rxref

rxref is an R package that includes a set of tidy utilities for querying the National Library of Medicine’s RxNorm API. RxNorm is a system of normalized names for clinical drugs as well as linkages from these names to many of the drug vocabularies commonly used in pharmacy management and drug interaction software, including those of First Databank, Micromedex, Multum, and Gold Standard Drug Database.

rxref was originally built to facilitate pharmacoepidemiologic research in the UF CVmedLab, where we often need to identify medication prescriptions or pharmacy dispensings as a proxy for medication exposure or outcomes.

The core use case for rxref is identifying a set of RxCUIs (Rx Concept Unique Identifiers) and/or NDCs (national drug codes) that relate to a single medication or set of medications (i.e., a class of medications) supplied by the user. Additional functionality (still in early stage development) will include extracting additional properties (e.g., strength, dosage form, indications, adverse events, and so on) related to a user-supplied list of RxCUIs.

Installation

You can install the development version of rxref from GitHub with:

# install.packages("remotes")
remotes::install_github("ssmithm/rxref")

Example

This is a basic example for querying RxCUIs associated with lisinopril (a blood pressure-lowering drug):

library(rxref)
lisinopril.ing <- find_ingredients('lisinopril')
lisinopril.ing |> knitr::kable()

input	rxcui	name	tty	score
lisinopril	29046	lisinopril	IN	11.9192

lisinopril.rxcuis <- products_for_ingredients(lisinopril.ing$rxcui, ttys = c("SCD", "SBD"), include_combos = TRUE)

# Resulting table of all related products with TTY in {SCD, SBD}
lisinopril.rxcuis |> 
  dplyr::mutate(name = paste0("`", name, "`")) |> 
  knitr::kable()

ingredient_rxcui	product_rxcui	name	tty	n_ingredients
29046	104375	lisinopril 2.5 MG Oral Tablet [Zestril]	SBD	1
29046	104376	lisinopril 5 MG Oral Tablet [Zestril]	SBD	1
29046	104377	lisinopril 10 MG Oral Tablet [Zestril]	SBD	1
29046	104378	lisinopril 20 MG Oral Tablet [Zestril]	SBD	1
29046	1806890	lisinopril 1 MG/ML Oral Solution [Qbrelis]	SBD	1
29046	206765	lisinopril 10 MG Oral Tablet [Prinivil]	SBD	1
29046	206766	lisinopril 20 MG Oral Tablet [Prinivil]	SBD	1
29046	206771	lisinopril 40 MG Oral Tablet [Zestril]	SBD	1
29046	213482	lisinopril 30 MG Oral Tablet [Zestril]	SBD	1
29046	823971	hydrochlorothiazide 25 MG / lisinopril 20 MG Oral Tablet [Zestoretic]	SBD	2
29046	823982	hydrochlorothiazide 12.5 MG / lisinopril 20 MG Oral Tablet [Zestoretic]	SBD	2
29046	823986	hydrochlorothiazide 12.5 MG / lisinopril 10 MG Oral Tablet [Zestoretic]	SBD	2
29046	1806884	lisinopril 1 MG/ML Oral Solution	SCD	1
29046	197884	lisinopril 40 MG Oral Tablet	SCD	1
29046	197885	hydrochlorothiazide 12.5 MG / lisinopril 10 MG Oral Tablet	SCD	2
29046	197886	hydrochlorothiazide 12.5 MG / lisinopril 20 MG Oral Tablet	SCD	2
29046	197887	hydrochlorothiazide 25 MG / lisinopril 20 MG Oral Tablet	SCD	2
29046	205326	lisinopril 30 MG Oral Tablet	SCD	1
29046	311353	lisinopril 2.5 MG Oral Tablet	SCD	1
29046	311354	lisinopril 5 MG Oral Tablet	SCD	1
29046	314076	lisinopril 10 MG Oral Tablet	SCD	1
29046	314077	lisinopril 20 MG Oral Tablet	SCD	1

# Count of TTYs in resulting table
aggregate(
  x = list(count = rep(1, nrow(lisinopril.rxcuis))), 
  by = list(tty = lisinopril.rxcuis$tty), 
  FUN = sum
) |> knitr::kable()

tty	count
SBD	12
SCD	10