- Females (#1) - PONV Hx (#2) - Non-smoker (#3) - Age PONV than R) - Volatile anesthetics and N2O - > Duration of procedure (q 30 min > risk -60%) - Type of procedure (cholecystectomy, gynecological, laparoscopic) Risk factors 1:20%, 2:40%, 3:60%, 4:80%

- Dexamethasone - 5HT3 (Serotonin) antagonists - H1 Blocklers (antihistamines) - Scopolamine Patch (anticholinergic) - NK1 antagonists - Droperidol -Hydration (ensure correct fluid status before incision.

GI Medications Flashcards by Gary Whitaker

General pop __% vomiting, __% nausea

N/V % in > risk patients?

N/V may > d/c time by __%

30%v, 50%n

70-80%

25%

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Pathways that effect N/V:

Medulla
Chemoreceptor “TRIGGER ZONE”
Neural path in vestibular system
Reflex afferent pathways
Midbrain afferents

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Chemoreceptor Trigger Zone:

Located outside BBB, these meds don’t have to be super lipophilic to act.

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The Vomiting Center is in the _______.

Medulla

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Post Op N/V

Early, Late, Delayed

Early: 2-6 hours
Late: 6-24 hours
Delayed: >24 hours

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What is “Post-Op N/V?

N/V 24 hours or later after surgery (post dc)

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> PONV Risk Factors

Females (#1)
PONV Hx (#2)
Non-smoker (#3)
Age <50
General vs Regional (G > PONV than R)
Volatile anesthetics and N2O
> Duration of procedure (q 30 min > risk -60%)
Type of procedure (cholecystectomy, gynecological, laparoscopic)

Risk factors 1:20%, 2:40%, 3:60%, 4:80%

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PONV dc > Risk Factors:

Female
< 50 y/o
Hx of PONV
Opiates in PACU
Nausea in PACU

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Risk Factors for Children N/V:

Procedure > 30 Mins
> 3 y/o
Strabismus (eye) surgery
Hx of or a relative who had Hx PONV

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Who needs pretreatment?

Anyone who has 3 or more risk factors need pre-Tx for PONV

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Anesthesia Considerations

Propofol
Regional “9x lower incidence of PONV to use R rather than G”
NSAIDS over Opiates
Don’t need to reduce Neostigmine dose any more

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7 Pre Tx Options:

Dexamethasone
5HT3 (Serotonin) antagonists
H1 Blocklers (antihistamines)
Scopolamine Patch (anticholinergic)
NK1 antagonists
Droperidol

-Hydration (ensure correct fluid status before incision.

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Is Reglan a supported PONV med?

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Rescue Meds

5HT3 (serotonin) antagonists
D2 blockers
Reglan
H1 Blocker

(Try a different med with a different mech of action)

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What % of pt will experience some sort of PONV?

1/3 (especially with > risk patients)

Give dexamethasone (longest duration of action)

Scopolamine patch

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When to give anti NV meds
-setron (serotonin agents)
Dexamethasone
Scopolamine Patch
Aprepitant

-setron (serotonin agents): End
Dexamethasone : Before induction
Scopolamine Patch: prior evening
NK receptor antagonist (Aprepitant): 1-3 hours prior

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What anti NV med is the best?

None. All equally effective

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5HT3 Serotonin Antagonists

…setron (ondansetron …)

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Where are the 5HT3 receptors primarily located?

GI tract

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5HT3 Antagonists are metabolized by the _____.

Liver (CYP450)

Dolasetron needs to be metabolized 1st before it is active (prodrug)

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Half life of 
Ondonsetron
Granisetron
Dolasetron
Palonosetron

Ondonsetron: 4 hours
Granisetron: 9-11 hours
Dolasetron: 7-9 hours
Palonosetron: 40 hours

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Side effects of 5HT3 Antagonists

EKG QT prolongation (Torsads)

Mild constipation/Diarrhea, Nausea, dizziness

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Dexamethasone is a ___________.

Corticosteroid

Endorphin release
Prostaglandin antagonist

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Dexamethasone Side Effects:

Impaired wound healing/infection
> glucose
HTN, edema
AMS

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1/2 life of Dexamethasone

35-54 hours

Dexamethasone onset

4-6 hours

Droperidol is a ___________

Anti-dopaminergic

Droperidol works on the ____ receptor.

Other effects of Droperidol other than being anti-dopaminergic?

Mild Antihistamine | Mild antiserotonergic

Chemoreceptor trigger zone relates to what drug?

Droperidol

Does > 5 mg of droperidol could cause?

``` QT prolongation (Torsades) (Rare)(like Zofran) ```

Side Effect of Droperidol:

Dysphasia Hypotension Extra Perametal Symptoms (movements, jerks).

Parkinsons is too > or < of dopamine?

Decreased

Too much of dopamine leads to ________.

Euphoria

1/2 life of Droperidol?

2.3 hours

Droperidol is metabolized by the _____

Liver (hepatic)

Phenothiazines (phenergan and compazine) are ...

D2 Receptor antagonist

Phenothiazines are metabolized ...

Hepatic (CYP)

1/2 life of Phenothiazines

4-8 hours

Phenothiazines and H1 Antagonists are highly _________.

Sedating

H1 Antagonists (antihistamine)

Dimenhydrinate (Dramamine) (CNVIII) Histamine (1) Highly sedating

Scopolamine Patch

Anticholinergic | Prior to surgery or 4 hours after waking up.

Aprepitant (Emend)

Neurokinin 1 Receptor Antagonist (Blocks substance P) -Brain stem -Dorsal vagal complex CYP3A4 Not many side effects

1/2 life of Aprepitant (Emend)is...

9-13 hours

Aprepitant (Emend) is highly _______ _______.

Protein bound

Metoclopramide (Reglan)

``` Dopamine antagonist (Antagonizes dopamine’s effect on the CTZ and contribute to an antiemetic effect) ``` > L.E.S. tone > peristaltic contraction > gastric emptying Does NOT alter gastric H+ ion secretion

Metoclopramide (Reglan) ____ metabolism with _______ elimination.

Hepatic (CYP with extensive 1st pass effect) Renal

Adjust the dose of Reglan on w pt with....

Renal impairment (prolongs 1/2 time)

Metoclopramide (Reglan) is excreted in _______ _____.

Breast milk

Does Metoclopramide (Reglan) readily cross BBB and placental barriers?

Yes.

Side effects of Metoclopramide (Reglan)

Abd cramping Akathesia (restlessness) Systolic extrapyramidal reactions

Interaction and cautions with Metoclopramide (Reglan):

Inhibit effect on plasma cholinesterase > sedative actions of CNS depressants > extrapyramidal reaction (additive effect) Avoid with Hx seizure or mechanical gastric outlet obstruction.

Metoclopramide (Reglan) helps to < ...

Aspiration risk. | < gastric volume, not pH change

________ ______ can be caused by a fast administration of Metoclopramide (Reglan)

Gastric cramping

H2 Receptor Antagonist inhibit histamine binding to the receptors on ____ ______ _____.

Gastric parietal cells

H2 Receptor Antagonist produce _______ and _______ inhibition of H2 receptor mediated secretion of acidic gastric fluid.

selective and reversible

H2 Receptor Antagonist drugs end in ...

“tidine”

Most potent H2 Receptor Antagonist:

Famotidine

Least potent H2 Receptor Antagonist:

Cimetidine

Shortest acting H2 Receptor Antagonist drug:

Cimetidine

Histamine activated _______ ______ buy binding to H2 receptors on parietal cells.

Adenylate cyclase

H2 Receptor Antagonist do or don’t have a consistent effect on L.E.S. function or the rate of gastric emptying?

Don’t

How long to give oral H2 Receptor Antagonist before surgery?

1.5 - 2 hours

Do H2 Receptor Antagonist reduce gastric volume?

No. Just changes the pH

H2 Receptor Antagonist Clinical Uses:

Allergic prophylaxis | Drug-induced histamine release

With only H2 receptor antagonism, effects of drug-induced histamine release may actually be _________.

Exaggerated

To with only an H1 or H2 antagonist alone is not effective in preventing the _____________ effects of histamine

Cardiovascular

Side effects of H2 Receptor Antagonist

- Diarrhea, HA, fatigue, skeletal muscle pain. - Rare thrombocytopenia (< Platelets) - Mental confusion - Arrhythmias (rare) Brady, hypotension

What H2 Receptor Antagonist inhibits CYP450?

Cimetidine (Lesser extent ranitidine) This < metabolism for other drugs also leading to toxicity.

H2 Receptor Antagonist effect other drugs how?

Altered absorption by > gastric pH Acids helps absorb iron products, mag and calcium products, B12

PPIs end in ...

“prazole”

PPis are used to Tx:

Mod to severe GERD Hypersecretory disorders PUD

Onset of PPIs:

2-6 hours

What is faster onset on action PPIs or H2 Receptor Antagonist?

H2 Receptor Antagonist

Adverse reactions of PPIs

C. Diff Kidney injury Dementia < absorption (Ca, Fe, Mg, B12) (Confusion, arrhythmias, muscle weakness, fractures)

GI Medications Flashcards

(75 cards)