VARIABLE DESCRIPTION CODEBOOK agent_type - Type of drug bnfcode - BNF code bnfhead - BNF header bnfheader - BNF header dbasebuild - Build of CPRD first used code drug_substance - Name of drug substance gemscriptcode - Gemscript code medcode - Medical term prodcode - Product code prodname - Name of product readcode - Read code used in CPRD database readterm - Descriptive term used in CPRD dataset substancestrength - Strength of prescription