Pharm 16- Anesthetic Agents I Flashcards
Anesthetic agent
any drug used to induce a loss of sensation without or without unconsciousness
Adjunct
a drug that is not a true anesthetic, but htat is used during anesthesia to produce other desired effects such as sedation, muscle relatxation analgesia reversal neuromuscular blockage or parasympathethic blocker
4 Classifications of Anesthetic Agents and Adjuncts
Route of administration
Time of administration
Principal effect
Chemistry
Route of administration classificiations
Inhalant
Injectable
Oral
Topical
time of administration classifications
preanesthetic
induction
maintenance
Principle effect classificaitons
local vs. general sedatives and tranquilizers vs analgesics neuromuscule blockers anticholinergic agents reversal agents
Describe general anesthesia
Reversible
produced by administration of one or more anesthetic drugs
4 characteristics of general anesthesia
Unconsciousness
Immobility
Muscle relaxation
loss of sensation
Describe surgical anesthesia
A stage of general anesthesia
Analgesia and muscle relaxation
eliminate pain and patient movement during the proceudre
Sedation
CNS depression drowsiness drug-induced various levels slightly aware or unaware of surroundings aroused by noxious stimulation
What are the uses for sedation
minor proceudres
Tranquilization
calmness
patient is reluctant to move
aware of surroundings but doesn’t care
hyponosis
drug-induced
sleeplike state
impairs patient’s ability to respond to stimuli
patient can be arroused with sufficient stimulation
Narcosis
drug-induced sleep
patient is not easily aroused
associated with narcotic drugs
Local anesthesia targets what?
Small, specific area of the body
Local anesthesia produces what effect?
Loss of sensation to a specific area
Drug is infiltrated into the desired area
Where is topical anesthesia applied?
Body surfaces or a wound
What does topical anesthesia produce?
Superficial loss of sensation
What does regional anesthesia produce
Loss of sensation to a limited area of the body
Ex. nerve blocks, epidural
Balanced Anesthesia
Multiple drugs in smaller quantities
Maximizes benefits
Minimizes adverse risks
Gives anesthetist greater control
Agonists
bind to and stimulate target tissue; most anesthetic agents and adjuncts
Antagonists
Bind to target tissue but don’t stimulate reversal agents
Partial Agonists and Agonist-Antagonists
Opioids
Partial agonists
Agonist-antagonists
used to block pure agonists
Analgesia
most general anesthetics are not analgesics
Must provide analgesic pre- and post operatively
no pain perception while anesthetizes
Do true analgesics provide general anesthesia?
NO
Why shouldn’t you mix drugs in a single syringe?
They may not be compatible
What should you look for when mixing two drugs?
A precipitate
Most anesthetic agents and adjuncts are soluble in what?
Water
What is an example of a drug that is not water soluble?
Diazepam (Valium)
Opioids are derivatives of what?
Opium
Opioids produce what?
Analgesia and sedation; result of action on receptors in the brain and spinal cord
What can be used for anesthesia induction when combined with other drugs?
Opioids
How are opioids classified?
Agonists, partial agonists, agonist-antagonists, or antagonists
Common Opioid Agonists
Morphine (Contin) Oxymorphone (Oxycontin) Hydromorphone (Dilaudid) Fentanyl (Actiq, Duragesic) Meperidine (Demerol) Remifentanil (Ultiva) Hydrocodone (Vicodin)
Common Opioid Partial Agonist
Buprenorphine (Buprenex)
Common Opioid Agonist-Antagonists
Butorphanol (Stadol)
Nalbuphine (Nubain)
Pentazocine (Talwin)
Common Opioid Antagonists
Naloxone (Narcan)
Naltrexone (Depade, Revia)
Methynaltrexone (Relistor)
Which opioids are not controlled substances?
Antagonists and Nalbuphine
How are opioids administered?
IV, IM, SC, Oral, Rectal, Intranasal inhalant, transdermal, subarachnoid, and epidural
Describe the margin to safety for opioids
Wide; reversal agents
What are class C1 drugs used for?
Just for research
How do opioids work?
Mimic endogenous opioid peptides
-B-Endorphins, dynorphins, enkephalins “Runner’s High”
Prevent nerves from transmitting impulses; prevent presynaptic release of neurotransmitters, particularly excitatory afferent neurotransmitter; decrease perception of pain
Agonists MOA
Bind to and stimulate mu and kappa receptors
Best for moderate to severe pain
Partial Agonists MOA
For moderate pain- they have lower efficacy
Agonist-Antagonists
Typically bind to delta, mu, and kappa receptors but typically stimulate only kappa receptors (reversal agent/mild pain)
Antagonists MOA
Bind to but don’t stimulate delta, mu and kappa receptors (reversal agents)
What are the best things we have for severe pain?
Pure opioid agonists; used as a premedication for painful surgery
Effects of Opioids: CV Effects
Bradycardia, except meperidine which has antimuscarinic effects that can produce tachycardia
Effects of Opioids: Respiratory Effects
Decreased rate and tidal volume (dose-related)
Effects of Opioids: Cough Suppression
codeine (usually), morphine
Effects of Opioids: Miosis
Small pupil size
Effects of Opioids: GI
Salivation, vomiting by stimulation of the chemoreceptor trigger zone (CTZ)
Initial diarrhea, vomiting, flatulence
GI stasis follows initial GI stimulation
Effects of Opioid: Urinary Retention
Deaden ability to respond to a full bladder
Effects of Opioid: Histamine Release
Allergic rxns very common with morphine use
Avoid in asthmatics
Effects of Opioids: Intraoccular pressure and intracranial pressure
(in red)
What are opioids used for?
Cough Suppressants (codeine, dextromethorphan)
Preanesthetic
Analgesia
Acute pulmonary Edema (CHF)- vasodilation, reduce anxiety and “drowning”
Opioids as a preanesthetic
Agonists, partial agonists, agonist-antagonist
May be used along or in combination with:
Tranquilizers
Anticholinergics
Opioids as analgesia
prevent and tx postop pain
used with tranquilizer to produce neuroleptanalgesia
Neuroleptanalgesia
a state of quiescence, altered awareness, and analgesia produced by a combination of an opioid analgesic and a neuroleptic. “Tranquil dreaming”
What two types of drugs are used to create a neuroleptanalgesia?
Opioids
Tranquilizers
Opioids
Morphine
Buprenorphine
Butorphanol
Hydromorphone
Tranquilizers
Diazepam
Midazolam
Thorazine
Opioid Antagonists
Reversible undesirable effects (CNS/Respiratory depression)
Wake up the patient following sedation
Emergensices/overdoses
What are two examples of opioid antagonists?
Naloxone (Narcan) Hydrochloride
Naltrexone
Naloxone (Narcan) hydrochloride
IM- 5 minutes to reversal
or slow IV administration- 2 min to reversal
Duration of action 30-60 minutes
Naltrexone
Like naloxone but longer-acting and has the potential for liver toxicity
Tramadol (Ultram)
Like an opiate but not one
Usually give P.O.
Like opioids it is a weak centrally acting u receptor agonist providing moderately strong analgeisa
How does Tramadol (Ultram) work?
Blocks serotonin release and reuptake of norepinephrine
What is Tramadol (Ultram) prescribed for?
Rheumatoid arthritis
Fibromyalgia
Tramadol (Ultram) Side Effects
Similar to opioids but geerally milder (Except serotonin syndrome which can be fatal)
- Agitation
- Muscular tremors
- Sweating
- Hyperthermia
- Seizures
What type of problems are seen with tramadol (Ultram)
dependence and withdrawal problems with long-term use similar to opioids
How can tramadol (ultram) be partially reversed?
Opioid antagonists
Injectable Anesthetics
Can produce unconsciousness
Don’t provide analgesia or muscle relaxation
Used with other agents
Administered “to effect” IV
Name 3 injectable anesthetics
- Barbiturates
- Propofol
- Etomidate
Subclasses of barbiturates are based on what?
Duration of action OR chemical structure
Types of Barbiturates
Ultrashort
Short
Intermediate
Long-acting
OR: Oxybarbiturates vs Thiobarbiturates
Ultrashort Barbiturates
Thiopental Sodium & Methohexital
Induce general anesthesia
Short Barbiturates
Pentobarbital
Induce general anesthesia
Tx epilepsy
Oxybarbiturates
Penobarbitol
Pentobarbital
Methohexital
Thiobarbiturates
Thiopental and thiamylal
Action of Barbiturates
Not fully understood
Mimics inhibitory neurotransmitter GABA
Causes CNS depression and loss of consciousness
Termination effect: agent leaves brain; is metabolized, excreted, or redistributed
A “Normal” dose of barbiturates could produce what
Prolonged unconsciousness or death in hypoproteinemia
Protein Binding- Barbiturates
Free (unbound) drug enters the brain
Hypoproteinemia results in more free drug
Increased drug amounts to brain
Thiopental
Ultra short-acting
Redistributed to muscle and fat slowly released
Continuous or repeated dosing may lead to full muscle nad fat and prolonged recovery, amking it “seem” like a longer-acting drug (first order»_space; zero order kinetics)
Methohexital
Ultra short acting
Redistributed to muscle nad fat but released faster
Muscle and fat don’t get “full” saturate so there is no prolonged recovery with continuous or repeated doses (zero order kinetics avoided)
Phenobarbital
Long acting
Sustained effect caused by slow uptake and rleease from the brain, therefore good for seizure disorders.
Release is dependent on kidney excretion which is slowest
Pentobarbital
Short acting
Brain levels decresae based on liver metabolism
Faster than kidney excretion
What is the #1 drug for anesthetic induction in most of hte owrld?
Propofol (PropoFlo, Diprivan)
How is propofol’s action terminated?
Both metabolized by liver and excreted by the kidneys, the primary way Propofol’s action is terminiated is by redistribution
