Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Gastrointestinal System > Drugs used for Acid Associated Diseases > Flashcards

Drugs used for Acid Associated Diseases Flashcards

1
Q

What are the factors that may lead to the development of peptic ulcer disease

A

An ulcer is basically lesions of the gastric and duodenal mucosa:

  1. Gastric Acid
  2. H. pylori
  3. NSAIDS, Smoking as well as excessive alcohol intake, GI Ischeamia
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

MECHANISM OF GASTRIC

ACID SECRETION

A

By a proton pump( H+K+ ATPase)

Acid stimuli:
- Acetycholine via M1 and M3 receptors
- Gastrin via Gastrin G-receptors
- Histamine via H2- receptors.
By a proton pu
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Drugs which are used in the treatment of Peptic Ulcers disease/Reduce gastric acidity) and describe the mechanism of action of each pump.

A
  1. Antacids
  2. Acid anti-secretory agents:
  • H2-antagonists
  • Proton pump inhibitors
  1. Mucosal protective agents
    - Prostaglandin-analogues
    - Sucralfate
    - Bismuth
    - Carbenoxolone
  2. Antimuscarinic agents
  3. Antibiotics
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Antacids

A

They chemically neutralize stomach acid by increasing the GI pH sufficiently to relieve the pain of dyspepsia and acid indigestion enabling peptic ulcers to heal

  • Sodium bicarbonate
  • Calcium carbonate
  • Magnesium hydroxide or oxide
  • Aluminium hydroxide
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Sodium Bicarbonate

A

Sodium bicarbonate + H+ => CO2 + H2O
- Belching and abdominal distension (CO2).
- Systemic alkalosis [HCO3]
- Na is absorbed => c/i HT, renal failure and
cardiac failure [Na+].

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Calcium Bicarbonate

A

Calcium carbonate + 2H+ => CO2 + H2O
• Belching and abdominal distension (CO2).
• Hypercalcemia or milk alkaline synd.
• Rebound acid hypersecretion (Ca2+)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Magnesium Hydroxide/Oxide

Aluminium Hydroxide

A 
Magnesium hydroxide => Diarrhea.
Aluminium hydroxide => Constipation.
Is c/i in renal failure (neurotoxic).
Combination of Al and Mg (OH) reduces
diarrhea and constipation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Anti-secretory agents

A
  1. H2 -receptor antagonists

2. Proton pump inhibitors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

List the H2-antagonists/Histamine H2-receptor antagonists

A

Cimetidine

Ranitidine,

Famotidine

Nizatidine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

MOA of H2-Antagonists

A

Similar structure to that of histamine thus the drug competes for binding on the H2 receptor on gastric parietal cells.

Potent inhibitors of Meal stimulated secretion and nasal secretion of gastric acid,They reduce the volume and conc. og gastric acid and they produce a proportionate reduction in the production of pepsin because gastric acid catalyzes the conversion of inactive pepsinogen>pepsin.

Also reduce the secretion of Intrinsic Factor but not enough to significatly reduce Vit. B12 absorption.

No effect on gastric emptying time, esophageal sphincter pressure or pancreatic enzyme secretion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

H2-Antagonists Uses

A
  • Duodenal and gastric ulcers
  • Hypersecretory states, ZES
  • Reflux eosophagitis
  • Prevention of recurrence
  • Prevention of aspiration syndrome
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Cimetidine:

MOA

A
  • Competitive inhibitor of histamine action
    on H2-receptors on the parietal cells.
  • CNS; dizziness and mental confusion esp. in elderly.
  • GIT; Diarrhea/constipation.
  • Endocrine: gyneacomastia, impotence & decreased libido
  • Hyperprolactinemia
  • Androgenic receptor antagonist.
  • Inhibits metabolism of estradiol (CYP450).
  • Dose = 400 mg tds plus a bed time dose, (or 800 mg bd)
    x 4-8 weeks.
    21
    Ranitidine
  • Safer than cimetidine
  • Little crosses BBB
  • No endocrine effects
  • No significant inhibition of CYP450
    Kinetics
  • Similar to cimetidine but F < 50%.
  • Dose = 15 mg BD x 4-6 weeks, or
    single bedtime 30 mg/day.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Cimetidine:

Kinectics

A
  • Well absorbed from GIT => F = 70-80%
  • Half-life = 2 hrs. 15-20% Prot. bound.
  • Excreted renally by filtration and
    secretion (same mechanism as creatinine).
  • Crosses placenta & BBB
  • CNS effects esp. elderly and sev. ill.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Cimetidine:

Drug Interactions

A

Inhibits cytochrome P450 isoenzymes,These isoenzymes are involved in the metabolism of numerous drugs including; Alprazolam,Carbamazepine warfarin, theophyline, Cisapride, DDisopyramide, Felodipine, Lovastatin, Saquinavir, Triazolame.

The dosagaes of these drugs need to be reduced in patients who are taking Cimetidine.

Reduces absorption of ketoconazole (high pH)

Inhibits renal excretion of metformin and procainamide.

Other H2 blockers do not inh Cytochrome P450 enzymes significantly and are prepared for patients receiving concomitant drug theraphy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Cimetidine:

Adverse Effects/Side Effects

A
  • CNS; dizziness and mental confusion esp. in elderly.
  • GIT; Diarrhea/constipation.
  • Endocrine: gyneacomastia, impotence & decreased
    libido
  • Hyperprolactinemia
  • Androgenic receptor antagonist.
  • Inhibits metabolism of estradiol (CYP450).
  • Dose = 400 mg tds plus a bed time dose, (or 800 mg bd) x 4-8 weeks.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Alternative drug to Cimetidine

A

Ranitidine:

  • Safer than cimetidine
  • Little crosses BBB
  • No endocrine effects
  • No significant inhibition of CYP450

Kinetics

  • Similar to cimetidine but F < 50%.
  • Dose = 15 mg BD x 4-6 weeks, or
    single bedtime 30 mg/day.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Proton Pump Inhibitos(PPI)

A

Omeprazole

Lansoprazole

Esomeprazole

Pantoprazole

18
Q

PPI MOA

A

Form a -Disulfide link with a cysteinyl residue in the proton pump(H+K+-ATPase) found in the luminal membrane of gastric parietal cells.

Irreversibly inhibit the proton pump and prevent the secretion of gastric acid for an extended period.

Activated by acid to active sulfenamic
acid.

The drugs can produce a dose-dependent inhibition of up tp 95% of gastric acid secretion and a single dose for 1-2 days

19
Q

Proton Pump Inhibitors Indications/Uses

A

Treatment of peptic ulcer disease-Duodenal and Gastric mucosa

Reflex and Erosion Esophagitis

Zollinger-Ellison Syndrome-Conditon characterised by severe ulcers resulting from gastrin-secreting tumours(Gastrinoma’s)

GERD

Tx of Heartburn and Dyspepsia

Prevention of peptic ulcers and bleeding in person recieving high-dose or long term theraphy with NSAIDs such as Diclofenac

20
Q

Proton Pump Inhibitors

Kinetics

A
  • Well absorbed from GIT.
  • Half-life 0.5-1.5 hrs. 95% protein bound.
  • Metabolized rapidly by liver
  • 20% excreted in feces.
21
Q

Proton Pump Inhibitors

Drug Interations

A
  • Inhibits metabolism of warfarin, diazepam
    & theophylline (CYP450).
    -Dose = 20 mg/d, ± antibiotics
  • NB: do not use with antacids.

Omeprazole and Esomeprazole prevent the activation of Clopidegrel by inhibiting CYP2C19, Leading to low clopidogrel levels.

Not to be used with antiplatelet drugs-Pantoprazole does not appear to cause this interaction and can be used concurrently with clopidogrel

22
Q

Proton Pump Inhibitors

Adverse Effects

A

Minor GI and CNS side effects have occured in some pts and skin rash.

Elevated Hepatic enzymes

Hypomagnesemia-In pts taking the drug for >1 year

CKD-Long term use of high dose

Increased risk of osteoporosis-small potential of malabsorption of Vit B12

Increased risk of community acquired pneumonia and certain GI infections including Clostridium difficile infection

Can elevated serum levels of Methotrexate in pts with high doses of Methotrexate.

23
Q

Mucosal protective agents/Cytoprotective Agents

A
  • Sucralfate
  • Prostaglandin analogues
  • Bismuth colloids (dicitrate).
  • Carbenoxolone
24
Q

Sucralfate

MOA

Sucralfate ctned
• Uses: Duodenal &amp; gastric ulcers, &amp;
reflux esophagitis
• Kinetics
- Poorly absorbed from GIT &amp; is
excreted in feces
• Adverse effects: Constipation.
• Interaction: Binds &amp; reduces abs. of
theophylline &amp; phenytoin.
• Dose; 1 g qid x 4 wks
A

Viscous polymer of sucrose octasulfate and aluminium hydroxide.

Sulfated polysaccharide adheres to ulcer craters and epithelial cells and inhibit pepsin-catalysed hydrolysis of mucosal proteins.

Stimilates PGE synthesis in mucosal cells

These actions form a protective barrier to acid and pepsin facilitating the healing of ulcers

Adsorbs bile acids in the duodenum.

25
Q

Sucralfate

Kinetics

A

Oral administration-Tablet/Suspension

Drug not absorbed significantly from the gut and is primarily excreted in the feces

Pts absorb a small amount of aluminium from the the drug, so sucralfate should be used cautiously in pts with renal impairements

26
Q

Sucralfate

Uses

A

The management of Peptic Ulcer diseases-treat active or supress the recurence of ulcers

Less effective than drugs that inh gastric acid secretion and is primarily used in pts who cannot tolerate H2 blockers or PPI’s

27
Q

Sucralfate

Adverse Effects/Side Effects

A

Few systemic adverse effects,constipation and other GI disturbances

Larygospasm

Impair absorption of other drugs-Digoxin, Fluroquinolones, Ketoconazole and Phention-This can be avoided by ingesting sucralfate 2 hrs before or after these other drugs

28
Q

Misoprostol

MOA

A

Misoprostol = Analogue of PgE1

  • Increases both mucus & bicarbonate production
  • Increases mucosal blood flow.
  • Inhibits gastric acid secretion (the proton pump) via a cAMP signal.
29
Q

Misoprostol

Uses

A
  • Prophylaxis: duodenal/gastric ulcers.

- Prevention of NSAID induced ulcers.

30
Q

Misoprostol

Adverse Effects

A

N, V, D and abd. pain/Intestinal cramping
(dose dependent)

Skin rashes

Can stimulate terine contraction which results in abortion
and abnormal vaginal bleeding.

  • c/i: pregnancy; Dose = 200 mg qid
31
Q

Misoprostol

Kinetics

A

Extensively Metabolised

32
Q

Bismuth colloids (dicitrate)

MOA

A
  • Precipitates in acid & coats ulcer base.
  • Increase mucus secretion.
  • Antibacterial effect (toxic to H.pylori).
  • NB: Do not use with antacids.
33
Q

Bismuth colloids (dicitrate)

Adverse Effects

A
  • Confusion.
  • Black discolouration of tongue, stools
  • c/i renal failure (neurotoxic)
34
Q

Carbenoxolone

MOA

A

Mechanism of action: unknown.

  • Increases mucosal secretion only.
  • No effect on acid secretion or gastric motility.
35
Q

Carbenoxolone

Adverse Effects

A

s assoc. with many s/e.
- Headache, Na+ and fluid retention due to
aldosterone action.
- Edema and hypokalemia. c/i HT, CCF
and epilepsy.
- Others: peripheral neuropathy, myasthenia,
and myoglobinuria

36
Q

Anti-muscarinic agents 1

A
  • Propantheline
  • Dicyclomine
  • Glycopyrrolate
  • Pirenzepine
  • Atropine
37
Q

Anti-muscarinic agents 2

Mechanism of action

A
  • They inhibit acid secretion (M1) and gastric
    motility(M2).
  • M1 and M3 receptors mediate glandular
    secretion.
  • M2 receptors mediate GIT motor functions.
  • Pirenzepine is selective for M1.
38
Q

Anti-muscarinic agents 3

• Adverse effects

A

Due to non-selective action

  • Dry mouth, constipation, tachycardia,
  • Urinary retention, blurring of vision,
  • Loss of accommodation and impotence.
39
Q

Anti-Muscarinic Agents

Uses

A
  • Non-ulcer dyspepsia.
  • Irritable bowel syndrome.
  • Diverticular disease.
  • Less frequently used for peptic ulcers.
40
Q

Anti-Bacterials

A

Amoxycillin; => diarrhea

Metronidazole; => mild GIT upset

Tetracycline; => mild GIT upset

Clarithromycin:=> taste disturbance

Bismuthsalicylate;=> melena & tinnitis

NB: combined with antisecretory agent.

41
Q

Examples of triple therapy regimens

A

• First choice:
– Omeprazole + Clarithromycin + amoxycillin => 90%
efficacy

– Substitution with amoxycillin for metronidazole or
doxycycline => efficacy of 80%.

Others:

• Bismuthsalicylate + tetracycline + metronidazole => 90%
efficacy rate.

• Ranitidine + metronidazole + amoxycillin = 90% efficacy.

Gastrointestinal System (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions