Anesthesia premed drugs

Question 1

What are the anticholinergic drugs used? (2 total)

Answer 1

Atropine and Glycopyrrolate

Question 2

What class of drug is acepromazine?

Answer 2

Phenothiazine (Major tranquilizer)

Question 3

What are the benzodiazepine drugs? (2 total)

Answer 3

Midazolam and Diazepam

Question 4

What are the opioid drugs? (9 total)

Answer 4

Butorphanol, Hydromorphone, Morphine, Fentanyl, Oxymorphone, Buprenorphine, Remifentanyl, Methadone, Tramadol

Question 5

What is used to reverse opioid drugs in small animals? In wild animals?

Answer 5

Small animals: Naloxone

Wild animals: Naltrexone

Question 6

What are the A-2 agonists? (4 total)

Answer 6

Xylazine, Dexmedetomidine, Detomidine, Romifidine

Question 7

What is used to reverse an A-2 agonist?

Answer 7

Atipamezole

Question 8

What muscle relaxants are used in premedication? (2 total)

Answer 8

Guaifenesin (GG) and Dantrolene

Question 9

CV effects of anticholinergics? Side effects?

Answer 9

Tachycardia; cardiac arrest, hypertension

Question 10

Respiratory effects of anticholinergics?

Answer 10

Bronchodilation (increases airway dead space)

Question 11

Other possible effects of anticholinergics?

Answer 11

Regurgitation, acute glaucoma, dries airway secretions, intestinal paralysis (colic in horses); Atropine can cause sedation/coma (crosses BBB)

Question 12

Indications for use of an anticholinergic?

Answer 12

Prevention/treatment of bradycardia, young animals or brachycephalic breeds

Question 13

Contraindications for use of anticholinergics?

Answer 13

Tachycardia, hyperthyroidism, most heart dz, narrow angle glaucoma

Question 14

CV effects of A-2 agonists?

Answer 14

Strong vasoconstriction (leads to reflex bradycardia)

Question 15

Respiratory effects of A-2 agonists?

Answer 15

Mild respiratory depression; increase upper airway resistance (nasal edema in horses); low V/Q in horses (decreased PaO2); Bronchoconstriction, V/Q mismatch, lung edema, hypoxemia in ruminants

Question 16

Other possible effects of A-2 agonists?

Answer 16

Sedation, analgesia, reduce stress response; vasoconstriction; inhibit lipolysis; inhibit insulin release (hyperglycemia); sedative effect (dog, cat, horse, ruminant > pig), muscle relaxation; decreased salivation

Question 17

Indications for use of A-2 agonists?

Answer 17

Sedation of aggressive animals or in ICU, to manage post op airway obstruction; prevention/treatment of seizures

Question 18

Contraindications of A-2 agonists?

Answer 18

Too young or too old; hemodynamic instability; severely debilitated; not suitable for high risk patients

Question 19

Side effects of xylazine?

Answer 19

Vomiting most likely to occur in cats; may cause uterine contractions and abortions in cattle; less preferred in dogs

Question 20

What is the most commonly used A-2 agonist in small animals?

Answer 20

Dexmedetomidine

Question 21

What A-2 agonist is used for large animals?

Answer 21

Detomidine

Question 22

CV effects of phenothiazines?

Answer 22

Vasodilation and hypotension (especially in hypovolemic patients)

Question 23

Respiratory effects of phenothiazines?

Answer 23

Mild depression

Question 24

Other effects of phenothiazines?

Answer 24

No analgesia; antiemetic; antihistamine; anti-arrhythmogenic; inhibit platelet fxn; penile prolapse in horses

Question 25

Indications for phenothiazines?

Answer 25

Mild sedation for premed or post OP; prevention/treatment of opioid dysphoria; sedation for dogs w/ laryngeal paralysis; enhance sedative effects of xylazine in horses

Question 26

Contraindications for phenothiazines?

Answer 26

Hypovolemia, hemodynamic instability; very young or old patients; Von-Willebrand dz; breeding stallions; Boxers may be sensitive (bradycardia)

Question 27

CV effects of benzodiazepines?

Answer 27

Minimal effects

Question 28

Respiratory effects of benzodiazepines?

Answer 28

Minimal effects

Question 29

Other effects of benzodiazepines?

Answer 29

GABA receptor agonist; sedative, anticonvulsant, muscle relaxant effects; no analgesia

Question 30

Indications for benzodiazepines?

Answer 30

Treatment of seizures; for premed, combine w/ opioids, A-2 agonist, or both; for induction, combine w/ ketamine, barbiturates, or propofol

Question 31

T/F: Medazolam is more potent and has a longer duration of action than Diazepam

Answer 31

False. More potent, but shorter acting than Diazepam

Question 32

CV effects of opioids?

Answer 32

Minimal CV effects; may indirectly reduce BP by reducing sympathetic outflow from the brain; may cause bradycardia (increase parasympathetic tone; treat w/ atropine); improves CV fxn by reducing the doses of anesthetics needed (decrease MAC of inhalants)

Question 33

Respiratory effects of opioids?

Answer 33

May depress respiration; antitussive effect

Question 34

Other effects of opioids?

Answer 34

Analgesia (good for acute pain, not as good for chronic pain); nausea, vomiting, defecation, obstipation; hypothermia, post OP hyperthermia (cats), myosis (dogs), mydriasis (cats), inhibition of urination, noise sensitivity

Question 35

Which of the following opioids is most likely to cause vomiting? Least likely to cause vomiting? ``` Morphine Hydromorphone Methadone Fentanyl Butorphanol Buprenorphine Tramadol ```

Answer 35

Most likely: morphine (enters brain slowly) | Least likely: fentanyl (enters brain quickly)

Question 36

Indications for opioids?

Answer 36

Alone or in combination w/ benzodiazepines, benzodiazepines and ketamine (cats, small dogs), acepromazine, A-2 agonists (xylazine, dexmedetomidine); preoperative analgesia; treatment of acute and chronic pain

Question 37

What receptors do the different opioids affect?

Answer 37

``` Butorphanol: kappa agonist, mu antagonist Hydromorphone: full mu agonist Fentanyl: full mu agonist Oxymorphone: full mu agonist Buprenorphine: partial mu agonist ```

Question 38

Contraindications for opioids?

Answer 38

Avoid morphine in CNS patients (vomiting increases ICP); caution in renal dz (decrease GFR)

Question 39

CV effects of muscle relaxants?

Answer 39

Minimal effects

Question 40

Respiratory effects of muscle relaxants?

Answer 40

Minimal effects

Question 41

Other effects of muscle relaxants?

Answer 41

Causes skeletal muscle relaxation; improve the muscle relaxation effects of other drugs (e.g. xylazine)

Question 42

Indications for muscle relaxants?

Answer 42

Part of TIVA infusion protocols in horses ("triple drip"; GG + A-2 agonist + ketamine