You can data mine the FDA, or the Dailymed : active ingredients and drug composition can be extracted. And for a subset of the FDA and European Medecine Agency active ingredients, you can check e-LEA3D

Sorry about reviving this, but it is a good question.

If you are looking for active ingredients, it is pretty straight forward to find them with RxNorm (alone or via UMLS).

As far as I know, if you are looking for inactive ingredients, this is more difficult. As different manufacturers have different inactive ingredients, you will likely need to know the NDC (or equivalent) of the product you are wanting to know about. From there, you could use UMLS to look up the FDA label ID (aka SPL Set ID) that corresponds to the NDC (SAB=MTHSPL). You can them obtain the XML for that label (either download the SPL library from the FDA web site, or possibly find a RESTful way to access it). The XML file will have inactive ingredients listed with their Unique Ingredient Identifier codes.

If there is an easier way, please let me know.

JLA

Have you tried ChEMBL?

you can contact me for detail, we have the detail Drug database, mark.xu at mims.com

Here are two of the best ones:

Merck Index: https://www.rsc.org/merck-index

Pubchem: https://pubchem.ncbi.nlm.nih.gov