rxref 0.4.0

New features

• Added support for retrieving active and historical RxNorm product concepts in product discovery workflows, including products_for_ingredients() and related search helpers.
• Added concept_status support to allow users to request active concepts only or active plus historical RxNorm concepts, where supported.
• Added exclude_products_with_ingredients(), a product-level filtering helper for removing RxNorm products that contain user-specified ingredients.
• exclude_products_with_ingredients() supports fixed-dose combination products represented with semicolon-delimited ingredient names or RxCUIs, such as "atenolol; chlorthalidone".
• Added safer internal handling for historical concept verification and lookups, reducing failures when RxNorm returns incomplete, empty, or unexpected API responses.

Improvements

• Improved retrieval of clinical product attributes for historical RxCUIs by attempting to recover dose form, dose form group, route, ingredient count, and ingredient metadata when available.
• Improved route filtering workflows for products that include historical RxNorm concepts.
• Improved fixed-dose combination formatting in get_clinical_attributes(). Ingredient fields such as ingredient_rxcui, ingredient_name, and ingredient_tty now use semicolon-delimited strings instead of pseudo-vector strings.
• Improved consistency of product-level ingredient metadata to support cleaner downstream joins and filtering.
• Improved reuse of cached API responses in product discovery, historical concept lookup, and clinical attribute workflows to reduce repeated calls to the RxNorm and RxClass APIs.
• Added or improved progress reporting for longer-running product discovery workflows, including API retrieval steps where appropriate.
• Updated route-specific vignette example datasets so package vignettes do not rely on live API calls during package checks.
• Updated vignette example datasets to avoid duplicated .x / .y join columns and to use current, singular column naming conventions.
• Updated README examples and package vignettes to reflect current function behavior, argument names, output columns, and recommended workflows.
• Improved internal helper functions for normalizing product ingredient fields and handling fixed-dose combination products.

Bug fixes

• Fixed issues where historical or obsolete RxCUIs could return incomplete clinical attributes and be unintentionally dropped from route-filtered workflows.
• Fixed cases where historical product concepts could produce incorrect or inflated ingredient counts.
• Fixed validation and test coverage for concept_status arguments.
• Fixed issues arising from incomplete or malformed historical concept lookups.
• Fixed vignette data-generation issues that could create unexpected NA rows in pre-built example datasets.
• Fixed CRAN submission issues related to API name formatting, web references, and package citation handling.

Documentation

• Updated package documentation to describe active and historical RxNorm concept support.
• Updated documentation for product discovery, clinical attribute retrieval, route filtering, and fixed-dose combination handling.
• Updated NEWS, README, vignettes, and CRAN-facing metadata for the 0.4.0 release.
• Updated package citation handling to avoid errors when the package is not installed.

rxref 0.3.0

• Removed the experimental set_backend() helper. rxref currently uses the RxNorm/RxClass APIs directly.