ANTITOXIC SERA 47 



standardization of tetanus antitoxin. The unit for the 

 United States is the smallest amount of immunized 

 horse's serum that will protect a guinea-pig weighing 

 350 grammes against 1000 times the fatal dose of 

 tetanus toxin. The serum having been standardized, 

 it is stored in syringes convenient for therapeutic use. 

 As in the case of diphtheria antitoxin, antitetanic 

 serum loses its potency after a variable length of time. 



Therapeutic Use of Antitetanic Serum. — ^The 

 therapeutic efficiency of antitetanic serum depends 

 chiefly on whether it is able to reach and neutralize the 

 toxin before the latter becomes fixed by the cells of the 

 central nervous system. Failure of tetanus antitoxin 

 to have therapeutic effects is due in most cases to 

 faulty administration. Ashhurst and John in a recent 

 article {Am, Jour, Med, Sc, June and July, 1913) 

 present what is undoubtedly the most able and com- 

 prehensive view of the whole subject of the treatment 

 of tetanus. Their recommendations will be followed 

 here to a great extent. 



Antitetanic serum is used both as a preventive and 

 a curative measure. For prophylactic use, in the case 

 of all wounds in which the development of tetanus is 

 feared, at least 1500 units of the antitoxin should be 

 injected as early as possible into the muscles or if 

 possible into the nerves in the immediate neighborhood 

 of the wound. The longer the interval that is allowed 



