| pubmed-article:13199652 | pubmed:abstractText | The International Reference Preparation of Penicillin K was established by the WHO Expert Committee on Biological Standardization at its fifth session, held in Geneva in 1951. Since the preparation is likely to be used for research only, no unit has been defined. The composition of the preparation, in terms of its activity against a strain of Bacillus subtilis, is penicillin K 89.9%, penicillin dihydro F 9.6%, and penicillin F 0.5%. | lld:pubmed |
