Drug is a type of Use. Use is a synonym of Custom. Custom is related to Introduce. 
Pan is a type of Travel. Pan is related to Pot. Pot is related to Drug. Drug is related to Tobacco. 
Drug --IsA--> Use <--Synonym--> Custom <--RelatedTo--> Introduce 
Travel <--IsA-- Pan <--RelatedTo--> Pot <--RelatedTo--> Drug <--RelatedTo--> Tobacco 