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Pharmacology

STUDY
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Pharmacology
the study of medications and their actions including drug origins, properties and uses. (pg. 204)
Pharmodynamics
study of the interaction of drug molecules with the target cells of living tissue.
Medication Actions
Agonists
Synergistic Agents
Additive Agents
Atagonists
Agonist
agonistic interaction occurs when a drug potentiates or enhances the effect of another substance.
Ex: synergists and additives
Synergistic Agents
Synergists act in combination to produce a stronger or more powerful effect than would be demonstrated if each agent was administed individually.
Additive Agents
Medication additives alter some aspect of the action of the original agent.
Example: adding epinephrine to lidocaine
Antagonists
an AGONIST is a medication that binds to a specific receptor site in the body, producing an alteration in biological function and resulting in a desired effect.
-an ANTAGONIST binds to the agonist's receptor site, preventing the agonist from binding there and causing it's desired effect.

(Basically, it is a drug that reverses the effects of another drug)
pg 205
Therapeutic Action:
INDICATIONS
listing of medical conditions that the medication is know to treat
pg 205
Therapeutic Action:
CONTRAINDICATIONS
list of circumstances or medical conditions under which the medication should not be used
Onset: effects of meds begin showing
Peak: effects of meds at peak
pg 205
Medication effect:
Therapeutic
the concentration or dose of a medication used to produce the desired result without producing a harmful effect
Medication Effect:
Side Effect
an expected, undesirable, but tolerable effect of a medication.
(ex: dry mouth, constipation, diarrhea, dizziness or drowsiness)
Adverse Effect:
an undesirable and potential harmful effect of a medication that can lead to organ damage or failure.
Toxic Effect
undesirable, unacceptable effects of a medication.
can cause CANCER
Drug Effect:
Tolerance
reduction in the effect of a medication given at the same dose over a period of time
Addiction
a physical or psychological dependency on the effects of medication
Pharamacokinetics
term to describe entire process of a drug within the body.
Absorption
Distribution
Biotransformation
Excretion
pg 206
Absorption
(Pharamacokinetics)
drug must be absorbed to produce an effect.
Distribution
(Pharamacokinetics)
involves the transport of the medication within the body once it enters the circulatory system
Biotransformation
(Pharamacokinetics)
Biotransformation = metabolism.
-mainly broken down in liver
Excretion
(Pharamacokinetics)
the effect of medication in the body continues until it is biotransformed or excreted.
Kidneys partially responsible for the filtration of medications
PO
Route of Administration
Oral
(meaning per os or by mouth) through the GI tract
Route of Administration:
Rectal
placed into the rectum
Route of Administration:
Intradermal
Between the layers of the skin
SC or SQ
Subcutaneous.
Under the skin into the adipose tissue layer
IM
Intramuscular
(within the muscle)
IV
Intravenous
(into a vein)
Route of Administration:
Intra-articular
within a joint
Route of Administration:
Intrathecal
Into the subarachnoid space
Route of Administration:
Intracardiac
Into the heart
Topical
applied to the skin or mucous membrain
Buccal
medication is placed between the cheek and the teeth until it is dissolved or absorbed
Instillation
Medication is placed in a hollow or cavity

(such as the conjunctival fold or bladder)
Inhalation
medication is directly administered via the
RESPIRATORY TRACT
Pg 209
Concentration
the concentration of a medication is the ratio of solute to solvent. The two components of a solution
4 stages of General Anesthesia
(pg 227)
Stage 1: amnesia stage
Stage 2: delirium stage (excitement)
Stage 3: surgical anesthesia stage
Stage 4: overdosage stage
4 Phases of General anesthesia
Induction phase
Maintenance phase
Emergence phase (hearing is the last thing to go)
Recovery phase
Drug Handling Techniques: pg 212

6 basic rights for correct drug handling
1. The right patient
2. The right drug
3. The right dose
4. The right route of administration
5. The right time and frequency
6. The right documentation, including labeling
Sellick's maneuver
cricoid pressure
Cricoid Pressure
(pg 228)
-performed to reduce the risk of aspiration.
-applied prior to induction of anesthesia and continue until the endotracheal tube is placed.
-employed in the OR in situations where the patient requires emergency surgery shortly after eating. or the NPO status is not verified, or GI bleeding
Laryngospasm and Bronchospasm
(pg 228)
-reactions demonstrated by the lightly anesthetized patient.
-a slight trigger of the "gag" reflex results in a spasm or rigidity of the upper respiratory tract....resulting in an inability of the air and waste gases to move in and out of the lungs.
-TRIGGERED BY SALIVA IN THE BACK OF THE THROAT

-SUCCINYLOCHOLINE = drug, neuromuscular blocker - relaxes spasm
(can cause Malignant Hyperthermia)
Malignant Hyperthermia
(pg 229)
-not "hypo"
(drug, SUCCINYLCHOLINE can cause this and
Halogenated inhalation agents such as...
(desflurane, isoflurane, sevoflurane)

MUSCLE RIGIDITY -

The skeletal muscles are stimulated to contract, but due to the inability of calcium to release, the muscles cannot relax, resulting in rigidity, heat generation, and a buildup of lactic acid and carbon dioxide.

-genetically transmitted disease seen more in males

First sign:
unexplained tachycardia (increase in heart rate), followed by tachypnea and an increased level of carbon dioxide.

Late sign: rise of temperature, as high as 107 degrees

-If it occurs, stop and give 100% oxygen
-MH cart on standby
Succinylcholine
neuro muscular blocker
can cause Malignant Hyerthermia
MH cart
(Malignant hyperthermia)
(designated for Malignant Hyperthermia, with supplies readily available)

-Dantrolene is the only phamacological agent for the treatment of MH, mixed with sterile water, given IV

-sodium bicarbonate,
dextrose and insulin,
furosemide or mannitol
heparin

- chilled IV fluids of saline dextrose (to regulate temp)
-chilled saline lavage - for body cavities
Drugs used during MH crisis
sodium bicarbonate:
to assist in metabolic and respiratory acidosis regulation

dextrose and insulin:
to provide available glucose to the cells to maintain cellular metabolism

furosemide or mannitol:
to promote renal clearance of waste products

heparin:
to prevent intravascular clot formation
Dantrolene
Only pharmacological agent for the treatment of MH
-mixed with sterile water
-IV
ANTAGONIST for MH (reverses)
Anesthetic agents:
3 categories
inhaltion agents
intravenous agents
local/regional agents
Inhalation agents
(pg 230)
Anesthetic agents that are inhaled and pass into the bloodstream via pulmonary function.
pulmonary function
pertaining to the lungs
oxygen
Inhalation agent:
-not an anesthetic agent
-essential for survival of the patient...promotes respiration and cellular function
Nitrous oxide
-clear, colorless, fruity odor
-only true gas still in use
-interacts with the cellular membrane of the CNS to produce ANALGESIA with some amnesia.
-eliminated by exhalation
-used in conjunction of other anesthetic agents (not strong enough alone)
- CONTRAINDICATING its use during some surgical interventions such as tympanoplasty
-may contribute to postoperative nausea and vomiting.
Agonist
Medication that helps enhance effect of other drug
Antagonist
reverses effects of other drug
Drug sources
(pg 205)
Plants
Animals
Minerals
Laboratory synthesis
Biotechnology
Plants
Drug source

-morphine
-digitalis
Animals
Drug source

Primarily hormones are derived form animal sources including human sources.
-Cows - bovine
-pigs - porcine

-Heparine
-thrombin
Minerals
Drug source

From the earth
-calcium
-gold
-iron
magnesium
-silver
-zinc
Laboratory synthesis
Drug source

manufactured in a laboratory.
-Two methods:
synthetic drugs
semisynthetic drugs
Synthetic drugs
manufactured totally from laboratory chemicals.
-Meperidine sulfate (Demerol)
Semisynthetic drugs
begin with a natural substance which is then chemically altered.

-aminoglycoside group of antibiotics
Biotechnology:
recombinant DNA technology
"recombinant DNA technology"

-DNA is artificially constructed by introducing foreign DNA into the DNA of a specific organism - daughter cell created
-cell reproduction

Hepatitis B vaccine
3 Legal Drug Classifications
Controlled Substances
Prescribed Medications
Over-the-counter medications
Controlled substances
drugs with a high potential to cause psychologigical and or physical dependence and abuse.
(labeled classes 1 - 4)
Prescribed Medications
medications that are prescribed but if used inappropriately, could cause significant harm to the patient
Over the Counter Medications
(OTC)
pharmacologic agents that are prepared in a dosage that are generally safe to administer without the direction of a physician
VOLATILE AGENTS
(ends in "ane" = can trigger MH)
drugs that are in liquid form - potent vapors are inhaled to cause effects
-sevolfurane, desflurane, isoflurane
less commonly used: enflurane and halothane
Sevoflurane
(Ultane)
Advantage:
Rapid and smooth onset and recovery
ideal agent for both adult and pediatric inhalation induction

Disadvantages: causes bradycardia, hypotension, cardiac dysrhythmias and reduces cardia output
-may also cause nausea and vomiting in the postoperative period.
-renal complications
Desflurane
(Suprane)
-requires the use of a heated vaporizer

It has a pungent aroma, CONTRAINDICATING its use during inhalation induction.
-Rapid onset and recovery
-not biotransformed in the liver, it is safe to use for patients with hepatic insufficiency
-Less expensive than sevoflurane
-causes nausea and vomiting like sevoflurane
Isoflurane
(Forane)

pungent, musty smelling

-rapid induction and recovery
-respiratory depressant
-potentiates neuromuscular blockade
-may cause hypotension
-increases intracranial pressure (ICP), which is reversible with hyperventalation
-
Barbiturate
sedative, hypnotic
Intravenous Agents I.V.
(pg 230)
Groups:
-induction agents
-dissociative agents
-opioids
-sedatives/tranquilizers
-neuromuscular blocking agents
antimuscarinic (anticholinergic) agents
-adjunctive agents
Induction agents (IV)
permit a rapid and pleasant transition from consciousness (Stage 1) to unconsciousness (Stage 3) by quickly passing through the delirium stage (Stage 2)

-Side effects: Hypotension and respiratory depression
- may also be used during maintenance of general anesthesia
Drugs: Propofol, Etomidate, Thiopental sodium, Methohexital sodium
Propofol
(Diprivan)

"Milk of amnesia"
-sedative-hypnotic agent
-discarded within 6 hrs of opening
-irritating to the vein and may cause patient discomfort at the IV site
(Lidocaine given IV just prior to propofol inj. may ease that discomfort)

-Rapid induction and emergence without the prolonged "hangover" effect

-CONTRAINDICATED: for patients with unstable hemodynamics or head trauma.
Etomidate
(Amidate)

nonbarbiturate hypnotic agent used for anesthesia induction
-similar to propofol, but does not produce analgesia

INDICATED: choice for anesthesia induction of the hemodynamically unstable patient indications

COMPLICATION - postoperative nausea and vomiting (POVN) as well as adreanal suppression are seem more frequently in patients given etomidate
Thiopental sodium
(Pentothal Sodium)

-short- acting potent barbiturate
-does NOT provide anesthesia or muscle relaxation
-has hypnotic, amnesic, and sedative effects.

-Leaves patient with a residual hangover effect lasting through and prolonging the patient's emergence and recovery phases.

ADVANTAGES:
-marked respiratory and circulatory depression immediately following injection, non flammability, inability to cause irritation to the respiratory tree, and lack of salivary stimulation
-Helps reduce Laryngospasm and Bronchospasm due to decreasing saliva

DISADVANTAGES:
-minor patient stimulation during the lighter stages of anesthesia administration, which may cause laryngospasm, and the alkaline nature of the drug, which may be locally irritating to the vein.
Halogenated anesthetic agents
considered triggering agents for malignant hypothermia
DISSOCIATIVE AGENTS
(pg 231)
Advantage:
selectively interrupt the associative pathways of the brain. Patients may appear wide awake, yet they are unaware of their surroundings.
-Produce amnesia and profound analgesia.

-Ketamine hydrochloride (Ketalar)
Ketamine hydrochloride
(Ketalar)
-most commonly used dissociative agent.
-administered IM or IV



DISADVANTAGE:
-production of vivid imagery and morbid hallucinations during administration and recovery.
-causes hypertention
-limited use to children 2 - 10 years old.

ADVANTAGE:
produces amnesia and analgesia while patient is wide awake

Contraindication: triggers laryngospasm due to SALIVA INCREASE
OPIATE/OPIOIDS
CLASS II controlled substances
-not handled by CSTs
-narcotics classified as analgesics = sedation

-Morphine sulfate, meperidine, fentanyl citrate, sufentanil citrate, alfentinal hydrochloride, remifentanil hydrochloride,
Morphine sulfate
used for the control of severe pain.
-given IM = preoperative sedative/analgesic
-postoperative = analgesic
iv - anesthetic agent
-intrathecally - spinal pain control

DISADVANTAGES:
side effects. bradycardia (slow heart), hypotension, vasodialation, nausea, vomiting, confusion, respiratory depression
Meperidine
(Demerol)
similar to morphine
-used to treat moderate to severe pain

DISADVANTAGES: side effects.
increased ICP, tachycardia and vasodilaton (causes Malignant Hyperthermia)
Fentanyl citrate
(Sublimaze)

RAPID ONSET, SHORT DURATION (on test)

the first of the synthetic narcotic analgesics to be used for anesthesia administration.

-use with patients with myasthenia gravis is contraindicated
Sufentanil citrate
(Sufenta)
similar to fentanyl, but five times more potent
-produces analgesia
-respiratory depressant
-has a rapid onset of action when given IV
-It has a short duration of activity and is rapidly eliminated
Alfentanil hydrochloride
(Alfenta)
similar in action and usage to fentanyl
-short acting analgesic

Disadvantage: induced respiratory depression may outlast the analgesic effect produced
Remifentanil hydrocholoride
(Ultiva)
short duration. 5 -10 min.
synthetic opiod metabolized in blood and muscle tissue.
DISADVANTAGE: may cause respiratory depression, brady cardia, hypotension, and muscle rigidity.
ADVANTAGE: short duration, allows more accurate dose titration (method of estimating amount of solution)
Muscle rigidity
...
Narcotic Antagonists
(pg. 232, important)
The opioid effect can be antagonized or reversed by the administration of
naloxone hydrochloride (Narcan)
Benzodiazeprines
(pg 232)
sedative tranquilizers
2 ways:
-to reduce the anxiety and apprehension of the preoperative patient
-as an adjunct to general anesthesia to reduce the amount and concentration of anther more potent agents

(Diazepam, Midazolam, Droperidol)
Diazepam
(Valium)
CLASS 4 controlled substance
-primary anesthetic use is to reduce ANXIETY and provide some skeletal muscle relaxation.
-provides retrograde amnesia of short duration.
-Given IV
-5 -15 min = onset of action
Midazolam
(Versed)

Class 4

-rapid onset and short acting
-ideal for patients undergoing outpatient procedures
-short duration memory impairment
-twice as potent as diazepam
-IV dosage is diluted with injectable dextrose/water/saline
Droperidol
(Inapsine)
-produces marked sedation with a long duration of action.
-mild amnesia
Droperidol premixed with fentanyl citrate
trade name: INNOVAR
-provides a combination of sedation and analgesia
Amino Amide Group
(pg 236)
drugs in this group are metabolized in the liver and excreted by the kidneys and include:
-lidocaine, mepivicane, bupivacain, etidocain
Regional Anesthesia
(refer to notes)
Hypertention
high blood pressure
Hypotention
LOW blood pressure