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SGU Pharm deck -term4 > GI - drugs > Flashcards

GI - drugs Flashcards

1
Q

Corroding Factors for Acid peptic disorders

A

Gastric acid
• Pepsin
• Bile
• Helicobacter pylori

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2
Q

Protective factors for acid peptic disorders

A

Secretion of mucus and bicarbonate
• Blood flow
• Mucosal cellular regeneration
• Prostaglandins

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3
Q

antacids overview ? PK ?

A
  • Weak bases obtained without prescription
  • Antacid + HCl -> salt + H2O
  • Therapeutic neutralization of low gastric pH protects esophageal mucosa from reflux corrosion.
  • Time of onset: 5 minutes • Duration of action: 30 mins – 1 hour
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4
Q

name antacids and ae ?

A
  • Aluminum Hydroxide – causes constipation.
  • Magnesium Hydroxide – causes osmotic diarrhea • Al and Mg often combined to produce no net change in bowel movements.
  • Calcium Carbonate – CO2 causes belching, can lead to metabolic alkalosis (milk alkali syndrome).
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5
Q

Anttacids drug interactions

A

Drug interactions
• Binding/ chelation of many drugs.
• Increased gastric pH alters dissolution of weakly charged drugs.
• Decreased absorption of co-administered tetracyclines, fluoroquinolones, itraconazole and iron.

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6
Q

H2 receptor antagonist overview and PK

A

Highly selective competitive inhibition at the parietal cell H2 Gs protein coupled receptor.
• Time of onset: 2.5 hours
• Duration of action: 4- 10 hours
•Tachyphylaxis develops in 2- 6 weeks

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7
Q

list H2 receptor antagonist and effects

A

Cimetidine – prototype with many adverse effects.
• Ranitidine, Famotidine, Nizatidine – second generation with no antiandrogenic or CNS adverse effects.

Effect of H2RAs on Gastric Acid Secretion
• H2RAs strongly suppress basal gastric acid secretion.
• Modest effect on meal stimulated secretion

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8
Q

H2 antagonist used for

A
  • GERD
  • PUD
  • Nonulcer dyspepsia
  • Prophylaxis against stress-related gastritis
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9
Q

List CIMETIDINE Ae

A

Gynecomastia, galactorrhea and male impotence. (Acts as a nonsteroidal anti-androgen and prolactin stimulant)
Crosses the blood-brain barrier (Confusion, dizziness and headaches)

Increased gastric pH:
•B12 deficiency and myelosuppression in long term use.

• Potent inhibition of CYP 450 system. (Increased serum concentration of many drugs including: • Warfarin • Diazepam •Phenytoin

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10
Q

proton pump inhibitor overview

A

vThe most potent inhibitors of gastric acid secretion.
• Inhibit 90–98% of 24-hour acid secretion.
• Irreversibly bind and inhibit the hydrogenpotassium (H+-K+) ATPase pump of gastric parietal cells
Suppress the final common pathway of gastric acid secretion.

PPIs effectively suppress both basal and meal stimulated gastric acid production

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11
Q

list Proton Pump Inhibitors

A

Drug names

•Omeprazole •Esomeprazole •Lansoprazole •Rabeprazole •Pantoprazole

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12
Q

PPI used for

A
  • Patients who fail twice-daily H2RA therapy
  • Severe symptoms of GERD that impair quality of life.
  • Peptic ulcer disease • H. pylori eradication • NSAID associated ulcers • Prevention of peptic ulcer rebleeding
  • Gastrinoma •Nonulcer dyspepsia •Prophylaxis against stress-related gastritis
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13
Q

AE of PPI

A
  • Generally safe drugs.
  • Diarrhea, abdominal pain and headache reported in less than 5% of patients

Current research shows some association of PPI use with :
•Vitamin B12 deficiency – due to reduced pepsin function •Increased risk of community acquired pneumonias and C. difficile colitis •Hypomagnesemia

• Osteopenia – possibly via reduced Ca2+ absorption or osteoclast inhibition. • All PPIs carry an FDA-mandated warning of a possible increased risk of hip, spine, and wrist fractures

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14
Q

CYP 450 interactions of PPI

A

Omeprazole may inhibit the CYP450 metabolism of:
• Warfarin • Diazepam • Phenytoin

  • Clopidogrel is a prodrug that requires activation by the hepatic P450 CYP2C19 isoenzyme.
  • CYP2C19 is inhibited by omeprazole, esomeprazole and lansoprazole.
  • Those PPIs may reduce clopidogrel activation in some patients.
  • Agents with minimal CYP2C19 inhibition (pantoprazole or rabeprazole) are preferred in persons taking clopidogrel
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15
Q

H. Pylori eradication triple therapy and quadruple therapy

A

Triple therapy for 10-14 days
• CLARITHROMYCIN + AMOXICILLIN + PPI
OR
• CLARITHROMYCIN + METRONIDAZOLE + PPI

Quadruple therapy for 14 days
• BISMUTH SUBSALICYLATE + METRONIDAZOLE + TETRACYCLINE + PPI

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16
Q

Mucosal Protective Agents

A

Misoprostol
Sucralfate
Bismuth-Subsalicylate

17
Q

Misoprostol overview

A
  • Analog of PGE1. • Binds the EP3 receptor stimulating the Gi pathway, to decrease gastric acid secretion.
  • Stimulates mucus and bicarbonate secretion.
  • Enhances mucosal blood flow.
18
Q

misoprostol uses ? AE? Pregnancy safe ?

A

Approved for prevention of NSAID-induced ulcers in high-risk patients.
• Diarrhea, abdominal pain and/or cramps, occur in 30% of patients.
• Contraindicated in pregnancy due to abortifacient effects.

19
Q

Sucralfate MOA

A

Sucralfate - salt of sucrose + sulfated aluminum hydroxide.
• Forms a viscous paste that binds selectively to ulcers.
• Negatively charged sucrose sulfate binds positively charged proteins forming a physical barrier.

Restricts further caustic damage.
• Stimulates mucosal prostaglandin and bicarbonate secretion.
• Limited to the initial management of gastroesophageal reflux disease in pregnancy

20
Q

Bismuth Subsalicylate

MOA ? uses ? AE

A

Bismuth subsalicylate (BSS) suppresses H. pylori. It has no neutralizing action on gastric acid.
• Used in quadruple antibiotic therapy of H. pyloripositive ulcers.
• Pepto-Bismol is widely used for dyspepsia and acute diarrhe
• Bismuth toxicity is rare.
• The metabolite bismuth sulfide causes harmless blackening of the stool, which may be confused with gastrointestinal bleeding.
• BSS can cause salicylate toxicity in combination with other salicylate products. Contraindicated in patients with renal failure

21
Q

Prokinetic agents

A 
bethanechol
neostigmine 
Erythromycin 
cisapride 
Metoclopramide
22
Q

erthromycin prokinetic effect

A
  • Antibiotic.
  • Agonist effects at the motilin receptor.
  • Rapid down-regulation of motilin receptors leads to early tolerance of this drug. Its use is limited to short courses.
  • Best established indication – diabetic gastroparesis
23
Q

cisapride prokinetic effect

A
  • Cisapride - 5-HT4 receptor agonist, 5-HT3 antagonist, direct smooth muscle stimulant.
  • Was commonly used for gastroesophageal reflux disease and gastroparesis.
  • No longer available in the U.S. because of its potential to induce serious and occasionally fatal cardiac ventricular arrhythmias.
24
Q

metoclopramide prokinetic effect

A
  • Metoclopramide • 5-HT4 receptor agonist • Vagal and central 5-HT3 antagonist • Dopamine (D2) receptor antagonist
  • Effects confined to the upper digestive tract: • Increases lower esophageal sphincter tone • Stimulates antral and small intestinal contractions
25
Q

metoclopramide indications

A

Indications
• Gastroparesis • Anti-emetic • Previously used in GERD for symptomatic relief. Acid suppression therapy is far more efficacious and now preferred.

26
Q

metoclopramdie AE

A

Adverse effects
• Extrapyramidal effects, due to DA antagonism. Occurs more commonly in children and young adults, at higher doses.
• Galactorrhea by blocking the inhibitory effect of dopamine on prolactin release. Rarely seen clinically.

27
Q

cannabinoids AE-Antiemetics

A

Paranoid reactions and thinking abnormalities.
• Abrupt withdrawal of dronabinol → an abstinence syndrome (irritability, insomnia, and restlessness).
• Prescribe with great caution to persons with a history of substance abuse.
• Marijuana-like “highs”.
• Prominent central sympathomimetic activity results in: • Palpitations, Tachycardia, Vasodilation, Hypotension, Conjunctival injection (bloodshot eyes

28
Q

cannabinoids MOA ? -Antiemetics

A

Dronabinol (Δ-9-tetrahydrocannabinol) is a naturally occurring cannabinoid.
• Synthesized chemically or extracted from the marijuana plant, Cannabis sativa.
• Stimulates CB1 receptors in the brainstem.
• Prophylactic agent in patients receiving cancer chemotherapy, when other anti-emetic medications are not effective

29
Q

Benzodiazepine drugs ? uses ? action ?-Antiemetics

A

• Lorazepam • Alprazolam • Diazepam

  • Do not have intrinsic antiemetic effects. • Useful adjuncts due to sedative, amnesic, and anti-anxiety effects which reduce the anticipatory component of nausea and vomiting. • Facilitate GABAA action in the central nervous system by increasing the frequency of chloride channel opening.
  • Adverse effects include CNS depression and dependence.
30
Q

Corticosteroids-Antiemetics

A

• Dexamethasone • Methylprednisolone

  • Highly effective adjuvants in the treatment of nausea in patients with metastatic cancer.
  • Via suppression of peritumoral inflammation and prostaglandin production
31
Q

D2 Antagonists-Antiemetics

A

• Promethazine • Droperidol

  • D2 receptor antagonism at the CTZ. • Antihistaminic and anticholinergic properties effectively treat motion sickness. • Not very effective in CINV.
  • Potential for adverse extrapyramidal effects.
32
Q

NK1 Antagonists -Antiemetics

A

anti emetic
• Aprepitant
• Parenteral formulation – fosaprepitant
• Antagonists of the NK1 receptors for substance P.
• Indicated for prophylaxis against delayed CINV, caused by moderate to highly emetogenic drugs.
• Given orally in combination with dexamethasone and a 5-HT3 receptor antagonist.
• Aprepitant undergoes extensive CYP3A4 metabolism and may affect the metabolism of warfarin and oral contraceptives

33
Q

5-HT3 Antagonists-Antiemetics

A
  • Ondansetron • Granisetron
  • Ondansetron is the prototypical drug of this class.
  • 5-HT3 receptors are present in several critical sites involved in emesis, including vagal afferents, the STN, CTZ and AP.
  • 5-HT3 receptor antagonists are the drug of choice for prophylaxis against immediate CINV.
  • Also effective against hyperemesis gravidarum.
  • Not very effective against: • Delayed CINV • Motion sickness.
  • Well tolerated
34
Q

H1 Antagonists-Antiemetics-Antiemetics

A

• Diphenhydramine • Meclizine • Cyclizine
Histamine H1 antagonists act on vestibular afferents, as well as the brainstem. Useful for motion sickness and postoperative emesis

35
Q

antimuscarinic -Antiemetics

A
  • Scopolamine - for the prevention and treatment of motion sickness.
  • It may have some activity in postoperative nausea and vomiting.
  • Anticholinergic agents are not the first-line choice for CINV.

SGU Pharm deck -term4 (10 decks)

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