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Chapter 1

Orientation to Pharmacology

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Pharmacology

A science that draws on information from multiple disciplines, including: Anatomy Physiology Psychology Chemistry Microbiology

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Four Basic Terms

Drug Any chemical that can affect living processes

Pharmacology Study of drugs and their interactions with living

systems

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Four Basic Terms

Clinical pharmacology Study of drugs in humans

Therapeutics A.k.a. pharmacotherapeutics The use of drugs to diagnose, prevent, or treat

disease or to prevent pregnancy Primary concern studied in this text

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Orientation to Pharmacology

Properties of an ideal drug The therapeutic objective Factors that determine the intensity of drug

responses Therapeutics

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Three Most Important Properties of an Ideal Drug

1. Effectiveness 2. Safety3. Selectivity

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Additional Properties of an Ideal Drug

Reversible action Predictability Ease of administration Freedom from drug interactions Low cost Chemical stability Simple generic name

But because no drug is ideal…

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Therapeutic Objective of Drug Therapy

To provide maximum benefit with minimum harm

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Factors That Determine the Intensity of Drug Responses

Administration Pharmacokinetics Pharmacodynamics Sources of individual variation

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Fig. 1-1. The four basic pharmacokinetic processes.Dotted lines represent membranes that must be crossed as drugs move throughout the body.

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Administration

Important determinants of drug responses: dosage size, route, timing

Medication errors Patient adherence

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Pharmacokinetics

Determining how much of administered dose gets to its sites of action

Impact of the body on drugs Four major pharmacokinetic processes

Drug absorption Drug distribution Drug metabolism Drug excretion

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Pharmacodynamics

Impact of drugs on the body Drug-receptor interaction

Binding of the drug to its receptor Patient’s functional state

Influences pharmacodynamic processes Placebo effects

Also help determine the responses a drug elicits

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Sources of Individual Variation

Physiologic variables Age, gender, weight

Pathologic variables Diminished function of kidneys and liver

Genetic variables Can alter metabolism of drugs and predispose

patient to unique interactions Drug interactions