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British Pharmacopoeia Volume III
Formulated Preparations: Specific Monographs
Paracetamol Tablets
General Notices
Action and use
Analgesic; antipyretic.
DEFINITION
Paracetamol Tablets contain Paracetamol.
The tablets comply with the requirements stated under Tablets and with the following requirements.
Content of paracetamol, C8H9NO2
95.0 to 105.0% of the stated amount.
IDENTIFICATION
Extract a quantity of the powdered tablets containing 0.5 g of Paracetamol with 20 ml of acetone, filter, evaporate the filtrate to
dryness and dry at 105°. The residue complies with the following tests.
A. The infrared absorption spectrum, Appendix II A, is concordant with the reference spectrum of paracetamol (RS 258).
B. Boil 0.1 g with 1 ml of hydrochloric acid for 3 minutes, add 10 ml of water and cool; no precipitate is produced. Add 0.05 ml
of 0.0167M potassium dichromate; a violet colour is produced slowly which does not turn red.
C. Melting point, about 169°, Appendix V A.
TESTS
Dissolution
Comply with the requirements for Monographs of the British Pharmacopoeia in the dissolution test for tablets and capsules,
Appendix XII B1, using Apparatus 2. Use as the medium 900 ml of phosphate buffer pH 5.8 and rotate the paddle at 50 revolutions
per minute. Withdraw a sample of 20 ml of the medium and filter. Dilute the filtrate with 0.1M sodium hydroxide to give a solution
expected to contain about 0.00075% w/v of Paracetamol. Measure the absorbance of this solution, Appendix II B, at the maximum at
257 nm using 0.1M sodium hydroxide in the reference cell. Calculate the total content of paracetamol, C8H9NO2, in the medium
taking 715 as the value of A(1%, 1 cm) at the maximum at 257 nm.
Related substances
Carry out the method for liquid chromatography, Appendix III D, using the following solutions. Prepare the solutions immediately
before use and protect from light. For solution (1) disperse a quantity of powdered tablets containing 0.2 g of Paracetamol in 8 ml
of the mobile phase with the aid of ultrasound, add sufficient mobile phase to produce 10 ml, mix well and filter. For solution (2)
dilute 1 volume of solution (1) to 20 volumes with mobile phase and dilute 1 volume of this solution to 20 volumes with mobile
phase. Solution (3) contains 0.002% w/v each of 4-aminophenol and paracetamol BPCRS in the mobile phase. Solution (4)
contains 0.00002% w/v of 4′-chloroacetanilide in the mobile phase.
The chromatographic procedure may be carried out using (a) a stainless steel column (25 cm × 4.6 mm) packed with octylsilyl
silica gel for chromatography (5 µm) (Zorbax Rx C8 is suitable), (b) as the mobile phase with a flow rate of 1.5 ml per minute, at a
temperature of 35°C, a mixture of 250 volumes of methanol containing 1.15 g of a 40% v/v solution of tetrabutylammonium
hydroxide with 375 volumes of 0.05M disodium hydrogen orthophosphate and 375 volumes of 0.05M sodium dihydrogen
orthophosphate and (c) a detection wavelength of 245 nm.
The test is not valid unless, in the chromatogram obtained with solution (3), the resolution factor between the two principal peaks is
at least 4.0.
Inject solution (1) and allow the chromatography to proceed for 12 times the retention time of the principal peak. In the
chromatogram obtained with solution (1) the area of any peak corresponding to 4-aminophenol is not greater than the area of the
corresponding peak in solution (3) (0.1%), the area of any peak corresponding to 4′-chloroacetanilide is not greater than the area of
the principal peak in solution (4) (10 ppm) and no other impurity is greater than the area of the principal peak obtained with solution
(2) (0.25%).
British Pharmacopoeia 2009 Online http://www.pharmacopoeia.co.uk/bp2009/ixbin/bp.cgi?a=print&id=5...
1 of 2 27/10/2009 10:23
ASSAY
Weigh and powder 20 tablets. Add a quantity of the powder containing 0.15 g of Paracetamol to 50 ml of 0.1M sodium hydroxide,
dilute with 100 ml of water, shake for 15 minutes and add sufficient water to produce 200 ml. Mix, filter and dilute 10 ml of the
filtrate to 100 ml with water. Add 10 ml of the resulting solution to 10 ml of 0.1M sodium hydroxide, dilute to 100 ml with water and
measure the absorbance of the resulting solution at the maximum at 257 nm, Appendix II B. Calculate the content of
C8H9NO2 taking 715 as the value of A(1%, 1 cm) at the maximum at 257 nm.
STORAGE
Paracetamol Tablets should be protected from light.
© Crown Copyright 2008
British Pharmacopoeia 2009 Online http://www.pharmacopoeia.co.uk/bp2009/ixbin/bp.cgi?a=print&id=5...
2 of 2 27/10/2009 10:23