Antiemetics/ GI drugs Flashcards
Droperidol
- 2nd generation typical antipsychotic
- dopamine receptor antagonist
- butyrophenone (fluorinated derivative of phenothiazine)
Uses;
- antiemetic; reduce post-op N/V
- sedative
- antipruritic
- antipsychotic
MOA;
-“Theoretically” occupies GABA receptors; reduces synaptic transmission and causes buildup of dopamine in the synaptic cleft
-antiemetic effects come from blocking chemoreceptor trigger zone from dopamine stimulation
Dose;
-N/V; 0.6 - 2.5 mg IV
-Sedation; 2.5 - 10 mg IV
risk of QT prolongation
Pharmacokinetics;
- E1/2 time; 1.7 - 2.3 hours
- DOA; 12 hrs
- peak effect; 30 min
- Vd; 2L/kg
- Pb; highly
metabolized;
bio-transformed in liver
excreted by kidneys;
75% urine
22% feces
Side Effects;
- Large doses decrease can cause tachy dysrhythmias
- QT prolongation
- tornadoes de pointes (has occurred at low dose)
- Antidysrhythmic, protects against epinephrine induced dysrhythmia
- vasodilation; hypotension
- cerebral vasoconstrictor
- dysphoria
- hallucinations
- neuroleptic malignant syndrome (rare)
- Extra pyramidal signs; EPS
- increased with reglan
- worsens Parkinsons Disease
Contraindicated;
- hypersensitivity
- known or suspected QT prolongation
- QT prolongation agents (Class I & III antiarrhythmics)
Caution
- increased sedative effects with CNS depressants (barbs, Benzos, opioids, ETOH, antipsychotics)
- Hypotension with Inhales Anesthetics
- w/ Propofol have risk of N/V
- Black Box Warning
- All patients get 12 lead prior to administration of droperidol
- Must be monitored prior to and continued for 2-3 hrs
- Caution with patients at risk of developing QT syndrome (TCAs, erythromycin)
Ranitidine (Zantac)
Histamine H2 antagonist
increasing gastric pH, decreasing gastric volume, inhibiting gastric acid secretion
Uses;
- preop to increase gastric pH before induction; decreasing risk of aspiration pneumonitis
- short term therapy for Peptic ulcer disease
- treatment for GERD
- part of multimodal tx for H. Pylori
MOA;
- selectively and competitively blocks H2 receptors of gastric parietal cells; inhibits gastric acid secretion, decreases gastric volume and secretion of gastric fluids with high hydrogen ion concentration
- inhibits basal, nocturnal and stimulated gastric acid secretion
Dose;
PO; 50 - 200 mg
IV; 50 - 100 mg
decreases gastric pH within 1 hr
Pharmacokinetics;
- DOA; 1.5 - 4 hrs
- Vd; 1 - 2 L/kg
- Pb; 15%
Metabolism by liver
75% for PO and 30% for IV
Excretion by kidneys
27% unchanged for PO dose
50 - 70% unchanged for IV dose
Common Side Effects;
-Diarrhea
-Fatigue
-skeletal muscle weakness
Severe Side effects;
rare but increased risk with renal/ liver disease; older age
-CNS changes from interaction with cerebral H2 receptors
(headache, confusion, dizziness, hallucination, somnolence)
-CV effects from interaction with cardiac H2 receptors (arrhythmias, bradycardia, hypotension, heart block, vasculitis)
-hematological issues (thrombocytopenia, hemolytic/aplastic anemia, leukopenia, pancytopenia)
-rash
-increased LFTs
-acute pancreatitis
Contraindications;
- hypersensitivity
- PORPHYRIA
Ondasetrone (Zofran)
Selective 5 HT receptor antagonist (Serotonin; 5HT)
Antiemetic
Uses;
- anti-emtic
- controlling N/V that occurs with chemo
- prevention of PONV
MOA;
-block the 5HT receptor blocking serotonin both peripherally on vagal nerve terminal and centrally in the chemo receptor trigger zone
Dose;
Prophylaxis; 4 - 8 mg IV
over 2 - 5 min immediately following induction for most effective at decreasing PONV
Tx of PONV; 1 - 8 mg IV
Pharmacokinetics; IV -onset; 30 min -E1/2t; 3 -4 hours -DOA; 4 - 8 hours -Vd; 2.5 L/kg -Pb; 75%
metabolism;
95% by liver
excretion;
5% by the kidneys
Side Effects;
- may have anxiolytic effects
- headache
- diarrhea
- slight QT prolongation
- arrhythmias
- bronchospasm
Contraindications;
-hypersensitivity
Omeprazole (Prilosec)
Proton Pump Inhibitor (PPI)
anti-secretory
prodrug
Uses;
- Tx GERD, Peptic Ulcer Disease, Zollinger - Ellison Syndrome
- part of combination regimen to tx H. Pylori
MOA;
- prodrug; protonated into active from, irreversible inhibits the proton pump; H/K ATPase
- works on the pumps present on the gastric surface and further doses are required to inhibit newly generated proton pumps
- decreases both basal and stimulated gastric acid secretion
- peak effectiveness take 4 - 5 days
Dose;
IV; 40 mg
PO; 20 -80 mg 2-4 hrs before surgery or night before
Pharmacokinetics;
- Peak plasma level; 0.5 - 3.5 hrs
- Pb; 95%
Metabolism; by the liver then moves into gastric parietal cells and accumulates in the canaliculi
Excretion; none of the original drug excreted unchanged in urine
Side Effects;
- crosses the BBB
- headache
- confusion
- agitation
- dizziness
- rash
- diarrhea/constipation
- ab pain
Contraindicated
-hypersensitivity
Diphenhydramine (Benadryl)
First Generation Antihistamine
H1 receptor antagonist
Uses;
- Prevention and Tx of allergic reaction/ hypersensitivity to allergens/other drugs/ blood products (given with epi)
- Anti-emetic/ anti-nausae
- Anti-pruritic
- Anticholinergic
- Tx of motion sickness
- Parkinsonism/ EPS
- Sedation
- Prophylaxis for allergic reaction in atopic pt (w/ H2 antagonist and steroid)
MOA;
-competitively blocks H1 receptors from histamine on the effector cell; preventing effects of histamine peripherally (hypotension, tachycardia, bronchospasm)
Dose;
IV; 10 - 50 mg q 6 - 8hrs
PO; 25 - 50mg q 6 - 8hrs
Pharmacokinetics; -onset; Rapid E1/2t; variable 2 - 8 hrs up to 13.5 in elderly -DOA; 4 - 6hrs -Pb; 78%
Metabolism;
- significant 1st pass effect;
- extensive hepatic metabolism
Excretion;
-some excreted unchanged in urine
Side Effects; (anticholinergic effects) -dry nose/ mouth -hypotension -tachycardia -urinary retention -constipation -thickening of secretions -moderate somnolence -sedation; -parodoxial effect (excitation) in young pedi patients and elderly
Contraindications;
-premi, neonate, breastfeeding mom
Caution;
-administration near end of case can delay recovery from anesthesia
Metoclopramide (Reglan)
Dopamine (D2) receptor Antagonist
Pro-kinetic/gastrokinetic
(no change is gastric pH)
Antiemetic
Uses;
- Preop to decreases gastric volume
- Prevent PONV
- Tx Opioid induced N/V
- Used to improve drug absorption in people with slow gastric emptying
- Tx for GERD
MOA;
- Centrally; Antagonizes D2 receptor in the chemoreceptor trigger zone
- Peripherally; on the GI tract by increasing motility of the esophagus, stomach and intestine causing antiemetic effects
- 5HT receptor agonist causing increased/ coordinated peristaltic activity (pro-kinetic effect)
- promotes gastric emptying by increasing GI motility and increases LES tone
Dose;
IV; 10 - 20 mg over 3-5 min
Pharmacokinetics; -onset; 1 -3 min E1/2t; 2 - 4 hrs -DOA; 1 - 2 hrs -Vd; 2 - 4L/kg -Pb; 30 - 40%
Hepatic metabolism
Elimination; 40% unchanged in urine
Side Effects
- dysrhythmias
- Extrapyramidal symptoms (EPS)
- occulogyric crisis
- Ab cramping with rapid administration
- irritability/ agitation
- stimulates prolactin release; galactorrhea/ abnormal menstruation
Contraindication
- Bowel obstruction
- Parkinson’s disease
- Pheochromocytoma ; can cause HTN crisis
- Epileptics
Caution;
-crosses placenta
Sodium citrate (Bicitra)
Non-particulate Antacid
systemic alkalizer
Uses;
- preop to increase gastric fluid pH
- improves metabolic acidosis in pt with chronic renal insufficiency
MOA;
-sodium citrate has a pH of 8.4; directly neutralization of gastric pH
-metabolized into sodium bicarb (HC03) in the body raising systemic pH
Thought is that by increasing the gastric pH it will decrease the severity of aspiration pneumonitis in the high risk non fasted patent if aspiration of gastric fluid were to occur
Dose;
PO; 30 mL of 0.3 M
15 - 30 min before surgery
“if surgery gets delayed repeat 1hr after initial dose” Allen
Pharmacokinetics;
- pH 8.4
- effective within 15 - 20 min
Metabolism; completely oxidized by the liver
Excretion; <5% unchanged in the urine
Side Effects;
- unpleasant taste r/t to pH can cause N/V “throw it back like a shot” Nicole
- increased gastric volume; may decrease gastric emptying (give with reglan)
Contraindicated;
- low Na diet
- Severe renal impairment
Cimetidine
H2 receptor antagonist
Uses;
- Tx PONV
- Aspiration prophylaxis
- Tx PUD
- Tx GERD
MOA;
competitively inhibits H2 receptors of gastric parietal cells; blocking gastric acid secretion, increases gastric pH and decreases gastric volume
Dose;
IV 300 mg
PO 300 mg night before surgery and morning of
give slow over 15 - 30 min to prevent bradycardia, hypotension
Pharmacokinetics;
- onset; 45 - 90 min
- E1/2t; 1.5 - 2.5 hrs
- DOA; 4hrs
- Vd; 0.8 - 1.2 L/kg
- Pb; 20%
-metabolized by the liver
-75% excreted unchanged by the kidneys
(renal failure increases E1/2t)
Side Effects;
- venous irritation
- diarrhea
- headache
- fatigue
- skeletal muscle pain
- bradycardia
- hypotension
- cardiac dysrhythmias
- may exacerbate bronchospasm in asthmatics (blocking H2 bronchodilation that offsets H1 bronchoconstriction)
Contraindicated;
-hypersensitivity
Caution;
- asthmatics
- renal failure
- rapid administration
hepatic metabolism of many drugs effects by cimetidine (propranolol, diazepam, lidocaine, phenytoin, meperidine)
absorption of drugs can be. impaired from increased gastric pH
Famotidine (Pepcid)
H2 receptor antagonist
Uses;
- Tx PONV
- Aspiration prophylaxis
- PUD
- GERD
MOA;
(competitive) selective and reversible inhibition of H2 receptor; blocking secretion of gastric acid from parietal cells; increasing gastric acid pH and decreasing gastric volume and gastric acid secretion
(block H2 receptors; decreases intracellular cAMP; decreases H+ ion secretion by parietal cells)
Dose;
IV; 20 mg 15 min before surgery
over at least 2 min (can be given faster than ranitidine and cimetinde)
PO; 40 mg 1.5 - 3 hrs before surgery
Pharmacokinetics; crosses BBB onset; 30 min (IV) 1-2 hrs (PO) E1/2t; 3 hrs (increased in elderly) DOA; 8 - 12 hrs Vd; 1 - 1.5 L/kg Pb; 15 -20%
Metabolism; 30 - 35 % hepatic
Excretion 65 - 70% unchanged in urine
Side Effects;
- fatigue
- headache
- diarrhea
- skeletal muscle weakness
- *With rapid administration (histamine binds to H1 receptors)
- bradycardia
- hypotension
- cardiac dysrhythmias
- may exacerbate bronchospasm in asthmatics (blocking H2 bronchodilation that offsets H1 bronchoconstriction)
Contraindicated
-hypersensitivity
Caution;
- renal failure
- rapid administration
- asthmatics
absorption of drugs dependent on gastric pH may be impaired
Promethazine
Phenothiazines
Dopamine receptor antagonist
H1 receptor antagonist
Uses;
- Tx/ prophylaxis PONV
- Tx for anaphylaxis
- Tx blood transfusion rxn
- Sedation
MOA;
- Dopamine antagonist in the CRTZ, giving antiemetic effect
- H1 antagonist; blocking histamine from binding to H1 receptors (blocking hypotension, bradycardia, edema, itching, bronchoconstriction)
Dose; 6.25 -12 mg (max 25mg) Pharmacokinetics; -Onset; 5 min Following IV administration -E1/2t; 9 -16 hrs -DOA; 4 – 6 hrs
Liver metabolism
Side Effects;
- arrhythmias
- sedation
- burns in injection
- extravasation
- Fatal respiratory depression in kids under 2
Contraindicated
-under 2 years of age (fatal resp depression)/ comatose states
