chapter 2 pharmacologic principles copyright © 2014 by mosby, an imprint of elsevier inc

Chapter 2

Pharmacologic Principles

Copyright © 2014 by Mosby, an imprint of Elsevier Inc.


Drug Any chemical that affects the physiologic

processes of a living organism Pharmacology

Study or science of drugs

2Copyright © 2014 by Mosby, an imprint of Elsevier Inc.

Drug Names

Chemical name Describes the drug’s chemical composition and

molecular structure

Generic name (nonproprietary name) Name given by the United States Adopted Names

Council

Trade name (proprietary name) The drug has a registered trademark; use

of the name is restricted by the drug’s patent owner (usually the manufacturer)


Chemical, Generic, and Trade names and Chemical Structure of Ibuprofen

Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 4


Pharmaceutics Pharmacokinetics Pharmacodynamics Pharmacotherapeutics Pharmacognosy Pharmacoeconomics


Pharmaceutics

The study of how various drug forms influence the way in which the drug affects the body


Pharmacokinetics

The study of what the body does to the drug Absorption Distribution Metabolism Excretion


Classroom Response Question

The nurse is giving a medication that has a high first-pass effect. The health care provider has changed the route from IV to PO. The nurse expects the oral dose to be

A.higher because of the first-pass effect.

B.lower because of the first-pass effect.

C.the same as the IV dose.

D.unchanged.


Pharmacodynamics

The study of what the drug does to the body The mechanism of drug actions in living tissues Drug-receptor relationships


Phases of Drug Activity



A patient is complaining of severe pain and has orders for morphine sulfate. The nurse knows that the route that would give the slowest pain relief would be which route?

A.IV

B.IM

C.Subcut

D.PO


Pharmacotherapeutics

The clinical use of drugs to prevent and treat diseases

Defines principles of drug actions—the cellular processes that change in response to the presence of drug molecules

Drugs are organized into pharmacologic classes


Pharmacognosy

The study of natural (versus synthetic) drug sources (i.e., plant, animals, minerals)


Pharmaceutics

Different drug dosage forms have different pharmaceutical properties.

Dosage form determines the rate of drug dissolution (dissolving of solid dosage forms and their absorption from the GI tract). Enteric-coated tablets Extended-release forms


Classroom Response QuestionA patient is prescribed ibuprofen 200 mg PO every 4 hours as needed for pain. The pharmacy sends up enteric-coated tablets, but the patient refuses the tablets, stating that she cannot swallow pills. What will the nurse do?

A.Crush the tablets and mix them with applesauce or pudding.

B.Call the pharmacy and ask for the liquid form of the medication.

C.Call the pharmacy and ask for the IV form of the medication.

D.Encourage the patient to try to swallow the tablets.


Pharmacokinetics

A drug’s time to onset of action, time to peak effect, and duration of action

Study of what happens to a drug from the time it is put into the body until the parent drug and all metabolites have left the body


Pharmacokinetics: Absorption

Movement of a drug from its site of administration into the bloodstream for distribution to the tissues Bioavailability First-pass effect


Routes

A drug’s route of administration affects the rate and extent of absorption of that drug Enteral (GI tract) Parenteral Topical


Enteral Route

The drug is absorbed into the systemic circulation through the oral or gastric mucosa or the small intestine Oral Sublingual Buccal Rectal (can also be topical)


Parenteral Route

Intravenous (fastest delivery into the blood circulation)

IntramuscularSubcutaneousIntradermalIntraarterialIntrathecalIntraarticular


Topical Route

Skin (including transdermal patches) Eyes Ears Nose Lungs (inhalation) Rectum Vagina



The nurse is preparing to administer a transdermal patch to a patient and finds that the patient already has a medication patch on his right upper chest. What will the nurse do?

A.Remove the old medication patch and notify the health care provider

B.Apply the new patch without removing the old one

C.Remove the old patch and apply the new patch in the same spot

D.Remove the old patch and apply the new patch to a different, clean area


The transport of a drug by the bloodstream to its site of action Protein-binding Water-soluble vs. fat-soluble Blood-brain barrier Areas of rapid distribution: heart, liver, kidneys, brain Areas of slow distribution: muscle, skin, fat

Distribution

Copyright © 2014 by Mosby, an imprint of Elsevier Inc. 24

Protein Binding of Drugs


Metabolism/Biotransformation

The biochemical alteration of a drug into an inactive metabolite, a more soluble compound, a more potent active metabolite, or a less active metabolite Liver (main organ) Skeletal muscle Kidneys Lungs Plasma Intestinal mucosa


Drug Transport in the Body


Metabolism/Biotransformation (cont’d.)

Factors that decrease metabolism Cardiovascular dysfunction Renal insufficiency Starvation Obstructive jaundice Slow acetylator Ketoconazole therapy


Metabolism/Biotransformation (cont’d)

Factors that increase metabolism Fast acetylator Barbiturate therapy Rifampin therapy Phenytoin therapy


Excretion

The elimination of drugs from the body Kidneys (main organ) Liver Bowel

Biliary excretion Enterohepatic recirculation


Renal Drug Excretion


Half-life

The time it takes for one half of the original amount of a drug to be removed from the body

A measure of the rate at which a drug is removed from the body

Most drugs considered to be effectively removed after about five half-lives

Steady state


The Movement of DrugsThrough the Body

Drug actions The cellular processes involved in the drug and cell

interaction

Drug effect The physiologic reaction of the body to the drug Includes onset, peak, and duration of action


Onset, Peak, and Duration

Onset The time it takes for the drug to elicit a

therapeutic response

Peak The time it takes for a drug to reach its maximum


Duration The time a drug concentration is sufficient to elicit a



Therapeutic Drug Monitoring

Peak levelHighest blood levelTrough levelLowest blood level


Pharmacodynamics: Mechanisms of Action

Receptor interactions Enzyme interactions Nonselective interactions


Pharmacotherapeutics: Types of Therapies

Acute therapy Maintenance therapy Supplemental/replacement therapy Palliative therapy Supportive therapy Prophylactic therapy Empiric therapy


Contraindications

Any characteristic of the patient, especially a disease state, that makes the use of a given medication dangerous for the patient

It is important to assess for contraindications!


Monitoring

Evaluating the clinical response of the patient to the treatment

One must be familiar with the drug’s: Intended therapeutic action (beneficial) Unintended but potential adverse effects

(predictable, adverse drug reactions)


Monitoring (cont’d)

Therapeutic index Drug concentration Patient’s condition Tolerance and dependence Drug interactions (additive effect, synergistic

effect, antagonistic effect, incompatibility) Adverse drug events


Monitoring (cont’d)

Adverse drug reactions Pharmacologic reactions, including adverse effects Hypersensitivity (allergic) reaction Idiosyncratic reaction Drug interaction


Other Drug-Related Effects

Teratogenic Mutagenic Carcinogenic


Pharmacognosy

Four main sources for drugs Plants Animals Minerals Laboratory synthesis


Toxicology

The study of poisons and unwanted responses to drugs and other chemicals

Overlaps with pharmacotherapeutics


chapter 2 pharmacologic principles copyright © 2014 by mosby, an imprint of elsevier inc

Documents

imprint of elsevier

drug names chemical

various drug forms

mechanism of drug actions

synthetic drug sources

rate of drug dissolution

phases of drug activity

drugs chemical composition