Pyridostigmine Tablets
Action and use
Cholinesterase inhibitor.
Definition
Pyridostigmine Tablets contain Pyridostigmine Bromide.
Content of pyridostigmine bromide, C9H13BrN2O2
92.5 to 107.5% of the stated amount.
Identification
5 volumes of water, 10 volumes of formic acid, 35 volumes of methanol and 50 volumes of chloroform.
The principal spot in the chromatogram obtained with solution (1) corresponds to that in the chromatogram obtained with solution (2).
Tests
Related substances
Carry out the method for liquid chromatography, Appendix III D, using the following solutions.
30 volumes of acetonitrile and 70 volumes of a 0.43% w/v solution of sodium dodecyl sulfate, previously adjusted to pH 2.0 with orthophosphoric acid.
Use the chromatogram obtained with solution (4) to identify the peak due to impurity A. When the chromatograms are recorded under the prescribed conditions, the relative retentions with reference to pyridostigmine (retention time = about 32 minutes) are: impurity B = about 0.75; impurity A = about 0.92.
The test is not valid unless, in the chromatogram obtained with solution (4), the resolution factor between the peaks corresponding to pyridostigmine impurity A and pyridostigmine bromide is at least 1.5.
In the chromatogram obtained with solution (1):
the area of any peak corresponding to pyridostigmine impurity B is not greater than the area of the principal peak in the chromatogram obtained with solution (2) (6%);
the area of any peak corresponding to pyridostigmine impurity A is not greater than the area of the principal peak in the chromatogram obtained with solution (3) (0.4%);
the sum of the areas of any other secondary peaks is not greater than the area of the principal peak in the chromatogram obtained with solution (3) (0.4%).
Disregard any peak with an area less than the area of the principal peak in the chromatogram obtained with solution (5) (0.04%).
Assay
Weigh and powder 20 tablets. Shake a quantity of the powdered tablets containing 0.15 g of Pyridostigmine Bromide with 50 mL of water for 30 minutes, filter, wash the residue with water and add sufficient water to produce 250 mL. Dilute 5 mL to 100 mL with water and measure the absorbance of the resulting solution at the maximum at 270 nm, Appendix II B. Calculate the content of C9H13BrN2O2 taking 186 as the value of A(1%, 1 cm) at the maximum at 270 nm.
Storage
Pyridostigmine Tablets should be protected from light.
Impurities
The impurities limited by the requirements of this monograph include impurities A and B listed under Pyridostigmine Bromide.