Download Ch. 6-Basic Pharmacology - NAC / CNA Certification Spokane

Basic Pharmacology
Chapter 6
Pharmacology
• Study of drugs and their actions on living
organisms
• Drug Names:
– Drugs have different names, many have similar
spelling.
• Exact names and spelling are imperative
Drug Names
• Chemical Name:
– Exact chemical structure of a drug
• Ex. 4-Thia-1-azabicyclo[3.2.0]heptane 2-carboxylic acid, 6[(aminophenylacetyl)amino]-3,3-dimethyl-7-oxo-,[2S-[2α,-5 α,6β(S*)]]-
• Generic Name:
– Drugs common name
• Ex. Ampicillin
• Official Name:
– Name under which the drug is listed by the FDA
• Ex. Ampicillin, USP
• Trademark:
– Brand or Trade name
– Only the manufacture who owns the drug can use the brand/trade
name
• Ex. Principen, Polycillin
Drug Classifications
• Drugs are classified by:
– Body System
• Which body system the affect?
– Therapeutic use or clinical indications
• What disease or illness is being treated?
– Physiological or chemical action
• What does the drug do in the body?
– Prescription or non-prescription
• Does the medication require a prescription or can it be
purchased OTC?
– Illegal Drugs
• Is the drug used for non-therapeutic reasons?
Basic Principles
• Drugs act in the human body in the following
ways:
– Drugs change a physiological activity within the body
• They do no create new responses
– Ex. Blood Pressure Medication
– Drug forms a chemical bond within specific sites
(receptors) within the body
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Relationship between drug and receptor is like a key
Basic Principles (continued)
• Agonist:
– Drugs that interact with a receptor to cause a
response
• Antagonist:
– Drugs that attach to a receptor but do not cause
a response
• Partial Agonist:
– Drugs that interact with a receptor to cause a
response but prevent other responses
4 Stages
• All drugs go through 4 Stages:
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4.
Absorption
Distribution
Metabolism
Excretion
Absorption
• Process by which a drug is transferred from its
site of the body entry to circulating body fluids
(blood, lymph) for distribution
– Rate of absorption depends upon:
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Route of administration
Blood flow through the tissue where drug administered
How well the drug can dissolve (solubility)
Proper reconstitution and dilution of drugs
Administration into the correct tissue
Absorption (continued)
• Routes of Administration:
– Enteral:
• Drugs administered directly into the GI tract
– Ex. Orally
– Parenteral:
• Drugs administered that bypass the GI tract
– Ex. Injections
» Subcutaneous
• Beneath the skin
» Intramuscular:
• Within a muscle
» Intravenous:
• Within a vein
– Percutaneous:
• Drugs administered through the skin or a mucous membrane
– Ex. Inhalation, sublingual and topical
Absorption (continued)
• Absorption of drugs applied to the skin
(topical) in influence by:
– Amount and strength of drug
– Length of contact time
– Size of the affected area
– Thickness of the skin surface
– Tissue hydration
– Skin condition—intact or non-intact
Distribution
• The ways drugs are transported by circulating body
fluids to the sites of action (receptors) and to the site
of metabolism & excretion
– Organs with the greatest blood supply (heart, liver, kidneys
& brain) receive the drug most rapidly
– Tissues with lesser blood supply (muscle, skin, fat) receive
the drug move slowly
• Once absorbed, a drugs distribution rate is determined
by:
– Chemical properties
– How the drug is affected by the blood and tissues it
contacts
Metabolism
• Process by which the body in-activates drugs
– Liver is the primary site for drug metabolism
• Other tissues & organs that metabolize drugs:
– White Blood Cells
– GI Tract
– Lungs
– Other factors that help to regulate drug metabolism
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Genetics
Environment
Physiology
Other drugs
Illnesses
Age
Excretion
• Elimination of a drug from the body
– Urine and feces are the primary routes
– Other routes of elimination include:
• Evaporation from skin
• Exhalation from lungs
• Secretion into saliva & breast milk
Drug Action
• No drug has a single action
– When a drug is absorbed & distributed, the desired action
(expected response) usually occurs
• All drugs can affect more than one body system, therefore
potentially causing side effects and adverse drug reactions
– Side Effects:
» Unintended reactions to a drug given in a normal dose
– Drug Reaction:
» Unintended effect on the body from using a legal drug, illegal drug
or 2 or more drugs
• Each drug has parameters—therapeutic actions to expect, side
effects to expect, adverse drug reactions to report and probable
drug interactions.
– Dosages are adjusted and monitored for the nest therapeutic effect
Allergic Reactions
• Unfavorable response to a substance that
causes a hyper-sensitivity reaction.
– Occur in persons previously exposed to a drug
• Person develops antibodies to the drug, on re-exposure
the antibodies cause a reaction
– Most common reaction:
» Urticaria (Hives)
– Anaphylaxis
» Severe, life threatening sensitivity to an antigen
• Sweating, shortness of breath, low blood pressure,
irregular pulse, respiratory congestion, swelling of
the larynx, hoarseness, dyspnea
Reactions
• Mild Reactions
– Warning to not take medication again
• Anaphylaxic Reaction:
– Never use the drug again
– Receive information about the drug
– Tell health professional about the reaction
– Wear a medical alert bracelet
Factors Influencing Drug Action
• Some people react differently to same drug at the
same dosages
– Factors that affect a person’s response to a drug:
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Age
Body Weight
Metabolic Rate
Illness
Willingness to take drugs
Placebo effect
Tolerance
Dependence
Cumulative Effect
Drug Interactions
• Drug interaction occurs when the action of
one drug is altered by the action of another
drug
– Occurs in 2 ways:
• Drugs, when combined, INCREASE the actions of one or
both drugs
• Drugs, when combined, DECREASE the effectiveness of
on or both drugs
Drug Information
• With thousands of drugs it is impossible to
memorize information about all of them
– Be familiar with resources:
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American Hospital Formulary Service Drug Information
Drug Interaction Facts
Drug Facts and Comparison
Handbook of Nonprescription Drugs
Natural Medications Comprehensive Database
Physicians Desk Reference (PDR)
Package Inserts