Scheda di revisione: Rapid Relief: Antacids and PPIs

📋 Course Outline

1. Antacids Mechanism
2. Types of Antacids
3. Antacids Uses
4. Antacids Side Effects
5. PPIs Mechanism
6. Types of PPIs
7. PPIs Clinical Uses
8. PPIs Pharmacokinetics
9. PPIs Adverse Effects
10. Antiemetics Mechanisms
11. Types of Antiemetics
12. Antiemetics Uses

📖 1. Antacids Mechanism

🔑 Key Concepts & Definitions

• Antacids: Basic substances that neutralize gastric acid, providing symptomatic relief in acid-related disorders.
• Neutralization Reaction: The chemical process where antacids react with hydrochloric acid (HCl) to produce water and salt, increasing gastric pH.
• Gastric pH: The measure of acidity in the stomach; normal gastric pH ranges from 1.5 to 3.5.
• Acid Rebound: A phenomenon where gastric acid secretion increases after the effect of antacids wears off, potentially worsening symptoms.
• Rapid Onset: Antacids act quickly, usually within minutes, to neutralize existing stomach acid.
• Duration of Action: The period during which antacids maintain elevated gastric pH, typically 1-2 hours.

📝 Essential Points

• Antacids provide immediate symptomatic relief by directly neutralizing gastric acid.
• They are most effective for mild to moderate heartburn and indigestion.
• Different formulations contain aluminum, magnesium, calcium, or sodium compounds, each with specific side effects (e.g., constipation, diarrhea).
• Overuse can lead to side effects like electrolyte imbalances and acid rebound.
• They do not affect acid secretion; their action is purely chemical neutralization.
• Antacids are often used as adjuncts with other acid-suppressing drugs like PPIs for symptomatic control.

💡 Key Takeaway

Antacids act rapidly to neutralize stomach acid through chemical reactions, providing quick relief of symptoms, but they do not reduce acid production and may cause rebound or side effects with excessive use.

📖 2. Types of Antacids

🔑 Key Concepts & Definitions

• Antacids: Basic compounds that neutralize stomach acid by increasing gastric pH, providing symptomatic relief in acid-related disorders.
• Aluminum Hydroxide: An antacid that neutralizes acid and is associated with constipation; often combined with magnesium to balance effects.
• Magnesium Hydroxide: An antacid that acts quickly to neutralize acid but can cause diarrhea; used for rapid symptom relief.
• Calcium Carbonate: A common antacid that provides quick relief but may cause acid rebound and hypercalcemia if overused.
• Sodium Bicarbonate: A fast-acting antacid that neutralizes acid but can lead to systemic alkalosis and sodium overload, especially in renal impairment.

📝 Essential Points

• Antacids act locally in the stomach to neutralize acid, offering rapid symptom relief, typically within minutes.
• They are mainly used for episodic relief of heartburn, indigestion, and mild gastritis.
• Different antacids have distinct side effect profiles: magnesium-based cause diarrhea, aluminum-based cause constipation, and calcium carbonate may induce acid rebound.
• Overuse or chronic use can mask underlying conditions and lead to complications like electrolyte imbalances.
• Combining antacids (e.g., aluminum with magnesium) can balance side effects and improve tolerability.

💡 Key Takeaway

Antacids provide quick, symptomatic relief of gastric acidity by neutralizing stomach acid, but their choice depends on patient-specific factors and side effect profiles; they are best used for short-term management rather than long-term therapy.

📖 3. Antacids Uses

🔑 Key Concepts & Definitions

• Antacids: Basic substances that neutralize gastric acid, providing symptomatic relief in acid-related disorders.
• Gastric pH: The acidity level in the stomach, normally between 1.5-3.5; antacids increase pH to reduce acidity.
• Rapid Onset: Antacids act quickly, typically within minutes, to alleviate symptoms like heartburn.
• Rebound Acid Hypersecretion: Increased acid production after antacid use, especially with calcium carbonate, due to feedback mechanisms.
• Symptomatic Relief: Primary use of antacids to relieve discomfort without necessarily healing mucosal damage.
• Limitations: Not suitable for long-term management of GERD or ulcers; may mask serious conditions.

📝 Essential Points

• Antacids are mainly used for immediate relief of mild to moderate heartburn, indigestion, and gastritis.
• They are often used as adjuncts in peptic ulcer disease but do not promote mucosal healing.
• Different types (aluminum, magnesium, calcium, sodium bicarbonate) have varying side effects; magnesium can cause diarrhea, aluminum constipation.
• Overuse can lead to electrolyte imbalances, especially in patients with renal impairment.
• Antacids are contraindicated in certain conditions like renal failure, congestive heart failure (due to sodium content), and in patients prone to electrolyte disturbances.
• They are often combined with other drugs to reduce side effects (e.g., magnesium with aluminum).

💡 Key Takeaway

Antacids provide quick, symptomatic relief of acid-related discomfort but are not suitable for long-term treatment; understanding their types and side effects is essential for safe and effective use.

📖 4. Antacids Side Effects

🔑 Key Concepts & Definitions

• Aluminum Hydroxide: An antacid that neutralizes stomach acid; can cause constipation and, in rare cases, aluminum toxicity with prolonged use.
• Magnesium Hydroxide: An antacid that neutralizes acid rapidly; may lead to diarrhea and hypermagnesemia in renal impairment.
• Calcium Carbonate: An antacid providing quick relief; associated with acid rebound and hypercalcemia if overused.
• Sodium Bicarbonate: A fast-acting antacid; can cause metabolic alkalosis, sodium overload, and gas bloating.
• Rebound Acid Hypersecretion: Increased acid production following discontinuation of antacids, especially calcium carbonate, due to feedback mechanisms.
• Electrolyte Imbalance: Disruption of electrolyte levels (e.g., hypokalemia, hypermagnesemia) caused by certain antacids, particularly in renal impairment.

📝 Essential Points

• Common Side Effects: Magnesium-based antacids may cause diarrhea; aluminum-based ones may cause constipation.
• Rebound Phenomenon: Acid rebound occurs especially with calcium carbonate, leading to increased acid secretion after initial relief.
• Electrolyte Disturbances: Excessive or prolonged use can lead to electrolyte imbalances, notably in patients with renal dysfunction.
• Drug Interactions: Antacids can interfere with absorption of other medications (e.g., tetracyclines, fluoroquinolones) by altering gastric pH.
• Use Caution in Renal Disease: Magnesium and aluminum antacids should be used cautiously due to risk of accumulation and toxicity.
• Long-term Use Risks: Chronic use may lead to phosphate depletion, osteomalacia, or aluminum toxicity.

💡 Key Takeaway

While antacids provide rapid symptomatic relief for acid-related conditions, their side effects—such as electrolyte imbalances, rebound acid secretion, and drug interactions—necessitate cautious, short-term use and monitoring, especially in patients with renal impairment.

📖 5. PPIs Mechanism

🔑 Key Concepts & Definitions

• Proton Pump (H+/K+ ATPase): The enzyme located in parietal cell membranes responsible for secreting hydrogen ions (H+) into the stomach lumen in exchange for potassium (K+), leading to gastric acid production.

• Proton Pump Inhibitors (PPIs): A class of drugs that irreversibly inhibit the H+/K+ ATPase enzyme, resulting in a profound and sustained reduction in gastric acid secretion.

• Irreversible Inhibition: PPIs form a covalent disulfide bond with the cysteine residues of the proton pump, permanently inactivating the enzyme until new enzymes are synthesized.

• Activation in Acidic Environment: PPIs are prodrugs that require activation in the acidic environment of the parietal cell canaliculi, where they convert into active sulfenamide forms.

• Duration of Effect: Due to irreversible binding, the acid suppression lasts until new proton pumps are synthesized, typically 24-48 hours, despite the drug's short plasma half-life.

📝 Essential Points

• PPIs selectively target and irreversibly inhibit the final pathway of gastric acid secretion, making them highly effective for conditions like GERD and peptic ulcers.
• They require acidic conditions for activation, which is why they are administered before meals.
• The inhibition is long-lasting because the body must synthesize new proton pumps to restore acid secretion.
• PPIs are more potent and have a longer duration of action compared to H2 receptor antagonists.
• Overuse or long-term use of PPIs can lead to adverse effects such as increased risk of infections, nutrient malabsorption, and potential renal issues.

💡 Key Takeaway

Proton Pump Inhibitors irreversibly block the gastric proton pump, providing potent and sustained acid suppression essential for treating acid-related GI disorders, with their effectiveness dependent on activation in an acidic environment.

📖 6. Types of PPIs

🔑 Key Concepts & Definitions

• Proton Pump Inhibitors (PPIs): Drugs that irreversibly inhibit the H+/K+ ATPase enzyme in gastric parietal cells, leading to a profound reduction in gastric acid secretion.
• H+/K+ ATPase (Proton Pump): The enzyme responsible for the final step of acid production in parietal cells, exchanging intracellular H+ for extracellular K+.
• Prodrug Activation: PPIs are administered as inactive prodrugs that require activation in the acidic environment of parietal cell canaliculi to bind the proton pump.
• Irreversible Inhibition: PPIs form a covalent disulfide bond with the proton pump, leading to long-lasting suppression of acid secretion until new enzymes are synthesized.
• Common PPIs: Omeprazole, Esomeprazole, Lansoprazole, Pantoprazole, Rabeprazole.

📝 Essential Points

• Mechanism: PPIs block the final common pathway of acid secretion, making them more effective than H2 receptor antagonists for long-term acid suppression.
• Administration: Usually taken orally before meals to maximize activation and efficacy.
• Duration of Effect: Despite a short plasma half-life (1-2 hours), their effect lasts approximately 24 hours due to irreversible enzyme binding.
• Clinical Uses: Treatment of GERD, peptic ulcers, Zollinger-Ellison syndrome, and prevention of NSAID-induced ulcers.
• Pharmacokinetics: PPIs are metabolized mainly in the liver via CYP2C19 and CYP3A4 enzymes; genetic polymorphisms can affect drug metabolism.
• Adverse Effects: Increased risk of infections (Clostridium difficile), osteoporosis-related fractures, hypomagnesemia, and potential kidney disease.

💡 Key Takeaway

Proton pump inhibitors are potent, long-lasting inhibitors of gastric acid secretion that are essential for managing chronic acid-related gastrointestinal conditions, but their use requires consideration of potential long-term adverse effects and drug interactions.

📖 7. PPIs Clinical Uses

🔑 Key Concepts & Definitions

• Gastroesophageal Reflux Disease (GERD): A chronic condition where stomach acid frequently flows back into the esophagus, causing symptoms like heartburn and potential mucosal damage. PPIs are first-line therapy for symptom relief and mucosal healing.

• Peptic Ulcer Disease (PUD): Ulcers that develop in the lining of the stomach or duodenum due to acid and pepsin activity. PPIs promote ulcer healing by significantly reducing gastric acid secretion.

• Zollinger-Ellison Syndrome: A rare disorder characterized by gastrin-secreting tumors (gastrinomas), leading to excessive gastric acid production. PPIs are essential in controlling acid hypersecretion in these patients.

• NSAID-Induced Gastric Injury: Nonsteroidal anti-inflammatory drugs can damage the gastric mucosa, leading to ulcers. PPIs are used prophylactically to prevent NSAID-related gastric damage.

• Helicobacter pylori (H. pylori) Eradication Therapy: PPIs are combined with antibiotics as part of triple therapy to eradicate H. pylori infection, which is associated with PUD and gastric cancer risk.

📝 Essential Points

• PPIs are highly effective in suppressing gastric acid secretion, making them the drugs of choice for acid-related disorders requiring long-term management.

• They are used for both symptomatic relief and mucosal healing in conditions like GERD, PUD, and Zollinger-Ellison syndrome.

• PPIs are also employed prophylactically in high-risk patients (e.g., those on long-term NSAIDs) to prevent gastric ulcers.

• In H. pylori eradication, PPIs enhance antibiotic efficacy by increasing gastric pH, creating an unfavorable environment for bacteria.

• Long-term PPI use may be associated with adverse effects such as increased risk of infections, fractures, and nutrient deficiencies, necessitating careful patient selection and monitoring.

💡 Key Takeaway

Proton pump inhibitors are potent, long-acting agents crucial for managing acid-related gastrointestinal conditions, especially when mucosal healing or acid suppression is needed over extended periods. Their judicious use can prevent complications like ulcers and bleeding, but long-term therapy requires careful consideration of potential adverse effects.

📖 8. PPIs Pharmacokinetics

🔑 Key Concepts & Definitions

• Absorption: The process by which PPIs are taken up into the bloodstream, primarily occurring in the small intestine after oral administration.
• Bioavailability: The proportion of the administered PPI that reaches systemic circulation; varies among different PPIs but generally around 30-40% due to first-pass metabolism.
• Metabolism: PPIs are extensively metabolized in the liver, mainly via cytochrome P450 enzymes (CYP2C19 and CYP3A4), affecting their plasma levels and interactions.
• Half-life: The time required for plasma concentration of a PPI to decrease by 50%; typically short (~1-2 hours), but pharmacodynamic effects last longer due to irreversible enzyme binding.
• Activation: PPIs are prodrugs that require activation in the acidic environment of parietal cell canaliculi, where they form a covalent bond with the H+/K+ ATPase.
• Elimination: Primarily through renal excretion of metabolites; some PPIs have minor biliary elimination.

📝 Essential Points

• PPIs are prodrugs activated in acidic conditions, leading to irreversible inhibition of the proton pump.
• They are administered orally, with absorption influenced by gastric pH and food intake.
• The duration of acid suppression exceeds their plasma half-life because of irreversible enzyme binding.
• Variability in metabolism, especially due to CYP2C19 polymorphisms, affects drug levels and efficacy.
• PPIs have a delayed onset of action (hours to days), requiring consistent dosing for optimal effect.
• Long-term use may lead to decreased absorption of certain nutrients (e.g., vitamin B12, magnesium) and increased risk of infections.

💡 Key Takeaway

Proton pump inhibitors are prodrugs with rapid absorption and hepatic metabolism, whose prolonged acid-suppressive effects stem from irreversible enzyme binding rather than plasma half-life, making understanding their pharmacokinetics crucial for effective and safe therapy.

📖 9. PPIs Adverse Effects

🔑 Key Concepts & Definitions

• Clostridium difficile Infection: An overgrowth of C. difficile bacteria in the gut, often associated with prolonged PPI use, leading to diarrhea and colitis.
• Bone Fractures: Increased risk of osteoporosis-related fractures, particularly in the hip, spine, and wrist, linked to long-term PPI therapy due to decreased calcium absorption.
• Vitamin B12 Deficiency: Reduced gastric acid impairs absorption of vitamin B12 from food, potentially causing deficiency with extended PPI use.
• Renal Disease: Chronic PPI use has been associated with acute interstitial nephritis and increased risk of chronic kidney disease.
• Gastrointestinal Infections: Elevated susceptibility to infections like Salmonella and Campylobacter due to decreased gastric acidity, which normally acts as a barrier.

📝 Essential Points

• PPIs cause profound, long-lasting suppression of gastric acid by irreversibly inhibiting the H+/K+ ATPase enzyme.
• Adverse effects are more common with long-term or high-dose therapy.
• The risk of C. difficile infection and other GI infections increases due to reduced gastric sterilization.
• Long-term PPI use can lead to mineral and vitamin deficiencies, notably calcium, magnesium, and B12, contributing to osteoporosis and anemia.
• Renal adverse effects include acute interstitial nephritis and potential progression to chronic kidney disease.
• Monitoring renal function, bone health, and nutritional status is recommended during prolonged therapy.

💡 Key Takeaway

While PPIs are highly effective for acid suppression, their potential adverse effects—particularly with long-term use—necessitate careful patient selection, monitoring, and consideration of the lowest effective dose to minimize risks.

📖 10. Antiemetics Mechanisms

🔑 Key Concepts & Definitions

• Emesis (Vomiting) Reflex: A complex coordinated response involving the central nervous system and gastrointestinal tract, resulting in forceful expulsion of stomach contents.
• Chemoreceptor Trigger Zone (CTZ): A region in the area postrema of the medulla that detects blood-borne emetics and triggers nausea and vomiting.
• Serotonin (5-HT3) Receptors: Receptors located in the gut and brain involved in transmitting signals that induce nausea; antagonized by 5-HT3 antagonists.
• Dopamine (D2) Receptors: Receptors in the CTZ that, when stimulated, promote nausea; antagonized by dopamine antagonists.
• Histamine (H1) Receptors: Receptors involved in motion sickness and vestibular-induced nausea; blocked by antihistamines.
• Neurotransmitter Blockade: The primary mechanism by which antiemetics prevent nausea by inhibiting specific receptors involved in the vomiting pathway.

📝 Essential Points

• Multiple Pathways: Nausea and vomiting involve several pathways, including serotonin, dopamine, histamine, and neurokinin pathways.
• Receptor Targets: Effective antiemetics target specific receptors—5-HT3, D2, H1, and NK1—to block signals that trigger vomiting.
• Indications: Used in chemotherapy, postoperative recovery, motion sickness, and gastrointestinal illnesses.
• Mechanisms of Action:
  • 5-HT3 antagonists (e.g., ondansetron) block serotonin receptors in the gut and brain.
  • Dopamine antagonists (e.g., metoclopramide) inhibit D2 receptors in the CTZ.
  • Antihistamines (e.g., dimenhydrinate) block H1 receptors in the vestibular system.
  • Neurokinin (NK1) antagonists (e.g., aprepitant) inhibit substance P from binding to NK1 receptors in the brain.
• Side Effects: Vary depending on the drug class, including drowsiness, extrapyramidal symptoms, and QT prolongation.

💡 Key Takeaway

Antiemetics work by blocking specific neurotransmitter receptors involved in the vomiting reflex, with different agents targeting serotonin, dopamine, histamine, or neurokinin pathways to effectively prevent nausea across various clinical scenarios.

📖 11. Types of Antiemetics

🔑 Key Concepts & Definitions

• Antiemetics: Medications that prevent or alleviate nausea and vomiting by blocking specific neurotransmitter receptors involved in the vomiting reflex.

• Serotonin (5-HT3) Receptor Antagonists: Drugs that block serotonin receptors in the central and peripheral nervous systems, notably used to prevent chemotherapy-induced nausea.

• Dopamine (D2) Receptor Antagonists: Medications that inhibit dopamine receptors in the chemoreceptor trigger zone (CTZ), effective against various causes of nausea, including postoperative and drug-induced vomiting.

• Antihistamines (H1 receptor antagonists): Agents that block histamine H1 receptors, useful in motion sickness and vertigo-related nausea.

• Cannabinoids: Compounds like dronabinol that activate cannabinoid receptors, used for nausea associated with chemotherapy, especially when other agents are ineffective.

• Mechanisms of Action: Different classes target specific neurotransmitter pathways involved in nausea and vomiting, such as serotonin, dopamine, histamine, and cannabinoids.

📝 Essential Points

• Indications: Antiemetics are primarily used in chemotherapy, postoperative settings, motion sickness, and gastroenteritis.

• Drug Examples:

  • 5-HT3 antagonists: Ondansetron, Granisetron
  • D2 antagonists: Metoclopramide, Prochlorperazine
  • Antihistamines: Dimenhydrinate, Meclizine
  • Cannabinoids: Dronabinol

• Side Effects:

  • 5-HT3 antagonists: Headache, constipation
  • D2 antagonists: Extrapyramidal symptoms, tardive dyskinesia
  • Antihistamines: Drowsiness, dry mouth
  • Cannabinoids: Dizziness, euphoria, sedation

• Clinical Considerations:

  • Choice depends on cause and patient factors.
  • Be cautious of extrapyramidal side effects with dopamine antagonists.
  • Use in combination for refractory nausea (e.g., in chemotherapy).

• Emerging Therapies: Newer agents targeting additional pathways are under investigation to improve efficacy and reduce side effects.

💡 Key Takeaway

Different classes of antiemetics target specific neurotransmitter receptors involved in nausea and vomiting; selecting the appropriate agent depends on the underlying cause and patient profile, with awareness of potential side effects guiding safe and effective therapy.

📖 12. Antiemetics Uses

🔑 Key Concepts & Definitions

• Antiemetics: Drugs that prevent or alleviate nausea and vomiting by blocking specific neurotransmitter receptors involved in the vomiting reflex.

• Chemotherapy-Induced Nausea and Vomiting (CINV): Nausea and vomiting caused by chemotherapeutic agents, often severe and requiring specific antiemetic therapy.

• Serotonin (5-HT3) Receptor Antagonists: A class of antiemetics (e.g., Ondansetron) that block serotonin receptors in the gut and brain, effectively preventing nausea, especially in CINV.

• Dopamine Receptor Antagonists: Drugs like Metoclopramide and Prochlorperazine that block dopamine receptors in the chemoreceptor trigger zone (CTZ), used for general nausea and vomiting.

• Motion Sickness Antiemetics: Antihistamines (e.g., Dimenhydrinate, Meclizine) that block H1 histamine receptors, preventing nausea related to motion sickness.

• Cannabinoids: Agents like Dronabinol that activate cannabinoid receptors, used in refractory nausea, especially in chemotherapy patients.

📝 Essential Points

• Mechanisms of Action: Different antiemetics target various receptors involved in the vomiting pathway, including serotonin, dopamine, histamine, and cannabinoid receptors.

• Clinical Uses:

  • CINV: 5-HT3 antagonists are first-line agents.
  • Postoperative Nausea/Vomiting: Often managed with dopamine antagonists or antihistamines.
  • Motion Sickness: Primarily treated with antihistamines.
  • Refractory Nausea: Cannabinoids are used when other agents fail.

• Selection of Antiemetics depends on the cause, severity, and patient-specific factors, including contraindications and side effect profiles.

• Adverse Effects:

  • Dopamine antagonists: Extrapyramidal symptoms, sedation.
  • 5-HT3 antagonists: Headache, constipation, rare QT prolongation.
  • Antihistamines: Drowsiness, dry mouth.
  • Cannabinoids: Dizziness, euphoria, potential for abuse.

• Combination Therapy: Often used for severe nausea, combining agents targeting different receptors for synergistic effect.

💡 Key Takeaway

Antiemetics are a diverse group of drugs targeting specific neurotransmitter pathways involved in nausea and vomiting; their appropriate selection based on etiology and patient factors is essential for effective management.

📊 Synthesis Tables

Aspect	Antacids	PPIs
Mechanism of Action	Neutralize existing gastric acid chemically	Irreversibly inhibit H+/K+ ATPase (proton pump) in parietal cells
Onset of Action	Rapid (minutes)	Delayed (hours; requires activation and accumulation)
Duration of Effect	Short (1-2 hours)	Long (up to 48 hours; until new pumps are synthesized)
Effect on Acid Secretion	No effect; neutralizes acid chemically	Significant reduction in acid secretion
Use in Acid-related Conditions	Symptomatic relief of mild to moderate heartburn	Long-term management of GERD, ulcers, Zollinger-Ellison syndrome
Side Effects	Electrolyte imbalances, rebound hyperacidity, constipation/diarrhea	Headache, GI disturbances, risk of infections, osteoporosis with long-term use

Aspect	Types of Antacids	Types of PPIs
Composition	Aluminum hydroxide, magnesium hydroxide, calcium carbonate, sodium bicarbonate	Omeprazole, Esomeprazole, Lansoprazole, Pantoprazole, Rabeprazole
Side Effect Profile	Constipation (Aluminum), diarrhea (Magnesium), hypercalcemia (Calcium), systemic alkalosis (Sodium bicarbonate)	Headache, GI upset, risk of infections, hypomagnesemia (long-term)
Pharmacokinetics	Rapid onset, short duration	Oral absorption, long half-life, activated in acidic environment
Clinical Use	Episodic heartburn, indigestion	GERD, peptic ulcers, Zollinger-Ellison syndrome, H. pylori eradication

⚠️ Common Pitfalls & Confusions

1. Confusing antacids' quick relief with PPIs' long-term effect.
2. Assuming all antacids have the same side effect profile.
3. Overlooking rebound acid hypersecretion after stopping antacids.
4. Misunderstanding that PPIs irreversibly inhibit the proton pump.
5. Ignoring the delayed onset of PPIs compared to antacids.
6. Using antacids in renal failure without caution due to electrolyte risks.
7. Assuming PPIs are suitable for immediate symptom relief—incorrect, they need time to act.
8. Confusing the mechanism of neutralization (antacids) with enzyme inhibition (PPIs).
9. Neglecting drug interactions of PPIs with other medications (e.g., clopidogrel).
10. Overusing antacids leading to electrolyte disturbances or masking serious conditions.

✅ Exam Checklist

• Describe the mechanism of action of antacids.
• List different types of antacids and their side effects.
• Explain the clinical uses of antacids.
• Identify common side effects and contraindications of antacids.
• Describe the mechanism of PPIs and how they differ from antacids.
• List types of PPIs and their pharmacokinetics.
• Explain the clinical indications for PPIs.
• Discuss adverse effects associated with long-term PPI use.
• Describe the mechanisms of antiemetics.
• List different types of antiemetics and their mechanisms.
• Outline the primary uses of antiemetics.
• Recognize common pitfalls in the use of antacids, PPIs, and antiemetics.