iMeds XL - The Medication Reference 1.0

the author of this app says:

Most Complete Medication App now on iPad--Over 7,300 FDA-approved medications; ONLY App to provide full Prescribing Info (all sections, not just a fraction). Unrivaled Search features--Search by drug name or DRUG CLASS (find meds for ADHD, Alzheimer's, Anxiety, Diabetes, Smoking Cessation, and 300+ more classes). No internet connection required.

Note

Requires iPhone OS 3.2 or later.