barbiturate vs tranquilizer

barbiturate

noun
  • Any of derivatives of barbituric acid that act as depressants of the central nervous system and are used as sedatives or hypnotics. 

  • Any salt or ester of barbituric acid. 

tranquilizer

noun
  • A drug used to reduce anxiety or tension. 

  • That which tranquillizes or soothes. 

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