Get NDC and RxCui from openFDA via generic drug name

query_fda.R

query_fda <- function(dname, route){
  dname <- gsub(" ", "%", dname)
  dname <- sprintf('"%s"', dname) # enclose in quotes
  
  if (!missing(route) & !is.null(route)){
    dname <- sprintf('%s+AND+route:"%s"', dname, route)
   }
  
  url <- sprintf('https://api.fda.gov/drug/ndc.json?search=generic_name:%s&limit=100', dname)
  res <- httr::GET(url)$content |>
    rawToChar() |> 
    jsonlite::fromJSON()
  
  if ("error" %in% names(res) | !"results" %in% names(res)){
    NULL
  } else{
    res$results
  }
}

get_fda <- function(druglist, route=NULL){
  lapply(druglist, \(x) lapply(x, query_fda, route=route))
}

get_ndc <- function(fda){
  lapply(fda, \(x) sapply(x, \(xx){
    if ("packaging" %in% names(xx)){
      sapply(xx$packaging, \(xxx) xxx$package_ndc) |>
        unlist() |> 
        unique()
    } else{
      NULL
    }
  })
  )
}

get_rxcui <- function(fda){
  lapply(fda, \(x) sapply(x, \(xx){
    if ("openfda" %in% names(xx)){
      xx$openfda$rxcui |>
        unlist() |> 
        unique()
    } else {
      NULL
    }
  })
  )
}