Week 7: GI Meds Flashcards
Scopolamine
- Mechanism of action
- Use
- Side Effects
- Anticholinergic
- Prevention of motion sickness and PONV
- Sedation, cyclopegia, aniscoria, and drying of secretions -> central anticholinergic syndrome: restlessness, hallucinations, somnolence, unconsciousness
Metoclopramide
- Mechanism of action
- Use
- Key points
- Benzamide: Dopamine antagonist: stimulates GI tract via cholinergic mechanism-> increases gastric and small intestinal motility
- PONV, pre-operatively to decrease gastric contents in a patient that is not NPO, is obese, trauma, DM or parturients (needs 20-30 minutes to work)
- **DO NOT use with Parkinson’s Disease or Restless Leg Syndrome because of effects on Dopamine pathway
Droperidol
- Mechanism of action
- Use
- Key points
- Butyrophenone: effects dopamine pathway
- PONV (rescue or intra-op)
- Black box warning for long QT: need previous 12 lead
Dexamethasone
- Mechanism of action
- Use
- Key points
- Corticosteroid: mechanism not fully known
- PONV
- Synergistic effect with zofran; Caution with diabetic patients; Use low dose (4mg) for antiemetic effects
Ondansetron
- Mechanism of action
- Use
- Metabolism
- Dose
- 5-HT3 receptor antagonist: receptors in GI tract (vagus) and Brain (CTZ)
- Nausea
- Metabolized in liver, excreted in urine and stool
- 4mg IV or 8mg oral dis
**Half life is 4 hours and is BETTER at the end -> give at the end of the case
Granisetron
- Mechanism of action
- Use
- Metabolism
- Dose
- 5-HT3 receptor antagonist: receptors in GI tract (vagus) and Brain (CTZ)
- Nausea
- Metabolized in liver, excreted in urine and stool
- 1mg
Palenosetron
- Mechanism of action
- Use
- Metabolism
- Dose
* *Advantages
- 5-HT3 receptor antagonist: receptors in GI tract (vagus) and Brain (CTZ)
- Nausea
- Metabolized in liver, excreted in urine and stool
- .075 mg, .25 mg
- *Newest, greatest affinity for 5HT3, WORKS FOR 72 hours (give at beginning of case)
- **NO QT prolongation
Promethazine
- Mechanism of Action
- Use
- Cons
- Histamine Receptor Antagonist
- Rescue for nausea or for motion sickness due to high number of histamine receptors in vestibular center
- Sedating, Drying
**BAD if infiltrates in IV
Diphenhydramine
- Mechanism of Action
- Pros
- Cons
- Histamine Receptor Antagonist
- Rescue for nausea or for motion sickness due to high number of histamine receptors in vestibular center
- Sedating, Drying
Dimenhydrinate
- Mechanism of Action
- Pros
- Cons
- Histamine Receptor Antagonist
- Rescue for nausea or for motion sickness due to high number of histamine receptors in vestibular center
- Sedating, Drying
Aprepitant
- Mechanism of Action
- Pros
- Cons
- Neurokinin-1 antagonist
- Lasts up to 48 hours, as effective as zofran
- Must be taken PRE-OP (3 hrs before anesthesia), expensive and not covered by insurance, not a rescue
Propofol Key Points
- Subhypnotic doses have been shown to have antiemetic effect for PONV
- Mostly due to helping decrease use of volatiles (risk factor for PONV)
Clonidine
- Use
- Mechanism
- PONV
- Alpha 2 Agonist: Decreases opioid need, decreased PONV risk VS. direct effect??
* *Use with dexmedetomidine for a weak short lived antinausea effect
Midazolam
- Use
- Timing
- Some antiemetic effect
2. Can be given at end of case to decrease PONV -> subhypnotic dose during case was as effective as propofol use
Gabapentin
- Use/Mechanism
- Dose/Timing
- PONV due to opioid sparing effect
2. 600-800mg 2 hours pre-op
Sodium Bicarb
- Mechanism of action
- Key points
- Increases pH (neutralizes HCl)
- -Caution in renal patients
- Neutralization increases gastric motility and LES tone
Milk of Magnesia
- Mechanism of action
- Key points
- Neutralizes HCl to increase pH
- **Unique to MOM = NO ACID REBOUND
- prominent laxative effect
- systemic absorption can lead to neurologic, neuromuscular and cardiac effects
Ca++ Carbonate
- Mechanism of action
- Key points
- Neutralizes HCl
- Acid rebound
- Can increase plasma Ca++ levels transiently
- Can cause hypophosphatemia
Aluminum Hydroxide
- Mechanism of action
- Key points
- Neutralizes HCl
2. Acid rebound; Minimal systemic absorption
Na+ Citrate
- Mechanism of action
- Key points
- Neutralizes HCl
2. Non-particulate (aka clear)-> less risk of aspiration
Chlorpheniramine and Diphenhydramine
- Mechanism of action
- Side effects
- First generation selective H1 antagonist: act on muscarinic cholinergic and alpha adrenergic receptors
- Dry mouth, blurred vision, tachycardia, long QT, Sedation
Hydroxyzine
- Mechanism of action
- Side effects
- First generation selective H1 antagonist: act on muscarinic cholinergic and alpha adrenergic receptors
- Dry mouth, blurred vision, tachycardia, long QT, Sedation
Loratidine
- Mechanism of action
- Advantages
- Second generation highly selective H1 antagonist: act on muscarinic cholinergic and alpha adrenergic receptors
- NO CNS effects
Arivastine
- Mechanism of action
- Advantages
- Second generation highly selective H1 antagonist: act on muscarinic cholinergic and alpha adrenergic receptors
- NO CNS effects
Azelastine
- Mechanism of action
- Advantages
- Second generation highly selective H1 antagonist: act on muscarinic cholinergic and alpha adrenergic receptors
- NO CNS effects
Cimetidine
- Mechanism of Action
- Use
- SE
- H2 antagonist: selective, reversible inhibition of H2 receptor mediated secretion of hydrogen ions from parietal cells
- Prevent aspiration in at risk individuals (not routine for everyone)
- HA, somnolence, confusion, bradycardia, hypotension
**Many drug interactions
What drugs increase Cimetidine plasma concentrations?
- Warfarin, propranolol, nifedipine, lidocaine, meperidine, procainamide
(even more)
Famotidine
- Mechanism of Action
- Use
- SE
- H2 antagonist: selective, reversible inhibition of H2 receptor mediated secretion of hydrogen ions from parietal cells
- Prevent aspiration in at risk individuals (not routine for everyone)
- HA, somnolence, confusion, bradycardia, hypotension
Ranitidine
- Mechanism of Action
- Use
- SE
- H2 antagonist: selective, reversible inhibition of H2 receptor mediated secretion of hydrogen ions from parietal cells
- Prevent aspiration in at risk individuals (not routine for everyone)
- HA, somnolence, confusion, bradycardia, hypotension
Omeprazole
- Mechanism of Action
- Use
- SE
- Proton pump inhibitor: block hydrogen movement to suppress stomach acid
- PONV
- Crosses BBB so can cause HA, agitation, confusion; also bacterial overgrowth due to acid suppression; Calcium leaching (should supplement)
Pantoprazole
- Mechanism of Action
- Use
- SE
- Proton pump inhibitor: block hydrogen movement to suppress stomach acid
- PONV
- Crosses BBB so can cause HA, agitation, confusion; also bacterial overgrowth due to acid suppression; Calcium leaching (should supplement)
Lansoprazole
- Mechanism of Action
- Use
- SE
- Proton pump inhibitor: block hydrogen movement to suppress stomach acid
- PONV
- Crosses BBB so can cause HA, agitation, confusion; also bacterial overgrowth due to acid suppression; Calcium leaching (should supplement)