Midterm Study Guide Flashcards
(17 cards)
What are the pharmacokinetic steps (LADME)? and
at which steps drug-herb interactions can occur?
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Which electrolyte imbalances can affect serum concentrations of digoxin and risk for digoxin toxicity?
Hypokalemia: Low potassium levels can increase digoxin’s effect on the heart, leading to toxicity even with normal digoxin concentrations. This is because potassium competes with digoxin for binding sites on the Na+/K+-ATPase pump.
Hypomagnesemia: Magnesium deficiency can also enhance digoxin’s effects and increase the risk of toxicity, as magnesium is a cofactor for the Na+/K+-ATPase pump.
Hypercalcemia: High calcium levels can exacerbate digoxin’s effects, increasing the risk of arrhythmias and toxicity.
Hyperkalemia: In acute digoxin toxicity, increased potassium levels can be seen due to the inactivation of the Na+/K+-ATPase pump.
Which antihypertensive drugs have a comparable or similar effect to herbs that drain dampness?
Thiazide diuretics: These are frequently prescribed for hypertension and work by inhibiting sodium reabsorption in the distal convoluted tubule, leading to increased sodium and water excretion.
Loop diuretics: More potent than thiazides, they are used for conditions requiring significant fluid removal and work by inhibiting sodium reabsorption in the ascending limb of the loop of Henle.
Potassium-sparing diuretics: These are weaker diuretics and are often combined with other types. They prevent potassium loss while promoting sodium and water excretion.
Which herbs have mechanisms of action or specific physiological effects that overlap with specific classes of antihypertensive drugs?
How can herbal or dietary factors affect the therapeutic action or toxicity of warfarin.
Warfarin works by interfering with the body’s use of vitamin K, which is essential for blood clotting.
1. Vitamin K:
Foods high in vitamin K: Consuming foods rich in vitamin K can decrease warfarin’s effectiveness, making the blood more prone to clotting.
- Herbs and Supplements:
Increased bleeding risk: Some herbal supplements can enhance the effect of warfarin, increasing the risk of bleeding.
Decreased warfarin effectiveness: Some supplements can decrease warfarin’s blood-thinning effect, potentially increasing the risk of blood clots.
What are the clinical and laboratory monitoring parameters for warfarin?
- Laboratory Monitoring:
International Normalized Ratio (INR): This is the primary laboratory test used to monitor warfarin’s effectiveness. The INR is a standardized way of expressing the prothrombin time (PT), which measures how long it takes blood to clot.
Target INR Range: The therapeutic INR range generally falls between 2.0 and 3.0 for most conditions requiring warfarin therapy.
INR Monitoring Frequency: Initially, INR testing is more frequent, possibly every 1 to 3 days or weekly, until the INR stabilizes within the desired therapeutic range. - Clinical Monitoring:
Bleeding: Warfarin, as a blood thinner, increases the risk of bleeding.
Black or tarry stools
Nosebleeds
Unusual bruising
Hematuria (blood in the urine)
Severe headaches
Vomiting blood or material resembling coffee grounds
Hemoglobin and Hematocrit Levels:
Urinalysis
Occult blood tests
Liver function tests
Kidney function tests (eGFR or serum creatinine)
Full blood count
Thyroid function tests
What are the clinical and laboratory monitoring parameters for digoxin?
Clinical Monitoring:
Symptoms of Heart Failure:
Heart Rate and Rhythm: Monitor for changes in heart rate and rhythm, particularly bradycardia (slow heart rate), as digoxin can decrease heart rate. ECGs are essential for detecting arrhythmias like atrioventricular block or ventricular arrhythmias, which may indicate toxicity.
Symptoms of Digoxin Toxicity:
General: Fatigue, malaise, insomnia, loss of interest, depression, anxiety, restlessness, weakness.
Gastrointestinal: Loss of appetite, nausea, vomiting, diarrhea, abdominal pain, constipation.
Neurological: Headache, confusion, anxiety, hallucinations, altered mental status, vertigo, dizziness.
Visual: Blurred vision, seeing halos around bright objects, changes in how colors look (particularly green or yellow), blind spots.
Cardiac: Irregular heartbeat, palpitations, ventricular tachycardia or fibrillation, asystole, symptomatic high-degree atrioventricular block, symptomatic bradycardia.
Renal Function: Digoxin is primarily eliminated by the kidneys, so monitoring renal function (e.g., BUN and creatinine) is essential, especially in patients with impaired renal function.
Electrolyte Levels: Low levels of potassium (hypokalemia) and magnesium (hypomagnesemia), and high levels of calcium (hypercalcemia) can increase the risk of digoxin toxicity. Therefore, electrolyte levels should be monitored regularly.
Drug Interactions: Be aware of other medications (including over-the-counter and herbal supplements) that can interact with digoxin and potentially increase or decrease its levels.
Laboratory Monitoring:
Serum Digoxin Levels: A digoxin test measures the amount of digoxin in the blood to ensure it is within the therapeutic range. Blood samples should be drawn at least 6-8 hours after the last dose, ideally 8-12 hours, for accurate results.
Therapeutic Range:
For heart failure: 0.5 to 0.8 ng/mL.
For atrial fibrillation: 0.5 to 2.0 ng/mL.
Toxicity Level: Serum digoxin concentrations
greater than 2.0 ng/mL increase the risk of toxicity,
above 4.0 ng/mL may be life-threatening.
Kidney function tests (BUN and creatinine)
What are the clinical and laboratory monitoring parameters for cardiac function, kidney function and liver function?
Key parameters include:
heart rate, blood pressure, EKG for cardiac function;
serum creatinine, BUN, and GFR for kidney function;
ALT, AST, ALP, bilirubin, and albumin for liver function.
What are clinical manifestations of Fu Zi toxicity?
Early Symptoms:
Gastrointestinal: Nausea, vomiting, diarrhea, and abdominal colic.
Neurological: Numbness and tingling (paresthesia) in the mouth, face, and limbs; headache, dizziness, and restlessness.
Cardiovascular Symptoms:
Arrhythmias: Palpitations, bradycardia, tachycardia, and potentially fatal ventricular fibrillation (VF) or ventricular tachycardia (VT).
Hypotension: Low blood pressure.
Cardiac Failure: In severe cases, heart failure and cardiac arrest.
Other Potential Symptoms:
Respiratory Distress: Difficulty breathing.
Neurological: Confusion, seizures, and coma in severe cases.
Muscle Dysfunction: Muscle weakness or twitching.
Shock: In severe cases, leading to organ damage and potentially death.
Which herbs are likely to interact with antiarrhythmic drugs?
Herbs that affect blood clotting: Herbs such as Salvia (Danshen), Ginkgo biloba, Ginseng (Asian), Ginger, Garlic, and Tang-kuei (Dong quai) may increase the risk of bleeding, especially when taken with blood thinners like warfarin. Danshen, in particular, may increase bleeding risk when taken with warfarin or other blood thinners.
Herbs that influence heart rate or blood pressure:
Ma-huang (Ephedra): This stimulant can increase heart rate and blood pressure, potentially increasing the risk of stroke or heart attack, and interfering with cardiovascular drugs.
Night-blooming cereus: This may increase the effects of various cardiovascular drugs, including antiarrhythmics, beta-blockers, and calcium-channel blockers.
Oleander: Can cause heart block, hyperkalemia, arrhythmia, and even death.
St. John’s Wort: This may increase heart rate and blood pressure (especially with MAO inhibitors) and can decrease the concentration of certain medications like digoxin. It can also induce intestinal P-glycoprotein, stimulating the efflux of digoxin and decreasing its plasma concentration and efficacy.
Rhubarb (Dahuang) and Aloe: These herbs may potentiate the effects of cardiac glycosides and antiarrhythmic agents by reducing potassium levels through their laxative effect.
Hawthorn (Crataegus): This can increase the hypotensive effects of nitrates and antihypertensives and may increase the risk of arrhythmias with depolarizing muscle relaxants. Hawthorn has shown potential in increasing cardiac contractility and prolonging the effective refractory period.
Danshen (Salvia miltiorrhiza): This can interact strongly with certain heart medications, including blood thinners and blood pressure medications. It may also interact with digoxin by potentially increasing its effects and raising the risk of irregular heartbeat.
Berberine (found in Coptis chinensis): Studies show that this can lower blood pressure and may significantly reduce it when combined with oral hypotensors. However, it can also inhibit the CYP3A4 enzyme, which is involved in the metabolism of many medications.
Corydalis turtschaninovii: This may have rhythm control and antiplatelet aggregation functions and can inhibit inflammatory response, which may affect myocardial remodeling and thrombosis.
Leonurus cardiaca (Motherwort): This may decrease blood pressure and heart rate, increase coronary blood flow, and treat tachyarrhythmias.
Ephedra sinica (Ma huang): Contains ephedrine and pseudoephedrine, which can interfere with certain drugs, including anti-seizure medications.
What are the advantages and disadvantages of various information resources (e.g. textbooks,
databases, primary literature, etc.)?
Know the concepts of pharmacokinetics, pharmacodynamics, toxicokinetics, and toxicodynamics
Explain the process of drug metabolism and the cytochrome P450 system.
Drug metabolism is the process by which the body chemically modifies drugs, primarily in the liver, to facilitate their elimination. This often involves cytochrome P450 (CYP) enzymes, a large family of heme-containing enzymes that catalyze a wide range of reactions, including oxidation, reduction, and hydrolysis. These reactions generally make drugs more water-soluble, allowing them to be excreted more easily by the kidneys.
Describe the physiological effects of beta-blockers.
Beta-blockers primarily work by slowing down the heart rate and reducing the force of heart contractions, which in turn lowers blood pressure. They achieve this by blocking the effects of stress hormones like epinephrine (adrenaline) and norepinephrine, which normally cause the heart to beat faster and with more force.
What are the characteristics of toxicity.
What herbs are contraindicated for use in hypertension, coagulopathies, and arrhythmias
Which frequently used herbs can contribute to hyperkalemia?
