Pentazocine Injection

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

Pentazocine Injection is a sterile solution of Pentazocine in Water for Injection, prepared with the aid of Lactic Acid. It contains NLT 95.0% and NMT 105.0% of the labeled amount of pentazocine (C₁₉H₂₇NO).

2 IDENTIFICATION

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

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

3 ASSAY

Procedure

Solution A: 15 mM sodium borate in water. Adjust with 10 N sodium hydroxide to a pH of 10.0.

Solution B: Methanol

Mobile phase: See Table 1.

Table 1

Diluent: Methanol, phosphoric acid, and water (500:1:500)

Standard solution: 0.024 mg/mL of USP Pentazocine RS in Diluent

Sample solution: Nominally 0.024 mg/mL of pentazocine from Injection in Diluent

3.1 Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 225 nm. For Identification B, use a diode array detector in the range of 200–400 nm.

Column: 4.6-mm × 10-cm; 2.6-µm packing L1

Column temperature: 40°

Flow rate: 0.5 mL/min

Injection volume: 20 µL

3.2 System suitability

Sample: Standard solution

Suitability requirements

Tailing factor: NMT 2.0

Relative standard deviation: NMT 1.0%

3.3 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of pentazocine (C₁₉H₂₇NO) in the portion of Injection taken:

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

r_U = peak response of pentazocine from the Sample solution

r_S = peak response of pentazocine from the Standard solution

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

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

Acceptance criteria: 95.0%–105.0%

4 IMPURITIES

Organic Impurities

Solution A, Solution B, Mobile phase, Diluent, and Chromatographic system: Proceed as directed in the Assay.

Sensitivity solution: 0.5 µg/mL of USP Pentazocine RS in Diluent

Standard solution: 0.002 mg/mL of USP Pentazocine RS in Diluent

Sample solution: Nominally 1 mg/mL of pentazocine from Injection in Diluent

4.1 System suitability

Samples: Sensitivity solution and Standard solution

Suitability requirements

Relative standard deviation: NMT 5.0%, Standard solution

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

4.2 Analysis

Samples: Standard solution and Sample solution

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

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

r_U = peak response of each impurity from the Sample solution

r_S = peak response of pentazocine from the Standard solution

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

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

Acceptance criteria: See Table 2. The reporting threshold is 0.05%.

Table 2

^a (2R,6R,11R)-1,2,3,4,5,6-Hexahydro-6,11-dimethyl-2,6-methano-3-benzazocin-8-ol.

^b (2R,6R,11R)-3-(3-Hydroxy-3-methylbutyl)-6,11-dimethyl-1,2,3,4,5,6-hexahydro-2,6-methanobenzo[d]azocin-8-ol.

5 SPECIFIC TESTS

Bacterial Endotoxins Test 〈85〉: NMT 5.8 USP Endotoxin Units/mg of pentazocine

pH 〈791〉: 4.0–5.0

Other Requirements: It meets the requirements in Injections and Implanted Drug Products 〈1〉.

6 ADDITIONAL REQUIREMENTS

Packaging and Storage: Preserve in single-dose or multiple-dose containers, preferably of Type I glass. Store at 20°–25°. • USP Reference Standards 〈11〉

USP Pentazocine RS