Pharma Notes: Gastrointestinal Medications and Pathophysiology of the Stomach PDF

# Pharma Notes: Gastrointestinal Medications and Pathophysiology of the Stomach ## Pathophysiology of the Stomach ### Cell Types * Parietal cells * Chief cells * Surface epithelium cells ### Functions * **Surface Epithelium Cells:** Secrete mucus for protection * **Parietal Cells:** * Pr...

# Pharma Notes: Gastrointestinal Medications and Pathophysiology of the Stomach ## Pathophysiology of the Stomach ### Cell Types * Parietal cells * Chief cells * Surface epithelium cells ### Functions * **Surface Epithelium Cells:** Secrete mucus for protection * **Parietal Cells:** * Produce hydrochloric acid (HCl) * Intrinsic factor (Vitamin B12 absorption) * **Chief Cells:** Secrete pepsinogen, converted to pepsin for digestion. * **Enteroendocrine Cells and G Cells:** * Secrete various substances, including gastrin. ### Imbalance Acid-related disorders result from secretion imbalances. ### Common Conditions * GERD (Gastroesophageal reflux disease) * PUD (Peptic ulcer disease) ## Nursing Considerations for Hyperacidity Medications ### Assessments * Abdominal assessment and bowel pattern documentation * Monitor for medication interactions, side effects and Vitamin B12 malabsorption ### Implementation * Follow drug label information * Modify care plans for safe use with alternative methods ### Evaluation * Monitor symptom improvement * Notify the provider if no improvement or worsening occurs ## Hyperacidity Medication Classes ### 1. Antacids * **Indications:** * Heartburn * Acid indigestion * Upset stomach * **Mechanism:** * Neutralize gastric acidity * Elevate stomach pH * Inactivate pepsin. * **Example:** Calcium carbonate * **Administration Considerations:** * Various formulations (tablet, chewable, liquid) * Caution with kidney disease * **Patient Teaching:** * Chewable, liquid ### 2. H2-Receptor Antagonist (Famotidine) * **Indications:** * GERD * Peptic ulcer * Erosive esophagitis * Hypersecretory conditions * **Mechanism:** Blocks histamine's action, reducing hydrochloric acid production. * **Administration Considerations:** * Take 15-60 minutes before potential heartburn triggers. * Dosage adjustment for liver/kidney disease. * **Patient Teaching:** * Shake oral suspension. * Encourage fluids and a high-fiber diet. ### 3. Proton Pump Inhibitors (Pantoprazole) * **Indications:** * GERD * Excess stomach acid * Zollinger-Ellison syndrome * **Mechanism:** Inhibit hydrogen/potassium ATPase, reducing hydrochloric acid. * **Administration Considerations:** * Oral, NG tube, IV. * Mix granules with applesauce or apple juice * **Patient Teaching:** * Call provider if no improvement or worsening. * Discourage alcohol, NSAIDs, and irritating foods. ### 4. Mucosal Protectant (Sucralfate) * **Indications:** Treatment of ulcers * **Mechanism:** Locally covers and protects ulcer sites. * **Administration Considerations:** * Consider cultural preferences. * Administer on an empty stomach. * Cautious use in chronic renal failure. * **Patient Teaching:** * Call provider if no improvement or worsening. ### 5. Antiflatulent (Simethicone) * **Indications:** Relief of gas discomfort * **Mechanism:** Alters elasticity of gas bubbles, facilitating expulsion. * **Administration Considerations:** * Usually taken four times a day. * Shake liquid drops before administering. * **Patient Teaching:** * Educate on additional measures for gas expulsion. ## Antidiarrheals ### 1. Various Causes * Bacteria * Viruses * Parasites * Medications * Food intolerances * Diseases ### 2. Severe Threat: Dehydration due to water and electrolyte loss. ## Nursing Considerations ### 1. Assessment * Abdominal assessment, bowel movement frequency, stool characteristics and skin breakdown * Priority on monitoring dehydration, especially in vulnerable populations. ### 2. Implementation * Caution against exceeding OTC medication dosages. * Advocacy for probiotics use. * Nonpharmacological interventions: fluid replacement, soft foods. ### 3. Evaluation * Notify provider if symptoms persist after 48 hours. * Monitor for adverse effects: increased bleeding, abnormal heart rhythms. ## Medication Classes ### 1. Adsorbents (e.g., Bismuth Subsalicylate) * **Mechanism:** Coats GI tract, binds causative bacteria/toxins; decreases fluid flow. * **Administration Considerations:** * Avoid in salicylate allergy, ulcer, bleeding, or black stool. * **Patient Teaching:** * Take as directed. * Be aware of color changes. * Discontinue on tinnitus. ### 2. Antimotility * **Anticholinergics (e.g., Hyoscyamine):** * **Mechanism:** Inhibits propulsive motility; decreases gastric acid secretion. * **Administration Considerations:** * Contraindications: * Glaucoma * Myasthenia Gravis * **Patient Teaching:** * May cause dizziness, drowsiness. * Alleviate dry mouth with oral hygiene. * **Opioid-Like Medication (e.g., Loperamide):** * **Mechanism:** Decreases fluid flow, slows bowel movement. * **Administration:** Consideration: Monitor for side effects, QT prolongation. ### 3. Probiotics (e.g. Lactobacillus): * **Mechanism:** Replenishes normal bacterial flora in the GI tract. * **Administration Considerations:** Mild side effects (gas, bloating), safe for children. ## Nausea and Vomiting ### Definition * **Nausea:** Unpleasant urge to vomit * **Vomiting (emesis):** Forceful expulsion of gastric contents. ### Causes * Morning sickness (pregnancy) * Infections (gastroenteritis) * Migraines * Motion sickness * Food poisoning * Medication side effects * GERD, ulcers * Intestinal obstruction * Poisoning or exposure * Diseases in other organs (cardiac, renal, liver) ### Serious Conditions * Vomiting > 24 hours * Blood in vomit (hematemesis) * Severe abdominal pain * Severe headache, stiff neck * Signs of dehydration ### Pathophysiology of Nausea and Vomiting * **Vomiting Center (VC):** * Activated by irritants or input from the gastrointestinal tract, cerebral cortex, vestibular region, and chemoreceptor trigger zone (CTZ) * Not restricted by blood-brain barrier, responds to toxins in bloodstream. * Receives stimuli from various locations in the body * **Chemoreceptor Trigger Zone (CTZ):** * Located in the area postrema in the brain * Not restricted by blood-brain barrier * Responds directly to toxins in the bloodstream. * Receives stimuli from vestibular center, visceral organs, thalamus, cerebral cortex * **Vestibular Center and Cerebal Cortex:** * Vestibular system (inner ear) contributes to motion sickness-related nausea * Gastrointestinal tract sends stimuli via cranial nerves IX and X * Cerebral cortex responds to odors, tastes, images, sending stimuli to CTZ. ### Vomiting Process * VC initiates vomiting by inhibiting peristalsis. * Produces retro-peristaltic contractions. * Autonomic stimulation causes symptoms like salivation, pallor, sweating, tachycardia. * Involves various neurotransmitters. ## Medication Classes and Mechanisms ### 1. Anticholinergics * **Example:** Scopolamine * **Mechanism:** * Blocks ACh receptors in vestibular system. * Dries GI secretions, reduces smooth muscle spasms. * **Administration:** * Transdermal patch for continuous release. * **Considerations:** * Contraindicated in glaucoma. * Monitor for anticholinergic side effects. ### 2. Antihistamines * **Example:** Meclizine * **Mechanism:** * Blocks H1 receptors in vestibular center. * May block acetylcholine. * **Administration:** * Contraindicated in Glaucoma. * **Considerations:** * Dosage before travel. * May cause drowsiness. ### 3. Dopamine Antagonists * **Example:** Prochlorperazine. * **Mechanism:** * Blocks dopamine in CTZ. * Calms the central nervous system. * **Administration:** * Oral, intramuscular, rectal, intravenous. * **Considerations:** * Avoid in children under 2 * Monitor for side effects. ### 4. Prokinetics * **Example:** Metoclopramide * **Mechanism:** * Promotes peristalsis, reduces nausea. * **Administration:** * Oral, intramuscular, intravenous * **Considerations:** * Contraindications in certain conditions. * Monitor for adverse reactions. ### 5. Serotonin Antagonists * **Example:** Ondansetron * **Mechanism:** * Blocks serotonin in GI tract, CTZ, VC. * **Administration:** * Oral, injectable * **Considerations:** * Contraindicated with apomorphine * Monitor for side effects, QT prolongation ### 6. Neurokinin Receptor Antagonists * **Example:** Aprepitant * **Mechanism:** * Inhibits substance-P neurokinin receptors * **Administration:** * Oral, intravenous. * **Considerations:** * Administered with dexamethasone, ondansetron. * CYP3A4 drug interactions. ### 7. Tetrahydrocannabinoids (THC) * **Example:** Dronabinol/Medical Marijuana * **Mechanism:** * Inhibitory effects in the cerebral cortex. * Alters mood, perception, relieves nausea. * **Administration:** * Oral, controlled substance. * **Considerations:** * Caution in elderly patients. * Dose-related "high" ## Herbal and Vitamin Supplements * **Ginger:** * Used traditionally as an antiemetic. * Antagonizes 5HT, cholinergic receptors. * Considerations for reflux, heartburn, bleeding. * **Pyridoxine (Vitamin B6):** * Recommended for nausea in pregnancy. ## Respiratory Medications ### Antihistamines * **Examples:** * First-generation: Diphenhydramine * Second-generation: Cetirizine * **Mechanism of Action:** * Blocks histamine at H1 receptors. * Inhibits smooth muscle constriction. * Decreases capillary permeability, salivation, and tear formation. * **Indications:** * Relief of allergy or cold symptoms. * **Nursing Considerations:** * Not safe for children under 2 years without a healthcare provider's order. * Caution in the elderly with first-generation antihistamines. * **Adverse/Side Effects:** * First-generation: * Anticholinergic effects, CNS depression or stimulation. * Second-generation: Headache, nausea, vomiting, fatigue. * **Patient Teaching:** * May cause drowsiness; avoid alcohol and CNS depressants. * Take the recommended amount; be cautious about side effects like dry mouth, headache, insomnia. ### Expectorants * **Example:** Guaifenesin * **Mechanism of Action:** * Reduces viscosity of respiratory secretions. * **Indication:** * Productive cough, loosening mucus * **Nursing Considerations:** Safe for all ages. * **Adverse/Side Effects:** Skin rash, headache, nausea, vomiting. * **Patient Teaching:** * Avoid irritants; may cause drowsiness * Avoid with CNS depressants. ### Beta-2 Agonists * **Examples:** * Short-acting: Albuterol * Long-acting: Salmeterol * **Mechanism of Action:** * Stimulates Beta 2-adrenergic receptors for bronchodilation. * **Indications:** * Albuterol for bronchospasm. * Salmeterol for bronchospasm prevention. * **Adverse/Side Effects:** Muscle tremor, cardiac stimulation, CNS stimulation. * **Patient Teaching:** * Take as directed; report sustained or worsening symptoms. * Rinse mouth after albuterol use. * Understand usage of short-acting and long-acting inhalers. ### Long-acting: Tiotropium * **Mechanism of Action:** * Blocks acetylcholine action; reduces bronchoconstriction. * **Indications:** * Maintenance therapy for asthma, chronic bronchitis and emphysema. * **Adverse/Side Effects:** * Cough, nasal dryness, nervousness, headaches, dizziness. * **Patient Teaching:** * Use as directed; do not exceed dosage; understand differences in short- and long-acting usage. ### Corticosteroids * **Examples:** * Inhaled: Fluticasone * Oral: Prednisone * IV: Methylprednisolone * **Mechanism of Action:** * Anti-inflammatory and immune modulation. * **Indications:** * Fluticasone for asthma control. * Prednisone and methylprednisolone for severe allergic conditions. * **Adverse/Side Effects:** * Fluticasone: Hoarseness, dry mouth, candidiasis. * Prednisone and methylprednisolone: Varied systemic effects. * **Patient Teaching:** * Not for acute asthma attacks; may cause immunosuppression and varied side effects. ### Leukotriene Receptor Antagonists * **Example:** Montelukast * **Mechanism of Action:** * Blocks leukotriene receptors; decreases inflammation. * **Indications:** * Long-term control of asthma, prevention of asthma attacks, exercise-induced bronchospasm, allergic rhinitis. * **Adverse/Side Effects:** * Headache, cough, nasal congestion, nausea, hepatotoxicity. * **Patient Teaching:** * Take as directed; not as a rescue medication; notify healthcare provider before discontinuation. ## Cardiology Medications ### Antiarrhythmics **Introduction:** * **Arrhythmia:** Deviation from normal heartbeat rate or pattern. * **ECG:** Identifies and monitors arrhythmias. **Overview:** * Medications regulate heart rate and rhythm. * Risk: All carry the risk of producing arrhythmias. **Class I - Sodium Channel Blockers** * **Subgroups:** IA, IB, IC. * **Examples:** Quinidine (IA), Lidocaine (IB), Flecainide (IC). * **Mechanism:** Slows conduction, prolongs depolarization. **Quinidine:** * **Nursing Considerations:** * Contraindications: Thrombocytopenia, myasthenia gravis. * Adverse Effects: Prolonged QT interval, thrombocytopenia. **Class II - Beta Blockers** * **Examples:** Sotalol (also Class III), Metoprolol. * **Mechanism (Sotalol):** Non-selective beta-adrenergic blocker. * **Indications for Sotalol:** Life-threatening ventricular arrhythmias. **Sotalol:** * **Nursing Considerations:** * Black Box Warning: Can cause arrhythmias. * Adverse Effects: Arrhythmias, chest pain, fatigue. **Class III - Potassium Channel Blockers** * **Mechanism:** Prolongs repolarization by blocking potassium channels. * **Indications for Amiodarone:** Life-threatening recurrent ventricular arrhythmias. **Amiodarone:** * **Nursing Considerations:** * Black Box Warnings: Fatal toxicities. * Adverse Effects: Neurological impairments, Gl disturbances. **Class IV - Calcium Channel Blockers:** * **Examples:** Verapamil, Diltiazem * **Mechanism (Diltiazem):** Inhibits calcium, decreases workload. **Diltiazem:** * **Nursing Considerations:** * Not for hypotensive patients. * Adverse Effects: Worsening heart failure, bradycardia. **Adenosine:** * **Mechanism:** Slows conduction through AV node. * **Indications:** Paroxysmal supraventricular tachycardia. * **Nursing Considerations:** * Contraindications: 2nd or 3rd degree AV block. * Adverse Effects: Prolonged asystole, facial flushing. **Cardiac Glycosides:** **Digoxin:** * **Mechanism:** Inhibits sodium and potassium pump, increases intracellular sodium. * **Indications:** Heart failure, atrial fibrillation. * **Nursing Considerations:** * Monitor apical pulse, serum digoxin, potassium levels. * Adverse Effects: Digoxin toxicity, GI symptoms. **Antianginals - Nitrates:** * **Introduction:** * **Angina Pectoris:** Chest pain due to inadequate blood flow. * **Antianginals:** Increase blood flow to the heart or decrease oxygen demand. **Nitrates:** * **Mechanism of Action:** Nitroglycerin relaxes vascular smooth muscle. * **Indications for Use:** Relief of angina due to coronary artery disease. * **Nursing Considerations Across the Lifespan:** * Contraindications: Patients on sildenafil, pregnant/breastfeeding. * Adverse Effects: Hypotension, headache. **Atorvastatin:** * **Mechanism:** Inhibits HMG-CoA reductase, reduces LDL. * **Indications:** Hyperlipidemia, prevention of cardiovascular disease. * **Nursing Considerations:** * Contraindications: Hepatic disease, pregnancy. * Adverse Effects: Myalgia, muscle spasms. * **Patient Teaching & Education:** * Take at the same time each day. * Report muscle weakness, abdominal pain. **Ezetimibe:** * **Indications:** Hyperlipidemia, familial hypercholesterolemia. * **Nursing Considerations:** * Use with caution when combined with other medications. * **Patient Teaching & Education:** * Take at the same time each day. * Report muscle weakness, abdominal pain. **Blood Coagulation Modifiers:** **Anticoagulants:** * **Heparin Sodium:** * **Mechanism** Inhibits activated coagulation factors. * **Indications:** DVT, pulmonary embolism. * **Nursing Considerations:** * Reversal: Protamine sulfate. * Monitor for bleeding, especially in >60. * **Patient Teaching & Education:** * Report bleeding/bruising promptly. * Avoid aspirin/NSAIDs. * **Low Molecular Weight Heparin (LMWH) - Enoxaparin:** * **Mechanism:** Higher anti-Factor Xa to anti-Factor lla activity. * **Indications:** Prevention/treatment of DVT. * **Nursing Considerations:** * Caution in renal impairment. * Overdosage neutralized with protamine sulfate * **Patient Teaching & Education:** * Report bleeding/bruising promptly. * Avoid aspirin/NSAIDs. * **Warfarin:** * **Mechanism:** Inhibits synthesis of vitamin K-dependent clotting factors. * **Indications:** Venous thrombosis, pulmonary embolism. * **Nursing Considerations:** * Contraindicated in pregnancy, reversible with vitamin K. * Close monitoring of PT or INR. * **Patient Education:** * Avoid alcohol, cranberries, grapefruit. * Adhere strictly to prescribed dosage. ## Study Highlights **Class I - Sodium Channel Blockers:** * **Examples:** Quinidine (IA), Lidocaine (IB), Flecainide (IC). * **Mechanism:** Slows conduction, prolongs depolarization. **Class II - Beta Blockers (also Class III, Metoprolol)** * **Mechanism (Sotalol):** Non-selective beta-adrenergic blocker. Also can be consider as Type III: (Prolongs repolarization by blocking potassium channels.) **Class III - Potassium Channel Blockers:** * **Example:** Amiodarone: * **Mechanism:** Prolongs repolarization by blocking potassium channels. * **Indications for Amiodarone:** Life-threatening recurrent ventricular arrhythmias. **Class IV - Calcium Channel Blockers:** * **Examples:** Verapamil, Diltiazem * **Verapamil:** antiarrhythmic and commonly used to control heart rate associated with supraventricular tachycardias is Verapamil. * **Diltiazem:** Class IV antiarrhythmic, inhibits calcium during depolarization. (Blocks/Stops Calcium during heartbeats.) **Quinidine:** * **Nursing Considerations:** * **Contraindications:** Thrombocytopenia, myasthenia gravis. * **Adverse Effects:** Prolonged QT interval, thrombocytopenia. **Adenosine:** * **Mechanism:** Slows conduction through AV node. (Slowing down the heart's Electrical Signals) * **Indications:** Paroxysmal supraventricular tachycardia. * **Nursing Considerations:** * **Contraindications:** 2nd or 3rd degree AV block. * **Adverse Effects:** Prolonged asystole, facial flushing. **Cardiac Glycosides:** * **Digoxin:** * **Mechanism:** Inhibits sodium and potassium pump, increases intracellular sodium. * **Indications:** Heart failure, atrial fibrillation. * **Nursing Considerations:** * Monitor apical pulse, serum digoxin, potassium levels. * **Adverse Effects:** Digoxin toxicity, GI symptoms. **Diuretics:** * **Loop Diuretic - Furosemide:** * **Mechanism:** Inhibits sodium and chloride absorption. * **Indications:** Treats edema, manages hypertension. * **Nursing Considerations:** * Onset of diuresis: Within 1 hour. * **Adverse Effects:** Dehydration, hypokalemia. **Antihypertensives:** * **Alpha-2 Agonist - Clonidine:** * **Mechanism:** Stimulates alpha-adrenergic receptors. * **Indications:** Treats hypertension, ADHD. * **Nursing Considerations:** * Dosage adjusted to patient's BP. * **Caution:** Higher bleeding incidence in >60. * **Beta Blocker - Metoprolol:** * **Mechanism:** Blocks Beta-1 receptors, decreases heart rate. * **Indications:** Treats high blood pressure, chest pain. * **Nursing Considerations:** * ER formulations should not be crushed. * Assess apical pulse rate before administering. * **Hydralazine:** * **Mechanism:** Direct vasodilator, relaxes vascular smooth muscle. * **ACE Inhibitor - Captopril:** * **Mechanism:** Blocks conversion of Angiotensin I to Angiotensin II. * **Indications:** Treats hypertension, heart failure. * **Nursing Considerations:** * Contraindicated in pregnancy. * Use with caution in diabetic patients. **Respi Additional Notes** * Montelukast is approved for use in children as young as 6 months of age and older for the treatment of asthma. * Fluticasone nasal spray formulations, for the treatment of allergic rhinitis, are often approved for use in children aged 2 years or older. ## GI Additional Notes - This harmless but temporary side effect, known as "black hairy tongue", can occur with the use of bismuth subsalicylate and may cause discoloration of the tongue - it's essential for patients to be aware of this potential effect to prevent unnecessary concern.