Hydroxyzine

Question 1

Brand Name

Answer 1

Vistaril
Atarax

Question 2

Broad Category

Answer 2

Antiemetic / Antihistamine / Sedative

Question 3

Pharmacological Class

Answer 3

H1 receptor antagonist

Question 4

MOA

Answer 4

competitive H1 receptor antagonist blocking H1 receptors located in the solitary tract and ACh in the vestibular apparatus

Question 5

Indications / Clinical Uses

Answer 5

***PONV prophylaxis and treatment
- only thing we use it for really
antianxiety
antipruritic (particularly during pregnancy)
- not by us
Analgesic adjunt (rare)

Question 6

Perioperative Antiemetic dose / regimen

Answer 6

25 mg vistaril with 25 mg Ephedrine IM 20 mins before end of surgery

Question 7

Important note on availability

Answer 7

Current National Shortage

Question 8

Onset

Answer 8

15 - 30 mins

Question 9

Duration

Answer 9

4 - 12 hours

Question 10

CNS effects

Answer 10

marked sedation
somnolence

Question 11

Pain on injection?

Answer 11

Yes

Question 12

Precautions

Answer 12

HTN / Outpatient
- mixed with ephedrine due to CV effects of ephedrine and prolonged sedation of hydroxyzine

Question 13

Metabolism

Answer 13

Hepatic
- CYP3A4
- CYP3A5

Question 14

Active metabolite

Answer 14

Cetirizine

Question 15

Elimination

Answer 15

Renal

Question 16

Vd Considerations

Answer 16

Very high
- highly lipophilic
- extensive tissue distribution
- crosses BBB obvi

Question 17

Protein binding

Answer 17

High
80-90%
albumin

Question 18

Absolute Contraindications

Answer 18

Known hypersensitivity
Early pregnancy (fetal abnormailities in animal studies)
QT prolongation

Question 19

Precautions

Answer 19

Elderly
- increased anticholinergic effects and sedation
Renal impairment
- accumulation of active metabs
Hepatic impairment
- prolonged duration
Glaucoma / BPH
- Anticholinergic effects

Question 20

General Dose Range (PO or IM)

Answer 20

25 - 100 mg PO or IM