506 VITAMIN Bi2 



XII. Pharmacology 



FRANK H. BETHELL 



A. ACTION AND USES 



Vitamin B12 is probably concerned with a wide variety of metabolic 

 processes which include factors affecting growth, hemopoiesis, and the 

 maintenance of the integrity of nerve cells. The primary therapeutic use 

 of B12 is in the treatment of pernicious anemia and certain related megalo- 

 blastic anemias which are due to deficiency of the vitamin. B12 has also 

 been employed as a growth-promoting agent in children with retarded 

 physical development, and promising results have followed its use in a 

 variety of neurologic disorders characterized by painful peripheral neuro- 

 pathy, 



B. DOSE 



In pernicious anemia the usual dose is 10 to 30 7 by intramuscular in- 

 jection daily or thrice weekly during the initial period of treatment and at 

 intervals of 1 to 3 weeks for maintenance of remission.^ 



Oral B12 therapy in pernicious anemia is relatively ineffective and un- 

 reliable unless a source of intrinsic factor of potency proved by clinical 

 trial is administered together with the vitamin.^ 



Nutritional megaloblastic anemia due to B12 deficiency may be effectively 

 treated by the daily oral administration of 10 to 50 7 without a source of 

 intrinsic factor. In most complex deficiency states associated with mega- 

 loblastic anemia, the use of both vitamin B12 and pteroylglutamic acid is 

 indicated.^ 



As a dietary supplement to promote growth in retarded children, 10 7 

 daily has been employed.^ 



In the treatment of neuropathies other than pernicious anemia, a wide 

 range of doses has been used, but best results have been reported following 

 the parenteral administration of 500 to 1000 7, which can be repeated with- 

 out ill effect at frequent intervals.^ 



C. TOXICITY 



No acute or chronic toxic effects have been observed even after the par- 

 enteral administration of very large doses of B12. 



1 F. H. Bethell, Wisconsin Med. J. 51, 1082 (1952). 



2 J. W. R. Everse, K. W. Thompson, H. G. Wijmenga, and R. Wolff, Blood (In 

 press). 



' F. H. Bethell, M. E. Swendseid, S. Miller, and A. A. Cintron-Rivera, Ann. Internal 



Med. 35, 518 (1951). 

 * N. C. Wetzel, W. C. Fargo, I. H. Smith, and J. Helikson, Science 110, 651 (1949). 

 6 W. S. Fields and II. E. Hoff, Merck Kept., October, 1952. 



