: 0.5 µg/mL of USP Pilocarpine Hydrochloride RS

Sample solution: Nominally 100 µg/mL of pilocarpine hydrochloride in water from Sample stock solution. Pass a suitable amount of solution through a PVDF filter of 0.45-µm pore size, and discard the first 5 mL of the filtrate.

5.1 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 215 nm

Column: 4.6-mm × 15-cm; 5-µm packing L1

Flow rate: 1.5 mL/min

Injection volume: 100 µL

5.2 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of each impurity in the portion of Tablets taken:

Result = (r_U /r_S ) × (C_S /C_U ) × (1/F) × 100

r_U = peak response of each impurity from the Sample solution

r_S = peak response of pilocarpine hydrochloride from the Standard solution

C_S = concentration of USP Pilocarpine Hydrochloride RS in the Standard solution (mg/mL)

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

F = relative response factor for each impurity (see Table 1)

Acceptance criteria: See Table 1.

Table 1

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in tight containers, and store at controlled room temperature.

USP Reference Standards 〈11〉

USP Pilocarpine Hydrochloride RS