Preanesthetic Drugs: Alpha 2 Agonists (Cram)

Alpha–2 agonists are also called what?

Thiazine derivatives

What are the three alpha–2 agonists commonly used in veterinary medicine?

1. Xylazine

2. Detomidine

3. Dexmedetomidine (medetomidine used less)

Fill in the blank: These drugs are called alpha–2 agonists because they act on specific alpha–2 receptors which causes a decrease in the neurotransmitter ________.

norepinephrine

Name some of the beneficial effects of alpha–2 agonist drugs (5 total)

1. Muscle relaxation

2. Reversal agents

3. Analgesia (good enough for minor procedures)

4. Potent sedation (appear almost anesthetized)

5. Short duration of action

Name some of the undesirable effects of alpha–2 agonists (9 total)

1. Vomiting

2. Hypotension

3. Bradycardia

4. Respiratory depression

5. Sudden aggressive behaviour

6. Abortion

7. Depress GI activity

8. Many contraindications (not good for high risk patients)

9. Risk to humans (absorbed through skin)

Which class of animal is very sensitive to alpha–2 agonists?

Ruminants

What is the generic name for the alpha–2 agonist Rompun®?

Xylazine

What is the generic name for the alpha–2 agonist Dexdomitor®?

Dexmedetomidine

What is the generic name for the alpha–2 agonist Dormosedan®?

Detomidine

Can xylazine and dexmedetomidine be administered SQ, IM, and/or IV?

IM or IV (carefully, drops BP)

What is the reversal agent for xylazine?

Yohimbine (Yobine®)

What is the reversal agent for dexmedetomidine?

Atipamezole (Antisedan®)

Why is detomidine prefered in horses over xylazine?

Detomidine lessens how much horses will kick

Fill in the blank: Both xylazine and detomidine are used in horses with ______ (for analgesia and sedation) but analgesia is effective enough that it may mask worsening condition

colic

What is the reversal agent for detomidine, yohimbine and/or atipamezole?

Both yohimbine and atipamezole

Dexmedetomidine (Dexdomitor®) can decrease blood pressure, respiratory rate, temperature, and heart rate. But what does it increase?

Dexmedetomidine increases urine production

True or false: The cardiovascular effects of dexmedetomidine (eg. very slow heart rate) are dose dependent, so dosing less makes this adverse effect less

False. The cardiovascular effects of dexmedetomidine (eg. very slow heart rate) are NOT dose dependent so dosing less does not make this adverse effect less – and nor does partial reversal of the drug