surgical pharmacology and anesthesia

Surgical Pharmacology and

Anesthesia

Chapter 9

© 2004 by Delmar Learning, a division of Thomson Learning, Inc. All Rights Reserved.

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Pharmacology

• Pharmacology: Study of drugs and their actions

• Drug: Diagnosis, treatment, cure, mitigation (lessen), or prevention of disease or a condition

• Prophylaxis: Treatment to prevent disease: treatment such as vaccination that prevents disease or stops it spreading


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Drug Sources

• Drugs are derived from 5 main sources:

• Plants• Animals• Minerals• Laboratory synthesis• Biotechnology


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Drug Sources

• certain plants and plant parts may contain medicinal properties

• Ex: digitalis

• Plants


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Drug Sources

• Essential hormones are derived from animal (including human ) sources

• Bovine• Porcine • EX: Bovine

insulin

• Animals


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Drug Sources

• Variety of applications

• from the earth• EX: gold, iron,

magnesium, silver, and zinc

• Minerals and mineral salts


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Drug Sources

• manufactured in a lab in 1 of 2 methods:

• Synthetic• Semisynthetic

• Laboratory Synthesis


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Drug Sources

• Synthetic: Drugs manufactured totally from lab chemicals EX: Meperdine Sulfate (Demerol)

• Semisynthetic: Drugs which begin with a natural substance which begins with a natural substance that is then chemically altered


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Drug Sources

• Biotechnology• genetic engineering• also called recombinant DNA

technology


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Drug Sources

• Recombinant DNA technology

• DNA is made artificially• introduces foreign DNA into the

DNA of a specific organism. • 2 DNA types combine• new DNA/specific proteins are

replicated in the daughter cells of an organism


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Drug Sources

• Recombinant DNA technology

• Cell reproduction occurs rapidly

• provides large amounts of the desired protein for use in the manufacture of certain drugs

• EX: Hepatitis B vaccine


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Pharmacodynamics

• The interaction of drug molecules with the target cells

• resulting action is biochemical and physiological


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Pharmacokinetics

• The entire process of the drug within the body:

• absorption• distribution• bio-transformation

(metabolism)• excretion


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Indication

• Reason to perform a specific procedure or prescribe a certain drug


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Contraindication

• Reason why a specific procedure or drug may be undesirable or improper in a particular situation


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Drug Forms

• Drugs are prepared for administration in several different forms

• the type of form in which the drug is made available will determine the route of administration as well as the pharmacodynamics and pharmacokinetics


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Drug Nomenclature

• 3 names are assigned to each drug

• chemical name• generic name• Trade or brand name


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Drug Nomenclature

• Chemical name:• precise chemical composition

and• precise molecular structure of

a drug• complex• difficult to use


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Drug Nomenclature

• Generic name:• nonproprietary name for a drug • often the shortened version of

the chemical name• may include a reference to the

intended use• Advocated in the health care

setting to avoid confusion


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Drug Nomenclature

• Trade or Brand name:• Drug name selected and

copyrighted by the manufacturer for marketing purposes

• Name of drug is capitalized and may be followed by the trademark sign


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Route of Administration

• Oral/enteral• PO• Ingest


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• Buccal• between the cheek and teeth• dissolved or absorbed• (considered topical)


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• Sublingual• placed under tongue until

dissolved or absorbed• (considered topical)


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• Topical• applied to skin or mucous

membrane• provides a localized or

systemic effect


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• Inhalation• Direct administration via

respiratory tract


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• Parenteral• other than enteral - by injection


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• Dermal• between the layers of the skin


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• Subcutaneous (SC or SQ)• Under the skin, into the

adipose tissue


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• Intramuscular (IM)• Within a muscle


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• Intravenous (IV)• Into a vein


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• Intra-articular• Within a joint


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• Intrethecal• Into the subarachnoid space


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• Intracardiac• into the heart


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Drug Classifications

• Keeps drugs organized• classifications overlap, or have

several sub-classifications• drugs for sale are classified in

2 ways:• OTC• Require prescription


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• Controlled Substance Act 1970

• designates certain drugs as controlled substances and defines 5 classifications or schedules:


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• Schedule I• EX: heroin,

LSD, other hallucinogens and certain opiates and opium derivatives

• High abuse potential

• no current approved medical use


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• Schedule II • High abuse potential

• high ability to produce

• physical / and or

• psychological dependence

• there is current approved or acceptable medical use


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• Schedule III • Less potential for abuse

• current approval for medical use

• contain limited quantities of codeine

• anabolic steroids


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• Schedule IV • Relatively low abuse potential

• current medical use


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• Schedule V • antitussives• antidiarrheals

• Contains limited amounts of certain narcotic drugs for use

• limited quantities can be purchased without prescription (>18)

• must be purchased from a pharmacist

• state laws vary


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• Drugs are also classified according to:

• chemical type (barbituate)• body system affected

(neurologic agent)• physiological action (CNS

depression)• therapeutic action

(anticonvulsant)


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Pharmacokinetics

• Term used to describe the entire process of the drug within the body which involves:

• absorption• distribution• biotransformation

(metabolism)• excretion


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Pharmacokinetics

• Absorption• must be absorbed to produce

an effect• occurs at the site of

administration• substance is taken into the

bloodstream by the capillaries - passive transport


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Pharmacokinetics

• Absorption• passive transport - drug

substance is transferred from a an area of high concentration to an area of lower concentration until the concentration on both sides of the cell membrane is equal

• requires no energy• most drugs are transported this

way


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Pharmacokinetics

• Absorption• Active transport required for

limited number of drugs (glucose, amino acids)

• energy source in the form of a cation (ion that has a + charge)(sodium) carries the substance from a lower concentration to a higher concentration


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Pharmacokinetics

• Absorption• rate of absorption affects final

drug action (pharmacodynamics) of a substance

• influenced by several factors- drug type, dosage, route of administration, patient’s condition

• a vasoconstrictor may be added to the drug prep to slow absorption


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Pharmacokinetics

• Distribution• transport of the drug substance

that occurs once it enters the circulatory system

• distributed to target cells for action or to the liver for biotransformation


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Pharmacokinetics

• Distribution• affected by the rate of

absorption, systemic circulation (cardiovascular function) and regional blood flow to the target organ or tissue.

• Drug is carried to all parts of the body

• effects other than those that are intended may be noted


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Pharmacokinetics

• Distribution• also affected by plasma protein

binding, tissue binding, certain barriers established by the body (blood - brain barrier)


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Pharmacokinetics

• Biotransformation• metabolism• most often occurs in the liver

and may involve other tissues (intestinal mucosa, lungs, kidneys, blood plasma)


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Pharmacokinetics

• Biotransformation• a few drugs are converted into

ac active substance by the liver, but the main function is to breakdown of drug molecules with enzymes for excretion

• the breakdown of metabolism are called metabolites - less active or inactive substances


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Pharmacokinetics

• Biotransformation• the hepatic first pass effect

must be considered when planning drug dosage and administration route


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Pharmacokinetics

• Excretion• drug’s effect continues until it is

biotransformed and/or excreted• drugs are physiologically

removed from the target organ or tissue through the circulatory system in the intact or biotransformed (changed or inactivated) state


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Pharmacokinetics

• Excretion• The kidneys are primarily

responsible for excretion• also may be excreted through

feces, sweat, saliva, or exhaled, also through breast milk


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Pharmacodynamics

• Describes the interaction of drug molecules with the target cells

• action of substance causes an alteration in physiological activity but is incapable of initiating a new function


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Pharmacodynamics

• Drug actions include inhibition or destruction of foreign agents, supplementation or replacement of specific hormones, vitamins, or enzymes

• increasing/decreasing speed of physiological function


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Pharmacodynamics

• Drugs are administered to produce an expected or therapeutic effect

• there are 3 time and action related aspects of pharmacodynamics:

• onset• peak effect• duration of action


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Pharmacodynamics

• Onset• time it takes from

administration of the drug for it’s action to become evident


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Pharmacodynamics

• Peak effect• period of time during which the

drug is at it’s maximum effectiveness


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Pharmacodynamics

• Duration of action• time between the onset of

action to the cessation of action

• timing of future doses of drug will depend on time of onset, peak effect, and duration of action


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The Five R’s of Drug Handling

• Right patient• Right drug• Right dose• Right route of administration• Right time and frequency


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Drug Identification on the Sterile Field

• Labeled immediately• Policies and procedures of the

facility• Some medications require

different handling procedures


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Balanced Anesthesia

• Hypnosis• Anesthesia• Amnesia• Muscle relaxation


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Phases of General Anesthesia

• Induction • Maintenance • Emergence• Recovery


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Laryngospasm and Bronchospasm

• Spasm or rigidity of upper respiratory tract

• Inability of patient to breathe• Inability of anesthesia provider

to move air and waste gases in and out of the lungs


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Malignant Hyperthermia

• Potentially fatal• Genetically transmitted• Stop anesthetic gases• Administer 100% 02 • Chilled IV fluids• Chilled saline lavage of body

cavities• Dantrolene


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Anesthetic Agents

• Inhalation agents• IV agents• Local/regional agents


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Monitoring Devices

• Electrocardiogram• Blood pressure monitor• Temperature monitor• Pulse oximeter


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Types of Anesthesia

• Local– Monitored anesthesia care

(MAC)

• Regional– Nerve plexus block– Bier block– Spinal block

surgical pharmacology and anesthesia

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