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A 78-year-old woman is brought to the hospital because of suspected aspirin overdose*. She has taken aspirin for joint pain for many years without incident, but during the past year, she has exhibited signs of cognitive decline. Her caregiver finds her confused, hyperventilating, and vomiting. The caregiver finds an empty bottle of aspirin tablets and calls 9-1-1. In the emergency department, samples of venous and arterial blood are obtained while the airway, breathing, and circulation are evaluated. An intravenous (IV) drip is started, and gastrointestinal decontamination is begun. After blood gas results are reported, sodium bicarbonate is administered via the IV. What is the purpose of the sodium bicarbonate?

Pharmacology can be defined as the study of substances that interact with living systems through chemical processes. These interactions usually occur by binding of the substance to regulatory molecules and activating or inhibiting normal body processes. These substances may be chemicals administered to achieve a beneficial therapeutic effect on some process within the patient or for their toxic effects on regulatory processes in parasites infecting the patient. Such deliberate therapeutic applications may be considered the proper role of medical pharmacology, which is often defined as the science of substances used to prevent, diagnose, and treat disease. Toxicology is the branch of pharmacology that deals with the undesirable effects of chemicals on living systems, from individual cells to humans to complex ecosystems (Figure 1–1). The nature of drugs—their physical properties and their interactions with biological systems—is discussed in part I of this chapter.


Major areas of study in pharmacology. The actions of chemicals can be divided into two large domains. The first (left side) is that of medical pharmacology and toxicology, which is aimed at understanding the actions of drugs as chemicals on individual organisms, especially humans and domestic animals. Both beneficial and toxic effects are included. Pharmacokinetics deals with the absorption, distribution, and elimination of drugs. Pharmacodynamics concerns the actions of the chemical on the organism. The second domain (right side) is that of environmental toxicology, which is concerned with the effects of chemicals on all organisms and their survival in groups and as species.

New drugs are added every year; they are needed for several reasons including: (1) increasing resistance by bacteria and other parasites; (2) discovery of new target processes in diseases that have not been adequately treated; and (3) recognition of new diseases. Furthermore, a dramatic increase has occurred in the number of large molecule drugs (especially antibodies) approved during the last two decades. The development of new drugs and their regulation by government agencies are discussed in part II.

*The author thanks Barry Berkowitz, PhD, for contributions to the second part of this chapter in previous editions.

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