20 Questions
What is the pharmacologic action of organic nitrates?
Vasodilation
How can nitrate tolerance be managed to avoid its development?
Taking nitrate-free intervals
What is a common adverse effect of potassium channel activators?
Hypotension
What is a contraindication of PDE5 inhibitors?
Nitrate use
How do Viagra® and Cialis® differ in terms of duration of action?
Viagra® has a longer duration of action
Which type of drugs are vasodilators?
Calcium channel blockers
What is the pharmacologic action of potassium channel activators?
Bronchodilation
How do organic nitrates primarily function?
By relaxing blood vessels
What is a common adverse effect of PDE5 inhibitors?
Hypotension
How do organic nitrates differ from potassium channel activators in terms of mechanism of action?
Organic nitrates primarily affect heart rate while potassium channel activators target blood vessels
What is a key difference between Viagra® and Cialis®?
Duration of action
Which class of drugs is known for activating potassium channels?
Potassium channel activators
How does nitrate tolerance affect the efficacy of nitrates?
Decreases efficacy
What is a common adverse effect associated with PDE5 inhibitors?
Priapism
How do ISDN and ISMN differ in terms of their pharmacologic action?
They have the same pharmacologic action
What is a key difference between the mechanism of action of organic nitrates and potassium channel activators?
Potassium channel activators relax vascular smooth muscle
Which drug class is known for its ability to prevent the breakdown of cGMP in smooth muscle cells?
PDE5 inhibitors
What is a common adverse effect associated with nitrate therapy?
Reflex tachycardia
How do ISDN and ISMN differ in terms of their administration route?
ISDN is administered sublingually, while ISMN is administered orally
What is a major difference between Viagra® and Cialis® in terms of duration of action?
Cialis® has a shorter duration of action than Viagra®
Study Notes
Vasodilators
- Vasodilators are drugs that dilate blood vessels, decreasing blood pressure and increasing blood flow
- Classes of vasodilators include:
- Organic nitrates
- Potassium channel activators
- PDE5 inhibitors
Vascular Smooth Muscle Contraction and Relaxation
- Vascular smooth muscle contraction:
- Caused by calcium ions and calmodulin
- Leads to vasoconstriction
- Vascular smooth muscle relaxation:
- Caused by decreased calcium ions and increased cGMP
- Leads to vasodilation
Organic Nitrates
- Pharmacologic action: release NO, which increases cGMP, causing vasodilation
- Examples: nitroglycerin, isosorbide dinitrate (ISDN), isosorbide mononitrate (ISMN)
- MOA: donate NO, which activates guanylate cyclase, increasing cGMP
- ADRs: headache, dizziness, flushing, nausea
- Benefits: treat angina, heart failure, and hypertension
- Problems: nitrate tolerance, headaches, and dependence
Nitrate Tolerance and Management
- Mechanism: decreased ability of nitrates to release NO
- Management:
- Dose titration
- Nitrate-free periods
- Combination with other vasodilators
Potassium Channel Activators
- MOA: open potassium channels, leading to hyperpolarization and relaxation
- Drug names: nicorandil, pinacidil
- ADRs: headache, dizziness, hypotension
PDE5 Inhibitors
- MOA: inhibit phosphodiesterase 5, increasing cGMP
- Examples: sildenafil (Viagra), tadalafil (Cialis)
- ADRs: headache, flushing, dyspepsia
- Contraindications: nitrates, alpha-blockers
- Duration of action:
- Viagra: 4-6 hours
- Cialis: up to 36 hours
Viagra vs. Cialis
- Both PDE5 inhibitors
- Differences:
- Duration of action
- Onset of action
- Food effects
ISDN vs. ISMN
- Both organic nitrates
- Differences:
- Pharmacokinetics
- Dosing schedules
- ADR profiles
Test your knowledge on the use, classes, mechanisms, and pharmacological actions of vasodilators including organic nitrates, potassium channel activators, and PDE5 inhibitors. Learn about nitrate tolerance management and important drug names and adverse drug reactions.
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