Gastric Acid Secretion Mechanisms Quiz

Pharmacotherapy of GIT and Respiratory Disorders RPB20403

• Course name: Pharmacotherapy of GIT and Respiratory Disorders
• Course code: RPB20403
• Instructor: Dr. Omar AH
• Date: 20.08

Topic 2: Drugs used to inhibit or neutralize gastric acid secretion

• Learning Outcomes:
  • Pathophysiology of ulcers
  • Regulation of acid secretion by Parietal cells
  • Causes and risk factors
  • Signs and Symptoms/Diagnosis
  • Antacids & dimethicone
  • Histamine (2) antagonist
  • Proton Pump Inhibitors
  • Prostaglandin analogues
• Drugs are used to reduce gastric acid secretion for conditions like ulcers.

Prevalence of Gastric Acid in Malaysia

• Study conducted in Selangor, Malaysia in 2017
• Participants were Malaysians aged 18+
• Malay ethnicity had the highest percentage of gastritis (50.8%)
• 56.6% of Malaysians were affected by H. pylori induced gastritis.

The pH Scale

• Ranges from 0 to 14
• 0 to 6.9: Acidic
• 7: Neutral
• 7.1 to 14: Alkaline
• Common examples of substances on the scale are shown:
  • Battery (0)
  • Lemon (-)
  • Tomato
  • Milk (+)
  • Blood (+)
  • Stomach Tablets
  • Soap (-)
  • Drain Cleaner (-)

GIT is part of the digestive system

• Nervous and endocrine systems work together
• Controlling gastric secretions and motility
• Movement of food throughout the GIT

Where gastric secretion starts

• Food triggers digestive juices secretion.
• Stomach releases gastrin to promote stomach acid production.
• Intestine releases secretin and cholecystokinin to stimulate pancreatic juice and bile secretion

Gastric Acid Secretion Mechanism

• Acetylcholine (ACh) signal from the vagus nerve activates parietal cells.
• Activating enterochromaffin-like cells (ECL) cells.
• Activation of G-cells.
• G and ECL cells further activate parietal cells

Parietal Cell Mechanism

• Active transport of H+ ions from the cell occurs in exchange for K+ ions.
• Cl- ions are secreted into the lumen by simple diffusion
• Stomach's acidic environment (HCl) is crucial for digestion.

Mechanism of gastric acid secretion

• Acetylcholine (ACh) from vagus nerve activates parietal cells.
• Gastrin-releasing peptide (GRP) releases gastrin which activates parietal cells.
• Histamine from ECL cells activates neighboring parietal cells.

Causes & risk factors of peptic ulcer

• Factors that stimulate gastric acid secretion:
  • Stress
  • Alcohol
  • Caffeine
  • Smoking
  • Spicy foods
  • Oily foods
• Factors that cause the breakdown of the protective layer
  • H. Pylori infection
  • Medications
    • Steroids
    • NSAIDs (Nonsteroidal anti-inflammatory drugs)

Causes and risk factors that contribute to ulcer

• A bacterium (Helicobacter pylori) lives in the mucous layer.
• Pain relievers (NSAIDs) irritate or inflame the stomach lining.
• Other medications with NSAIDs.
• Smoking increases the risk of peptic ulcers, particularly in people infected with H. pylori.
• Alcohol irritates, erodes the stomach’s lining. Increased stomach acid production.
• Untreated stress
• Spicy and oily foods

Helicobacter pylori

• Gram-negative, flagellated, spiral bacterium
• Infection does not always cause illness
• Chronic infection can cause inflammation, leading to peptic ulcers.
• Treatment includes triple-drug therapy with a proton-pump inhibitor, amoxicillin, and clarithromycin for 14-21 days.

Gastric Acid Secretion Mechanism (Pathophysiology)

• H. pylori produces urease, neutralizing gastric acid, damaging the mucosa

Factors that cause the breakdown of the protective layer of stomach

• NSAIDs inhibit cyclooxygenase (COX) enzyme.
• Inhibiting the production of prostaglandins, which are crucial for mucosal protection.

Peptic Ulcers Signs and Symptoms

• Common symptoms include: Nausea, vomiting, hematemesis (vomiting blood), coffee-ground vomit, indigestion, dyspepsia, epigastric discomfort, iron deficiency anemia, melena (tarry black stools), dull stomach pain.

Peptic Ulcers Signs and Symptoms

• Symptoms (further details on types of pain, possible improvement with food or antacids, and other symptoms like weight loss.)

Diagnosis of Peptic Ulcer

• Medical history
• Physical exam
• H. pylori tests (Urea breath test)
• Endoscopy and biopsy.
• X-rays (barium swallow)

Peptic Ulcer Diagnosis

• Laboratory testing for H. pylori.
• Endoscopy (upper digestive tract examination using a scope).
• Upper gastrointestinal (GI) series X-rays (barium swallow).

Types of Peptic Ulcer Disease

• Duodenal ulcers
• Esophageal ulcers
• Gastric ulcers

Peptic Ulcer Management

• Non-pharmacological treatment
  • Avoiding spicy and oily foods, alcohol, smoking.
  • Encouraging small, frequent meals, eating healthy and green vegetables and fruits
  • Avoiding ulcerating drugs (e.g., NSAIDs, corticosteroids)
  • Managing stress

15 Foods to Avoid if you have a Stomach Ulcer

• List of foods to avoid

Pharmacological treatment of Ulcer & GERD

• Systemic vs. Non-systemic medications.

MOA: Non-systemic anti-acids

• Antacids work by neutralizing gastric acid.

What is gastroesophageal reflux disease (GERD)?

• Stomach acids, food and fluids flowing back into the esophagus.
• Issues like inflammation that can lead to esophageal cancer
• Respiratory problems (asthma, fluid in lungs, chest congestion), damaging the teeth.

E.g. of Non-systemic anti-acids

• Different types of anti-acids, including Maalox and Gaviscon

Dimethicone (Simethicone)

• Anti-foaming agent, reducing bloating or excessive gas.

How about peptic ulcer long-term treatment

• Reducing gastric acid secretion
• Protecting stomach mucosa
• Conditions like peptic ulcers, GERD, and Zollinger-Ellison syndrome.

MOA: Systemic anti-acids

• Reduce gastric acid secretion by preventing the stimulation of parietal cells.
• Prostaglandin analogues, proton pump inhibitors, and H2 receptor antagonists.

Antiacid classes

• Systemic and Non-systemic antacids
• Antacids, H2 receptor antagonists, proton pump inhibitors
• Adjunct medications
  • Prokinetics, bismuth chelates
• Types of medications used

Antibiotic medications for H. pylori

• Medications to kill bacteria
• Amoxicillin, Clarithromycin, Metronidazole, and Levofloxacin
• Combining PPI with Antibiotic

Histamine-2 (H2) receptor antagonists (H2 blockers)

• Cimetidine, Famotidine, and Ranitidine.
• Different dosages for different illnesses.

Proton pump inhibitors (PPIs)

• Omeprazole, Pantoprazole, Dexlansoprazole.
• Different dosages for different illnesses, depending on the illness or procedure.

Mucosal Protective Agents

• Sucralfate and Bismuth subsalicylate
• Effectiveness as a protective agent.

Treatment and drugs action in ulcer

• Antibiotics for H. pylori infection
• Medications to block acid production
• Medications that reduce acid
• Medications that protect the stomach lining

Complications of untreated ulcers

• Perforation of the stomach
• Bleeding
• Scarring and stricture.