Exam 1: Preop Meds Flashcards by Carlos Valerio

Histamine Induces

contraction of smooth muscles in airways, secretion of acid in the stomach, release of NT in the CNS: ACh, Norepi, 5 HT

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Drugs that induce Histamine release

Morphine, mivacurium (Mivacron), protamine, atracurium (isomer of Nimbex)

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Treatment of Histamine Release

Must be treated with H1 and H2 antagonist.

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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.

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Histamine effects on H1

Hyperalgesia and inflammatory pain (insect stings). Allergic rhino-conjuctivitis symptoms

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Histamine effects on H2

Elevates CAMP (B1 like stimulation). Increases acid/volume production

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H1/H2 Receptor activation leads to

hypotension d/t NO release, capillary permeability, flushing, prostacyclin release, tachycardia

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H1 antagonist receptor locations

Vestibular system, airway smooth muscle, cardiac endothelial cells

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H1 receptor antagonists general effects

Motion sickness, possible protection against bronchospasm, provides some cardiac stability (indicated in anaphylaxis)

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H1 antagonists side effects

Blurred vision, urinary retention, dry mouth, drowsiness 1st gen

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List H1 antagonists

1st gen: diphenhydramine (Benadryl), promethazine (Phenergan)

2nd gen: cetirizine (Zyrtec), loratadine(Claritin)

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Diphenhydramine (Benadryl) uses

Antipruritic
Pre medication for Allergy to ivp dye or shellfish

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Diphenhydramine (Benadryl)
Dose and E 1/2

Dose: 25-50 mg IV
E 1/2: 7-12 hours

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Promethazine (Phenergan) use

Anti emetic

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Promethazine (Phenergan)
Dose, onset and E 1/2

Dose: 12.5- 25 mg IV
Onset: 5 minutes
E 1/2: 9-16

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Promethazine (Phenergan) black box warning

Respiratory arrest in <2 years old
Necrosis if infiltrated

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H2 antagonist most common use

Duodenal ulcer disease/GERD

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H2 antagonist action

Decreases hypersecretion of gastric fluid (H+)
Decreases gastric volume (less amount to be aspirated)
Decreases pH (less acidic gastric aspirate)

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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%

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H2 antagonist drugs

Cimetidine (Tagamet)
Ranitidine (Zantac)
Famotide (Pepcid)

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Tagamet dose

150-300 mg IV
1/2 dose for renal impairment

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Cimetidine (Tagamet) metabolism

Met. By liver. Strongly inhibits CYP450.
Prolongs effects of many other drugs

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Tagamet side effects

Brady, hypotension.
Increased prolactin levels
Inhibits dihydrotestosterone binding to androgen receptor (male breast growth)

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Ranitidine (Zantac) metabolism

Hepatic metabolism, renal clearance.
Less inhibition of hepatic enzymes than Tagamet

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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.

Exam 1: Preop Meds Flashcards

(67 cards)