Treatment of Acute Aortic dissection Flashcards
what are the main affects of Beta blockers
1.Beta blockers work by blocking the effects of
the hormone epinephrine (aka; adrenaline)
2.Beta blockers cause your heart to beat more
slowly and with less force, which lowers blood
pressure
3.Beta blockers also open your veins and
arteries up to help improve blood flow
what are 4 common examples of Beta bockers
- Labetalol
- Esmolol
- Nitroprusside
- Nitrocardipine
MOA of Labetalol
• Typically given as a racemic mixture
• Achieves both a- and b-receptor
blocking activity
decreases peripheral vascular resistance without significant alteration of HR or CO
Contraindictions 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 • Those with hypersensitivity to the drug
Adverse effects of Labetalol
- dizziness
- tingling scalp or skin
- lightheadedness
- excessive tiredness
- headache
- upset stomach
- stuffy nose
Drug interactions of Labetalol
• Tricyclic antidepressants - may experience tremor
• Beta-receptor agonist-
• Drugs in patients with bronchospasm - greater doses than normal
of the beta-agonist drug may be required
• Cimetidine
• Halothane anesthesia - notify anesthesiologist when a patient is
receiving Labetalol
• Nitroglycerin - additional antihypertensive effects may occur
• Calcium antagonists- of the verapamil type
• Digitalis glycosides - increase risk of bradycardia
how does Labetalol affect pregnancy and pediatric patients
Pregnancy Category C:
Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and wellcontrolled
studies in humans, but potential benefits may warrant use of the drug in pregnant women despite
potential risks
• Nursing Mothers: Small amounts are excreted in
human milk
Ø Use caution when administered to a nursing
woman
• Pediatric Patients: Safety and effectiveness have
not been established
how is clearance affected in Labetalol
goes up in pregnancy making it fall below therapeutic value
how are geriatric patients affected by Labetalol
Geriatric Patients:
§ Caution elderly patients about the possibility of
orthostatic symptoms during treatment
§ Elimination of Labetalol is reduced in elderly
patients
§ May require a lower maintenance dosage (100-200
mg twice daily) than non-elderly patients
are there any black box warnings with Labetalol?
None
How is Labetalol metabolized? and distributed
absorbed via oral
distributed to the Plasma protein binding, found in breast milk, and crosses the placenta
Metabolized via conjugation to glucuronide and excreted via urine, bile and feces
is elimination of Labetalol reduced in elderly patients?
Yes
Mechanism of Action of Esmolol?
Affects the response to nerve impulses in heart
-Decreased Heart beat and lowers blood pressure
Class II anti-arrhythmic
-blocks response to B1-adrenergic stimulation (little to no effect of B2 receptors except at high doses
what are the indications for Esmolol
Control rapid heartbeats or abnormal heart rhythms
used to treat fast heartbeat and high blood pressure during surgery, after surgery, or during other medical procedures
Esmolol Contraindictions
• Contraindications • Bronchial asthma • Overt cardiac failure • Cardiogenic shock • Severe sinus bradycardia • Other conditions associated with severe and prolonged hypotension
History of, hypersensitivity, Obstructive airway disease including asthma, and Heart block greater than first degree
(except patients with a functioning artifical pacemaker)
Decompensated heart failure
IV administration of calcium channel blockers
Pulmonary hypertension
Major side effects of Esmolol
Hypotension, Heart block, bradycardia, bronchospasm, HF
How is esmolol considered in pregnancy?
May cause fetal bradycardia
fetal growth and newborn should be monitored for 48 hours after delivery for bradycardia, hypoglycemia, and respiratory depression
skeptical of being in breastmilk
is Esmolol a short acting beta blocker? and can it be used in an emergency
yes it is short acting and can be used as a alternative agent for hypertensive emergency in pregnancy
How does Esmolol affect geriatric populations?
Brady cardia may be observed more frequently and dosage reductions may be necessary
what are some adverse effects of Esmolol
Anaphylatic reaction
Extravasation
Hyperkalemia (especially in patients with renal impairment)
Hypotension
how is Esmolol Metabolized?
considered a soft drug meaning is rapidly metabolized to an inactive form
-elimination half-life = 9 minutes
metabolized by hydrolysis of the ester linkage (found in the cytosol of RBCs
MOA of Nitroprusside?
NO activates the Guanylate Cyclase Enzyme increasing cGMP and activation of protein kinase G
-PKG activates phosphatases which inactivated myosin light chains
i.e muscle relaxation
What happens to sodium Nitroprusside as it breaks down in circulation
- Bides to oxyhemoglobin to release
- NO
- Cyanide (toxic)
- Methaemoglobin
what are the indications of Nitroprusside?
Lowers BP immediately in children and adults
- reduces bleeding during surgery
- treats acute congestive heart failure
Contraindictions of Nitroprusside?
Should not be used for compensatory Hypertension
-due to anteriovenous stent, or coarctation of the aorta
Not used in patients with inadequate cerebral circulation, near death, Vit B12 deficiency, anaemia, severe renal disease, hypovolaemia
used in great caution in patients with conditions associated with cyanide/thiocyanate ratio:
- Congenital (lebers) optic atrophy
- tobacoo amblyopia
Not with patients with acute congestive heart failure, or Hepatic impairment
Can pregnant woman use Nitroprusside?
advised against but available evidence suggests it may be safe
-Maternal pH and Cyanide levels are closely monitored
Nitroprusside Adverse effects
- Ileus
- Reduced platelet aggregation
- Hemorrhage
- Increased intracranial pressure
- Metabolic acidosis
- Methemoglobinemia
- Cyanide poisoning
- Thiocyanate toxicity
what to administer if the patient reaches cyanide toxicity under the use of Nitroprusside?
administer
Sodium thiosulfate
what s a rare condition patients receiving Nitroprusside?
sequesteration of hemoglobin to Methemoglobin
can lead to thiocyanate toxicity
What are the Black BOx warnings for Nitroprusside?
• Not suitable for direct injection
§ Requires dilution prior to infusion
• Hypotension may occur, leading to irreversible ischemic
injury or death
§ Requires appropriate monitoring equipment and experienced personnel
• Cyanide toxicity may occur because of accumulation of
cyanide ion through metabolic processes
Mechanism of action for Nicardipine?
Calcium entry blocker in the Dihydropyridine class
-slow channel blocker
-calcium ion antagonist
(does not change the serum calcium concentrations)
more selective to vascular smooth muscle than carduac muscle
What are the indications of Nicardipine?
Short term treatment of hypertension when oral therapy is not feasible or desirable
Prolonged control of blood pressure
what are patients that are contraindicated in Nicardipine
Patients with advanced aortic stenosis
what are the adverse effects of patients taking Nicardipine?
- Headache
- Hypotension
- Tachycardia
- Nausea/vomiting
what are some warnings and precautions when using Nicardipine?
Patients with angina because can increase the severity and frequency
Patients with Heart failure due to negative inotropic effects
Patients with Impaired Hepatic function
-since it is metabolized in the liver
Patients with impaired renal function and must titrate gradually
How should Nicardipine be administered in geriatric patients?
use low initial doses in elderly
what are 4 drug interactions of Nicardipine?
Beta blockers
Cimetidine
Cyclosporine
(CYP3A4)
Tacrolimus
(CYP3A4)
How is Nicardipine Metabolized?
CYP3A4 enzymes
P-GP MDR1
