Pharm PNS III Flashcards
For sympathoMIMETICS, which drugs are direct-acting catecholamines?
- epinephrine
- norepinephrine
- isoproterenol
- dopamine
- dobutamine
For sympathoMIMETICS, which drugs are direct-acting alpha-1 agonists?
Phenylephrine
For sympathoMIMETICS, which drugs are non-selective Beta agonists?
- Ractopamine
- Zilpaterol
For sympathoMIMETICS, which drugs are Beta2 agonists?
- Albuterol
- Terbutaline
- Clebuterol
For sympathoMIMETICS, which drugs are mixed (direct and indirect acting) agonists?
- ephedrine
- pseudoephedrine
- phenylpropanolamine (PPA)
For sympathoLYTICS, which drugs are direct-acting alpha antagonists?
- phenoxybenzamine
- Prazosin
For sympathoLYTICS, which drugs are direct-acting beta antagonists?
- Propanolol
- Sotalol
- Atenolol
- Metoprolol
For sympathoLYTICS, which drugs are direct-acting mixed alpha and beta antagonists?
Carvedilol
For sympathoLYTICS, which drugs are indirect-acting antagonists?
Reserpine
For D1 receptors what organs can it be found on and what is the action once it has been bound to its substance?
- smooth muscle of blood vessels in most organs
- JG apparatus
- renal tubules
- direct vasodilation
- natriuresis
- inhibit 2Na+/K+ ATPase and Na+/H+ exchanger in PCR, ALOH, CCDs
- diuretic response due to increased RBF and GFR as well as direct natriuresis
For D2 receptors what organs can it be found on and what is the action once it has been bound to its substance?
- post-ganglionic sympathetic nerve terminals
- glomeruli, renal cortex and renal tubules
- adrenal cortex (zona glomerulosa cells)
- chemoreceptor trigger zone in the brain
- indirect vasodilation –> inhibits NE release from sympathetic terminals (pre-junctional)
Which catecholamines can be found endogenously?
- Epinephrine
- Norepinephrine
- Dopamine
What are some general properties for catecholamines?
- direct acting sympathoMIMETICS
- orly absorbed after oral administration (usually given by injection
- readily absorbed from respiratory tract –> inhalation is the next best route for absorption and distribution if IV route is not an option
- SQ absorption is slower for a1 agonists
- does not readily cross the BBB
- rapid onset of action and inactivation –> EMERGENCY USE
What are some precautions and adverse effects for catecholamines?
- potent drugs with narrow say margin (if your off by 0.1 your patient may die)
- very short half life (within minutes)
- predispose myocardium to tachycardia and tachyarrhythmias
- altered perfusion leads blood flow to “flight tissue” and vasoconstriction to other vital organs like the kidneys
- extravasation of NE or Dopamine can cause tissue damage and sloughing
- cerebral hemorrhage (not so much in vet med)
- anxiety, restlessness, tremors
Which of the following will result in the least amount of vasodilation?
A. Epinephrine B. Norepinephrine C. Isoproterenol D. Dopamine E. Dobutamine
B. Norepinephrine
Which of the following causes D1 receptor mediated vasodilation at low doses?
A. Epinephrine B. Norepinephrine C. Isoproterenol D. Dopamine E. Dobutamine
D. Dopamine
Selective B-2 agonists are primarily used as bronchodilators in the treatment of lower respiratory diseases like asthma and COPD.
A. True
B. False
A. true
Which of the following is the drug of choice for treatment of bronchial asthma?
A. Norepinephrine
B. Isoproterenol
C. Albuterol
D. Zilpaterol
C. Albuterol
What are the mechanisms of action of epinephrine?
- competitive agonist on all alpha and beta receptors (a1, a2, B1, B2)
- B-1 –> cardiac contractility
- B-2 –> bronchodilator and vasodilation at low doses
- a-1 –> vasoconstriction (dose-dependent) and increase venous return to the heart during CPR
What are the routes of administration of epinephrine?
- IV, IM, SQ, inhaled, IO
- NOT PO
What is 1:1000 equivalent to in mg/mL?
1 mg/mL
What are some indications and clinical effects of epinephrine?
- systemic effects
- cardiopulmonary arrest (CPA)
- Anaphylaxis/anaphylactoid reactions
- used as Vasopressor
- used as positive inotrope (IV CRI)
- local effects
- used with local anesthetics to produce
regional vasoconstriction (potentiate local
anesthetic) - topically used to treat local hemorrhage like
epistaxis
- used with local anesthetics to produce
What are some precautions and contraindications of epinephrine?
- cause massive sympathetic output which increases myocardial workload, oxygen demand and oxygen consumption (MVO2) –> myocardial ischemia
- cardiac arrest
What is the mechanism of action of Norepinephrine?
- competitive agonist mainly on a-1 (not active on B-2)
- it is a vasopressor
What are some indications of Norepinephrine?
- used where vasopressor support is needed like anesthesia
- used in the treatment of hypotension due to inadequate vascular tone (like in septic shock)
What are some precautions of Norepinephrine?
- cardiac arrhythmia/tachyarrhythmias –> to correct this you can discontinue and use another vasopressor
- NEED TO USE ECG MONITORING AND ARTERIOLE PRESSURE MONITORING
- caution with certain cardiac diseases
What are some clinical effects of Norepinephrine?
- vasoconstriction (a-1 agonist) and is the most important catecholamine vasopressor –> cardiac out put increases due to increase in systolic/diastolic arteriole pressure
- less of an increase in MvO2 compared to epinephrine
- no significant bronchodilation because of no B-2 activity
- no vasodilatory effects counteracting a-1 vasoconstriction
- stronger vasoconstriction than epinephrine
- strong vasopressor action –> strong baroreceptor response –> decrease HR and contractility
What are some contraindications for Norepinephrine?
- contraindicated in hypertensive patients
- extravasation (if administered outside the vein) can cause tissue damage
What are the mechanisms of action for Isoproterenol?
- synthetic catecholamine
- potent non-specific B-agonist (B1 and B2)
- no a-adrenergic activity
What are some precautions and contraindications of Isoproterenol?
- side effects similar to dopamine and dobutamine like tachycardia, anxiety, tremors and arrhythmias
- IV CRI must be titrated to effect
- ECG MONITORING AND ARTERIOLE BLOOD PRESSURE MONITORING
What are some indications and clinical effects of Isoproterenol?
- cardiac stimulatory (positive inotropic effect and mild positive chronotropic effect)
- increase coronary, skeletal, renal, and mesenteric blood flow
- bronchodilation
- given IV and paraenternally in people for treatment of asthma
- not commonly used as other catecholamines
What are the mechanisms of action of Dopamine?
- it acts on dopamine receptors with dose dependent effects at alpha and beta receptors
- its indirect effect is that it stimulates the release of norepinephrine
What are the dose dependent factors of Dopamine?
- low dose: dopamine agonist (D1 and D2 receptors) –> activates visceral dopamine receptors which dilates renal, messenteric, coronary and intracerebral vascular beds
- medium-low dose:B-1 agonist –> positive inotrope
- medium-high dose: B-1 agonist –> positive chronotrope and increase cardiac automacity
- high dose –> a-1 agonist (vasoconstriction)
- NO B-2 EFFECTS
What are some indications and clinical effects of Dopamine?
- vasopressor support
- treatment of hypotension due to inadequate vascular tone
- post-arrest vasopressor of choice
- it is no longer advocated for the use in oliguric renal failure
What are some precautions and contraindications of Dopamine?
- IV has potential for necrosis if extravasation occurs
- contraindicative in hypertensive patients
- MONITOR ECG AND ARTERIAL BLOOD PRESSURE
- tachycardia, tachyarrhythmia, fluctuations in blood pressure
What are the mechanisms of actions of Dobutamine?
- synthetic B-1 agonist
- structurally similar to Dopamine
- No dopamine receptor activity
- minimal a-1 and B-2 agonism
What are some indications and clinical effects of Dobutamine?
- positive inotropic effect in patients that need it
- moderate positive chronotropic effects
- treatment of anesthesia associated hypotension where inotropic support is indicated to maintain cardiac output and tissue/organ perfusion
- increase coronary, skeletal, renal and mesenteric blood flow
What are some precautions and contraindications of Dobutamine?
- side effects similar to other catecholamines like tachycardia and/or tachyarrhythmias
- twitching and seizures
- tachyphylaxis (acute tolerance)
- contraindicated with left atrial rupture or in cases where myocardial integrity is a concern like heart disease/failure
What are the mechanisms of action of Phenylephrine?
- direct acting a-1 selective agonist (non-catecholamine)
- vasopressor
- potent and used more in anesthesia
- no B-2 effects so vasoconstriction can be severe
What are some routes of administration for Phenylephrine?
- IV, ophthalmic drops, oral tablets and liquids (decongestant), intranasal spray (decongestant)
What are some indications and clinical effects of Phenylephrine?
- increase in peripheral vascular resistance through systemic vasoconstriction
- may cause reflex bradycardia
- treatment of hypotension in dogs and cats
- systemic vasopressor effects immediately IV and lasts less than 20 minutes
- local/topical use for vasoconstriction of hemorrhage such as epistaxis and ophthalmic use as a mydriatic agent and aids in treatment of open angle glaucoma
What are some precautions and contraindications for Phenylephrine?
- renal and GI vasoconstriction
- chronic use can rebound nasal congestion
- contraindicated with hypertension
What is the mechanism of action of Ractopamine and Zilpaterol?
It is a non-selective agonist of B-1, B-2 and B-3 receptors
What are some indications and main effects of Ractopamine and Zilpaterol?
it increases the rate of weight gain, feed efficiency and carcass leanness in food animals and can just be added to the food
What are some random facts about Albuterol?
- human approved for inhalers
- Salmeterol and Fluticasone (steroid)
- most selective B-2 agonist
What are some random facts about Terbutaline?
- human approved and in small animal in tablet or injectable form
What are some random facts about Clenbuterol?
- veterinary approved oral syrup in equines
- contraindicated in food animals
- least affinity to B-2 but more affinity to B-1 (affects heart)
What are some precautions and contraindications for Albuterol, Terbutaline, and Clenbuterol?
- cardiac stimulation causes tachycardia
- vasodilation
- uterine relaxation –> tocolytic agent and may cause fetal retention
- contraindications in patients with cardiovascular disease
- nervousness, sweating, muscle tremors, weakness, and vomiting
- ARCI class 3 agent so may be prohibited by some equine associations like horse shows
- receptor down-regulation can occur with chronic use
