Exam 1: Preop Meds Flashcards
Histamine Induces
contraction of smooth muscles in airways, secretion of acid in the stomach, release of NT in the CNS: ACh, Norepi, 5 HT
Drugs that induce Histamine release
Morphine, mivacurium (Mivacron), protamine, atracurium (isomer of Nimbex)
Treatment of Histamine Release
Must be treated with H1 and H2 antagonist.
Why must both H1 and H2 antagonist be given
Hit both receptors so you don’t have the effects from one of the receptors still active.
Histamine effects on H1
Hyperalgesia and inflammatory pain (insect stings). Allergic rhino-conjuctivitis symptoms
Histamine effects on H2
Elevates CAMP (B1 like stimulation). Increases acid/volume production
H1/H2 Receptor activation leads to
hypotension d/t NO release, capillary permeability, flushing, prostacyclin release, tachycardia
H1 antagonist receptor locations
Vestibular system, airway smooth muscle, cardiac endothelial cells
H1 receptor antagonists general effects
Motion sickness, possible protection against bronchospasm, provides some cardiac stability (indicated in anaphylaxis)
H1 antagonists side effects
Blurred vision, urinary retention, dry mouth, drowsiness 1st gen
List H1 antagonists
1st gen: diphenhydramine (Benadryl), promethazine (Phenergan)
2nd gen: cetirizine (Zyrtec), loratadine(Claritin)
Diphenhydramine (Benadryl) uses
Antipruritic
Pre medication for Allergy to ivp dye or shellfish
Diphenhydramine (Benadryl)
Dose and E 1/2
Dose: 25-50 mg IV
E 1/2: 7-12 hours
Promethazine (Phenergan) use
Anti emetic
Promethazine (Phenergan)
Dose, onset and E 1/2
Dose: 12.5- 25 mg IV
Onset: 5 minutes
E 1/2: 9-16
Promethazine (Phenergan) black box warning
Respiratory arrest in <2 years old
Necrosis if infiltrated
H2 antagonist most common use
Duodenal ulcer disease/GERD
H2 antagonist action
Decreases hypersecretion of gastric fluid (H+)
Decreases gastric volume (less amount to be aspirated)
Decreases pH (less acidic gastric aspirate)
H2 antagonist side effects
HA, diarrhea, skeletal muscle pain. Weakened gastric mucosa d/t bacteria, (increased pulmonary infections candida Albicans)
Bradycardia increase serum creatinine by 15%
H2 antagonist drugs
Cimetidine (Tagamet)
Ranitidine (Zantac)
Famotide (Pepcid)
Tagamet dose
150-300 mg IV
1/2 dose for renal impairment
Cimetidine (Tagamet) metabolism
Met. By liver. Strongly inhibits CYP450.
Prolongs effects of many other drugs
Tagamet side effects
Brady, hypotension.
Increased prolactin levels
Inhibits dihydrotestosterone binding to androgen receptor (male breast growth)
Ranitidine (Zantac) metabolism
Hepatic metabolism, renal clearance.
Less inhibition of hepatic enzymes than Tagamet
Ranitidine (Zantac) dose
50 mg diluted to 20cc over 2 minutes
1/2 dose renal impairment
Famotidine (Pepcid) metabolism
Hepatic with no P450 interference
How does famotidine (Pepcid) differ from other H2 antagonist
Most potent
E 1/2: 2.5-4 hours
Pepcid dose
20 mg IV
What precaution must be taken when giving Pepcid
Phosphate levels. Pepcid interferes with phosphate absorption leading to potential hypophosphatemia
How do PPIs work
They irreversibly bind to acid secretion pumps. This inhibits movement of protons across gastric parietal cells. Only works on pumps that are present. (New ones can be generated)
Why does the onset of PPI limit its use in surgery
The onset of 5 days makes it ineffective to start day of surgery.
PPI is most effective at
Decreasing gastric volume and acidity
PPIs are more effective that H2 antagonists in what conditions
Healing esophagitis/ulcers
Relieving GERD symptoms
Best pharm tx for Zollinger-Ellison Syndrome
PPI adverse effects
Bone fx, SLE, acute interstitial nephritis (extremely painful), C -Diff, vit B 12/Mag deficiency
Inhibits warfarin metabolism (increased bleeding risk)
Blocks enzyme that activates Plavix
Examples of PPIs
Omeprazole (Prilosec)
Pantoprazole (Protonix)
Lansoprazole (Prevacid)
Dexlansoprazole (Dexilent)- good result but too expensive. Insurance won’t approve
Omeprazole (Prilosec) dose
40 mg in 100 mL over 30 minutes
Omeprazole (Prilosec) side effects
HA, Agitation, confusion. Since drug crosses BBB.
Abd pain, n/v, flatulence, small bowel bacterial overgrowth
Pantoprazole (Protonix) dose
40 mg IV in 100 mL over 2-15 mins
Studies show PPI are treatment of choice for
GERD/gastroduodenal ulcers, acute upper GIB (PPI infusion post EGD)
Studies show Omeprazole is treatment of choice for
NSAID ulcerations
Studies show H2 antagonists are drug of choice for
Aspiration pneumonitis concerns
Particulate antacids properties
Aluminum or magnesium based. Aspiration contents still acidic
Examples: maalox and Mylanta
Non particulate antacids
Neutralize acids
Ex: sodium citrate (Bicitra)
Sodium Bicitra MOA
Prevents aspiration pneumonia NOT aspiration.
Increases intra gastric volume
Works immediately
Sodium Bicitra dose
15-30 mL PO
Metoclopramide (Reglan) dose
Dose: 10-20 mg IV over 3-5 mins (15-30 mins prior to induction)
Domperidone is a dopamine blocker that is diff from reglan in that it
Does not cross BBB
Droperidol (Inapsine) developed initially for
Schizophrenia and psychosis
Adverse effects droperidol (Inapsine)
Strong D2 antagonist extrapyramidal symptoms, neuroleptic malignant syndrome
Avoid with other CNS depressants
Droperidol (Inapsine) dose
Dose: 0.625-1.25 mg IV
5HT3 receptors are located
They are ubiquitous: kidneys, colon, liver, lung, stomach.
High concentration in brain and GI tract
5HT3 antagonists examples
Zofran
Kytril and Anzemet
The first 5HT3 antagonist
Ondansetron (Zofran)
Zofran side effects
QT prolongation
HA, diarrhea
Zofran dose. Plasma 1/2 life
4-8 mg IV
Plasma half life: 4 hours
Decadron dose
4 mg/8mg up to 12 and up if diff airway.
Decadron onset
Delay in onset of 2 hours.
Efficacy persists for 24 hours
Decadron timing of dose
Give 2 hours before closing d/t delay in onset
Side effects of Decadron
Perioperative hyperglycemia with DM patients. (Minimal effect with 1 dose).
Perineal burning/itching with rapid IV admin.
Anticholinergics drug
Scopolamine patch
Scopolamine patch dose, onset, peak?
Dose: 1 patch
Onset: 4 hours
Peak: 8-24 hours
Scopolamine side effects
Pupil dilation, sensitivity to bright lights
Benefit of scopolamine compared to other anticholinergics
Sedation, antisialagogue, decreased motion sickness WITHOUT causing increased HR or relaxation of smooth muscles.
SABA administration via inhaler
Inhaled for 5-6 seconds and hold breath for 5-6 seconds
How much of inhaled SABA reaches lungs? How much does this decrease with ETT
12% reaches lungs.
ETT decreases the delivery by 50-70%
Frequency of inhaled SABA
Q4H
Side effects of beta agonist
Tremor, tachycardia, hyperglycemia (unlikely for 1 dose) transient decrease in arterial oxygenation.
