Alprostadil

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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C₂₀H₃₄O₅ 354.48

Prost-13-en-1-oic acid, 11,15-dihydroxy-9-oxo-, (11α, 13Ε,155)-;

(1R,2R,3R)-3-Hydroxy-2-[(E)-(3S)-3-hydroxy-1-octenyl]-5-oxocyclopentaneheptanoic acid CAS RN: 745-65-3; UNII: F5TD010360.

1 DEFINITION

Alprostadil contains NLT 95.0% and NMT 105.0% of alprostadil (C20H340g), calculated on the anhydrous basis.

[CAUTION-Great care should be taken to prevent inhaling particles of Alprostadil and exposing the skin to it.]

2 IDENTIFICATION

Change to read:

A. (USP 1-MAY-2022) SPECTROSCOPIC IDENTIFICATION TESTS (197), Infrared Spectroscopy: 197M

3 ASSAY

3.1 PROCEDURE

Use freshly prepared solutions.

Mobile phase: Methanol, acetonitrile, and 0.1 M monobasic potassium phosphate (2:1:2). Adjust with phosphoric acid to a pH of 3.0.

Diluent: Methanol and water (90:10)

Internal standard solution: 0.05 mg/mL of ethylparaben in Diluent

Standard stock solution: 0.3 mg/mL of USP Alprostadil RS in Diluent

Standard solution: 0.2 mg/mL of USP Alprostadil RS prepared by combining 2.0 mL of Standard stock solution with 1.0 mL of Internal standard solution

System suitability stock solution: 4.5 µg/mL of USP Prostaglandin A1 RS in Standard stock solution

System suitability solution: Combine 2.0 mL of System suitability stock solution with 1.0 mL of Internal standard solution.

Sample stock solution: 0.3 mg/mL of Alprostadil in Diluent

Sample solution: 0.2 mg/mL of Alprostadil prepared by combining 2.0 mL of Sample stock solution and 1.0 mL of Internal standard solution

3.2 Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: Photodiode array detector or equivalent capable of detecting UV wavelengths of 200-300 nm

Analytical wavelength: 200 nm

Column: 4.6-mm x 25-cm; packing L1

Column temperature: 40°

Flow rate: 1 mL/min

Injection volume: 20 µL

System suitability

Sample: System suitability solution

Suitability requirements

Resolution: NLT 7.5 between prostaglandin A₁ and alprostadil, and NLT 2.0 between prostaglandin A₁ and ethylparaben

Relative standard deviation: NMT 2.0%, determined from the peak area ratio of alprostadil to ethylparaben

3.3 Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of alprostadil (C₂₀H₃₄O₅) in the portion of Alprostadil taken:

Result = (R_U/R_S) x (C_S/C_U) x 100

R_U = peak area ratio of alprostadil to the internal standard from the Sample solution

R_S = peak area ratio of alprostadil to the internal standard from the Standard solution

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

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

Acceptance criteria: 95.0%-105.0% on the anhydrous basis

4 IMPURITIES

4.1 RESIDUE ON IGNITION (281)

Sample: 0.3 g

Acceptance criteria: NMT 0.5%

Delete the following:

4.2 LIMIT OF CHROMIUM

Standard stock solution: 3.04 µg/mL of chromium trichloride in 0.05 M nitric acid

Standard solution: 20 ng/mL of chromium (Cr) in alcohol, prepared as follows. Transfer 2 mL of the Standard stock solution to a 100-mL volumetric flask, and dilute with alcohol to volume.

Sample solution: 1.0 mg/mL of Alprostadil in alcohol

Blank: Alcohol

Instrumental conditions

(See Atomic Absorption Spectroscopy (852).)

Mode: Atomic absorption spectroscopy

Lamp: Chromium hollow-cathode

Analytical wavelength: 357.9 nm

Atomization type: Graphite furnace

Temperatures

Drying: 100°

Ashing: 1000°

Atomization: 2700°

Injection volume: 20 µL

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of chromium (Cr) in the portion of Alprostadil taken:

Result = (A_U/A_S) × (C_S/C_U) × 100

A_U = absorbance of the Sample solution

A_S = absorbance of the Standard solution

C_S = concentration of chromium in the Standard solution (mg/mL)

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

Acceptance criteria: NMT 0.002% (USP 1-May-2022)

Delete the following:

4.3 LIMIT OF RHODIUM

Standard stock solution: 100 µg/mL of rhodium in 1.2 M hydrochloric acid, prepared by diluting rhodium chloride hydrate

Standard solution: 50 ng/mL of rhodium (Rh) in alcohol from Standard stock solution

Sample solution: 2.0 mg/mL of Alprostadil in alcohol

Blank: Alcohol

Instrumental conditions

(See Atomic Absorption Spectroscopy (852).)

Mode: Atomic absorption spectroscopy

Lamp: Rhodium hollow-cathode

Analytical wavelength: 343.5 nm

Atomization type: Graphite furnace

Temperatures

Drying: 100°

Ashing: 1000°

Atomization: 2800°

Injection volume: 20 µL

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of rhodium (Rh) in the portion of Alprostadil taken:

Result = (A_U/A_S) × (C_S/C_U) × 100

A_U = absorbance of the Sample solution

A_S = absorbance of the Standard solution

C_S = concentration of rhodium in the Standard solution (mg/mL)

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

Acceptance criteria: NMT 0.002% (USP 1-May-2022)

Change to read:

4.4 LIMIT OF FOREIGN PROSTAGLANDINS, TEST 1

Use freshly prepared solutions.

Mobile phase: Methanol, acetonitrile, and 0.1 M monobasic potassium phosphate (2:1:2). Adjust with phosphoric acid to a pH of 3.0.

Diluent: Methanol and water (90:10)

Standard solution: 6 µg/mL of USP Alprostadil RS, 15 µg/mL of USP Prostaglandin A1 RS, and 6 µg/mL of USP Prostaglandin B1 RS in Diluent

Sample solution: 3.0 mg/mL of Alprostadil in Diluent

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: Photodiode array detector or equivalent capable of detecting UV wavelengths of 200-300 nm

Analytical wavelengths

Prostaglandin A₁: 224 nm

Prostaglandin B₁: 280 nm

Other foreign prostaglandins: 200 nm

Column: 4.6-mm x 25-cm; packing L1

Column temperature: 40°

Flow rate: 1 mL/min

Injection volume: 20 µL

System suitability

Sample: Standard solution

Suitability requirements

Resolution: NLT 7.5 between prostaglandin A, and alprostadil

Relative standard deviation: NMT 4.0%, determined from the peaks at their respective wavelength for replicate injections

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of prostaglandin A₁ and prostaglandin B₁ in the portion of Alprostadil taken:

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

r_U = peak response of prostaglandin A₁ or prostaglandin B₁ from the Sample solution

r_S = peak response of prostaglandin A₁ or prostaglandin B₁ from the Standard solution

C_S = concentration of USP Prostaglandin A1 RS or USP Prostaglandin B1 RS in the Standard solution (mg/mL)

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

Calculate the percentage of each impurity occurring at 200 nm and eluting before prostaglandin A, in the portion of Alprostadil taken:

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

r_U = peak response for each impurity from the Sample solution

r_S = peak response for alprostadil from the Standard solution

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

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

Calculate the percentage of any (USP 1-May-2022) impurity having a relative retention time of 0.6, relative to the prostaglandin A₁ peak detected at 224 nm, in the portion of Alprostadil taken:

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

r_U = peak response for any impurity having a relative retention time of 0.6, relative to the prostaglandin A, peak, from the Sample solution

r_S = peak response for prostaglandin A, from the Standard solution

C_S = concentration of USP Prostaglandin A1 RS in the Standard solution (mg/mL)

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

Acceptance criteria

Prostaglandin A₁: NMT 1.5%

Prostaglandin B₁: NMT 0.1%

Any foreign prostaglandin impurity eluting before prostaglandin A₁: NMT 0.9%

Impurity at relative retention time 0.6, relative to prostaglandin A₁: NMT 0.9%

Change to read:

4.5 LIMIT OF FOREIGN PROSTAGLANDINS, TEST 2

Mobile phase: Methanol, acetonitrile, and 0.02 M monobasic potassium phosphate (2:1:1). Adjust with phosphoric acid to a pH of 3.

System suitability solution: 6 µg/mL of USP Alprostadil RS, 15 µg/mL of USP Prostaglandin A1 RS, and 6 µg/mL of USP Prostaglandin B1 RS in methanol and water (9:1)

Standard solution: 10 µg/mL of USP Alprostadil RS in acetonitrile and water (1:1)

Sample solution: 5.0 mg/mL of Alprostadil in acetonitrile and water (1:1). [NOTE-Sonicate if necessary.] necessary.

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: Photodiode array detector or equivalent, capable of detecting UV wavelengths of 200-300 nm FICIAL

Analytical wavelengths

Prostaglandin A₁: 224 nm

Prostaglandin B₁: 280 nm

Other foreign prostaglandins: 200 nm

Column: 4.6-mm x 25-cm; packing L1

Flow rate: 1.2 mL/min

Injection volume: 20 µL

System suitability

Samples: System suitability solution and Standard solution

[NOTE-The relative retention times for alprostadil and prostaglandin A, are 1.0 and 1.2, respectively. (USP 1-May-2022)]

Suitability requirements

Resolution: NLT 4.0 between prostaglandin A, and alprostadil, System suitability solution

Relative standard deviation: NMT 2.0%, determined from the main peak, Standard solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of each impurity, excluding prostaglandin B,, observed at 200 nm and eluting after prostaglandin A₁ in the portion of Alprostadil taken:

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

r_U = peak response for each impurity from the Sample solution

r_S = peak response for alprostadil from the Standard solution

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

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

Acceptance criteria

Sum of the impurities at relative retention times 2.0 and 2.3: NMT 0.6%

Any other foreign prostaglandin impurity eluting after prostaglandin A₁: NMT 0.9%

Total impurities: The sum of the impurities from Limit of Foreign Prostaglandins, Test 1 and Test 2, is NMT 2.0%.

5 SPECIFIC TESTS

WATER DETERMINATION (921), Method I

Sample: 0.5 g

Acceptance criteria: NMT 0.5%

6 ADDITIONAL REQUIREMENTS

PACKAGING AND STORAGE: Preserve in tight containers, and store in a refrigerator.

USP REFERENCE STANDARDS (11).

USP Alprostadil RS

USP Prostaglandin A1 RS

USP Prostaglandin B1 RS

(13E,15S)-15-Hydroxy-9-oxoprosta-8(12), 13-dien-1-oic acid.

C₂₀H₃₂O₄ 336.47