Pre-Anesthetic Drugs Flashcards by Christina George

Atropine

Anticholinergic
Decreases vagal stimulation
Quicker action, slow duration
Best to use in emergency bradycardia

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Atropine Toxicity

Drowsiness
Dry mm
Excitability
Dilated pupils 
Tachycardia

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Glycopyrrolate

Anticholinergic
K9/Fel
Doesn't cross blood-brain barrier
Reduced risk of inducing cardiac arrhythmias
IV, IM, SQ, IT

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Major Effects of Anticholinergics

Prevention of bradycardia
Increased HR
Reduction of Respiratory, GI, Salivary and Lacrimal secretions 
Mydriasis
Bronchodilation

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Major Adverse Effects of Anticholinergics

Cardiac arrhythmias
Thickening of respiratory/salivary secretions
Inhibition of peristalsis

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Tranquilizer

Reduces anxiety (not necessarily mental awareness/wakefulness)

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Sedatives

A drug to cause reduced mental activity and sleepiness

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Phenothiazine

Non-controlled, water soluble sedative

Ex. Acepromazine Maleate

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Acepromazine Maleate

Phenothiazine-sedative
Wide safety margin
IV, IM, SQ, PO
No analgesic effects
Causes sedation, peripheral vasodilation (hypotension)
Anti arrhythmic effect
Antiemetic effect
Antihistamine effect

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Major Effects of Phenothiazines

Calming, sedation
Peripheral vasodilation
Anti arrhythmic effects
Antiemetic effects

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Major Adverse Effects of Phenothiazines

Reduction of seizure threshold
Hypotension
Penile prolapse (large animal)
Decreased PCV

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Benzodiazepines

Minor tranquilizers
Controlled, reversible drugs
IM, IV
Depress the CNS
Primary effects of increasing activity of endogenous GABA (inhibitory neuron)
Rapid onset, short duration

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Major Effects of Benzodiazepines

Anti Anxiety, calming (in old/ill)
Anticonvulsant
Skeletal muscle relaxation
Appetite stimulant (Fel, ruminants)

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Diazepam

Benzodiazepine 
Not water soluble
Fairly safe
Enhances analgesia/sedation
Light sensitive
Soluble in plastic

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Midazolam

Benzodiazepine
Water soluble
Light sensitive
Causes less tissue irritation
Reliable IM, SQ absorption 
Unreliable sedation in dogs

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Major Adverse Effects of Benzodiazepines

Disorientation, excitement (young/healthy dogs)
Dysphoria, aggression (Fel)
Ataxia, recumbency (Lg animal)
Muscle fasciculations (equine)
Pain at IM inj of diazepam

Alpha 2 Adrenoreceptor Agonists

“Alpha2Agonists”
Non-controlled drugs for sedation, analgesia, and muscle relaxation
Rapid sedation, reversible
IV, IM
Act on alpha2adrenergic receptors of the SNS within the CNS and peripherally
Metabolized in the liver/excreted as metabolites in the urine
Decreases release or norepinephrine

Major Effects of Alpha2Agonists

Dose-dependant sedation 
Analgesia
Decreased cardiac output and HR
Decreased BP
Decreased RR and tidal volume 
Muscle relaxation
Vomiting (k9/Fel)

Major Adverse Effects of Alpha2Agonists

Agitation, aggression when touched
Reaction to loud noises
Ataxia, falling (bovine)
Severe bradycardia, hypotension, decreased cardiac output 
Severe respiratory depression

Dexmedetomidine

Alpha2Agonist
“Dexdomitor”
Most common
IV, IM
Can cause profound sedation, short-lived analgesia
Antagonized by antipamezole (Antisedan)
*dont give w/Anticholinergics @high doses (paradoxic bradycardia)

Detomidine

Alpha2Agonist
Equine
Produces sedation, analgesia and muscle relaxation

Xylazine

Alpha2Agonist
Cattle require low doses due to tolerance level
First alpha2agonist in sm/Lg animal medicine

Opioids

Provide analgesia 
Derivative of opium
Can be used for anesthetic induction
May be agonists, partial agonists, agonist-antagonist, antagonists
Causes CNS depression 
Prevent/tx post-op pain, premed
Reversible 
Act centrally by inhibiting Brain perception and central sensitization on the spinal cord
Metabolized in the liver

Mu Opioid Receptor Agonists

Morphine
Fentanyl
Hydromorphone 
Oxymorphone 
Methadone
Meperidine 
Most potent analgesic effects, higher chance for adverse reactions 
Moderate-severe pain

Partial Mu Agonists

Buprenorphine Nalbuphine Less potent, less sedation, less adverse reactions

Agonist-Antagonist

Nalbuphine Butorphanol Less potent, less sedation, less adverse reactions

Morphine

Opioid Agonist, controlled drug Can be used IV, IM, SQ, epidural Provides analgesia, reduces cardiac afterload Primarily binds to Mu and Kappa receptors *may cause facial swelling and hypotension after rapid IV inj* Moderate-severe pain

Opioids Major Effects

``` CNS depression (k9) Excitement (Fel) Sedation Bradycardia Decreased RR and tidal volume ```

Major Adverse Effects of Opioids

``` Hyperventilation, miosis (k9) Mydriasis (Fel) Urine retention Salivation/vomiting Hypotension (from vasodilation) React to noise ```

Oxymorphone

``` Opioid Agonist Provides analgesia High potency/sedation, few adverse effects Expensive Doesn't induce histamine May cause vomiting, resp depression IV, IM, SQ, epidural ```

Hydromorphone

``` Opioid Agonist Provides analgesia Less potent then Oxymorphone Similar duration as of Oxymorphone Adverse Effects: resp depression, bradycardia, vomiting, panting, excess sedation, excitement ```

Fentanyl

``` Opioid Most potent analgesic Rapid onset, short duration IV, IM, SQ, epidural, transdermal patch Adverse effect: panting, noise sensitive ```

Butorphanol

Synthetic Opioid Agonist-Antagonist (can partially reverse effects of other Mu opioids) Used as premed, sedative, post-op pain control (mild-moderate visceral pain), cough suppressant SQ, IM, IV *toxic to spinal cord* Short duration Less sedation, dysphoria, resp depression Decreased HR, BP, cardiac output, some resp depression Adverse Effects: panting, vomiting, histamine release

Buprenorphine

Partial Mu Opioid Agonist Stimulates Mu receptors, provides some analgesia IV, IM, epidural, bucally (Fel) Delayed onset, longer duration Can reverse sedation, resp depression induced by Mu agonist opioids

Neuroleptanalgesia

The use of opioids with a tranquilizer to achieve a state of sedation and analgesia

Anticholinergics

"Parasympatholytics" Used to tx/prevent bradycardia, increases HR, reduces resp/GI/salivary/lacrimal secretions Causes mydriasis and bronchodilation Blocks the binding of Acetylcholine at the muscarinic receptors (target organ)

Naloxone

Antagonist for Opioids