Haloperidol is the most common neuroleptic drugs associated with a range of side effects caused by interactions with other drugs. In The Pharmacological Guide to Haloperidol, the authors review cases that report common pharmacodynamic and pharmacokinetic drug interactions of haloperidol in vivo. Next, this compilation investigates methods for the determination of haloperidol in body fluids such as blood, urine and cerebral spinal fluid. Several techniques discussed include magnetic resonance spectroscopy, spectrophotometry and high performance liquid chromatography. Also included is a description of haloperidol derivatives and their applications as antimicrobial agents, vasodilators and calcium channel blockers. Additionally, haloperidol derivatives that have potential applications for improving cardiac function and reducing oxidative stress are also addressed. The authors present some studies which use functional magnetic resonance imaging to study aspects of haloperidol on facial expressions. Emotion processing is often notable in neurodegenerative diseases such as schizophrenia and evaluated in cerebral blood flow response in diseased patients. The following chapter focuses on a literature analysis of the use of haloperidol, with studies indicating a potential limit for haloperidol efficacy; values above this limit don’t appear to provid any supplementary clinical improvement. Lastly, the authors provide a review of studies that have used magnetic resonance imaging to monitor haloperidol in vivo. Applications of 1H and 19F MRI in drug monitoring are discussed and a list of relevant studies is presented.