U.S. PHARMACOPEIA

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Milk Thistle Tablets
» Milk Thistle Tablets are prepared from Powdered Milk Thistle Extract. They contain not less than 90.0 percent and not more than 110.0 percent of the labeled amount of silymarin as silybin (C25H22O10), calculated as the sum of silydianin, silychristin, silybin A, silybin B, isosilybin A, and isosilybin B.
Packaging and storage— Preserve in tight, light-resistant containers.
Labeling— The label states the Latin binomial and, following the official name, the article from which the Tablets were prepared. The label also indicates the content of silymarin, in mg per Tablet.
Identification—
A: Thin-Layer Chromatographic Identification Test 201—
Standard solution, Developing solvent system, and Procedure— Proceed as directed for the Identification test under Milk Thistle.
Test solution— Weigh and finely powder not fewer than 20 Tablets. Transfer a portion of the powder, equivalent to about 50 mg of silymarin, to a test tube, add 10 mL of methanol, shake for 1 minute, and sonicate for 10 minutes. Allow to stand for 15 minutes before use.
B: The retention times of the peaks for silydianin, silychristin, silybin A, silybin B, isosilybin A, and isosilybin B in the chromatogram of the Test solution correspond to those in the chromatogram of Milk thistle standard solution, as obtained in the test for Content of silymarin.
Microbial enumeration 2021— The total bacterial count does not exceed 104 cfu per g, the total combined molds and yeasts count does not exceed 103 cfu per g, and the enterobacterial count does not exceed 102 per g. It meets the requirements of the tests for absence of Salmonella species and Escherichia coli.
Disintegration and dissolution 2040: meet the requirements for Dissolution. Proceed as directed in the test for Dissolution under Milk Thistle Capsules.
Weight variation 2091: meet the requirements.
Content of silymarin—
Solution A, Solution B, Mobile phase, Silybin standard solutions, and Chromatographic system— Proceed as directed in the test for Content of silymarin under Milk Thistle.
Milk thistle standard solution— Prepare as directed for Milk thistle standard solution in the test for Content of silymarin under Powdered Milk Thistle Extract.
Test solution— Weigh and finely powder not fewer than 20 Tablets. Transfer an accurately weighed quantity of the powder, equivalent to about 100 mg of silymarin, to a 100-mL volumetric flask, add 90 mL of methanol, and sonicate for 20 minutes with occasional shaking. Cool to 20, and dilute with methanol to volume. Filter through a membrane having a 0.45-µm or finer porosity.
Procedure— Proceed as directed in the test for Content of silymarin under Milk Thistle, except to separately calculate the amount, in mg, of each relevant component of silymarin as silybin (C25H22O10) in the portion of Tablets taken by the formula:
100C,
in which the term, C, is as defined therein. Calculate the amount of silymarin, in mg, in the portion of Tablets taken by adding the individual amounts obtained.
Residual solvents 467: meet the requirements.
(Official January 1, 2007)
Auxiliary Information— Staff Liaison : Maged H. Sharaf, Ph.D., Senior Scientist
Expert Committee : (DSB05) Dietary Supplements - Botanicals
USP29–NF24 Page 2364
Pharmacopeial Forum : Volume No. 28(2) Page 422
Phone Number : 1-301-816-8318