Phenoxymethylpenicillin Tablets
Action and use
Penicillin antibacterial.
Definition
Phenoxymethylpenicillin Tablets contain Phenoxymethylpenicillin Potassium.
Content of phenoxymethylpenicillin, C16H18N205S, calculated as the sum of the contents of phenoxymethylpenicillin and 4-hydroxyphenoxymethylpenicillin
92.5 to 107.5% of the stated amount of phenoxymethylpenicillin.
Identification
Tests
Dissolution
Comply with the requirements for Monographs of the British Pharmacopoeia in the dissolution test for tablets and capsules, Appendix XII B1.
Calculate the total content of phenoxymethylpenicillin, C16H18N2O5S, in the medium from the absorbances obtained and from the declared content of C16H18N2O5S in phenoxymethylpenicillin potassium BPCRS.
Assay
Weigh and powder 20 tablets. Shake a quantity of the powder containing the equivalent of 0.125 g of phenoxymethylpenicillin with 300 mL of water for 30 minutes, add sufficient water to produce 500 mL, dilute 25 mL to 100 mL with water and filter. Place two 2-mL aliquots of the filtrate in separate stoppered tubes. To one tube add 10 mL of imidazole-mercury reagent, mix, stopper the tube and immerse in a water bath at 60° for exactly 25 minutes, swirling occasionally. Remove from the water bath and cool rapidly to 20° (solution A). To the second tube add 10 mL of water and mix (solution B). Without delay measure the absorbances of solutions A and B at the maximum at 325 nm, Appendix II B, using in the reference cell a mixture of 2 mL of water and 10 mL of imidazole-mercury reagent for solution A and water for solution B. Calculate the content of C16H18N2O5S from the difference between the absorbances of solutions A and B, from the difference obtained by repeating the operation using 0.14 g of phenoxymethylpenicillin potassium BPCRS in place of the preparation being examined and from the declared content of C16H18N2O5S in phenoxymethylpenicillin potassium BPCRS.
Labelling
The quantity of active ingredient is stated in terms of the equivalent amount of phenoxymethylpenicillin.