Nifedipine Pharmacology Quiz
86 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary therapeutic use of nifedipine?

  • Heart failure
  • Type 2 diabetes
  • Arrhythmias
  • Hypertension (correct)

Which of the following is a key difference between immediate-release (IR) and sustained-release (SR) nifedipine?

  • SR formulation is associated with increased mortality
  • IR peaks in 30 minutes while SR peaks in 6 hours (correct)
  • IR is preferred for hypertensive emergencies
  • IR has fewer side effects than SR

What adverse effect is NOT typically associated with nifedipine?

  • Headache
  • Flushing
  • Peripheral edema
  • Constipation (correct)

Combining nifedipine with which type of medication can help prevent reflex tachycardia?

<p>β-adrenergic blockers (C)</p> Signup and view all the answers

Which of the following statements regarding nifedipine's use in angina is accurate?

<p>Nifedipine is often combined with a β blocker for optimal results (B)</p> Signup and view all the answers

What is the primary therapeutic use of calcium channel blockers?

<p>To treat hypertension, angina pectoris, and cardiac dysrhythmias (B)</p> Signup and view all the answers

How do calcium channel blockers influence vascular smooth muscle function?

<p>They prevent contraction and promote vasodilation (D)</p> Signup and view all the answers

What effect does calcium channel blockade have on the heart's sinoatrial node?

<p>It decreases the pacemaker activity (D)</p> Signup and view all the answers

Which of the following statements about calcium channels is true?

<p>Calcium entry into cells is essential for muscular contraction (A)</p> Signup and view all the answers

Calcium channel blockers do NOT have a significant effect on which of the following?

<p>Veins (A)</p> Signup and view all the answers

What mechanism do calcium channel blockers and β1-adrenergic receptors share in the heart?

<p>Both affect calcium influx into cardiac tissues (A)</p> Signup and view all the answers

Which type of calcium channel blockers does NOT include dihydropyridines?

<p>Nondihydropyridines (C)</p> Signup and view all the answers

What adverse effect has been debated regarding the use of calcium channel blockers?

<p>Potential harm in patients with hypertension and diabetes (D)</p> Signup and view all the answers

What is the primary action of norepinephrine in relation to heart function?

<p>Increase heart rate, AV conduction, and force of contraction (A)</p> Signup and view all the answers

What is the main cardiovascular effect of verapamil on patients?

<p>Vasodilation and reduced arterial pressure (C)</p> Signup and view all the answers

Why must verapamil doses be reduced in patients with hepatic impairment?

<p>It is primarily eliminated by hepatic metabolism (C)</p> Signup and view all the answers

Which condition is verapamil widely used to treat?

<p>Angina pectoris (A)</p> Signup and view all the answers

What is a common adverse effect associated with both verapamil and diltiazem?

<p>Constipation (C)</p> Signup and view all the answers

What type of drug interaction should be monitored closely when verapamil and digoxin are used together?

<p>Risk of AV block due to combined effects (B)</p> Signup and view all the answers

How does grapefruit juice affect drug metabolism?

<p>It increases the levels of medications by inhibiting metabolism (C)</p> Signup and view all the answers

What is the primary route of elimination for diltiazem?

<p>Urine and feces after extensive metabolism (A)</p> Signup and view all the answers

In which patient population should verapamil be used with caution?

<p>Patients with cardiac failure (B)</p> Signup and view all the answers

What effect does diltiazem have on the gastrointestinal system compared to verapamil?

<p>Less frequent constipation (B)</p> Signup and view all the answers

What is the primary therapeutic indication for both verapamil and diltiazem?

<p>Hypertension (C)</p> Signup and view all the answers

Which patient population requires a careful discussion of the risks and benefits when considering calcium channel blocker therapy?

<p>Pregnant women (B)</p> Signup and view all the answers

Which side effect is associated specifically with the use of nifedipine?

<p>Reflex tachycardia (C)</p> Signup and view all the answers

What is a key difference between nifedipine and verapamil regarding their effects on the heart?

<p>Verapamil can reduce contractile force. (C)</p> Signup and view all the answers

What monitoring is generally not required for patients starting therapy with verapamil or diltiazem?

<p>Routine blood monitoring (B)</p> Signup and view all the answers

In which group of patients have calcium channel blockers been associated with chronic eczematous eruptions?

<p>Older adults (C)</p> Signup and view all the answers

What effect does nifedipine have on blood pressure and heart rate?

<p>Lowers blood pressure and increases heart rate (A)</p> Signup and view all the answers

Which condition is a contraindication for the use of verapamil and diltiazem?

<p>Sick sinus syndrome (A)</p> Signup and view all the answers

Which of the following statements regarding diltiazem is true?

<p>It reduces contractile force of the heart. (D)</p> Signup and view all the answers

What should be initiated with low doses and adjusted carefully to minimize adverse effects?

<p>Verapamil therapy (D)</p> Signup and view all the answers

What regulates the excitability of AV nodal cells?

<p>Calcium entry (D)</p> Signup and view all the answers

What is the result of calcium channel blockade in the AV node?

<p>Decreased velocity of conduction (B)</p> Signup and view all the answers

Which type of adrenergic receptor enhances calcium influx when activated?

<p>β1-adrenergic receptors (A)</p> Signup and view all the answers

Which drug is the prototype for the dihydropyridine class of calcium channel blockers?

<p>Nifedipine (D)</p> Signup and view all the answers

What effect does verapamil have on the SA node?

<p>Decreases heart rate (A)</p> Signup and view all the answers

What is one of the primary actions of nondihydropyridine calcium channel blockers like verapamil?

<p>Decrement AV nodal conduction (A)</p> Signup and view all the answers

How do calcium channel blockers and β blockers affect cardiac function?

<p>They decrease force of contraction and slow heart rate (B)</p> Signup and view all the answers

What physiological change occurs due to baroreceptor reflex activation following verapamil-induced blood pressure lowering?

<p>Increased firing of sympathetic nerves (C)</p> Signup and view all the answers

What dictates the direct effect on cardiac function in different myocardial cells when calcium channels are activated?

<p>Type of cell involved (A)</p> Signup and view all the answers

Which of the following is NOT an effect of blocking calcium channels with verapamil?

<p>Increased force of contraction (B)</p> Signup and view all the answers

What is one of the reasons nifedipine is preferred over verapamil for certain patients?

<p>Nifedipine is less likely to cause constipation. (A)</p> Signup and view all the answers

What type of formulation of nifedipine is contraindicated for use in hypertensive emergencies?

<p>Immediate-Release (IR) (B)</p> Signup and view all the answers

How can peripheral edema, an adverse effect of nifedipine, be effectively managed?

<p>By incorporating a diuretic (D)</p> Signup and view all the answers

Which of the following therapeutic areas does nifedipine primarily target?

<p>Vasospastic angina (A)</p> Signup and view all the answers

What potential risk is associated with immediate-release (IR) nifedipine in patients with myocardial infarction?

<p>Increased mortality rates (C)</p> Signup and view all the answers

What effect does blocking calcium channels have on vascular smooth muscle?

<p>Promotes vasodilation (C)</p> Signup and view all the answers

How do calcium channel blockers impact heart rate?

<p>They can decrease heart rate. (A)</p> Signup and view all the answers

Which type of calcium channel blocker is primarily linked to an increase in force of cardiac contraction?

<p>Dihydropyridines (C)</p> Signup and view all the answers

What physiological role does calcium influx serve in the sinoatrial (SA) node?

<p>Enhances spontaneous discharge (A)</p> Signup and view all the answers

What is a critical consequence of calcium channel blockade in the myocardium?

<p>Diminished contractile force (B)</p> Signup and view all the answers

In which of the following does calcium channel blockade primarily lead to vasodilation?

<p>Peripheral arterioles (D)</p> Signup and view all the answers

What characterizes the action of calcium channel blockers on veins?

<p>No significant effect noted (C)</p> Signup and view all the answers

Which condition presents a controversial safety concern when using calcium channel blockers?

<p>Diabetes (C)</p> Signup and view all the answers

In which patient population is close monitoring advised when using diltiazem concurrently with digoxin?

<p>Older adults (A)</p> Signup and view all the answers

What is the primary reason nifedipine cannot be used to treat cardiac dysrhythmias?

<p>It primarily acts on vascular smooth muscle rather than cardiac channels. (C)</p> Signup and view all the answers

Which condition should be a contraindication for the use of verapamil?

<p>Heart failure (C)</p> Signup and view all the answers

What adverse effect is uniquely associated with the immediate-release formulation of nifedipine?

<p>Reflex tachycardia (A)</p> Signup and view all the answers

Which of the following is a common adverse effect when using both nifedipine and verapamil?

<p>Hypotension (C)</p> Signup and view all the answers

Which of these statements regarding calcium channel blockers in breastfeeding women is correct?

<p>Certain drugs may pose harm, while others lack data on transmission through milk. (B)</p> Signup and view all the answers

How does the hemodynamic effect of nifedipine primarily manifest?

<p>Vasodilation leading to lowered blood pressure with potential increase in heart rate (A)</p> Signup and view all the answers

What is the preferred dosing strategy to minimize adverse effects when starting treatment with calcium channel blockers?

<p>Low doses initiated and adjusted carefully (A)</p> Signup and view all the answers

In older adults, calcium channel blockers are associated with which specific skin condition?

<p>Chronic eczematous eruptions (A)</p> Signup and view all the answers

What factor should be monitored in patients taking diltiazem and digoxin in conjunction?

<p>Cardiac status (A)</p> Signup and view all the answers

What is the primary effect of verapamil on the cardiovascular system?

<p>Promotes vasodilation and lowers arterial pressure (D)</p> Signup and view all the answers

How does verapamil affect cardiac conduction in patients with atrial flutter?

<p>Slows ventricular rate through AV node suppression (A)</p> Signup and view all the answers

What is a significant pharmacokinetic characteristic of oral verapamil administration?

<p>Extensive first-pass metabolism reducing systemic exposure to 20% (A)</p> Signup and view all the answers

What common side effect should patients anticipate when taking verapamil?

<p>Constipation due to calcium channel blockade in the intestine (C)</p> Signup and view all the answers

What is the effect of combining digoxin with verapamil?

<p>Increased risk for AV block due to additive effects (D)</p> Signup and view all the answers

In which condition should verapamil be used with special caution?

<p>Patients with sick sinus syndrome (C)</p> Signup and view all the answers

What is the approximate bioavailability of oral diltiazem after first-pass metabolism?

<p>50% (B)</p> Signup and view all the answers

Which of the following statements is true regarding the adverse effects of diltiazem compared to verapamil?

<p>Diltiazem generally causes less constipation than verapamil (A)</p> Signup and view all the answers

What is a key factor that affects the use of verapamil in patients with liver disease?

<p>Severe liver impairment necessitates dose reduction (B)</p> Signup and view all the answers

What cardiovascular effect does verapamil primarily have when treating essential hypertension?

<p>Reduces blood pressure through arteriolar dilation (A)</p> Signup and view all the answers

What is the main effect of calcium channel blockade on the atrioventricular node?

<p>Decreases velocity of conduction (C)</p> Signup and view all the answers

How does activating cardiac β1-adrenergic receptors affect calcium entry?

<p>It enhances calcium entry. (A)</p> Signup and view all the answers

What distinguishes dihydropyridines from nondihydropyridines in terms of their action sites?

<p>Dihydropyridines mainly affect blood vessels. (B)</p> Signup and view all the answers

What is a major hemodynamic effect of verapamil on blood vessels?

<p>Reduces arterial pressure (A)</p> Signup and view all the answers

Which of the following best describes the overall action of calcium channel blockers and β blockers on the heart?

<p>They both decrease force of contraction. (A)</p> Signup and view all the answers

What is the role of cAMP in the context of β1-adrenergic receptor activation?

<p>It promotes the phosphorylation of calcium channels. (A)</p> Signup and view all the answers

Which of the following medications belongs to the dihydropyridine class of calcium channel blockers?

<p>Nifedipine (B), Amlodipine (D)</p> Signup and view all the answers

What effect does the baroreceptor reflex have when blood pressure decreases due to verapamil?

<p>It increases sympathetic nerve firing to the heart. (C)</p> Signup and view all the answers

Which of the following actions is a result of calcium entry in SA nodal cells?

<p>Increased heart rate (D)</p> Signup and view all the answers

What type of receptor mediates the effects of norepinephrine that enhance calcium entry in cardiac cells?

<p>β1-adrenergic receptors (D)</p> Signup and view all the answers

Flashcards

What are Calcium Channel Blockers (CCBs)?

Drugs that prevent calcium ions from entering cells, primarily affecting heart and blood vessels.

What are calcium channels?

Calcium channels are pores in cell membranes that regulate calcium flow into cells, crucial for muscle function.

How do CCBs affect blood vessels?

CCBs block calcium channels in vascular smooth muscle, preventing contraction and leading to vasodilation.

How do CCBs affect the heart?

CCBs affect the heart's myocardium, SA node, and AV node, all of which are connected to β1-adrenergic receptors.

Signup and view all the flashcards

How do CCBs affect the heart muscle (myocardium)?

Calcium influx in myocardium increases contractility. Blocking calcium channels reduces heart muscle force.

Signup and view all the flashcards

How do CCBs affect the SA node?

Calcium influx in the SA node increases pacemaker activity. Blocking calcium channels slows heart rate.

Signup and view all the flashcards

How do CCBs affect the AV node?

Calcium influx in the AV node helps transmit signals from the SA node to the ventricles. Blocking calcium channels can affect the heart's conduction.

Signup and view all the flashcards

What are common uses for CCBs?

CCBs are commonly used to treat hypertension, angina pectoris, and cardiac dysrhythmias.

Signup and view all the flashcards

How are β1-adrenergic receptors linked to calcium channels?

In the heart, β1-adrenergic receptors are linked to calcium channels. When stimulated by hormones like norepinephrine, these receptors increase calcium influx into heart cells.

Signup and view all the flashcards

How are CCBs classified?

CCBs can be classified into two main families: dihydropyridines and nondihydropyridines. Each family has different effects and primary sites of action.

Signup and view all the flashcards

How do CCBs affect heart rate?

CCBs can reduce heart rate by inhibiting calcium influx in the SA node, which is the heart's natural pacemaker.

Signup and view all the flashcards

What is the baroreceptor reflex response to CCB use?

By lowering blood pressure through vasodilation, CCBs can trigger a reflex response from the baroreceptor reflex, which can increase sympathetic nerve activity to the heart.

Signup and view all the flashcards

How do CCBs affect AV nodal conduction?

CCBs can reduce the rate of conduction through the AV node, which is the pathway between the atria and ventricles. This can slow down the transmission of electrical signals.

Signup and view all the flashcards

What is the net effect of Verapamil on the heart?

Verapamil's direct effects on the heart (slowing heart rate, conduction, and contraction) are countered by its indirect effects, leading to a minimal overall impact on cardiac performance.

Signup and view all the flashcards

What is the overall cardiovascular effect of Verapamil?

Verapamil's main cardiovascular effect is vasodilation, resulting in lowered blood pressure and improved blood flow to the heart (coronary perfusion).

Signup and view all the flashcards

When are verapamil's effects on the heart a concern?

Verapamil's effects on the heart, such as slowing heart rate and conduction, are rarely clinically significant in healthy individuals.

Signup and view all the flashcards

In which patients is Verapamil contraindicated?

Verapamil is contraindicated in patients with sick sinus syndrome and second or third-degree AV block due to its potential to worsen cardiac dysfunctions.

Signup and view all the flashcards

How does Verapamil interact with digoxin?

Verapamil increases plasma levels of digoxin, potentially leading to digoxin toxicity. Therefore, digoxin dosage may need to be adjusted.

Signup and view all the flashcards

How do Verapamil and Diltiazem compare in action and uses?

Diltiazem has similar actions and uses as Verapamil, including treating angina, hypertension, and certain arrhythmias.

Signup and view all the flashcards

What are the common adverse effects of Diltiazem?

Diltiazem's main adverse effects are dizziness, flushing, headache, and ankle edema, similar to Verapamil, but it causes less constipation.

Signup and view all the flashcards

In which patients is Diltiazem a potential concern?

Diltiazem, similar to Verapamil, can worsen cardiac dysfunction in patients with bradycardia, sick sinus syndrome, heart failure, or second or third-degree AV block.

Signup and view all the flashcards

What are the therapeutic uses of Diltiazem?

Diltiazem, as a calcium channel blocker, is indicated for the management of angina pectoris (chest pain), essential hypertension (high blood pressure), and certain cardiac arrhythmias.

Signup and view all the flashcards

How is Diltiazem eliminated from the body?

Although Diltiazem is primarily metabolized in the liver, it is eliminated through urine and feces.

Signup and view all the flashcards

What is Nifedipine?

Nifedipine is a calcium channel blocker (CCB) used to treat angina pectoris and hypertension. It works by blocking calcium channels in blood vessels, causing them to relax and dilate, reducing blood pressure and improving blood flow to the heart.

Signup and view all the flashcards

Why should you use caution with immediate-release nifedipine?

The immediate-release (IR) formulation of nifedipine is associated with an increased risk of mortality in patients with myocardial infarction and unstable angina. IR CCBs can also increase the risk of myocardial infarction in hypertensive patients. However, these findings have not been observed with the sustained-release (SR) formulation.

Signup and view all the flashcards

How is nifedipine eliminated from the body?

Nifedipine is metabolized in the liver before being excreted in the urine.

Signup and view all the flashcards

Why may nifedipine lead to an increased heart rate?

Reflex tachycardia, an unwanted increase in heart rate, can occur with nifedipine use. This can worsen angina, as it increases cardiac oxygen demand. To prevent reflex tachycardia, nifedipine is often combined with beta-blockers.

Signup and view all the flashcards

How quickly do the effects of Nifedipine appear?

Nifedipine's effects start rapidly and peak within 30 minutes for the immediate-release (IR) formulation. The sustained-release (SR) formulation takes effect within 20 minutes, peaking at 6 hours.

Signup and view all the flashcards

What are verapamil and diltiazem used for?

Verapamil and diltiazem are calcium channel blockers used to treat hypertension, angina pectoris, and cardiac dysrhythmias. They block calcium channels in the heart and blood vessels, leading to lower blood pressure and reduced heart rate.

Signup and view all the flashcards

Who should not take verapamil and diltiazem?

Verapamil and diltiazem can worsen heart problems, making them unsuitable for patients with hypotension, sick sinus syndrome, or second- or third-degree atrioventricular block.

Signup and view all the flashcards

What are some drug interactions to consider with verapamil and diltiazem?

Both verapamil and diltiazem can enhance digoxin-induced suppression of AV conduction and intensify the cardiosuppressant effects of β blockers.

Signup and view all the flashcards

What are dihydropyridines and how do they work?

Dihydropyridines, a type of calcium channel blocker, predominantly act on blood vessels, dilating them and lowering blood pressure. Nifedipine is a prominent example.

Signup and view all the flashcards

How does nifedipine differ from verapamil?

Nifedipine, unlike verapamil, has minimal effects on the heart. While it dilates blood vessels, it does not significantly affect heart rate or contractility.

Signup and view all the flashcards

What is a potential side effect of nifedipine?

Nifedipine, due to its vasodilatory action, can trigger a reflex tachycardia, increasing heart rate.

Signup and view all the flashcards

How does the formulation of nifedipine affect its side effects?

Nifedipine's immediate-release formulation is more likely to cause reflex tachycardia compared to the slow-release formulation.

Signup and view all the flashcards

What are the overall hemodynamic effects of nifedipine?

Nifedipine lowers blood pressure by dilating blood vessels, but this can also increase heart rate due to the baroreceptor reflex.

Signup and view all the flashcards

What are the pharmacokinetic characteristics of nifedipine?

Nifedipine is well absorbed after oral administration, but its bioavailability is reduced due to extensive first-pass metabolism.

Signup and view all the flashcards

What are calcium channel blockers used to treat?

Calcium channel blockers are used to treat various conditions related to the cardiovascular system, including hypertension, angina, and cardiac dysrhythmias.

Signup and view all the flashcards

How can reflex tachycardia be prevented?

To prevent reflex tachycardia, nifedipine can be combined with a β blocker (e.g., metoprolol).

Signup and view all the flashcards

What is the primary mechanism of action for calcium channel blockers?

CCBs prevent calcium ions from entering cells. This has a significant impact on the heart and blood vessels, leading to vasodilation, decreased heart rate, and reduced contractility.

Signup and view all the flashcards

Verapamil's net effect on the heart

Verapamil blocks calcium channels in the heart, causing decreased heart rate, AV conduction, and contractility. However, these effects are countered by reflex sympathetic stimulation, resulting in minimal overall impact on heart function.

Signup and view all the flashcards

Verapamil's overall cardiovascular effect

Verapamil's primary action is vasodilation, leading to reduced blood pressure and improved blood flow to the heart (coronary perfusion).

Signup and view all the flashcards

When is verapamil contraindicated?

Verapamil is contraindicated in patients with sick sinus syndrome and second or third-degree AV block due to its potential to worsen cardiac dysfunctions.

Signup and view all the flashcards

Verapamil's interaction with digoxin

Verapamil increases plasma levels of digoxin, potentially leading to digoxin toxicity. Therefore, digoxin dosage may need to be adjusted.

Signup and view all the flashcards

What are key features of Diltiazem?

Diltiazem's action on the heart is similar to verapamil, but it causes less constipation. Its primary use is for angina, hypertension, and certain arrhythmias.

Signup and view all the flashcards

When is Diltiazem a potential concern?

Diltiazem, similar to verapamil, can worsen cardiac dysfunction in patients with bradycardia, sick sinus syndrome, heart failure, or second or third-degree AV block.

Signup and view all the flashcards

What is the primary action of nifedipine?

Nifedipine primarily dilates blood vessels, leading to reduced blood pressure. It has minimal effects on heart rate and contractility.

Signup and view all the flashcards

How does nifedipine formulation affect side effects?

Nifedipine's immediate-release formulation is more likely to cause reflex tachycardia compared to the slow-release formulation.

Signup and view all the flashcards

Nifedipine's pharmacokinetics

Nifedipine is well absorbed after oral administration, but its bioavailability is reduced due to extensive first-pass metabolism.

Signup and view all the flashcards

What are the therapeutic uses of CCBs?

Calcium channel blockers (CCBs) are used to treat various cardiovascular conditions, including hypertension, angina, and cardiac dysrhythmias.

Signup and view all the flashcards

AV Node Excitability

Calcium entry into AV nodal cells regulates their excitability, influencing the speed of electrical signals through the AV node.

Signup and view all the flashcards

Calcium Channel Blocker Effects

Blocking calcium channels in the heart reduces the force of contraction, slows down the heart rate, and slows the transmission of signals through the AV node.

Signup and view all the flashcards

β1 Receptor & Calcium Channel Linkage

β1-adrenergic receptors in the heart are linked to calcium channels. When activated (e.g., by norepinephrine), they trigger increased calcium influx.

Signup and view all the flashcards

CCBs & β Blockers: Shared Effects

CCBs and β blockers have similar effects on the heart: reduced contractility, slower heart rate, and suppressed conduction through the AV node.

Signup and view all the flashcards

CCB Classification & Sites of Action

The dihydropyridines (e.g., nifedipine) mainly act on blood vessels, dilating them and lowering blood pressure. Nondihydropyridines (e.g., verapamil) act on both vessels and the heart.

Signup and view all the flashcards

Verapamil: Hemodynamic Effects

Verapamil, a nondihydropyridine CCB, affects both blood vessels and the heart, leading to dilation, increased coronary perfusion, and reduced heart rate, contractility, and AV conduction.

Signup and view all the flashcards

Verapamil & Baroreceptor Reflex

Verapamil's effects on blood pressure trigger the baroreceptor reflex, which attempts to increase heart rate and contractility to compensate.

Signup and view all the flashcards

Nifedipine: Selective Action

Nifedipine, a dihydropyridine CCB, primarily affects blood vessels, dilating them and reducing blood pressure, but has minimal direct effects on the heart.

Signup and view all the flashcards

Verapamil: Contraindications

Verapamil is contraindicated in patients with sick sinus syndrome and second or third-degree AV block as it can worsen these conditions.

Signup and view all the flashcards

Diltiazem: Actions & Uses

Diltiazem, similar to verapamil, is used for angina, hypertension, and certain arrhythmias. It also affects both blood vessels and the heart.

Signup and view all the flashcards

Study Notes

Calcium Channel Blockers (CCBs)

  • CCBs prevent calcium ions from entering cells, principally affecting heart and blood vessels.
  • Widely used to treat hypertension, angina pectoris, and cardiac dysrhythmias.
  • Controversy exists regarding CCB safety, particularly in hypertensive and diabetic patients. Safety concerns noted regarding increased mortality and MI risk with immediate-release nifedipine and some other immediate-release CCBs.

Calcium Channels: Physiologic Functions and Blockade

  • Calcium channels are gated pores controlling calcium ion entry into cells, vital for vascular smooth muscle (VSM) and heart function.
  • In VSM, calcium channel opening triggers contraction; blockade results in vasodilation.
  • CCBs, at therapeutic doses, selectively target peripheral arterioles/arteries, minimally affecting veins. CCB effects on heart function are dose-dependent, with therapeutic doses impacting vessels primarily. Toxic doses can still cause cardiac suppression in all classes.

Calcium Channel Blockers: Classification and Sites of Action

  • Two main categories: dihydropyridines and nondihydropyridines.
  • Dihydropyridines primarily impact arterioles; nondihydropyridines affect both arterioles and the heart.
  • Prototypes: Nifedipine (dihydropyridine), Verapamil and Diltiazem (nondihydropyridines). Several other dihydropyridines are available, including amlodipine, felodipine, etc. Table 39.1 details various agents, sites of action, and indications.

Nondihydropyridines: Verapamil and Diltiazem

  • Verapamil: Blocks calcium channels in blood vessels and heart. Used for angina pectoris, hypertension, and cardiac dysrhythmias.

    • Direct effects: Peripheral vasodilation, enhanced coronary flow, slowed heart rate, reduced AV nodal conduction, and decreased contractility.
    • Indirect (reflex) effects: Baroreceptor reflex to oppose direct heart effects, minimizing net cardiac impact.
    • Overall effect: Vasodilation, decreased arterial pressure, and increased coronary flow.
    • Oral administration; extensive first-pass metabolism; approximately 20% bioavailability.
    • Common uses: Angina, hypertension, and cardiac dysrhythmias.
    • Side effects: Frequent constipation, dizziness, flushing, headache, ankle edema. Careful use in patients with bradycardia, AV block, or heart failure; drug interactions (digoxin, beta-blockers, grapefruit juice) are significant.

  • Diltiazem: Similar actions and uses to verapamil, blocking calcium channels in heart and blood vessels for similar hemodynamic effects and therapeutic applications. Side effects generally similar to verapamil.

Dihydropyridines: Nifedipine

  • Nifedipine: Blocks calcium channels primarily in VSM, causing vasodilation and lowering blood pressure.
    • Minimal impact on the heart at therapeutic doses.
    • Useful for hypertension and angina but not dysrhythmias.
    • Reflex tachycardia (especially with immediate-release formulations) is a possible side effect.
    • Less likely than verapamil to worsen existing cardiac issues like AV block.
    • Often combined with beta-blockers to manage reflex tachycardia; drug interactions (beta blockers) are noted.
    • Immediate-release formulations linked to potential mortality and MI risks in certain patient populations (hypertension, unstable angina, MI), warranting particular caution; slow-release formulations are generally preferred.

Summary of Key Prescribing Considerations (Both Families)

  • General: Monitor blood pressure (BP) and pulse, assess hepatic/renal function before initiating therapy.
  • High-risk patients: Avoid in patients with hypotension, sick sinus syndrome, or second/third-degree AV block.
  • Monitoring effects: Periodic BP monitoring, patient records of angina frequency/severity.
  • Minimizing side effects: Start with low doses, adjust carefully, monitor weight daily, consider intermittent dosing schedule, note potential for chronic rashes in older patients.

Additional Considerations (from the new text)

  • Patient-Specific Considerations (infants, children, pregnant women, breastfeeding women, older adults): Specific treatment considerations relevant to these age groups are now addressed as well (e.g., verapamil use in infants, nifedipine use in pregnancy, avoiding verapamil in breastfeeding, and potential for rashes in older patients). This portion of the notes is now more complete and reflects the patient-centric approach.
  • Drug Interactions (Digoxin, Beta-blockers, Grapefruit Juice): Detailed drug interactions with other medications and food substances (i.e., digoxin, beta-blockers, and grapefruit juice) are now included for both Verapamil and Diltiazem.
  • Dihydropyridines (Amlodipine, Nicardipine, etc.): Information related to other dihydropyridines like amlodipine and nicardipine is now integrated, providing a more comprehensive overview. Their uses, and similar prescribing considerations are discussed.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Description

Test your knowledge on nifedipine, a calcium channel blocker, and its therapeutic uses, differences between formulations, and side effects. This quiz covers important aspects of nifedipine's clinical application in angina and other cardiovascular conditions.

More Like This

Amlodipine vs Nifedipine: Medication Comparison Quiz
10 questions

Amlodipine vs Nifedipine: Medication Comparison Quiz

ChivalrousSupernova avatar
ChivalrousSupernova
Nifedipine Flashcards
11 questions

Nifedipine Flashcards

UnparalleledEcoArt avatar
UnparalleledEcoArt
Nifedipine Flashcards
12 questions

Nifedipine Flashcards

SucceedingHexagon avatar
SucceedingHexagon
Nifedipine Flashcards
13 questions

Nifedipine Flashcards

AudibleFresno2256 avatar
AudibleFresno2256
Use Quizgecko on...
Browser
Open
Browser
Browser