Abacavir and Lamivudine 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

Abacavir and Lamivudine Tablets contain an amount of abacavir sulfate and lamivudine equivalent to NLT 90.0% and NMT 110.0% of the labeled amount of abacavir (C14H18N6O) and NLT 90.0% and NMT 110.0% of the labeled amount of lamivudine (C8H11N3O3S), respectively.

2 IDENTIFICATION

• A. The retention times of the major peaks of the Sample solution correspond to those of the Standard solution, as obtained in the Assay.

3 ASSAY

• PROCEDURE

Diluent: 0.1 N hydrochloric acid

Solution A: Water and trifluoroacetic acid (2000:1)

Solution B: Acetonitrile, methanol, and trifluoroacetic acid (1000:1000:1)

Mobile phase: See Table 1. [NOTE—Return to original conditions and re-equilibrate the system for about 7 min.]

System suitability solution: Dissolve the contents of one vial of USP Lamivudine Resolution Mixture C RS in 2.5 mL of Diluent. [NOTE—One vial of USP Lamivudine Resolution Mixture C RS contains 0.8 mg of USP Lamivudine Resolution Mixture C RS.]

Standard solution: 0.35 mg/mL of USP Abacavir Sulfate RS and 0.15 mg/mL of USP Lamivudine RS in Diluent. Sonicate to dissolve prior to final dilution.

Sample stock solution: Nominally 3 mg/mL of abacavir and 1.5 mg/mL of lamivudine in Diluent prepared as follows. Transfer NLT 5 Tablets to a suitable volumetric flask. Add Diluent to about 50% of the final volume and shake for NMT 30 min to disperse the Tablets. Dilute with Diluent to volume. Pass through a suitable filter.

Sample solution: Nominally 0.3 mg/mL of abacavir and 0.15 mg/mL of lamivudine in Diluent from Sample stock solution

Chromatographic system

(See Chromatography (621), System Suitability.)

Mode: LC

Detector: UV 270 nm

Column: 4.6-mm × 15-cm; 3.5-µm packing L1

Column temperature: 40°

Flow rate: 1.5 mL/min

Injection volume: 10 µL

System suitability

Samples: System suitability solution and Standard solution

[NOTE—The relative retention times for lamivudine-S-oxide and lamivudine-R-oxide, in relation to the lamivudine peak, are 0.31 and 0.36, respectively; the relative retention times for lamivudine diastereomer and lamivudine are 0.88 and 1.0, respectively; System suitability solution.]

Suitability requirements

Resolution: NLT 1.0 between lamivudine-S-oxide and lamivudine-R-oxide; NLT 1.0 between lamivudine diastereomer and lamivudine, System suitability solution

Relative standard deviation: NMT 1.5% each for abacavir and lamivudine, Standard solution

Analysis

Samples: Standard solution and Sample solution

Calculate the percentage of the labeled amount of abacavir (C14H18N6O) in the portion of Tablets taken:

Result = (ru/rs) × (Cs/Cu) × (M1/M2) × 100

ru = peak response of abacavir from the Sample solution

rs = peak response of abacavir from the Standard solution

Cs = concentration of USP Abacavir Sulfate RS in the Standard solution (mg/mL)

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

M1 = molecular weight of abacavir multiplied by 2.57266

M2 = molecular weight of abacavir sulfate, 670.74

Acceptance criteria: 90.0%–110.0% of the labeled amount of abacavir

Calculate the percentage of the labeled amount of lamivudine (C8H11N3O3S) in the portion of Tablets taken:

Result = (ru/rs) × (Cs/Cu) × 100

ru = peak response of lamivudine from the Sample solution

rs = peak response of lamivudine from the Standard solution

Cs = concentration of USP Lamivudine RS in the Standard solution (mg/mL)

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

Acceptance criteria: 90.0%–110.0% of the labeled amount of lamivudine

4 PERFORMANCE TESTS

• Dissolution (711)

Medium: 0.1 N hydrochloric acid; 900 mL

Apparatus 2: 75 rpm

Time: 30 min

Standard solution 1: 0.79 mg/mL of USP Abacavir Sulfate RS in Medium. Sonicate to dissolve prior to final dilution.

Standard solution 2: 0.33 mg/mL of USP Lamivudine RS in Medium. Sonicate to dissolve prior to final dilution.

Sample solution: Pass a portion of the solution under test through a suitable filter.

Instrumental conditions

Mode: UV

Wavelength: 240–320 nm

Cell length: 0.2 mm

Blank: Medium

Analysis: The calculations of the percentages dissolved are performed using multi-component analysis software.

Tolerances: NLT 80% (Q) of the labeled amount of abacavir and lamivudine is dissolved.

• Uniformity of Dosage Units (905): Meet the requirements

5 IMPURITIES

• Organic Impurities

Diluent, Solution A, Solution B, Mobile phase, System suitability solution, Standard solution, Sample stock solution, Sample solution, Chromatographic system, and System suitability: Proceed as directed in the Assay.

Analysis

Sample: Sample solution

Calculate the percentage of each individual abacavir related impurity and each unspecified impurity in the portion of Tablets taken:

Result = (rd/rT) × 100

rd = peak response of each abacavir related impurity or unspecified impurity

rT = sum of the peak responses of abacavir, all abacavir related impurities, and all unspecified impurities

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

Result = (rd/rT) × 100

rd = peak response of each lamivudine related impurity

rT = sum of the peak responses of lamivudine and all lamivudine related impurities

Acceptance criteria: See Table 2. Disregard any peak less than 0.05%.

a 4-Aminopyrimidin-2(1H)-one (lamivudine related impurity).

b 1-[(2R,3S,5S)-2-(Hydroxymethyl)-1,3-oxathiolan-5-yl]cytosine S-oxide.

c 1-[(2R,3R,5S)-2-(Hydroxymethyl)-1,3-oxathiolan-5-yl]cytosine S-oxide.

d (2RS,5SR)-5-(Cytosine-1-yl)-1,3-oxathiolane-2-carboxylic acid.

e Process impurity monitored in the drug substance.

f 1-[(2S,5S)-2-(Hydroxymethyl)-1,3-oxathiolan-5-yl]cytosine.

g 1-[(2R,5S,5SR)-2-(Hydroxymethyl)-1,3-oxathiolan-5-yl]uracil.

h N6-Cyclopropyl-9H-purine-2,6-diamine.

i [(1S,4R)-4-(2,6-Diamino-9H-purin-9-yl)cyclopent-2-enyl]methanol.

j (1R,2R,4S)-2-[2-Amino-6-(cyclopropylamino)-9H-purin-9-yl]-4-(hydroxymethyl)cyclopentan-1-ol.

k Includes all lamivudine related impurities.

l Includes all abacavir related and all individual unspecified impurities.

6 ADDITIONAL REQUIREMENTS

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

• USP Reference Standards (11)

USP Abacavir Sulfate RS

USP Lamivudine RS

USP Lamivudine Resolution Mixture C RS

This is a mixture of lamivudine and the following impurities (other impurities may also be present).

Uracil: Pyrimidine-2,4(1H,3H)-dione.

C4H4N2O2 112.09

Lamivudine-uracil derivative: 1-[(2R,5S)-2-(Hydroxymethyl)-1,3-oxathiolan-5-yl]uracil.

C8H10N2O4S 230.24

Cytosine: 4-Aminopyrimidin-2(1H)-one.

C4H5N3O               111.10

Lamivudine-S-sulfoxide: 1-[(2R,3S,5S)-2-(Hydroxymethyl)-1,3-oxathiolan-5-yl]cytosine S-oxide.

C8H11N3O4S                              245.26

Lamivudine-R-sulfoxide: 1-[(2R,3R,5S)-2-(Hydroxymethyl)-1,3-oxathiolan-5-yl]cytosine S-oxide.

C8H11N3O4S                              245.26

Lamivudine carboxylic acid: (2R,5S,5S)-5-(Cytosine-1-yl)-1,3-oxathiolane-2-carboxylic acid.

C8H9N3O5S                                 243.24

Lamivudine diastereomer: 1-[(2S,5S)-2-(Hydroxymethyl)-1,3-oxathiolan-5-yl]cytosine.

C8H11N3O3S                     229.26

Salicylic acid: 2-Hydroxybenzoic acid.

C7H6O3                 138.12