VITAMIN Bi2 (ERYTHROTIN) 



3. J. Dedichen, Lancet, 1949, 1, 369. 



4. W. F. J. Cuthbertson, J. F. Lloyd, W. B. Emery and K. A. Lees, 



/. Pharm. Pharmacol., 1949, 1, 705. 



5. U. J. Lewis, U. D. Register and C. A. Elvehjem, Proc. Soc. Exp. 



Biol. Med., 1949, 71, 509. 



6. J. F. Wilkinson, Lancet, 1949, 1, 249, 336. 



7. J. Innes and H. N. Robson, ibid., 1949, 2, 606. 



5. EFFECT OF VITAMIN B12 ON ANIMALS AND MAN 

 Efifect on Man 



Crystalline vitamin B12 prepared from liver extracts gave a positive 

 response when injected intramuscularly into patients with Addisonian 

 pernicious anaemia in doses as small as 3 ^g.,^ although to produce a 

 maximum reticulocyte response 6 to 10 /xg. were required, ^ the actual 

 amount varying with the individual. An average maintenance dose 

 was 10 /xg. every two weeks. ^ Vitamin Bj^g was also effective in nutri- 

 tional macrocytic anaemia and tropical sprue, and relieved sub-acute 

 combined degeneration of the cord in pernicious anaemia.* The 

 lingual manifestations of pernicious anaemia also responded,^ although 

 neither this condition nor the neurological symptoms responded to 

 pteroylglutamic acid. 



Vitamin B12 prepared from S. griseus cultures ^ and vitamin B^aj 

 prepared from S. aureofaciens cultures "^ were apparently as effective in 

 pernicious anaemia as vitamin B^^ prepared from liver extracts. A 

 crude concentrate prepared from beef muscle was also effective when 

 injected intramuscularly in pernicious anaemia patients in doses 

 equivalent to i /zg. of vitamin B^g daily. ^ Concentrates of a cobalt- 

 containing substance were prepared from cultures of S. griseus and 

 from cow-dung ; both were inactive in pernicious anaenaia, but 

 became active after digestion with hog-stomach mucosa or pancreatic 

 enzyme.^ 



Vitamin B12 was more effective by injection than by mouth, and 

 most patients responded slowly to oral vitamin B^g in amounts thirty 

 to sixty times those required by the parenteral route. ^^ Vitamin Bjgft 

 gave no response orally unless given with normal human gastric juice, 

 and an alcoholic extract of beef muscle also gave a good response only 

 when given with normal gastric human juice.^^ 



Vitamin B^g is ineffective in nutritional anaemias due to a deficiency 

 of folic acid (page 500), and cases have been reported where folic acid 

 has to be administered before a response to vitamin B^g can be obtained. 

 The response to vitamin B^g was delayed and sub-optimal when i mg. 

 per day of the folic acid antagonist, Aminopterin, was given for two 



538 



