The Pharmacological Guide to Phenytoin is a multi-authored text geared towards clinicians and pharmacists who will be prescribing and handling phenytoin or fosphenytoin. Each chapter in this book has been diligently written and peer reviewed by scholars in medical toxicology, pharmacology and emergency medicine. What makes this book special compared to others in this field is the level of detail and evidence-based literature supporting the text in each chapter. Each author has performed a rigorous investigation of all available literature in order to provide the most up-to-date information and recommendations in each chapter. We begin our journey in this book by delving into the history of phenytoin and fosphenytoin. After that, we establish guidelines for the administration, dosing and storage of the two drugs. These guidelines are supported by several previously published guidelines and landmark case reports. Majority of clinical trials focus on adults, and several studies utilize healthy, adult volunteers. Thus there is often scarce data on special populations such as pediatrics and patients with medical comorbidities. In the following chapter, we present how to manage phenytoin and fosphenytoin administration and toxicity in these populations. After pharmacokinetics and toxicokinetics, we shift our focus to drug and food interactions. This chapter provides exquisite pharmacological detail on phenytoin and fosphenytoin, as well as their interactions with multiple xenobiotics. Having access to this knowledge will aid the clinician in the management of patients on these medications in various clinical scenarios, including multiple comorbidities, coingestants and environmental exposures. Discussing the toxicological profile of phenytoin and fosphenytoin is perhaps the most interesting section of this book. As with most available medical toxicology literature, given the paucity of randomized controlled trials, emphasis is placed on case reports. Finally, we discuss the diagnosis and management of phenytoin toxicity. The clinical manifestations of toxicity can mimic other medical emergencies, and with the knowledge and tools described clinicians can diagnose and treat their patients effectively. The authors and I hope you find the information presented in this book educational as well as helpful in your practice, thus promoting the highest level of care to our patients.