Promethazine Flashcards
Please note that the drug card information is for Educational Use ONLY, and the source is from Carrie Bowman's glossary of drug cards permitted by use of Georgetown NAP students. No permission is given to use these cards for anything other than as a study resource for our program.
What are the trade names for Promethazine?
Atosil, Phenergan
What is the formal drug classification for Promethazine?
H1 (1st generation H1 antagonist), D2, and Muscarinic Antagonist
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
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
What is the IV onset of promethazine?
3-5 minutes
What is the IV DOA of promethazine?
2-4 hours
Is promethazine protein bound?
like 93%
Whats the elimination half-life of IV promethazine?
9-16 hours
What is the Vd of promethazine?
171L
How is promethazine metabolized?
by the hepatic microsomal mixed function oxidase system; significant FIRST PASS Hepatic Extraction
What do H1-antihistamines do to hepatic enzymes?
INDUCE hepatic cytochrome P450 enzyme
Are the metabolites inactive or active? where are they excreted?
Inactive metabolites excreted by the kidneys
When does the ORAL dose of promethazine peak and last until?
1-4 hours after dosage and last about 3-6 hours
What is the mean plasma half-life for promethazine after IM administration?
about 9.8-3.4 hours
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
