Pre-op Medications Flashcards
Histamines are endogenous substances that are released from ___________ and _______________.
Basophils; Mast Cells
What does histamine do to the airway?
What does histamine do in the stomach?
Histamine causes what NTs to be released in the CNS?
Contraction of smooth muscles in the airway.
Acid Secretions in the stomach.
Histamine will cause the release of serotonin, acetylcholine, and norepinephrine in the CNS.
What drugs will induce histamine release?
Morphine
Protamine
Mivacurium
Atracurium
When H1 histamine receptors are activated it can activate ______, _________, __________, and ________ receptors.
Muscarinic
Cholinergic
5HT3
Alpha-adrenergic
When H2 histamine receptors are activated, it can activate ________ and ________ receptors.
5HT3
Beta-1
When histamine binds to an H1-receptor what will be the result?
Hyperalgesia and inflammatory pain (insect sting)
Allergic rhino-conjunctivitis symptoms
When histamine binds to an H2-receptor what will be the result?
Elevate cAMP (Beta1-like stimulation, tachycardia)
Increase acid and volume production
Activation of both H1 and H2 receptors will result in what symptoms?
Prostacyclin Release
Capillary permeability
Tachycardia
Hypotension d/t release of NO
Flushing
What is the most accurate description of an antihistamine?
Inverse Agonist
They don’t prevent the release of histamine but responses
What are the effects of H1 receptor antagonists on the following areas?
Vestibular System:
Airway Smooth Muscle:
Cardiac Endothelial:
What are the effects of H1 receptor antagonists on the following areas?
Vestibular System: Effective for motion sickness
Airway Smooth Muscle: protection against bronchospasms
Cardiac Endothelial: provide cardiac stability
The first-generation H1 antagonist causes a lot of ____________ as a side effect.
sedation
Can you develop tachyphylaxis from H1 receptors?
No
What are the side effects of H1 receptor antagonists?
Blurred Vision
Urinary Retention
Dry Mouth
Drowsiness/Sedation (first gen)
What are examples of H1 receptor antagonist drugs?
Diphenhydramine (Benadryl)
Promethazine (Phenergan)
Cetirizine (Zyrtec)
Loratadine (Claritin)
This H1 receptor drug is mostly used as an antipruritic and pre-treat procedure-related allergy (IVP dye)
Benadryl
Diphenhydramine inhibits the afferent arc of the ________________.
Oculo-emetic reflex
Diphenhydramine can stimulate ventilation by augmenting the relationship of ____________ and ___________ drive.
Hypoxic, Hypercarbic
Only if given as a solo administration
What is the IV dose of Benadryl?
What is the half-time of Benadryl?
25-50mg IV
7-12 hours
Which H1 receptor antagonist is a great anti-emetic and is used as a rescue and reduces peripheral pain levels (anti-inflammatory effects).
Promethazine
What is the IV dose of Promethazine?
How long does it take to onset?
What is the half-time of Promethazine?
12.5-25mg IV (give less to the elderly)
5 minutes for onset
9-16 hours
What were the black box warnings for Phenergan?
Can cause death in children under the age of 2.
Can cause extravasation and ischemia to the tissue from IV injection.
H2 receptors antagonist are most commonly used in __________.
How does an H2 receptor antagonist work?
Duodenal ulcer disease / GERD
Decrease hypersecretion of gastric fluid (H+) from gastric parietal cells and decrease cAMP, which will decrease gastric volume and increase pH.
H2 receptor antagonist can increase serum creatine by _______% d/t competition for tubular secretion.
15%
What are the side effects of H2 receptor antagonists?
HA/Confusion (Elderly)
Bradycardia
Diarrhea
Skeletal Muscle Pain
Weakened Gastric Mucosa
Creatine Increase
Overgrowth of ____________ can increase pulmonary infections d/t weakened gastric mucosa from prolonged administration of H2 antagonist.
Candida Albicans
What are examples of H2 receptor antagonists?
Cimetidine (Tagamet)
Ranitidine (Zantac)
Famotidine (Pepcid)
How is Cimetidine metabolized?
CYP450, hepatic metabolism, renal clearance
Cimetidine strongly inhibits CYP 450 and can affect the metabolism of which drugs?
Warfarin
Phenytoin
Lidocaine
Tricyclics
Propranolol (Inderal)
Nifedipine
MEperidine
Diazepam
What are the adverse effects of Cimetidine?
Bradycardia
Hypotension (rapid infusion)
Increase Prolactin
Impotence (Inhibits dihydrotestosterone binding to androgen receptors)
What is the dose of cimetidine?
What about renal dosing?
150-300mg IV
75-150mg IV
How is Ranitine metabolized?
CYP450, hepatic metabolism, renal clearance
What is the dose of Ranitidine?
What about renal dosing?
50mg diluted to 20cc given over 2 minutes.
25mg diluted to 20cc given over 2 minutes.
How is Famotidine metabolized?
CYP450, hepatic metabolism, renal clearance
What interference is Famotidine involved with?
Interferes with phosphate absorption and can result in phosphatemia.
Bone fractures or hips hurting
What is the dosing for famotidine?
What about renal dosing?
What is the half-time for famotidine?
20mg IV
10mg IV
2.5-4 hours (most potent and longest of all H2 receptor antagonist)
What group of drugs irreversibly bind to acid secretion pumps and inhibit the movement of protons (H+) across the gastric parietal cells?
Proton Pump Inhibitors
How many days does it take for the onset of PPIs?
3 to 5 days