Lithium Carbonate Extended-Release Tablets
» Lithium Carbonate Extended-Release Tablets contain not less than 90.0 percent and not more than 110.0 percent of the labeled amount of lithium carbonate (Li2CO3).
Packaging and storage
Preserve in well-closed containers.
Labeling
The labeling indicates the Dissolution Test with which the product complies.
Identification
A portion of powdered Tablets responds to the Identification tests under Lithium Carbonate.
Uniformity of dosage units 905:
meet the requirements.
Dissolution 711
test 1
If the product complies with this test, the labeling indicates that it meets USP Dissolution Test 1.
Medium:
dilute hydrochloric acid (7 in 1000); 800 mL.
Apparatus 1:
100 rpm.
Times:
15, 45, 90, and 120 minutes.
Procedure
At each Time, withdraw 8.0 mL of the solution under test, and pass through a filter having a 35-µm or finer porosity. Using the filtrate as the Assay preparation, suitably diluted with Medium if necessary, and using Medium to prepare the Standard preparation, determine the amount of Li2CO3 dissolved by employing a flame photometer, as directed in the Assay.
Tolerances
The percentages of the labeled amount of Li2CO3 dissolved at the specified times conform to Acceptance Table 2.
test 2
If the product complies with this test, the labeling indicates that it meets USP Dissolution Test 2.
Apparatus and Procedure
Proceed as directed for Test 1.
Medium:
water; 900 mL.
Times:
1, 3, and 7 hours.
Tolerances
The percentages of the labeled amount of Li2CO3 dissolved at the specified times conform to Acceptance Table 2.
test 3
If the product complies with this test, the labeling indicates that it meets USP Dissolution Test 3.
Medium:
water; 250 mL.
Apparatus 3:
6 dips per minute, 20-mesh top screen and 100-mesh bottom screen.
Procedure
Proceed as directed for Test 1.
Times and Tolerances
The percentages of the labeled amount of Li2CO3 dissolved at the specified times conform to Acceptance Table 2.
test 4
If the product complies with this test, the labeling indicates that it meets USP Dissolution Test 4.
Medium, Apparatus, Times, and Procedure
Proceed as directed for Test 1.
Tolerances
The percentages of the labeled amount of Li2CO3 dissolved at the specified times conform to Acceptance Table 2.
test 5
If the product complies with this test, the labeling indicates that it meets USP Dissolution Test 5.
Medium:
water; 900 mL.
Apparatus 1:
100 rpm.
Times:
30, 90, and 150 minutes.
Procedure
Pass a portion of the solution under test through a 0.8-µm mixed cellulose esters filter, discarding the first 10 mL of the filtrate. Using the rest of the filtrate as the Assay preparation, suitably diluted with Medium if necessary, and using Medium to prepare the Standard preparation, determine the amount of Li2CO3 dissolved by employing a flame photometer, as directed in the Assay.
Tolerances
The percentages of the labeled amount of Li2CO3 dissolved at the specified times conform to Acceptance Table 2.
Assay
[noteThe Standard preparation and the Assay preparation may be diluted quantitatively with Dilute hydrochloric acid (1 in 200), if necessary, to yield solutions of suitable concentrations adaptable to the linear or working range of the instrument.]
Dilute hydrochloric acid
(1 in 200)Dilute 5 mL of hydrochloric acid with water to obtain 1000 mL of solution.
Standard preparation
Transfer to a 100-mL volumetric flask about 30 mg of USP Lithium Carbonate RS, accurately weighed. Add about 20 mL of water and 0.5 mL of hydrochloric acid, shake until dissolved, dilute with water to volume, and mix to obtain a solution having a known concentration of about 300 µg of USP Lithium Carbonate RS per mL.
Assay preparation
Transfer an accurately counted number of Tablets, equivalent to about 1200 mg of lithium carbonate, to a 250-mL screw-capped flask. Add 100.0 mL of Dilute hydrochloric acid (1 in 200), shake until the Tablets dissolve, and filter, discarding the first 25 mL of the filtrate. Transfer 5.0 mL of the filtrate to a 200-mL volumetric flask, dilute with Dilute hydrochloric acid (1 in 200) to volume, and mix.
Procedure
Employ a suitable flame photometer, and adjust the instrument with Dilute hydrochloric acid (1 in 200). Aspirate the Standard preparation and the Assay preparation into the instrument, in turn, and measure the emission at about 671 nm. Calculate the quantity, in mg, of lithium carbonate (Li2CO3) in each Tablet taken by the formula:
L(C/D)(A/S)
in which C is the concentration, in µg per mL, of USP Lithium Carbonate RS in the Standard preparation; L is the labeled quantity, in mg, of lithium carbonate in each Tablet; D is the concentration, in µg per mL, of lithium carbonate in the Assay preparation, based on the number of Tablets taken, the labeled amount, in mg, of lithium carbonate per Tablet, and the extent of dilution; and A and S are the photometric readings of the Assay preparation and the Standard preparation, respectively.
Auxiliary Information
Please check for your question in the FAQs before contacting USP.
USP32NF27 Page 2798
Pharmacopeial Forum: Volume No. 31(5) Page 1385
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