Pharm B Test 2 Flashcards
How does blocking alpha 2 receptors affect circulating levels of norepi
Blocking alpha2 blocks the reuptake of norepinephrine, thus increasing circulating levels of norepi
1st generation non-selective beta blockers, such as propranolol, should not be given to which patients?
Asthmatics
Effect of beta-1 activation on the heart
Increase HR, contractility, and conduction velocity
Examples of beta-1 agonists (3)
- Dobutamine
- Dopamine
- Isoproterenol
Examples of commonly used beta-1 specific antagonists (2)
- Metoprolol
- Esmolol
Effect of beta-2 activation on blood vessels
Dilation
Effect of beta-2 activation on bronchioles
Dilation
Effect of beta-2 activation on uterus
Relaxation
Effect of beta-2 activation on kidneys
Renin secretion
Effect of beta-2 activation on pancreas
Insulin secretion
Example of a commonly used beta-2 agonist
Albuterol
Effect of alpha-1 activation on blood vessels
Constriction
Effect of alpha-1 activation on pancreas
Inhibits insulin secretion
Effects of alpha-1 activation on intestines/bladder
Constriction
Example of alpha-1 agonist
Phenylephrine
Examples of alpha-1 antagonist (3)
- Prazosin
- Phentolamine
- Labetolol
Effect of alpha-2 activation on pre-synaptic sympathetic nerve endings
Inhibit norepinephrine release
Alpha-2 affects the central nervous system by increasing conductance of which electrolyte
K+
Effect of alpha-2 activation on platelets
Aggregation
Examples of alpha-2 agonists (2)
- Clonidine
- Dexmedetomidine
Examples of alpha-2 antagonists (2)
- Yohimbine
- Phentolamine
Clinical uses for alpha antagonists
- Pheochromocytoma
- CHF
- Benign prostatic hypertrophy
- Raynaud’s phenomenon
Effect of a-2 blockade on sympathetic NS
Increases sympathetic outflow and increases the release of norepi from nerve endings
MOA of alpha antagonists
Binds selectively to alpha receptors and blocks activity of catecholamines at receptor sites
Side effects of alpha antagonists
1) Orthostatic hypotension and syncope
2) Reflex tachycardia
3) Impotence
What is phentolamine
Competitive non-selective alpha blocker
Clinical uses for phentolamine
Acute hypertensive emergencies that can be seen in patients with pheochromocytoma or autonomic hyperreflexia
Effects of phentolamine due to its effects on alpha-1 receptors
- Decrease in systemic BP due to direct action on vascular smooth muscle
- Reflex tachycardia
Effects of phentolamine due to its effects on alpha-2 receptors
- Increases release of NE
- Increase HR and CO
- Abdominal pain/diarrhea
What is Prazosin
Alpha 1 selective blocker
Which vessels are affected by Prazosin
Both arterioles and veins are dilated by Prazosin
How is Prazosin used preoperatively?
Used to treat pre-op BP in patients with pheochromocytomia
Prazosin is commonly taken by patients with what diseases? (3)
- Pheochromocytoma
- Raynauds
- BPH
What drug class does Terazosin (Hytrin) belong to?
Alpha1 blocker
What drug class does Tamulosin (Flomax) belong to?
Alpha1 blocker
Tamulosin (Flomax) acts preferentially on alpha-1 receptors located where?
- Vesical trigone muscle
- Urethra
- Prostate
Tamulosin (Flomax) is primarily used to treat which disease?
BPH
What is Yohimbine
Selective alpha2 antagonist
How does Yohimbine work to increase BP
Causes increased release of NE
Clinical uses for Yohimbine
- Idiopathic orthostatic hypotension
- Impotence
What is Phenoxybenzamine
Non-competitive, irreversible, non-selective alpha blocker that is taken orally
Phenoxybenzamine has a greater effect on which alpha receptor?
Alpha-1
MOA of Phenoxybenzamine
Prevents inhibitory action of epinephrine on the secretion of insulin
Clinical uses for Phenoxybenzamine
- Orthostatic hypotension
- Pre-op tx for patients with pheo and Raynaud’s
Major sites of action for beta blockers
- Heart
- Smooth muscles of airway
- Smooth muscles of blood vessels
Should beta blockers be continued throughout the perioperative period?
Yes
In which surgery should you NOT give beta blockers or have patient’s continue their beta blockers?
Aortic valve surgeries in which they are planning to pace them to 200+ bpm to decrease blood flow to the heart
What is the first med you should consider when you see new ST changes on an EKG during surgery?
Beta blocker
Cardiovascular uses for beta blockers
- Essential HTN
- Angina pectoris
- Acute coronary syndrome
- Cardiac dysrhythmias
- CHF
- Preop prep of hyperthyroid
Therapeutic uses for beta blockers (other than cardiovascular)
- Prevention of bleeding in portal hypertension
- Treatment of migraine, tremor, anxiety, alcohol addiction
- Treatment of glaucoma
What determines the receptor selectivity of beta blockers?
Dose - if you give enough esmolol, it can start blocking beta 2 also
Negative cardiovascular side effects from beta blockers
- Negative iontropy and chronotropy
- Decrease AV node conduction
- Accentuate AV block
Beta blockers can increase the concentration of which drugs/drug classes?
- Local anesthetics
- Fentanyl
How do beta blockers affect MAC values?
Decreases MAC
Adverse effects of beta blockers on metabolism
- Increase in triglycerides
- Hypoglycemia
Should patients who are lactating be given beta blockers?
No - it is contraindicated because they can cross into breast milk
Beta blockers can aggravate which pre-existing diseases?
- CHF
- Asthma
- AV blocks
How can beta blockers affect an anaphylactic reaction?
They can impair the body’s response to epi
Prototype non-selective beta blocker
Propranolol
CV effects of Propranolol
Decrease heart rate, contractility, and cardiac output
Propranolol causes the retention of which electrolyte
Na+
Which beta blocker undergoes extensive first pass metabolism?
Propranolol
IV dose of propranolol
0.05mg/kg
Which non-selective beta blocker has a long duration of action
Nadolol
Which non-selective beta blocker is used to treat glaucoma and decrease IOP
Timolol
Which non-selective beta blocker prolongs cardiac action potential and can lead to v-tach
Sotalol
Which non-selective beta blocker is used to treat SVT
Sotalol
How do non-selective beta blockers affect diabetics
May potentiate insulin induced hypoglycemia due to beta-2 blockade
How do non-selective beta blockers affect asthma/COPD
Increases airway resistance
What is Metoprolol
B1 selective blocker
Dose of metoprolol
1-2mg
Concentration of metoprolol
1mg/ml
Which beta blocker is the MOST beta 1 selective?
Atenolol
Short acting beta-1 blocker
Esmolol
IV dose of esmolol
0.5mg/kg
Infusion dose of esmolol
0.1-0.3mg/kg/min
How is esmolol metabolized
Hydrolysis by plasma esterases
What is labetalol
Alpha1 antagonist and beta1/beta2 antagonist
Ratio of beta:alpha effects in oral labetalol
3:1
Ratio of beta:alpha effects in IV labetalol
7:1
CV effects of labetalol
- Decreases SVR (due to alpha1 activity)
- Decrease HR
- Blocks reflex tachycardia
Onset time of Labetalol
5-10minutes
IV dose of Labetalol
0.1-0.5mg/kg
Elimination half life of Labetalol
5 hours, hangs around for a long time
What is Carvedilol
Beta antagonist with alpha1 antagonist activity
Ratio of beta:alpha activity of Carvediolol
10:1
Clinical uses for Carvedilol
- Essential HTN
- Symptomatic heart failure
Most common adverse reactions to Carvedilol
- Edema
- Dizziness
- Bradycardia
- Hypotension
- Nausea
- Diarrhea
- Blurred vision
What is Clonidine
Non-selective alpha agonist
What can be caused by acute withdrawal of clonidine?
Hypertensive crisis
Clinical uses for clonidine
- Hypertension
- Used in caudals and epidurals for post-op pain
- Anxiety
- Sleep aid
What is dexmedetomidine
Short acting alpha-2 agonist with anxiolytic, anesthetic, hypnotic, and analgesic properties
Dexmedetomidine is a good drug to use for what airway management?
Awake fiberoptic
What is the method of action of an alpha-2 agonist?
It stimulates the reuptake of norepi, thus decreasing circulating levels. It’s a sympatholytic
2 main side effects of dexmedetomidine
- Hypotension
- Bradycardia
Under what circumstances should dexmedetomidine be used with caution? (7)
1) Hypovolemia
2) Hypotension
3) Chronic hypertension
4) Elderly
5) Diabetes mellitus
6) Advanced heart block
7) Severe ventricular dysfunction
IV dose of dexmedetomidine
1mcg/kg over 10 minutes
Infusion dosing of dexmedetomidine
0.2-0.7mcg/kg/hour
If you don’t start out with a bolus, how long will it take a dexmedetomidine infusion to reach effective plasma levels?
45 minutes to an hour
What are the benefits of dexmedetomidine over other available sedative agents?
- Lack of respiratory depression
- Decreases the need for opioid analgesics
- Less cardiovascular instability
IV dose of clonidine
4-8mcg/kg
Infusion dose of clonidine
2mcg/kg/hour
Epidural dose of clonidine
6-8mcg/kg
Intrathecal dose of clonidine
30-225mcg
A patient on chronic beta blockers must be given a beta blocker within __ hours of surgery
24
For cardiac cases, all patients must be given a beta blocker dose within __ hours of surgery
6
A beta blocker is contraindicated if the heart rate is below
50bpm
What is insulin?
A hormone secreted by pancreatic beta cells that causes the uptake of glucose into skeletal muscle and fat
Actions of insulin
- Carries glucose across cell membranes
- Increases synthesis of glycogen, protein, fatty acid (storage molecules)
- Decreases glycogenolysis, gluconeogenesis, lipolysis
Insulin is used for treatment of what electrolyte imbalance?
Hyperkalemia
How does insulin affect K+
Increases K+ entry into adipose and muscle tissue thus decreasing serum potassium levels
What other drug is given in combination with insulin to treat hyperkalemia?
Dextrose
What dose of insulin+dextrose is used to lower the serum K+ by 1meq/L?
10 units insulin + 25g dextrose
Level of serum K+ at which T wave abnormalities appear
5.5mEq/L
Level of serum K+ at which EKG intervals widen
6.5mEq/L
Level of serum K+ at which P wave changes start
7.0mEq/L
Level of serum K+ at which P waves disappear (atrial arrest)
8.8mEq/L
The EKG becomes a sine wave at what serum K+ level
9.0
What is the only type of insulin that is approved to be administered via IV route?
Humulin or Novolin (regular insulin)
Onset of regular insulin
30-60min
Duration of regular insulin
6-8hours
What percentage of regular insulin undergoes 1st pass metabolism by kidneys and liver?
50%
Basal rate of insulin production
1unit/hour (40unit/day)
Rapid acting insulin medication
Lispro
Short acting insulin medication
Regular insulin (CZI)
Intermediate acting insulin medication
Isophane (NPH)
Long acting insulin medication
Ultralente
What are the clinical uses for regular insulin?
- Hyperglycemia
- Hyperkalemia
- Ketoacidosis
Subcutaneous regular insulin is not reliable under what circumstances
- Peripheral edema
- Volume overload
- Temperature variations
When should you not use subq insulin?
- If there are expected electrolyte or acid/base changes during surgery
- Critically ill patients (they have variable tissue perfusion)