antivenin vs antivenom

antivenin

noun
  • Synonym of antivenom, (now) particularly for snakebites containing venin. 

antivenom

noun
  • A medicine that counteracts venom, an antidote to biological poisons from venomous animals such as snakes and spiders. 

How often have the words antivenin and antivenom occurred in a corpus of books? (source: Google Ngram Viewer )