Selegiline Hydrochloride Compounded Topical Gel

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

Selegiline Hydrochloride Compounded Topical Gel contains NLT 90.0% and NMT 110.0% of the labeled amount of selegiline hydrochloride (C₁₃H₁₇N · HCl).

Prepare Selegiline Hydrochloride Compounded Topical Gel 10 mg/mL as follows (see Pharmaceutical Compounding—Nonsterile Preparations 〈795〉). For this preparation, a soy lecithin–isopropyl palmitate mixture and a poloxamer gel need to be separately prepared.

Sorbic Acid: 0.2 g

Soy lecithin: 50 g

Isopropyl Palmitate: 50 g

Prepare a soy lecithin–isopropyl palmitate mixture by mixing 0.2 g of Sorbic Acid, 50 g of Soy Lecithin, and 50 g of Isopropyl Palmitate together. Allow the mixture to set overnight, and mix again.

Sorbic Acid: 0.2 g

Poloxamer 407: 30 g

Purified Water, a sufficient quantity to make: 100 mL

Separately, prepare a 30% poloxamer gel by mixing 0.2 g of Sorbic Acid, 30 g of Poloxamer 407, and a sufficient amount of Purified Water to bring to a final volume of 100 mL. Place the gel in the refrigerator overnight, and mix again.

Selegiline hydrochloride powder: 1 g

Purified Water: 5 mL

Soy lecithin–isopropyl palmitate mixture: 22 mL

Poloxamer gel (30%), a sufficient quantity to make: 100 mL

Dissolve 1 g of Selegiline hydrochloride powder in 5 mL of Purified Water in a suitable mortar. Add 22 mL of the previously prepared soy lecithin–isopropyl palmitate mixture to the mortar, and mix well. Add a sufficient amount of the previously prepared 30% poloxamer gel to bring to final volume, and mix using high-shear methods.

2 ASSAY

Procedure

Solution A: 0.1 M monobasic ammonium phosphate adjusted with phosphoric acid to a pH of 3.1

Mobile phase: Acetonitrile and Solution A (20:80). Filter, and degas.

System suitability solution: 0.4 mg/mL each of USP Selegiline Hydrochloride RS and USP Methamphetamine Hydrochloride RS in Mobile phase

Standard solution: 0.4 mg/mL of USP Selegiline Hydrochloride RS in Mobile phase

Sample solution: Shake thoroughly each container of Topical Gel. Transfer 0.4 mL of Topical Gel into a 10-mL volumetric flask, dilute with Mobile phase to volume, and mix well.

Chromatographic system

(See Chromatography 〈621〉, System Suitability.)

Mode: LC

Detector: UV 205 nm

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

Flow rate: 1.0 mL/min

Injection volume: 8 µL

System suitability

Samples: System suitability solution and Standard solution

[Note—The relative retention times for methamphetamine hydrochloride and selegiline hydrochloride are about 0.63 and 1.0, respectively.]

Suitability requirements

Tailing factor: NMT 2.0, Standard solution

Resolution: NLT 8.0 between selegiline and methamphetamine, System suitability solution

Relative standard deviation: NMT 2.0% for replicate injections, Standard solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of selegiline hydrochloride (C₁₃H₁₇N · HCl) in the portion of Topical Gel taken:

Result = (rᵤ/rₛ) × (Cₛ/Cᵤ) × 100

rᵤ = peak response of selegiline hydrochloride from the Sample solution

rₛ = peak response of selegiline hydrochloride from the Standard solution

Cₛ = concentration of selegiline hydrochloride in the Standard solution (mg/mL)

Cᵤ = nominal concentration of selegiline hydrochloride in the Sample solution (mg/mL)

Acceptance criteria: 90.0%–110.0%

3 SPECIFIC TESTS

pH 〈791〉: 4.6–5.6

4 ADDITIONAL REQUIREMENTS

Packaging and Storage: Package in a tight, light-resistant suitable calibrated dispenser. Store at 2°–8° or at controlled room temperature.

Beyond-Use Date: NMT 90 days after the date on which it was compounded when stored at 2°–8° or at controlled room temperature

Labeling: Label it to indicate that it is for external use only, keep out of the reach of children, use only as directed, and to state the Beyond-Use Date.

USP Reference Standards 〈11〉

USP Methamphetamine Hydrochloride RS

USP Selegiline Hydrochloride RS