Benzylpenicillin penicillin pharmacokinetics

Pharmacokinetics. Benzylpenicillin is destroyed by gastric acid and is unsuitable for oral use. Others, e.g. phenoxymethylpenicillin, resist acid and are absorbed in the upper small bowel. The plasma t of penicillins is usually < 2 h. They are distributed mainly in the body water and enter well into the ... 

After oral administration to the dog, penamecillin (VII), which is the acetoxymethyl ester of benzylpencillin, produces prolonged benzylpencillin serum levels.According to pharmacokinetic evidence O, the penamecillin is slowly absorbed unchanged throughout the intestinal tract and then is rapidly hydrolyzed to benzylpenicillin by nonspecific esterases. Compound VIII is an example of the hitherto unknown penicillin aldehydes for which a general synthesis was developed. 

Benzylpenicillinic Acid. 3,3>Dimerhyf-7-oxo-6-[tphenylacetyllamino]-4-th ia-l-azabicyclo 3.2.0]heptane-2-carboxylic acid free benzyl penicillin free penicillin G free penicillin II. C,jHI8Nj04S mol wt 334.38, C 57.47%, H 5.43%, N 8.38%, O 19.14%, S9,59%. Obtained by extraction at ice temp of the acidified (pH 2) aq soln of sodium benzyl -penicillin with ether Or chloroform. Shows correct analytical composition only it moisture is excluded completely during iis isoln from the ether extract (by lyophilizing from benzene). When kept dry the acid retains its antibiotic potency for limited periods, bui it is rapidly inactivated by small amounts of water. The product formed on slow inactivation by moisture seems to be benzylpenicilloic acid, cf. Clarke et [., The Chemistry of Penicillin (Princeton, 1949). Prepn of methyl ester Dan. pet. 85,976 (1958 to Leo Pharm.). Pharmacokinetics in humans M. Barza, L. Weinstein, Clin. 

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