Premedication

Question 1

MOA for Anticholinergics

Answer 1

competitive antagonist for muscarinic receptor

Question 2

Anticholinergics effects

Answer 2

o	CV- mainly tachycardia 
o	Lung- bronchodilation, reduces secretions & increases viscosity 
o	Eye- Mydriasis +/- increase IOP
o	GI- decreased motility 
o	CNS- sedation/ hallucination ( humans)

Question 3

What are two examples of anticholinergics?

Answer 3

Atropine and glycopyrrolate ( does not pass BBB or placenta)

Question 4

Metabolism differences with atropine

Answer 4

spp. dependent
• Dog & human- hydrolysis & excreted unchanged
• Cat & small ruminant- hepatic & renal esterase
• Rabbits have atropinase; so better to use glycopyrrolate

Question 5

Should anticholinergic be used as a premed?

Answer 5

No longer routinely used as premed, BUT should be used without hesitation to treat bradyarrhythmia & hypotension

Question 6

Phenothiazine MOA

Answer 6

D2, a1, H1 & muscarinic antagonist

Question 7

Phenothiazine Effects

Answer 7

o CV- potent vasodilation +/- antiarrhythmic
o GI- antiemetic, delay gastric emptying
o CNS- tranquilization (+ opioid= neuroleptoanalgesia), decreased MAC
 Less reliable than a2 agonist
o Hematologic: decreased hematocrit via vasodilation & decreased plt aggregation
o Antihistaminic
o Temperature: hypothermia

Question 8

Should I give acepromazine to a Boxer?

Answer 8

NO- can cause vasovagal syncope or CV collapse!

Question 9

Can acepromazine be reversed?

Answer 9

NO, it last 12 hours and relies on hepatic metabolism

Question 10

When should you not use acepromazine?

Answer 10

DO NOT use in pediatric, geriatric, debilitated & pt. with hepatic dysfunction
• Poor choice for aggressive or excitable patients because less reliable than a2 agonist!

Question 11

Acepromazine side effects

Answer 11

• Pro: good anti-emetic

* Con: vasodilation causing reduced BP, priapism, CV collapse in boxer (vasovagal syncope)

Question 12

Benzodiazepine MOA

Answer 12

allosteric modulator of GABA at GABA A receptor

NO DIRECT ACTION

Question 13

Benzodiazepine effects

Answer 13

sedation, anxiolytic, anticonvulsant & muscle relaxant

+/- excitement in healthy cat or dogs

Question 14

When should you use benzodiazepine as a sedative?

Answer 14

very young, very old, very sick, small ruminant and pigs

Question 15

CV & respiratory effect of benzodiazepine?

Answer 15

minimal

Question 16

Telazol spp. difference in metabolism:

Answer 16

Cat & Pig: Tiletamine > Zolazepam allowing for a smooth recovery

Dogs & Horses: Zolazepam > Tiletamine resulting in a rough recovery

Question 17

What is a competitive antagonist for benzodiazepines?

Answer 17

Flumazenil

Question 18

Why are ruminants more sensitive to a2 agonist?

Answer 18

Because have a2D receptor ( unique to ruminants)

Question 19

a2 agonist effects

Answer 19

 CNS- sedation (caution touch & sound sensitive) & analgesia
 GI- vomit & decreased motility
 CV- Biphasic & reduces CO!
• P1- increased BP & decreased HR
• P2- decreased BP & decreased HR
 Thermoregulation- decreased
 Respiratory: mild, cyanosis (turn grey), small ruminants can get pulmonary edema
 M/S: muscle relaxant
 Uterus: ecbolic effect (induce contraction)
 Renal: increased urine production
 Endocrine: hyperkalemia ( large cat) & endogenous insulin suppression causing hyperglycemia
 IOP & ICP: do not use rx if high, does not change but vomiting can increase!

Question 20

Should you give an a2 agonist to a neonate?

Answer 20

NO! They rely on HR to maintain CO!

Question 21

Why give a2 agonist?

Answer 21

Reliable (most recumbent, but horse will stay on feet), can be reversed, has analgesic effect and can be administered via a lot of routes.

Question 22

What are three a2 adrenergic antagonist?

Answer 22

1. Tolazoline
2. Yohimbine
3. Atipamezole

Question 23

What route should Atipamezole be given?

Answer 23

IM ONLY! IV is associated with sudden death