PHARMACOLOGY FOR NURSES A Pathophysiological Approach FOURTH EDITION

Pharmacodynamics and Clinical Practice • Pharmacodynamics – how a medicine changes the body •

Skill of Nurse Critical in Determining if Average Dose Is Effective • Patient observation

Drugs That Act as Agonists • Bind to receptor • Produce same response as

Drug Attaches to Receptor • Like key to lock • May trigger second messenger

Drugs That Act as Partial Agonists • Bind to receptor • Produce weaker response

Drugs That Act as Antagonists • Occupy receptor • Prevent endogenous chemical from acting

Therapeutic Index • Measure of a drug's safety margin • The higher the value,

Calculating Therapeutic Index Pharmacology for Nursing: A Pathophysiology Approach , Fourth Edition Michael Patrick

Example of Therapeutic Index • Therapeutic index of 4: need error four times dose

Figure 5. 2 Therapeutic index: (a) drug X has a therapeutic index of 4;

Two Ways to Compare Medications • Potency • Efficacy Pharmacology for Nursing: A Pathophysiology

Potency • Drug with higher potency produces a therapeutic effect at a lower dose,

Efficacy • Magnitude of maximal response that can be produced from a particular drug

Figure 5. 4 than drug B Potency and efficacy: (a) drug A has a

In the Future: Customized Drug Therapy • End of single-drug, one-size-fits-all policy • DNA

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Pharmacodynamics and Clinical Practice • Pharmacodynamics – how a medicine changes the body • Helps to predict if drug will produce change • Will ensure that drug will provide safe, effective treatment • Combination of drug guides and intuitive knowledge will guide safe treatment Pharmacology for Nursing: A Pathophysiology Approach , Fourth Edition Michael Patrick Adams | Leland N. Holland | Carol Urban

Skill of Nurse Critical in Determining if Average Dose Is Effective • Patient observation • Taking of vital signs • Monitoring lab data Pharmacology for Nursing: A Pathophysiology Approach , Fourth Edition Michael Patrick Adams | Leland N. Holland | Carol Urban

Drugs That Act as Agonists • Bind to receptor • Produce same response as endogenous substance • Sometimes produce greater maximal response Pharmacology for Nursing: A Pathophysiology Approach , Fourth Edition Michael Patrick Adams | Leland N. Holland | Carol Urban

Drug Attaches to Receptor • Like key to lock • May trigger second messenger events – e. g. , activation of specific G proteins and associated enzymes • Initiates drug action • Can stimulate or inhibit normal activity Pharmacology for Nursing: A Pathophysiology Approach , Fourth Edition Michael Patrick Adams | Leland N. Holland | Carol Urban

Drugs That Act as Partial Agonists • Bind to receptor • Produce weaker response than agonists Pharmacology for Nursing: A Pathophysiology Approach , Fourth Edition Michael Patrick Adams | Leland N. Holland | Carol Urban

Drugs That Act as Antagonists • Occupy receptor • Prevent endogenous chemical from acting • Often compete with agonists for receptor • Functional antagonists inhibit the effects of an agonist not by competing for a receptor, but by changing pharmacokinetic factors. Pharmacology for Nursing: A Pathophysiology Approach , Fourth Edition Michael Patrick Adams | Leland N. Holland | Carol Urban

Therapeutic Index • Measure of a drug's safety margin • The higher the value, the safer the drug Pharmacology for Nursing: A Pathophysiology Approach , Fourth Edition Michael Patrick Adams | Leland N. Holland | Carol Urban

Calculating Therapeutic Index Pharmacology for Nursing: A Pathophysiology Approach , Fourth Edition Michael Patrick Adams | Leland N. Holland | Carol Urban

Example of Therapeutic Index • Therapeutic index of 4: need error four times dose to be lethal Pharmacology for Nursing: A Pathophysiology Approach , Fourth Edition Michael Patrick Adams | Leland N. Holland | Carol Urban

Figure 5. 2 Therapeutic index: (a) drug X has a therapeutic index of 4; (b) drug Z has a therapeutic index of 2 Pharmacology for Nursing: A Pathophysiology Approach , Fourth Edition Michael Patrick Adams | Leland N. Holland | Carol Urban

Two Ways to Compare Medications • Potency • Efficacy Pharmacology for Nursing: A Pathophysiology Approach , Fourth Edition Michael Patrick Adams | Leland N. Holland | Carol Urban

Potency • Drug with higher potency produces a therapeutic effect at a lower dose, compared with another drug in the same class. Pharmacology for Nursing: A Pathophysiology Approach , Fourth Edition Michael Patrick Adams | Leland N. Holland | Carol Urban

Efficacy • Magnitude of maximal response that can be produced from a particular drug • From a pharmacotherapeutic perspective, efficacy is almost always more important than potency. Pharmacology for Nursing: A Pathophysiology Approach , Fourth Edition Michael Patrick Adams | Leland N. Holland | Carol Urban

Figure 5. 4 than drug B Potency and efficacy: (a) drug A has a higher potency than drug B; (b) drug A has a higher efficacy Pharmacology for Nursing: A Pathophysiology Approach , Fourth Edition Michael Patrick Adams | Leland N. Holland | Carol Urban

In the Future: Customized Drug Therapy • End of single-drug, one-size-fits-all policy • DNA test before receiving drug • Prevention of idiosyncratic responses— unpredictable and unexplained drug reactions • Pharmacogenetics—area of pharmacology that examines role of heredity in drug response Pharmacology for Nursing: A Pathophysiology Approach , Fourth Edition Michael Patrick Adams | Leland N. Holland | Carol Urban