Salsalate Capsules

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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» Salsalate Capsules contain not less than 90.0 percent and not more than 110.0 percent of the labeled amount of C₁₄H₁₀O₅.

Packaging and storage— Preserve in tight containers.

USP Reference standards 〈11〉—

USP Salsalate RS

USP Salicylic Acid RS

USP Trisalicylic Acid RS C₂₁H₁₄O₇ 378.34

1 Identification—

Transfer a quantity of Capsule contents, equivalent to about 500 mg of salsalate, to a stoppered glass test tube.

Add 20 mL of ether to the tube, close the tube tightly, shake by mechanical means for 10 minutes, and filter.

Evaporate the filtrate to dryness using a stream of nitrogen: the IR absorption spectrum of a Mineral oil dispersion of the residue thus obtained exhibits maxima only at the same wavelengths as that of a similar preparation of USP Salsalate RS.

Disintegration 〈701〉: 30 minutes, simulated gastric fluid TS (without pepsin) being used.

Uniformity of dosage units 〈905〉: meet the requirements.

Limit of salicylic acid—

Mobile phase, Diluent, Resolution solution, and Chromatographic system—Proceed as directed in the Assay.

Standard preparation—

Dissolve an accurately weighed quantity of USP Salicylic Acid RS in Diluent to obtain a stock solution having a known concentration of about 0.5 mg per mL.

Transfer 3.0 mL of this solution to a 100-mL volumetric flask, dilute with Diluent to volume, and mix.

This solution contains about 0.015 mg per mL.

Test preparation—

Use the Assay stock solution prepared as directed in the Assay.

Procedure—

Proceed as directed for Procedure in the Assay, except to inject equal volumes (about 10 µL) of the Standard preparation and the Test preparation.

Calculate the percentage of salicylic acid (C₇H₆O₃) in the portion of Capsules taken by the formula:

10,000(C/Oₗ)(rᵤ/rₛ)

in which:

C = concentration (mg/mL) of USP Salicylic Acid RS in the Standard preparation

Oₗ = quantity (mg) of salsalate in the portion of Capsules taken based on the labeled amount

rᵤ and rₛ = salicylic acid peak responses obtained from the Test preparation and the Standard preparation

Requirement: not more than 1.5% is found.

2 Assay—

Mobile phase, Diluent, Salsalate standard preparation, Resolution solution, and Chromatographic system—Proceed as directed in the Assay under Salsalate.

Assay preparation—

Transfer as completely as possible the contents of not less than 20 Capsules to a suitable tared container, and weigh.

Mix, and transfer an accurately weighed portion of the powder, equivalent to about 100 mg of salsalate, to a 100-mL volumetric flask, dilute with Diluent to volume, and mix.

Sonicate for about 10 minutes, and mix.

Filter a portion of this solution through a suitable filter of 0.5 µm or finer porosity.

Use the clear filtrate as the Assay stock solution.

Transfer 2.0 mL of the Assay stock solution to a 100-mL volumetric flask, dilute with Diluent to volume, and mix (Assay preparation).

Procedure—

Separately inject equal volumes (about 10 µL) of the Salsalate standard preparation and the Assay preparation into the chromatograph, record the chromatograms, and measure the responses for the salsalate peaks.

Calculate the quantity, in mg, of salsalate (C₁₄H₁₀O₅) in the portion of Capsules taken by the formula:

5000C(rᵤ/rₛ)

in which:

C = concentration (mg/mL) of USP Salsalate RS in the Salsalate standard preparation

rᵤ and rₛ = responses of the salsalate peaks from the Assay preparation and the Salsalate standard preparation, respectively.