A new "interface terminology", dubbed RxTerms, is available for downloading and testing from the NLM.  The dataset is derived from RxNorm,

the US national terminology standard for clinical drugs. RxTerms provides drug name information intended for use with electronic prescribing

and medication histories as needed in Personal Health Records.

  Attributes of RxTerms include:

• It's free.
• Links to RxNorm which can provide the EMR with RxNorm clinical identifiers.
• Intelligent data entry - designed to avoid big picklists with excessively long names.
• Has commonly used synonyms and abbreviations (e.g. HCTZ for hydrochlorothiazide) .
  
• There is "tall man" lettering (e.g. ChlorproMAZINE and ChlorproPAMIDE).
• Claims 99% coverage of both generic and brand names for most commonly prescribed U.S. drugs.
  
• It excludes drugs from RxNorm that are obsolete or unavailable in the U.S.

The current dataset has over 29,000 entries. Below is a snapshot of a couple of representative entries.

This view is from a quick report created in MS Access.

If you use Firefox, you can try a demo on the NLM site here.