Flashcards in Adrenergic 2 Deck (45):
1. What is Clonidine?
Partial a2-selective agonist that activates CENTRAL a2-adrenoreceptors. By activating central receptors it therefore passes through the BBB, then activates the pre-synaptic M2 receptors which are inhibitory therefore decreasing sympathetic outflow/release of NE. This drug is used to treat high blood pressure. It’s adverse side effects are lethargy, sedation and xerostomia.
2. What is Methyldopa?
Methyldopa is an a2-selective agonist that activates CENTRAL a2-adrenoreceptors. It is taken up by noradrenergic neurons and converted to a-methylnorepinephrine which is what activates the receptors. This drug is used to decreased blood pressure and is the drug of choice for HTN TREATMENT DURING PREGNANCY. Adverse side effects include sedation, impaired mental concentration and xerostomia.
3. What is Brimonidine?
Brimonidine is a highly selective a2 agonist used to lower intraocular pressure in glaucoma. It’s delivery method is eye drops. It reduces aqueous humor production AND increases outflow.
4. What is the role of a releasing agent (type of indirect-acting adrenergic agonist)?
Releasing agents cause NE release from presynaptic terminals thereby potentiating effects of norepinephrine produced endogenously. Ex. amphetamine, methylphenidate, tyramine
5. What is Amphetamine?
Amphetamine is an indirect-acting adrenergic agonist that acts as a releasing agent. It has CENTRAL stimulatory action and can increase blood pressure by a-agonist action on vasculature as well as B-stimulatory effects on the heart.
6. What is Methylphenidate?
Methylphenidate is a structural analogue of amphetamine that acts as an indirect-acting adrenergic agonist that acts as a releasing agent. It is widely used to treat ADHD in children.
7. What is tyramine?
Tyramine is an indirect-acting adrenergic agonist that acts as a releasing agent. It is found in fermented foods such as ripe cheese and Chianti wine. When consumed it is usually oxidized by MAO. When patients consume these products while taking MAO inhibitors it can precipitate serious vasopressor episodes with increasing blood pressure, causing headache, etc (“cheese effect”).
8. What is cocaine?
Cocaine is an uptake inhibitor that blocks monoamine reuptake thereby allowing them to accumulate in the synaptic space. This results in potentiation and prolongation of central and peripheral action of the monoamines.
9. What is Atomoxetine?
Atomoxetine is an uptake inhibitor selective for norepinephrine reuptake transporters. It is indicated for the treatment of ADHD.
10. What is Modafinil?
Modafinil is an uptake inhibitor that inhibits NE and dopamine transporters thereby increasing synaptic concentrations of NE, dopamine, serotonin and glutamate and decreasing GABA levels. The mode of action is not fully known. It is used for treatment of narcolepsy by acting as a psychostimulant.
11. What is ephedrine? (mechanism)
Ephedrine stimulates a and B receptors causing the release of NE from nerve endings. This is not a catecholamine thereby is not broken down by COMT and MAO. Because it is not broken down it has a prolonged duration of activity. This drug has excellent absorption orally and penetrates the CNS.
12. What are the actions of ephedrine?
1. increases systolic and diastolic blood pressure
2. causes bronchodilation
3. mild stimulation of CNS causing increased alertness, decreased fatigue and prevents sleep
4. improves athletic performance
**ephedrine-containing herbal supplements were banned by FDA due to life-threatening CV reactions
13. What are the uses of ephedrine?
1. pressor agent during spinal anesthesia when hypotension occur
2. myasthenia gravis as an adjuvant to cholinesterase inhibitors
3. allergic disorders
14. What is pseudoephedrine?
One of 4 ephedrine enantiomers that is available over the counter as a component of decongestant mixtures.
15. What is phenoxybenzamine?
Phenoxybenzamine is a non-selective, irreversible, a-adrenergic antagonist. It was discovered to treat HTN, but was unsuccessful. It is currently used to treat PHEOCHROMOCYTOMA. It is given prior to surgical removal of the tumor and for chronic management of inoperable tumors.
16. What is Phentolamine?
Phentolamine is a non-selective, reversible, a1 and a2 receptor antagonist. It is used…
1. to treat pheochromocytoma by controlling HTN in preoperative prep and during surgical excision
2. diagnose pheochromocytoma via phentolamine blocking test
3. prevent dermal necrosis after extravasation of NE
4. Hypertensive crisis due to stimulant drug overdose
5. Cocaine-induced acute coronary syndrome to reverse coronary artery vasoconstriction
6. Hypertensive crisis due to sudden withdrawal of sympatholytic antihypertensive drugs
7. Hypertensive crisis due to interaction b/t MAOIs and tyramine and other sypathomimetic amines
17. What is the epinephrine reversal?
All a-adrenergic blockers reverse the a-agonist effects of epinephrine. The vasoconstriction a1 action of epinephrine is blocked but vasodilation caused by activation of B2 is not blocked. Therefore, the systemic blood pressure decreases in response to epinephrine given in the presence of phenoxybenzamine (non-selective a blocker).
18. What is the a1-blocker effect of the cardiovascular system?
1-blockers lower arterial blood pressure by relaxing both arterial and venous smooth muscle. The initial dose produces an exaggerated hypotensive response resulting in syncope (fainting). Therefore the initial dose must be 1/3 or 1/4th of the normal dose.
Prazosin is the main a1-blocker!
19. What are a1-blockers (prazosin) used for?
1. HTN (but not drug of choice)
2. Benign prostate hypertrophy – providing symptom relief by relaxing smooth muscle in the bladder neck, prostate capsule and prostatic urethra improving urinary flow
20. What are Terazosin and Doxazosin?
These are Prazosin analogs with longer half-lives. They are used to treat HTN and BPH just like Prazosin.
21. What is Tamsulosin?
Tamsulosin is an a1-antagonist approved for BPH. It has minimal effect on blood pressure and is less likely to cause orthostatic hypotension.
22. What is Yohimbine?
A2-selective adrenergic blocker used in the past to treat erectile dysfunction. Phosphodiesterase type 5 inhibtors have since replaced it.
23. What is Propranolol?
The main (prototype) non-selective B-blocker.
24. What are the CV effects of propranolol?
Slow HR and decrease myocardial contractility. Treat angina pectoralis by decreasing O2 requirement and acting as a chronic manager of stable angina (not indicated for acute management). B-blockers can also control ventricular rate in pts with atrial fibrillation. B-blockers can also protect against myocardium.
25. What are the respiratory effects of propranolol?
Block B2 receptors in lungs resulting in respiratory crisis in pts with COPD and asthma. **do not use for pts with asthma
26. What are the metabolic effects of propranolol?
Decrease glycogenolysis, decrease glucagon secretion
27. What is the effect of propranolol on HTN?
B-blockers lower blood pressure in HTN by decreasing cardiac output.
28. What is the effect of propranolol on glaucoma?
B-blockers (esp timolol) are used to diminish intraocular pressure in glaucoma.
29. What is the effect of propranolol on migraines?
B-blockers are effective prophylaxis of migraines. It is thought that there is a blockage of catecholamine-induced vasodilation of brain vasculature.
30. What is the effect of propranolol on hyperthyroidism?
B-blockers blunt sympathetic stimulation that occurs in hyperthyroidism.
31. What type of drug is used to treat performance anxiety (“stage fright”)?
32. What is the effect of B-blockers on essential tremor?
Essential tremors are the most common neurologic cause of postural or action tremor. These are the most commonly used drugs for treatment of essential tremor.
33. What are the adverse effects of non-selective B-blockers (propranolol)?
1. bronchoconstriction – lethal for asthmatics
2. non-selective B-blockers may impair recovery from hypoglycemia in insulin-dependent diabetics and mask the tachycardia typically seen with hypoglycemia denying the patient an important warning sign
3. inhibit TG breakdown in adipose tissue reducing HDL and increasing LDL and TGs
4. sedation, dizziness, lethargy, fatigue, depression
34. What type of B-blocker will improve lipid profiles?
35. What are the warnings and precautions of using non-selective B-blockers?
Pts should be tapered off B-blocker therapy to avoid acute tachycardia, HTN and/or ischemia. These adverse effects may be due to up-regulation of B-receptors due to long-term therapy with B-blockers.
36. What is Nadolol?
Non-selective B-blocker that has a long duration of action. It is used to treat angina pectoralis and manage HTN.
37. What is Timolol?
Non-selective B-blocker that is used to treat HTN. It is given as a prophylaxis for migraine headaches. It is also used to treat intraocular HTN or open-angle glaucoma.
38. What are atenolol and metoprolol?
These are B1-selective adrenergic antagonists used for hypertensive pts with impaired pulmonary function or with diabetic hypertensive pts who are receiving insulin or oral hypoglycemic agents. In general these drugs manage HTN, long-term management of angina pectoris and management of MI to reduce CV mortality.
39. What is Esmolol?
B1-selective adrenergic antagonist that is ultra-short acting (half-life about 10 minutes). It is given via IV to treat supraventricular arrhythmias, arrhythmias associated with thyrotoxicosis, perioperative HTN and myocardial ischemia in acutely ill pts.
40. What is Labetalol?
Competitive antagonist at B and a1 receptors – much more potent as a B-antagonist than a-antagonist. It is used to treat HTN.
41. What is Carvedilol?
Competitive antagonist at B and a1 receptors. It is much more potent as a B-antagonist than a a-antagonist. It is used to treat HTN and congestive heart failure. It also has antioxidant properties.
42. What is pindolol?
A partial B-agonist that has intrinsic sympathomimetic activity. They are occasionally preferred as HTN drugs in individuals with diminished cardiac reserve or bradycardia propensity.
43. What is a-methyltyrosin (metyrosine)?
Competitive inhibitors of tyrosine hydroxylase thereby preventing production of L-DOPA. Metyrosine is used for management of malignant pheochromocytoma in preop prep prior to resection. [inhibitors of norepinephrine synthesis]
44. What is Reserpine?
Drug that irreversibly blocks VMAT preventing storage of NE and E in vesicles. This causes depletion of NE since MAO degrades NE in the cytoplasm. After giving the drug there is a gradual decrease in blood pressure and slowing of cardiac rate. It was used in the past to treat HTN.