The present invention relates to oxaloacetic acid preparations and the use of hygroscopic components to prevent decomposition of the oxaloacetic acid. These compounds can then be made into sublingual lozenges and buccal lozenges to serve as nutritional supplements, medical foods or drugs. These compounds can also be used in the manufacture of oxaloacetic acid preparations in transdermal patches, inhalation preparations and anal or vaginal suppositories. Also provided are simple inexpensive tests to monitor the decomposition of oxaloacetic acid in compositions.