Penicillin V Benzathine
4-Thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid, 3,3-dimethyl-7-oxo-6-[(2-phenoxyacetyl)amino-], [2S-(2,5,6)]-, compd. with N,N¢-bis(phenylmethyl)-1,2-ethanediamine (2:1).
(2S,5R,6R)-3,3-Dimethyl-7-oxo-6-(2-phenoxyacetamido)-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid compound with N,N¢-dibenzylethylenediamine (2:1) [5928-84-7].
Tetrahydrate 1013.21 [63690-57-3].
» Penicillin V Benzathine has a potency of not less than 1060 and not more than 1240 Penicillin V Units per mg.
Packaging and storage Preserve in tight containers.
Crystallinity 695: meets the requirements.
pH 791: between 4.0 and 6.5, in a suspension containing about 30 mg per mL.
Water, Method I 921: between 5.0% and 8.0%.
Penicillin V content Transfer about 40 mg, accurately weighed, to a 100-mL volumetric flask, add methanol to volume, and mix. Concomitantly determine the absorbances of this solution and of a similarly prepared Standard solution prepared with about 30 mg of USP Penicillin V Potassium RS at the wavelength of maximum absorbance at about 276 nm. Determine the percentage of penicillin V taken by the formula:
P(aU / aS)in which P is the percentage content of penicillin V in the USP Penicillin V Potassium RS, and aU and aS are the absorptivities of the solution of the specimen and the Standard solution, respectively: between 62.3% and 72.5% is found.
Standard preparation Prepare as directed for Standard preparation under Iodometric AssayAntibiotics 425, using USP Penicillin V Potassium RS.
Assay preparations Dissolve a quantity of Penicillin V Benzathine in 1.0 N sodium hydroxide to obtain a solution containing 2000 Penicillin V Units per mL. Pipet 2 mL of this solution into a glass-stoppered, 125-mL conical flask, and use as the Assay preparation for Inactivation and titration. Dilute a quantity of Penicillin V Benzathine quantitatively with water to obtain a suspension containing 2000 Penicillin V Units per mL. Pipet 2 mL of this suspension into a glass-stoppered, 125-mL conical flask, and use as the Assay preparation for the Blank determination.
Procedure Proceed as directed for Procedure under Iodometric AssayAntibiotics 425, except in the Inactivation and titration of the specimen to omit the addition of 2.0 mL of 1.0 N sodium hydroxide. Calculate the potency, in Penicillin V Units per mg, in the Penicillin V Benzathine taken by the formula:
(F)(B I) / (2D)in which D is the concentration, in mg per mL, of the Assay preparation for Inactivation and titration on the basis of the weight of Penicillin V Benzathine taken and the extent of dilution.
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USP32NF27 Page 3241