This document provides an overview of intravenous and inhalational anesthetic agents used in pharmacology. It discusses the primary uses, advantages, and disadvantages of benzodiazepines, barbiturates, opioids, ketamine, propofol, etomidate, desflurane, sevoflurane, isoflurane, halothane, and nitrous oxide. It also reviews neuromuscular blocking drugs including depolarizing and nondepolarizing agents as well as anticholinesterases used to reverse their effects. The document provides detailed information on specific anesthetic drugs and their properties.

1. Pharmacology of general
anesthetics
Dr. Ashraf Arafat Abdelhalim, MD
Professor of anesthesia
Department of Anesthesia, Alexandria
University, Egypt
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2. Intravenous Anesthetics
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3. Benzodiazepines (BZ)
The 3 main drugs used in this category are diazepam,
lorazepam and midazolam.
Primary uses:
Anti-anxiety agent pre-op for premedication.
Sedation
They are inadequate for use in surgical anesthesia “on
their own”, and must therefore be used with another
anesthetic agent (i.e. an inhalation anesthetic).
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4. Advantages:
Relatively rapid onset
Cause amnesia
Relatively little cardiovascular effect
Anti-convulsant
Disadvantages:
Not analgesic
Cause respiratory depression
Long-acting (diazepam or repeated inj. of
midazolam)
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5. a. diazepam (Valium)
It is water-insoluble, so IV use requires a non-
aqueous vehicle which can cause local irritation/pain
b. midazolam (Dormicum)
- water soluble, so drug of choice for IV administration
- It has a more rapid onset and more rapid
elimination than the other BZ’s.
- The most potent amnestic
c. lorazepam (Ativan)
water-insoluble, less potent amnestic than
midazolam, but a more potent amnestic than
diazepam.
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6. Barbiturates
 The 3 main drugs used in this category are
thiopental, thiamylal, and methohexital.
 Primary Use: Induction of anesthesia
Advantages:
Rapid onset (10 - 30 sec)
Short duration (5 – 8 min) initial dose; redistributed
from brain to muscle; prolonged on repeated
injection
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7. Disadvantages:
Not analgesic
Decrease blood pressure
Decrease respiratory rate and tidal volume or
apnea.
Coughing, laryngospasm, bronchospasm.
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8. Opioids
Opioids produce moderate sedation and profound
analgesia. They exert their effects by binding with
opioid receptors in CNS ( 3 major opioid receptors μ
(mu), κ (kappa), and δ (delta).
The opioids most commonly used are
fentanyl
sufentanil citrate (Sufenta)
alfentanil (Alfenta)
remifentanil (Ultiva)
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9. Primary uses:
Analgesia
Advantages:
Profound analgesia
Relative cardiovascular stability
High potency, short duration (15-30 min.;
Remifentanil; 5 min) except morphine
Reduces emergence phenomena
Reversible by opioid receptor antagonists
Disadvantages:
Nausea
Slow gastric emptying
Respiratory depression at high doses (assisted 9

10. Fentanyl
A potent synthetic opioid agonist with between 50-
100 times the analgesic potency of morphine.
Used to aid induction and maintenance of general
anesthesia and to supplement regional and spinal
anesthesia.
Ability to maintain cardiac stability.
Sufentanil citrate (Sufenta)
 Rapid induction of analgesia (similar to Fentanyl)
 Compared to fentanyl and sufentanil, alfentanil has
a shorter duration of action because its high protein
binding and relatively low lipid solubility .
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11. Remifentanil (Ultiva)
Ultra short acting and rapidly cleared because
it’s ester linkages are susceptible to hydrolysis
by esterases in tissues and RBC’s.
Morphine
May produce hypotension and bronchoconstriction
as a consequence of its histamine-releasing
action.
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12. Ketamine
A complete i.v. anesthetic -causes “dissociative
anesthesia”
Primary uses:
Induction or anesthesia in at risk patients w/
cardiovascular problems
Sedation or general anesthesia in children
Advantages:
Cardiovascular stimulant
Bronchodilator
Profound analgesia and amnesia 12

13. Disadvantages:
Emergence reactions (not in children <15;
adults >65)
Increases intracranial pressure
Suppresses respiration (less severe than
other anesthetics)
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14. Propofol (Diprivan)
Primary uses:
A sedative/hypnotic
Induction or maintenance of general anesthesia.
Sedating intubated, mechanically ventilated
patients.
Advantages:
Rapid induction and recovery times even after
repeated injections
Anti-emetic properties
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15. Disadvantages:
Pain on injection
Involuntary muscular movement
Respiratory depression ,apnea
bradycardia and hypotension.
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16. Etomidate
Primary use: Induction in patients w/ cardiovascular problems
Advantages:
Rapid induction
Ultra-short acting (5 min)
No cardiovascular depression
Minimal respiratory depression
Disadvantages:
Pain on injection
Involuntary muscular movement
Nausea and vomiting
Hiccups
Not analgesic
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17. Inhalational Anesthetics
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18. Desflurane
Advantages:
Rapid onset and recovery of anesthesia (useful for
outpatient procedures)
One of least metabolized to toxic byproducts
Disadvantages:
Low volatility, so requires a special vaporizer
Pungent and irritating to the airway (leading to more
coughing, laryngospasm, so it is not as useful for
extended surgical procedures)
High inspired gas concentrations lead to a
significant increase in the patient’s BP & HR.
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19. sevoflurane:
Advantages:
Rapid onset and very rapid recovery of anesthesia
(useful with children)
Not as pungent as desflurane (also useful with
children)
Has good bronchodilating properties and is the agent
of choice in patients with asthma, bronchitis, and
COPD. It has little effect on the heart rate.
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20. Disadvantages:
Carbon dioxide absorbents in anesthesia
machines degrade sevoflurane to a fluorinated
hydrocarbon, which is degraded by renal lyase
enzymes to a thioacylhalide.
This compound has been observed to cause
necrosis of the proximal tubule in rats.
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21. Isoflurane:
Advantages:
It causes peripheral vasodilation and increased
coronary blood flow (useful in patients with
ischemic heart disease)
Disadvantages:
Moderate solubility, so recovery from anesthesia
may be delayed
Isoflurane can make the heart “more sensitive” to
circulating catecholamines (like epinephrine).
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22. Halothane
Used for induction in children (sweet
pleasant odor);
Toxicity – cardiac arrhythmias,
“halothane hepatitis” (rare).
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23. Nitrous Oxide
Not used alone (except where full anesthesia
not necessary; e.g. dental procedures);
Causes more nausea/vomiting;
 Contraindicated in patients with air filled cavities
(e.g. air embolus, pneumothorax, etc) or vitamin
B12 deficiency.
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24. Neuromuscular blocking
drugs
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25. D. Neuromuscular blocking
drugs
Used to perform tracheal intubation, facilitate
ventilation and to provide optimal surgical operating
conditions, for example during laparotomy.
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26. Depolarizing(Succinycholine)
Structurally similar to acetylcholine and function as
competitive inhibitors.
Very short duration of action
Metabolized very quickly by an enzyme called
plasma cholinesterase.
A useful drug in situations where muscle
relaxation is needed for only a short time such as
to facilitate intubation.
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27. Side effects :
Fasciculations .
Muscle pain
Bradycardia.
Increases in ocular and gastric pressure,
Hyperkalemia .
Anaphylaxis.
Malignant hyperthermia: a dramatic increase in
body temperature, acidosis, electrolyte
imbalance and shock 27

28. Nondepolarizing blockers
They act by competitively blocking the binding of
ACh to its receptors and inhibit muscular
contraction.
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29. Pancuronium bromide (Pavulon)
The first steroid NMBD in clinical use has a slow
onset and long duration of action.
It does not cause histamine release
Weak sympathomimetic properties and causes
tachycardia.
It is partly de-acylated in the liver to a metabolite
with neuromuscular blocking properties, and
partly excreted unchanged in the urine.
Its action is prolonged in renal and hepatic
impairment.
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30. Atracurium besylate (Tracrium)
Widely used and have an intermediate onset
and duration of action .
It causes release of histamine but has no direct
cardiovascular effects.
Metabolism is by Hofmann degradation and
ester hydrolysis in the plasma, hence its duration
of action is independent of renal and hepatic
function.
A breakdown product of atracurium, laudanosine
may accumulate due to very slow hepatic
metabolism and upon crossing into the brain
may cause seizures 30

31. Cisatracurium(Nimbex)
Isomer of atracurium
Less laudanosine formed .
Unlike atracurium it does not release histamine.
It is metabolised by Hofmann degradation and
does not accumulate in renal failure.
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32. Vecuronium
bromide(Norcuron)
Vecuronium is structurally similar to pancuronium
but has a slightly faster onset and shorter
(intermediate) duration of action.
It does not release histamine or have any
cardiovascular effects.
Metabolism in the liver occurs active metabolites
before being excreted in the bile and urine.
Lack of dependence on good kidney function for
elimination provide advantages over other
neuromuscular blocking agents.
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33. Rocuronium.
The most rapid onset of the clinically available
non-depolarizing NMBDs. Intubating conditions
can be achieved in 60-90 seconds after an
induction dose of 0.6 mg/Kg.
An intermediate duration of action .
Metabolised in the liver and excreted in the bile.
Minimal cardiovascular effects .
Does not release histamine,
Higher incidence of anaphylactic reactions
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34. Anticholinesterases
(Neostigmine)
(acetylcholinesterase inhibitors) are agents
that inhibit the action of the acetylcholinesterase
enzyme at the neuromuscular
junction.
 Clinical tests of adequate resolution of
neuromuscular block include the ability to lift the
head from the bed for 5 seconds,
 No role for anticholinesterases in reversing the
effects of suxamethonium.
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35. Side effects
Bradycardia, miosis, GI upset,
Nausea, bronchospasm, increased bronchial
secretions, sweating and salivation.
For this reason an antimuscarinic such as
glycopyrronium or atropine must be
administered along with the anticholinesterase
to minimise these effects.
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