Under what health conditions do we use vasodilator drugs?
Hypertension (reduces BP), CHF (reduces preload and afterload), IHD (increases coronary blood flow).
What factors in our blood cause vascular inflammation?
High glucose, high blood pressure and high cholesterol.
What are your primary goals in prescribing vasodilator drugs? What is your secondary goal?
Lower BP, reduce cardiac workload and increase coronary blood flow. Your secondary goal is acknowledge risk factors.
How is vascular tone regulated?
ANS (neurotransmitters), Neurohormonal systems (catecholamines, RAAS, vasopressin), Vascular endothelium (NO, endothelin) and Local control (H+,CO2, O2, adenosine, lactate, K+)
What is the general mechanism of vasodilating drugs?
Reducer peripheral resistance, increase capacitance and improve coronary flow.
What are the six classes of vasodilating drugs?
ANS, renin-angiotensin-aldosterone, direct vasodilators, calcium channel blockers, phosphodiesterase inhibitors and endothelin receptors.
What vasodilating drugs target the autonomic nervous system?
What are the direct vasodilating drugs that act on smooth muscle or endothelium?
What are the vasodilating drugs that target calcium channels?
What are the vasodilating drugs that inhibit phosphodiesterase?
What are the vasodilating drugs that target the renin-angiotensin-aldosterone system?
What are the vasodilating drugs that target endothelia receptors?
What are the vasodilating drug combinations used in clinical settings?
What drugs act on alpha-2 receptors to inhibit NE release from vesicles?
What drugs displace NE and depend on MAO to deplete nerve ending stores of NE in lowering blood pressure?
Reserpine and guanadrel. They inhibit VMAT, which pushes NE into presynaptic vesicles, leaving NE out to be metabolized by MAO.
A 32 year old pregnant woman comes to the ED with a blood pressure o 200/100 and a pulse of 130. She is diagnosed with pre-eclampsia. What drug do you prescribe her to get her blood pressure under control? In what patients is this drug contraindicated?
Oral Hydralazine (Apresoline). It is an ARTERIOLAR vasodilator and will lower her blood pressure. Side effects include reflex tachycardia and increased contractility and thus is contraindicated in patients with heart failure.
Why is BiDil a good choice to treat a patient with high blood pressure and long-term chest pain?
Organic nitrates are often used to treat chest pain, but can develop a dependence. When combined with Hydralazine, the dependence disappears.
A patient comes to the ED with a blood pressure of 190/110. He is taking a strong antihypertensive drug that no longer is effective. He is also bald. What is a good choice of drug for him? In what patients is this drug contraindicated?
Oral Minoxidil (Loniten). It is an ARTERIOLAR vasodilator that activates the ATP-K+ channels, hyper polarizing the cells. It is good for hypertensive emergencies and refractory hypertension. It improves hair growth. It is contraindicated in patients with heart failure due to reflex tachycardia and increased contractility.
An 80 year old patient comes to the ED in hypertensive emergency. He also has severe congestive heart failure. What drug would prescribe to decrease his blood pressure as quickly as possible? In what patients is this drug contraindicated?
IV Sodium nitroprusside. It is a non-specific NO donor that does not need an enzyme to donate NO (as organic nitrate does). This results in ARTERIOLAR and VENOUS vasodilation. It is preferred in patients with CHF. It can result in coronary steal hypotension and is thus contraindicated in patients with ischemic heart disease.
Why is organic nitrate a good choice for vasodilation in a patient who is in hypertensive emergency with contiguous ischemic heart disease and CHF?
It preferentially vasodilates epicardial vessels and will keep the heart perfused. Sodium nitroprusside decreases flow because of coronary steal and will be a poor choice.
How can you induce ischemic heart disease in a patient in the cardiac lab?
Giving them IV sodium nitroprusside. It steals blood away from the coronary arteries.
What channel do the calcium channel blockers for hypertension block? How does this result in vasodilation?
L-type channels are blocked so extra-cellular Ca cannot induce intracellular calcium release. This prevents activation of Calmodulin -> Myosin Light Chain Kinase -> and ultimately prevents contraction.
How does vasculature smooth muscle relaxation differ between calcium channel blockers and organic nitrates?
Ca channel blockers relax arteries first where nitrates relax veins first.
How do calcium channel blockers affect vascular smooth muscle? Cardiac myocytes? Skeletal muscle?
How do dihydropyridine calcium channel blockers differ from non-dihydropyridine calcium channel blockers differ in the below categories?
A low renin 70 year old African American presents to the ED with angina pectoris and a BP of 220/120. He also has congestive heart failure. What drug class would be a good pick to get his symptoms under control? What side effects should you warn him of?
Calcium channel blockers, dihydropyridines to be specific. Non-dihydropyridines would be good if he suffered from arrhythmias. Side effects include hypotension.
A 71 year old male comes to see you with severe CHF. There is little hope for him to live more than a year and he is in hypertensive emergency. What would be a good drug to prescribe to this patient? What should you make sure he is not on before you give it to him?
Phosphodiesterase inhibitors. These drugs lead to accumulation of cAMP (increasing contractility) and cGMP (smooth muscle relaxation and vasodilation). You should make sure he is not taking nitrates because that will cause severe hypotension and coronary steal.
A 76 year old female with headache, nausea, vomiting, shortness of breath, pulse of 98 and BP 220/118 comes to see you on the side of the street. The only drugs you have are Nifedipine, Verapamil, Captopril, Minoxidil and Hydralazine. What drug do you choose?
Sublingual nifedipine. Nifedipine is a calcium channel blocker and will gradually lower the blood pressure, Verapamil has lots of heart side effects and doesn't do a great job of lowering blood pressure, Minoxidil and Hydralazine are both direct vasodilators (NO donors) and can result in severe hypotension (puts her at risk for MI) and reflex increase in heart rate.