Preop Flashcards
What cells release endogenous histamine?
- Basophils & Mast cells
What would be used to treat drug-induced histamine release?
- H1 & H2 antagonists
Histamine-1 receptor activation can mimic these other receptor types.
- Muscarinic
- Cholinergic
- 5HT3
- α-adrenergic
Histamine-2 receptor activation can mimic these other receptor types?
- 5-HT3
- β-1
What are the side effects of H1 antagonists?
- Drowsiness/sedation
- Blurred vision
- Urinary retention
- Dry mouth
What are four examples of H1 receptor antagonists?
- Diphenhydramine (Benadryl)
- Promethazine (Phenergan)
- Cetirizine (Zyrtec)
- Loratidine (Claritin)
What is the E ½ time of diphenhydramine?
7-12 hours
What is promethazine’s primary use?
What is it’s E ½ time?
- Rescue anti-emetic
- 9-16 hours
What are the black box warnings associated with promethazine?
- 2005: children under 2 shouldn’t take (resp depression)
- 2009 - Tissue extravasation injuries
What is the dosing of promethazine and when would one expect onset to occur?
- 12.5 - 25mg IV
- Onset: 5 minutes
Which H2 antagonist strong inhibits CYP450’s?
- Cimetidine
What is the dose for cimetidine?
What is the renal dose?
- 150 - 300 mg IV
- 150 mg IV
What is normal ranitidine dosing?
What is the renal dosing?
- 50 mg diluted in 20cc’s over 2 minutes
- 25 mg diluted in 20cc’s over 2 minutes
Which H2 antagonist is most potent and has the longest E ½ time? What is this E ½ time?
- Famotidine: E½ = 2.5 - 4 hours
What is the dose of famotidine?
What is the renal dose?
- 20mg IV
- 10mg IV
How do proton pump inhibitors work?
What is the onset of action for proton pump inhibitors?
- Irreversible binding to H⁺ pumps preventing acid creation.
- 3-5 days for full result.
What is pantoprazole dosing?
- 40mg in 100mL over 2-15 minutes
What is the time of onset for sodium citrate?
How long does it last?
What is the dose?
- Immediate onset
- Loses effectiveness in 30-60min
- 15 - 30 mL PO
What is the dosing for metoclopramide?
When should it be given?
- 10-20 mg IV over 3-5min
- 15-30 min prior to induction
What is the dose of Droperidol?
0.625 - 1.25 mg IV
What is the E ½ time of Ondansetron? Why is this relevant?
- 4 hours: dose must be given so that effect peaks towards end of the case.
What is the normal dose of Ondansetron?
- 4 - 8 mg IV
What is the normal dosing for dexamethasone? When would one consider giving more?
- 4 - 8 mg
- Consider 12mg if difficult airway or swelling exists.
What is scopolamine dosing and where do the patches need to be applied?
- 140mcg priming & 1.5mg over the next 72 hours.
- Apply to post-auricularly or on the back
