Anne B Ballinger & Michael J.G. (St Bartholomew’s and Royal London Sch Med, London, UK) Farthing 
Drug Therapy for Gastrointestinal Disease [PDF ebook] 

First published in 2001. This book is an invaluable clinical reference for the therapeutic management of gastrointestinal and liver diseases which the gastroenterologist and trainee encounter in their practice. Various drugs and their interactions with their intended site and also with other drugs are discussed from a practical point of view. This book is not a treatise on gastrointestinal pharmacology but a practical guide to the therapeutic use of GI drugs.