Drugs to treat Aortic Dissection Flashcards
What drugs can be used to treat Aortic dissection?
- Labetalol
- Esmolol
- Nitroprusside
- Nitrocardipine
old LENNy with that Aortic dissection amiright???
How do beta blockers treat Aortic Dissection?
- block the effects of epinephrine (aka; adrenaline)
- Cause heart to beat more slowly and with less force–> lowers blood pressure
- Vasodialate veins and arteries up to help improve blood flow
What is Labetalol MOA?
blocks alpha and beta receptors
-decreaes peripheral resistance w/o significantly altering HR or CO
When is labetalol indicated?
- arterial hypertension
- can be used alone or with other antihypertensives
What are the contraindications of labetalol?`
- Overt cardiac failure
- Greater-than-first-degree heart block
- Severe bradycardia
- Cardiogenic shock
- Severe hypotension
- Anyone with a history of obstructive airway disease
including asthma
7.Those with hypersensitivity to the drug
Who should be careful with labetalol/ what are precautions
- Cardiac failure
- Hepatic injury
- Can cause non allergic bronchospasm
- Take caution in pheochromocytoma, DM, and hypoglycemia
Can exacerbate ischemic heart disease if withdrawal is too fast*
What are drug interactions of labetelol?
- antidepressants –> can cause tremor
- Halothane anesthesia–> tell anesthesiologist before surgery
Is labetelol safe in pregnancy?
- Preg. Category Ct
- adverse effects in animal studies but not known in humans
- can cross the placenta
- may be used if potential benefit outweighs the risk
- be cautious in nursing mothers
Describe the metabolism of labetalol
- Approximately 55% to 60% of a dose appears in the urine as conjugates or unchanged labetalol within the first 24 hours of dosing
- Labetalol clearance goes up in pregnancy
- The increase in reproductive hormones–>Causes an increase in labetalol glucuronidation –> allows labetalol concentration to fall below the therapeutic value
What are black box warnings of labetalol
NONE
How should you counsel pt on Labetalol?
- take exactly as prescribed
- don’t interrupt or discontinue meds
- tell doc if sign/sx of impending cardiac failure or hepatic dysfunction
- may have scalp tingling-
- monitor for conditions over regular intervals
How does esmolol work?
Class II anti-arrhythmic:
- Competitively blocks response to b1-
adrenergic stimulation
- Little effect of b2-receptors, except at high doses
Esmolol Indications
fast heartbeat and high blood pressure during
- surgery
- after surgery
- during other medical procedures
(such as rate control for Afib or during other medical procedures)
What effect does esmolol have on Potassium?
Hyperkalemia
- esp in patients with risk such as renal impairment
What effect can esmolol on blood pressure?
- commonly causes hypotension– need to monitor patients
- stop if drops BP too much
What type of metabolism does esmolol have?
Erythrocytic!
- soft drug- short half life of 9 min
- Rapidly metabolized by ester linkage hydrolysis by esterase’s in cytosol of RBC
What is the mechanism of action of Nitroprusside?
NO activates Guanylate Cyclase Enzyme on vascular smooth muscle
- increases cyclic GMP –> PKG–> inactivate myosin light chains
- Causes smooth muscle relaxation and blood vessel dilation
What is the mechanism of nitroprusside similar to?
-PDE5 inhibitors like viagra and Cialis that elevate cGMP by degrading PDE5
What is the rxn and by product of nitroprusside?
Sodium nitroprusside breaks down and binds to oxyhemoglobin to release
- Nitric oxide
- Cyanide (Toxic!!)
- Methaemoglobin
What are contraindications of Nitroprusside?
- don’t use for compensatory HTN
- Careful in pts with a higher cyanide/thiocyante ration (Lebers optic atrophy and tobacco amblyopia
- don’t use in acute congestive heart failure or hepatic impairment
Is nitroprusside okay in pregnancy?
Idk…. just be careful and monitor maternal pH and cyaninde
What is a serious adverse effect of Nitroprusside? (2)
- cyanide poisoning
- Thiocyanate toxicity
How can cyanide toxicity of nitroprusside be avoided?
- administer sodium nitroprusside slowly ( slower than 2mcg/kg/min)
- Administer sodium thiosulfate to increase the rate of toxic cyanide processing
What should be monitored in patients on nitroprusside with head trauma, increased ICP, hyponatremia, hypothyroidism, severe hepatic/ renal impairment or the elderly
- Cyanide toxicity–> can develop within an hour
- Check thiocyanate levels
- Monitor pulse ox
The sequestration of hemoglobin as methemoglobin in nitroprusside use can result as…?
- Metheglobonemia
- Thiocyanate toxicity
What are the black box warnings of nitroprusside?
- do not directly inject, need to dilute first
- Hypotension–> can lead to irreversible ischemic injury/ death
- cyanide toxicity from the accumulation of cyanide ion through metabolic processing
What is the metabolism of nitroprusside?
- nitroprusside is metabolized in combo with hemoglobin to
1. one cyan-methemoglobin
2. four CN ions - Thiosulfate reacts with cyanide to produce thicyanate
- thiocyanate is eliminated in urine
What type of drug is nicardipine?
Calcium entry blocker –> Dihydropyridine class
- Slow channel blocker
- Calcium ion antagonist
inhibits Ca2+ influx without changing serum calcium
What is Nicardipine MOA?
- Inhibits the transmembrane influx of calcium ions into cardiac muscle and smooth muscle without changing serum calcium concentrations
- effects are more selective to vascular smooth muscle than
cardiac muscle
What are indications of Nicardipine?
- Short-term treatment of hypertension
- Prolonged control of blood pressure
When is nicardipine contraindicated?
Patients with advanced aortic stenosis
Adverse effects of Nicardipine?
- Headache
- Hypotension
- Tachycardia
- Nausea/vomiting
What are warnings of Nicardpine?
- Excessive pharmacodynamic effects –> can cause hypotention/tachycardia; avoid in cerebral infarction or hemorrhage
- Exacerbates Angina
- titrate slowly in heart failure -> can have negative inotropic effects (force/speed of contraction)
- Metabolized in liver–> be careful
- Impaired renal function lowers clearance
What should be considered in geriatric patients on Nicardipine?
Use lower dose to start!
What drugs interact with Nicardipine?
- Beta blockers
- Cimetidine
- Cyclosporine–>nicardipine inhibits hepatic CYP3A4–> can increase plasma Cyclosporine levels
- Tacrolimus–> nicardipine inhibits hepatic CYP3A4–> can increase plasma tacrolimus levels
is nicardipine used in pregnant mothers?
Maybe… Pregnancy category C
- be carefule
What enzyme is involved in nicardipine metabolism?
CYP450 –> CYP3A4 Substrate
What transporter is involved in Nicardipine metabolism?
P-GP (MDR1) substrate
What is the black box warning of Nicardipine?
None
