Pharmacology of peptic ulcer disease and drugs used in peptic ulcer disease

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1

using a single drug for the treatment of peptic ulcer disease lots of times can be very fustrating because peptic ulcer most times is resistant to single drug treatment… this article explains the pharmacology of peptic ulcer disease, classes of drugs as well as how to combine a therapy for the treatment of peptic ulcer disease

Classes of drugs used in peptic ulcer disease

Drugs used in peptic ulcer disease are;

  1. antacids

  2. anti-muscarinic

  3. H2- histamine receptor blockers

  4. proton pump inhibitors

  5. postagladins

  6. mucosal protective agents

  7. antimicrobial agents.

    3,4,5&6 above are collectively referred to as hyposecretory drugs because they cause remarkable decrease in the amount of gastric acid that is secreted in the stomach or inhibits the production of gastric acid by cutting off the H ion which is needed for gastric acid secretion, thereby increasing the healing of the peptic ulcer.

*Summary
Drugs used in treating peptic ulcer disease can be largely classified as; drugs that neutralizes stomach acids (antacids), drugs that inhibits or reduce gastric acid and gastric juice production (anti-muscarinics, H2-HISTAMINE receptor blockers, Proton pump inhibitors (PPIs), postagladins and Mucosal protective agents), Antimicrobial agents that aims at eradicating the causative organism (H.pylori) *

Also read
https ://howtodiscuss.com/t/botulism/19566.

Antacids

Mechanism of action ( M.O.A)

They promote the ulcer healing by;

  1. neutralizing the HCl in the stomach
  2. reducing pepsin formation.

They are used for promt symptomatic relief of peptic ulcer disease.

They’re not digestible
https ://howtodiscuss.com/t/digestion/13735. their function is to neutralize the acid present in the gastric juice in cases when prompt symptomatic relief is needed such as in acute ulcer pain.

Antacids are classified into two classes which are;

  1. systemic: sodium bicarbonate and calcium carbonate.
  2. non systemic: aluminum hydroxide and magnesium hydroxide.

The non systemic aluminum hydroxide and magnesium hydroxide are the most commonly used.

Side effects

Magnesium hydroxide causes diarrhea, while aluminum hydroxide causes causes constipation. Because of these opposing side effects, both of them are usually administered simultaneously so that the side effects of one will counter the side effects of the other.
All antacids causes hypokalemia.

Drug-drug interactions

Antacids generally decrease the absorption of other drugs. It is advisable to give other medications 1-2 hrs after the administration of antacids, because antacids can slow down their absorption.

Summary
Antacids are given for promt symptomatic relief

Also read
https ://howtodiscuss.com/t/peptic-ulcer-symptoms-pathophysiology-risk-factors-and-prophylaxis-preventative-measures/20171.

Anti-muscarinic drugs

Anti-muscarinics promotes the healing of peptic ulcer disease by reducing the parasympathetic action of the digestive tracts.
The most commonly used anti-muscarinics in treating peptic ulcer disease is pirenzepine.

Mechanism of action ( M.O.A)

Pirenzepine selectively blocks M1 muscarinic receptors thereby;

  1. decreasing vegar stimulation
  2. inhibiting gastric acid secretion.

Side effects

As with all anti-muscarinics, pirenzepine causes; dry mouth, blurred vision, tachycardia and increased sympathetic manifestations.

  • Summary
    The anti-muscarinics acts by blocking the parasympathetic stimulation of the stomach and duodenum thereby decreasing the secretion and action of gastric juice .*

H2-histamine receptor blockers

H2 is the histamine receptor that is found in the gastric mucosal. When histamine binds to this receptor, it activates the protein kinase which leads to the release of the proton (H+) which reacts with the Cl- to produce HCl in the lumen of the gastric mucosal.
H2 receptor blockers reversibly inhibits the H2 receptors thereby cutting off the H+ supply needed for the production of gastric juice . Examples of drugs in this category are ;

  1. cimentidine
  2. formatidine
  3. ranitidine.

Famotidine is the most potent.

All drugs in this category undergoes first pass metabolism in the liver and are inhibitors of the CYP450 enzyme
https ://howtodiscuss.com/t/enzymes/12657 system (especially cimentidine) hence they will increase the half life
https ://howtodiscuss.com/t/half-life-t/13054. of drugs like diazepam in the body.

Side effects

Headache, myalygia, diarrhea, confusion, renal impairment in the elderly.
They are contraindicated in pregnant
https ://howtodiscuss.com/t/affirmative-pregnant/13931. women.

Summary
Anti-histamines increase the healing of peptic ulcer by cutting off the H+ ion supply which is needed for the secretion of gastric acid

Proton pump inhibitors

These are the most effective drugs in anti-ulcer therapy.

Mechanism of action

PPIs ( proton pump inhibitors) irreversibly inhibits the H+K+ ATPase in the parietal cells thereby inhibiting the production of HCl.

Dosage

They’re usually taken once daily and does not need dose adjustment in liver and renal disease.

Examples of drugs in this category are ;
Omeprazole
Esomeprazole
Pantoprazole. Etc.
They are best given intravenously.
All PPIs are metabolised by the liver and all PPIs increase the risk of infection with pneumonia and C.difficle psuedomembranous colitis.
Omeprazole is the most potent.

Side effects

Diarrhea, nausea, weakness, headache.

Summary
PPIs inhibits the mechanism that results the production of H+ ion that is used for the production of HCL. Hence they cut of the production of HCL in the gastric mucosal.

Postagladins

Postagladins synthetic analogue inhibits the acid secretion and promotes mucus and bicarbonate secretion .
They have been shown to reduce the incidence of NSAIDs induced ulcers by 50% because of their cytoprotective action.
The drug used in this category is misoprosol.

Side effects

Diarrhea (https://howtodiscuss.com/t/food-poisoning/9402) and abdominal pain, vomiting and nausea and headache.
Misoprosol causes uterine contraction because of this it is contraindicated in pregnancy (https://howtodiscuss.com/t/teratogen/13832) because it can cause abortion.

Also read (https://howtodiscuss.com/t/gastroenteritis/20288)

Mucosal protective agents

The mucosal protective agents are;

  1. sucrafate
  2. bismuth subsalicylate.

Sucrafate

Sucrafate is a salt of sucrose complexed to sucrafated aluminum hydroxide.

Mechanism of action

It forms a gel complex that binds to the proteins found in the base of the ulcer to form a protective layer.
It also stimulates angiogenesis hence it speeds up the healing process.

Side effects

Constipation, headache (How To Get Rid of a Headache), ■■■■■■■■■■, dry mouth, and skin rash. It can also increase the risk of nosocomial pneumonia, hence it’s long term use should be avoided.

Bismuth subsalicylate

M.O.A
…acts in similar way to sucrafate.
… inhibits pepsin activity.
… increases postagladins production.
…it also have direct antimicrobial activities against H.pylori.

Side effects

Hairy tongue (darkening of the tongue) and darkening of stools, severe constipation
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Summary
The mucosal protective agents forms a proctective layer over the gastric mucosal thereby protecting the ulcerated area. They also stimulates angiogenesis which speeds up the healing of the ulceration.

Antimicrobial agents

Drugs in this category are;
Amoxicillin
Clarithromycin
Metronidazole
Tetracycline.
The antimicrobial agents works by eradicating the H.pylori from the guts.
The Antimicrobial agents eradicates the microorganism (H.pylori) that is triggering the ulceration .

Anti-ulcer therapy

Clinical administration of anti-ulcer therapy are grouped into;

  1. first line therapy (tripple therapy)
  2. second line therapy (quadruple therapy)
  3. third line therapy (rescue therapy).

The triple therapy consist of one PPI and two antimicrobial agents.

If the symptoms persist after treatment with the triple therapy…then the next line of action is to the quadruple therapy. It consists of* a PPI, bismuth subsalicylate and two antimicrobial agents.*

The third line or rescue therapy consist ofa PPI ( proton pump inhibitor), levofloxacin and an antimicrobial
https ://howtodiscuss.com/t/antibiotic/8734. agent.

Peptic ulcer is a chronic disease…for proper effectiveness, anti-ulcer drugs are usually given as a therapy consisting of combination of different categories of anti-ulcer drugs.

Frequently asked questions

Why is my ulcer keeps reoccurring amidst treatment
Check out post on
https://howtodiscuss.com/t/peptic-ulcer-symptoms-pathophysiology-risk-factors-and-prophylaxis-preventative-measures/20171.and refractory ulcer.

Conclusion

Effective anti-ulcer therapies are usually a combination of the different classes of anti-ulcer drugs. a typical anti-ulcer regimen includes; a PPI, two Antimicrobial agents and or a bismuth subsalicylate.
Anti-ulcer therapy grouped into; first line therapy, second line therapy, and rescue therapy. These are usually administered sequentially following the efficacy of the one before it.

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