Antacids: Uses and Adverse Reactions

Antacids

• These drugs neutralize or reduce acidity in the stomach and duodenum.
• They combine with hydrochloric acid (HCl), increasing the stomach's pH.
• Alkaline substances buffer stomach acid, raising the pH to >5, which makes it less acidic.
• Reduce acidity in the stomach and duodenum.
• They combine with hydrochloric acid (HCl) to increase pH and make it more alkaline.
• These are used to treat hyperacidity, heartburn, acid indigestion and sour stomach.
• Also used to treat gastroesophageal reflux disease (GERD) and peptic ulcers.

Adverse Reactions of Antacids

• These can cause adverse reactions based on their composition (aluminum, magnesium, or calcium).
• It is important to be aware of these to manage patient care effectively.

Aluminum-Containing Antacids

• Can cause constipation, anorexia, weakness, tremors and bone pain.
• Can cause hypophosphatemia (low phosphorus levels).

Magnesium-Containing Antacids

• Can cause severe diarrhea (leading to dehydration) and hypermagnesemia (high magnesium levels), especially in patients with impaired kidney function.

Hypermagnesemia

• Can cause CNS depression (lethargy, drowsiness, somnolence).

Calcium-Containing Antacids

• Can cause rebound hyperacidity and metabolic alkalosis.
• Can also cause headache, renal calculi (kidney stones), neurologic impairment and hypercalcemia.

Hypercalcemia Signs and Symptoms

• Hypercalcemia is a side effect of calcium-containing antacids.
• Can cause anorexia, nausea, vomiting and confusion.

Contraindications for Antacids

• Not suitable for all patients.
• Avoid use with severe abdominal pain of unknown origin.

Sodium-Based Antacids

• Contraindicated in patients with cardiovascular disease due to sodium's water-retention properties

Calcium-Based Antacids

• Contraindicated in patients with kidney stones or pre-existing hypercalcemia.

Interactions of Antacids

• These can interact with medications, reducing their absorption and effectiveness
• Separate antacid administration from other medications by at least one hour.
• Generally, antacids decrease the absorption of many medications.
• Wait one hour between administering antacids and other medications.

Aluminum-Containing Antacids Specific Interactions

• These can interact with Digoxin, Tetracycline and Warfarin.

Nursing Administration of Antacids

• Proper administration is essential for effectiveness.
• Chew tablets thoroughly, and drink water or milk afterward.
• Shake liquid suspensions well before use.

Tablets

• Should be chewed thoroughly, and drink 8 ounces of water or milk after.

Liquid Suspensions

• Shake well before administering.

Examples of Antacids

• Common examples of antacids include Amphojel, Tums, Mylanta, and Milk of Magnesia.

Math Equations for Acid-Base Balance

• Understanding acid-base balance involves several key equations.
• These equations help in assessing the patient's acid-base status and guiding appropriate interventions.

Henderson-Hasselbalch Equation

• This equation relates pH, bicarbonate ((HCO3^-)), and partial pressure of carbon dioxide (pCO2).
• Equation: pH = pKa + log \frac{[HCO3^-]}{[H2CO3]}

Acidosis

• A condition where the blood pH is less than 7.35.
• Equation: pH < 7.35

Alkalosis

• A condition where the blood pH is greater than 7.45.
• Equation: pH > 7.45

Calculating Anion Gap

• Used in metabolic acidosis to determine the cause.
• Equation: Anion\ Gap = Na^+ - [CI^- + HCO_3^-]$

Compensation

• The body's attempt to restore normal pH.
• Respiratory Compensation for Metabolic Acidosis: pCO2 = 1.5 \times [HCO3^-] + 8 \pm 2$

Base Excess/Deficit

• Indicates the amount of excess or deficit of base in the blood.
• Equation: $Base\ Excess = 0.93 \times [HCO_3^-] + (pCO_2 \times 0.03) - 40$

H2 Receptor Antagonists

• These are a class of drugs that inhibit the action of histamine at the H2 receptors located in the stomach.
• This action reduces the secretion of gastric acid, making them useful in treating various gastrointestinal conditions.
• They inhibit histamine's action at H2 receptors in the stomach.
• The primary effect is to reduce gastric acid secretion.
• Alternate names are histamine antagonists, H2 blockers.

Therapeutic Uses

• These are used to treat conditions related to excessive gastric acid production and gastrointestinal irritation.
• They can provide relief from burning sensations in the chest, caused by heartburn.
• They alleviate discomfort caused by excess stomach acid, which is acid indigestion.
• They manage symptoms and prevent esophageal damage caused by GERD.
• They aid in healing and reduce pain from gastric and duodenal ulcers.
• These control excessive gastric secretions, which is gastric hypersecretory conditions.
• Used with antibiotics to eradicate Helicobacter pylori infections for H. pylori treatment.

Adverse reactions

• These can cause several adverse reactions, ranging from mild to severe.
• It's important to monitor patients for these effects.

Central Nervous System (CNS) Effects

• Can cause Dizziness, somnolence, headache, confusion and hallucinations.

Gastrointestinal Effects

• Can cause diarrhea.

Endocrine Effects

• Can cause reversible impotence.

General Effects

• Can cause lethargy or restlessness.

Cimetidine-Specific Adverse Effects

• Cimetidine (Tagamet) is known to cause more pronounced adverse effects compared to other H2 receptor antagonists.
• Can cause decreased libido, gynecomastia, impotence.
• These effects are typically reversible upon discontinuation of the medication.

Special Populations and Precautions

• H2 receptor antagonists should be used with caution in certain populations, particularly older adults and those with kidney or liver dysfunction.
• Older adults are more susceptible to side effects due to age-related decline in organ function.
• Kidney and liver dysfunction impairs drug metabolism and excretion increase the risk of adverse effects.
• Use cautiously in patients with increased risk for pneumonia and COPD.

Risk of Gastrointestinal Bleeding

• Patients taking H2 receptor antagonists have an increased risk of gastrointestinal (GI) bleeding.
• Monitoring for signs of bleeding is crucial.

Signs of GI Bleed

• Can include frank bleeding (obvious, visible blood), dark, tarry stools (melena) and coffee-ground emesis (vomit that looks like coffee grounds).
• Report any signs of GI bleeding to the healthcare provider immediately.

Patient Education

• It is essential to educate patients about potential risks and necessary precautions for safe and effective use of H2 receptor antagonists.
• Inform patients about potential allergic reactions or sensitivities to the drug.
• Use cautiously in patients with kidney or liver impairment, and dosage adjustments may be necessary.
• Patients with kidney or liver disease may not metabolize or eliminate drugs effectively which can lead to toxicity.
• Avoid alcohol and foods that increase GI irritation.
• Limit aspirin products and NSAIDs due to the increased risk of GI bleeding.

Drug Interactions

• These can interact with other medications, affecting their absorption, metabolism, or elimination.
• Antacids decrease the absorption of many medications.
• Avoid taking antacids one hour before or after taking H2 antagonists.
• Opiates increase the risk of respiratory depression.
• Oral anticoagulants (Warfarin/Coumadin) increase the risk of bleeding.
• Monitor PT (Prothrombin Time) and INR (International Normalized Ratio) lab results.

Monitoring PT/INR

• PT/INR (Prothrombin Time/International Normalized Ratio) are blood tests used to measure how quickly your blood clots.
• Often monitored in patients taking anticoagulants to ensure the medication is working effectively and to prevent excessive bleeding.
• This assesses the blood's clotting ability
• Anticoagulant Monitoring is essential for patients on warfarin or similar drugs.
• Elevated PT/INR indicates a higher risk of bleeding.
• Aim to keep PT/INR within a specific range to balance clot prevention and bleeding risk.
• Factors like diet, other medications, and underlying health conditions can affect PT/INR levels, so consistency in these areas is important.
• Patients should report any signs of bleeding, such as nosebleeds, bruising, or blood in urine or stool, to their healthcare provider immediately.

Digoxin Interactions

• Certain medications can alter digoxin levels, potentially affecting its therapeutic efficacy.
• Some drugs may decrease digoxin levels, causing it to fall outside the therapeutic range.
• Close monitoring of digoxin levels is crucial when other interacting medications are used concurrently.

Theophylline Interactions

• Theophylline levels can be affected by other drugs, necessitating careful monitoring to avoid toxicity.
• Certain drugs can increase theophylline levels.
• Blood levels of theophylline must be monitored to ensure they remain within the therapeutic range and to prevent toxicity.

Smoking and Medication Effectiveness

• Smoking, specifically nicotine, can reduce the effectiveness of certain medications.
• Nicotine decreases the effectiveness of some medications, so this is an important consideration, although nicotine itself isn't a medication.

Proton Pump Inhibitors (PPIs)

• PPIs are medications that suppress gastric acid secretion by inhibiting the enzyme responsible for producing gastric acid.
• They work by inhibiting the enzyme that makes gastric acid.
• They are typically used for short-term treatment.

Indications

• PPIs are indicated for specific gastrointestinal conditions.
• Used for Gastric ulcers, duodenal ulcers, Gastroesophageal Reflux Disease (GERD) and erosive esophagitis
• Usually prescribed for 4-8 weeks.

Adverse Reactions

• Both short-term and long-term use of PPIs can lead to various adverse effects.
• Short-term includes headache, nausea, diarrhea, vomiting and abdominal pain
• Long-term (beyond 4-8 weeks) includes pneumonia, osteoporosis, fractures and decreased magnesium levels

Magnesium Deficiency

• Prolonged PPI use can lead to hypomagnesemia.
• Symptoms can include tremors, muscle cramps and seizures.
• Regular monitoring of magnesium levels is essential.

Clostridium difficile (C. diff) Diarrhea

• PPI use is associated with an increased risk of C. difficile-associated diarrhea.
• Report any diarrhea, especially if accompanied by fever, abdominal cramps or bloody stools

Contraindications and Precautions

• Specific conditions and patient populations require caution when using PPIs.
• Contraindicated if alleric to the drug.
• Precautions include older patients, hepatic impairment and kidney impairment.

Vitamin B12 Absorption

• Prolonged use of PPIs may impair vitamin B12 absorption.
• Vitamin B12 is crucial for various bodily functions.
• Monitor for signs of B12 deficiency in long-term PPI users.

Use During Lactation and Pregnancy

• Certain PPIs are contraindicated during lactation, and caution is advised during pregnancy.
• Misoprostol and Pantoprazole are contraindicated during lactation
• Use only if benefits outweigh risks during pregnancy and avoid pregnancy while taking these drugs.

Drug Interactions

• PPIs can interact with several other medications, altering their absorption or increasing the risk of adverse effects.
• Carafate decreases absorption of PPIs.
• Oral anticoagulants increase risk of bleeding.
• Digoxin increases absorption, potentially leading to toxicity.
• Plavix (clopidogrel) decreases effectiveness, which is a platelet inhibitor.

Medications at Risk for Toxic Levels

• Concurrent use of PPIs can elevate the risk of toxicity from certain drugs.
• Can cause toxic levels of benzodiazepines, methotrexate, diazepam, antifungals, phenytoin.
• Monitor drug levels and watch for signs and symptoms of toxicity.

Administration Guidelines

• Proper administration is crucial for the effectiveness of PPIs.
• Do not crush, chew, or break sustained-release capsules.
• Do not open sustained-release capsules and sprinkle on food.
• Administer omeprazole once daily before meals in the morning.
• Treatment duration is typically 4-8 weeks for active ulcers.
• Notify the provider if there are any signs of a GI problem.

Common PPI Names

• Nexium, Prilosec and Protonix.

Anti-Emetics

• Anti-emetics are medications used to prevent vomiting caused by various factors.
• Prevent vomiting caused by drugs, radiation, metabolic disorders and chemotherapy.
• Frequently used in chemotherapy to manage nausea and vomiting.

Common Adverse Reactions

• Many medications, particularly antiemetics, can cause a range of adverse reactions.
• It's crucial to understand these to provide appropriate patient care and education.
• Some medications produce varying degrees of drowsiness.
• Many drugs have anticholinergic properties.
• Remember the classic anticholinergic side effects: dry mouth, urinary retention and constipation.
• These effects occur because anticholinergics decrease secretions and cause a drying effect.

Ondansetron (Zofran) Side Effects

• Ondansetron is a commonly used antiemetic, but it's important to be aware of its potential side effects.
• Common side effects: Headache, diarrhea and dizziness.
• Ondansetron can cause a prolonged QT interval
• Understanding what this means is critical for patient safety.

Prolonged QT Interval

• The QT interval represents the time it takes for the ventricles of the heart to depolarize and repolarize.
• A prolonged QT interval increases the risk of dangerous arrhythmias.
• On an ECG rhythm strip, you have the P wave, QRS complex, and T wave.
• The QT interval is measured from the beginning of the Q wave to the end of the T wave.
• If this interval is longer than normal, it's considered a prolonged QT interval.
• If another heartbeat occurs during this prolonged repolarization period, it can disrupt the heart's rhythm.
• This can lead to a lethal arrhythmia, such as Torsades de Pointes.

Torsades de Pointes

• Torsades de Pointes is a specific type of ventricular tachycardia that is life-threatening.
• The ECG shows a twisting pattern around the baseline.
• The complexes appear large and small, creating a "twisting" appearance.
• Torsades de Pointes is a deadly arrhythmia requiring immediate intervention.

Arrythmia Induction

• If a subsequent heartbeat occurs during the prolonged QT interval, it can disrupt the heart's electrical activity.
• This disruption can lead to Torsades de Pointes or other lethal arrhythmias.

Adverse Effects of Dimenhydrinate and Promethazine

• Dimenhydrinate (Dramamine) and Promethazine (Phenergan) are antiemetics with significant sedative effects and other potential adverse reactions.
• Dimenhydrinate causes sedation.
• Promethazine causes serious sedation and can cause severe respiratory depression
• Severe CNS depression is a contraindication.
• Not for use in children less than two years old.
• Extreme caution should be used in older children due to the risk of respiratory depression.
• Contraindicated in pregnancy and lactation.

Interactions

• Drug interactions can significantly increase the risk of adverse effects.
• Opioids and alcohol increase the risk of respiratory depression when used with these medications.
• Concurrent use can worsen hypotension.

Medication Administration with Anticholinergics

• When administering anticholinergics, it's important to manage their drying effects.
• Encourage patients to increase their fluid intake to combat dry mouth and constipation.

Managing Constipation and Urinary Retention

• This section focuses on the importance of addressing constipation and urinary retention in a timely manner, especially in the context of medication side effects.
• It also covers interventions for dry mouth and introduces Reglan, highlighting its significant risks.
• Regularly check patients for bladder distention, as urinary retention can occur.
• Promptly manage constipation to prevent further complications.
• Always ask patients about their last bowel movement, this is a crucial assessment.
• Consider starting laxatives or stool softeners if the patient hasn't had a bowel movement by the third day
• Suggest sucking on hard candy or chewing gum to alleviate dry mouth.reglan

Reglan (Metoclopramide) and Tardive Dyskinesia

• This section discusses Reglan, a medication with a black box warning due to the risk of tardive dyskinesia with long-term use.
• Reglan carries a black box warning from the FDA, indicating significant risks.
• Using Reglan for longer than 12 weeks increases the risk of developing tardive dyskinesia.
• Involuntary movements, often of the face
• Chewing-type movements
• Movements of the upper extremities
• Stay under the 12-week usage limit.
• Immediately report any unusual movements to the provider.
• Discontinue the medication if tardive dyskinesia symptoms appear.
• Tardive dyskinesia can be very distressing for the individual.
• Some cases of tardive dyskinesia can become permanent.

Motion Sickness and Nausea Medications

• This section covers various medications used to prevent motion sickness and manage nausea, including options for chemotherapy patients.
• Scopolamine is used to prevent motion sickness.
• Available as a transdermal patch placed behind the ear, apply hours before travel.
• Tablet form should be taken at least one hour before travel.
• Zofran is presented as a newer alternative to Phenergan, with fewer sedative side effects.
• Reglan, Phenergan, Zofran and Scopolamine are common medications
• Additional medications for chemo patients include: Lorazepam, Dronabinol, Aprepitant and Dexamethaso