ABSTRACT
One can think of toxicology as being a science focusing on the abnormal or altered functions of the body as a drug or a poison interacts with or distorts the normal chemical processes. ese interactions produce physiologic and pathologic consequences that would not normally arise in the absence of the drug. Toxicology is, in essence therefore, a study of “broken biochemistry.” e consequences of drug or toxin action are expressed as a function of the physical actions and responses of the body and are therefore physiologic and pathologic. e factors controlling the magnitude of the eects of drugs are pharmacologic. Toxicology is therefore a unifying science in that aspects of many disciplines are involved and essential in nearly all aspects of the eld:
Mechanism: Biochemical Expression: Physiologic/pathologic Magnitude: Pharmacologic
Some useful basic denitions are
Pharmacokinetics: the biochemical fate of drugs in the body and the biochemical processes aecting that fate
Pharmacodynamics: the impact of the drug on the physiologic and biochemical processes in the body
Toxicokinetics: pharmacokinetics of drugs and poisons
Many of the interpretative issues that the forensic toxicologist has to deal with involve questions about the amount of drug that was in a body at a particular time. Oen the amount that has been delivered into the body (by whatever means) is known, but sometimes not. Nevertheless, in many cases, useful information or inferences can be derived based on what information is known, deduced or hypothesized based on an understanding of what can happen to drugs and toxins as they pass through and interact with living systems. e fate of drugs in the body is commonly viewed as the sum of the processes of absorption (the processes by which drugs and poisons are brought into the blood and cells
4.1 Introduction 35 4.2 Basic Denitions 35 4.3 Fate of Drugs and Poisons in the Body 35 4.4 Blood as the Central Factor 36 4.5 Routes in, Routes Out 36
4.5.1 Absorption 37 4.5.1.1 Mechanisms of Absorption 37 4.5.1.2 Factors Aecting Absorption 38 4.5.1.3 Drug Delivery Mechanisms 39 4.5.1.4 Bioavailability 41
4.5.2 Distribution 42 4.5.2.1 Distribution Processes 43 4.5.2.2 Compartments 44 4.5.2.3 Volume of Distribution 44
4.5.3 Elimination 46 4.5.3.1 Elimination Parameters 46 4.5.3.2 Elimination Kinetics 46 4.5.3.3 Multiple Dose Considerations 48
Bibliography 49
of body), distribution (the processes by which drugs and poisons are moved around the body and taken up into organs and tissues), metabolism (the processes by which drugs and poisons are biochemically altered or broken down), and elimination (the processes by which drugs and poisons are removed from the body). e sum of these processes is oen abbreviated as ADME.
