406 VITAMIN K GROUP 



showed the same potency whether given orally, intramuscularly, or intra- 

 venously.'^ 2-Methyl-l ,4-naphthoquinone appeared somewhat less potent 

 by the intravenous route/ • " An emulsion of vitamin Ki was effective by 

 intramuscular but not by subcutaneous administration.'^ 



For most purposes the oral dosing for 4 to 5 days should lead to a satis- 

 factory assay.'*' '^ If a quantitative assay is desired, a definite level of in- 

 take should be maintained in the test animal for a sufficient period of time 

 so that potency -modifying factors such as solubility, absorption, and rate of 

 metabolism have been able to approach a balance or plateau of influence 

 on activity. A period of 3 to 4 days is required for the depleted chick to 

 become adjusted to intake levels of the vitamin in an assay range. If the 

 work of setting up an assay has been carried out properly, the extra 3 or 

 4 days is only a small addition to the task and may lend greater precision. 

 From the emergency standpoint there is perhaps some advantage in a 

 very short assay which will evaluate a compound as much from its speed 

 of action as its intrinsic potency. For example, the effective dose of vitamin 

 Ki is greater for a 6-hour assay than for 18 hours.-" • ^' These are matters 

 to be adjusted to the particular problem and the purpose of the antihemor- 

 rhagic substances. 



Dam and S0ndergaard have recently shown that in promoting prothrom- 

 bin restoration in depleted chicks vitamin Ki is more rapidly effective than 

 menadione or the sodium salt of the corresponding hydroquinone diphos- 

 phoric acid ester .^'^ 



4. Measurement of Supplement Effect 



The earliest ciuantitative measurement of supplement effect was the 

 simple clotting time of whole blood. If a sufficiently large number of chicks 

 is included in each group, the average blood-clotting time for the group has 

 a fairly close relation to the activity of the supplement, like that of the 

 prothrombin time as illustrated in Fig. 4.-- Some objections to simple whole 

 blood-clotting time may be mentioned. 



1. Blood-clotting time may remain nearly normal when the blood pro- 

 's H. J. Almquist and A. A. Klose, J. Am. Chem. Soc. 61, 1923 (1939). 



17 D. Richert, S. A. Thayer, R. W. McKee, S. B. Binkley, and E. A. Doisy, Proc. 

 Soc. Exptl. Biol. Med. 44, 601 (1940). 



18 H. Dam, J. Glavind, L. Lewis, and E. Tage-Hansen, Skand. Arch. Physiol. 79, 121 

 (1938). 



19 H. J. Almquist and A. A. Klose, J. Biol. Chem. 130, 787 (1939). 



20 E. Fernholz, S. Ansbacher, and H. B. MacPhillamy, J. Am. Chevi. Soc. 62, 430 

 (1940). 



21 L. F. Fieser, M. Tishler, and W. L. Sampson, /. Biol. Chem. 137, 659 (1941). 

 2i» H. Dam and E. S0ndergaard, Experieniia 9, 26 (1953). 



22 H. J. Almquist, E. Mecchi, and A. A. Klose, Biochem. J. 32, 1897 (1938). 



