painkiller vs pharmacology

painkiller

noun
  • A drug that numbs the pain in the body. 

pharmacology

noun
  • The properties and reactions of drugs especially with relation to their therapeutic value. 

  • The science of drugs including their origin, composition, pharmacokinetics, therapeutic use, and toxicology. 

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