The following links are relevant to filing an Investigational New Drug Application(IND) in the US.
Procedural-Steps
Content and Format of Investigational New Drug Applications (INDs) for Phase 1 Studies of Drugs
Information for Sponsor-Investigators Submitting INDs (Note: this provides excellent instructions if you’ve not filed an IND before)
Exploratory IND Studies (aka microdose studies)
Emergency IND Applications for Antimicrobial Products
Expanded Access – August 13, 2009 Final Rule
Charging for Investigational Drugs – August 13, 2009 Final Rule
Submitting and Reviewing Complete Responses to Clinical Holds