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Flashcards in Promethazine Deck (27):
1

What are the trade names for Promethazine?

Atosil, Phenergan

2

What is the formal drug classification for Promethazine?

H1 (1st generation H1 antagonist), D2, and Muscarinic Antagonist

3

What are the clinical uses of Promethazine?

-Sedation as an adjunct to anesthesia
-to prevent/relieve the symptoms of allergic rhinoconjunctivitis (sneezing, nasal and ocular itching, rhinorrhea, tearing, and conjunctival erythema)
-used in acute treatment of anaphylactic reactions to block further histamine-mediated vasodilation and resulting hemodynamic instability, as well as decreasing respiratory and other systemic complications
-H1 receptor antagonists are useful in the ancillary treatment of pruritis, urticaria, and angioedema.
-These drugs may also be administered prophylactically for anaphylactoid reactions to radiocontrast dyes
-Also used to treat motion sickness

4

What is the MOA of Promethazine?

-H1 receptor antagonists are presumed to act by occupying receptors on effector cell membranes to the exclusion of agonist molecules, without themselves initiating a response. For histamine receptor agonists this is a competitive and reversible interaction. H1 receptor antagonists do not inhibit release of histamine but rather attach to receptors and prevent responses mediated by histamine. H1 receptor agonists are highly selective for H1 receptors having little effect on H2 or H3 receptors. An increased understanding of molecular pharmacologic features of these drugs has resulted in their reclassification as inverse agonists rather than H1 receptor antagonists. H1 receptor antagonists act as inverse agonists that combine with and stabilize the inactive form of the H1 receptor, shifting the equilibrium toward the active state

5

What is the IV onset of promethazine?

3-5 minutes

6

What is the IV DOA of promethazine?

2-4 hours

7

Is promethazine protein bound?

like 93%

8

Whats the elimination half-life of IV promethazine?

9-16 hours

9

What is the Vd of promethazine?

171L

10

How is promethazine metabolized?

by the hepatic microsomal mixed function oxidase system; significant FIRST PASS Hepatic Extraction

11

What do H1-antihistamines do to hepatic enzymes?

INDUCE hepatic cytochrome P450 enzyme

12

Are the metabolites inactive or active? where are they excreted?

Inactive metabolites excreted by the kidneys

13

When does the ORAL dose of promethazine peak and last until?

1-4 hours after dosage and last about 3-6 hours

14

What is the mean plasma half-life for promethazine after IM administration?

about 9.8-3.4 hours

15

What are the CNS side effects of promethazine?

somnolence
diminished alertness
slowed reaction time
impairment of cognitive function
sedative side effects that may delay recovery when given immediately before the end of anesthesia
**May lower seizure thresthold

16

What are the anticholinergic side effects of promethazine?

dry mouth
blurred vision
urinary retention
impotence

17

What are some CV side effects of promethazine?

-tachycardia
-prolongation of the QT interval
-Heart Block
-Cardiac dysrhythmias
-vascular necrosis

18

What patients are prone to adverse cardiovascular effects of H1 receptor agonists

Patients with hepatic dysfunction, cardiac disorders associated with prolongation of QT interval, or metabolic disorders such as Hypokalemia or Hypomagnesemia may be especially prone to adverse cardiovascular effects

19

What are the contraindications with Promethazine?

-Hypersensitivity
-Severe CNS depression
-Glaucoma
-Prostate Hypertrophy
-drug formula may contain sodium bisulfite (increase risk of allergic reaction)

20

When is promethazine contraindicated with the pediatric population?

in pediatric patients less than 2 yrs old

21

When should you use EXTREME caution/ contraindication with Promethazine?

Use with caution in patients with:
-Parkinsons disease
-Severe Cardiac
-Renal
-Pulmonary
-or Hepatic Disease

22

What's promethazine's affect on hepatic enzymes? which enzymes?

Inhibits CYP2D6

23

What medications if combined with promethazine produce an additive effect?

Additive effects when co-administered with Anticholinergics, Anti-hypertensives, CNS depressants, QT prolonging agents

24

What medications when combined with Promethazine increases the risk of toxicity?

Lithium
TSAs
Propranolol
Valproic Acid

25

What drug does promethazine interfere with it's effects?

Promethazine may interfere with the effect of Levodopa! Avoid co-administration

26

Co-administration of promethazine with which drug can cause VTach?

Macrolide Antibiotics

27

What is the IV dosage of Promethazine?

6.25-25mg