I am trying to find the drug registration info. Is there any FDA API available to gather drug register data set.
I am not sure if these are the data for which you are looking.
There is not an API of which I am aware. It would not be unreasonable to ask the openFDA team to add the following dataset: http://www.fda.gov/Drugs/InformationOnDrugs/ucm135778.htm
Or you can just download the zip file at the bottom of the page, the data is not that complex.