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Drugs Exam 1 Flashcards

1
Q

What are the mechanisms of action of Bethanechol?

A
  • direct acting parasympathomimetic
  • agonist of Acetylcholine
    Directly stimulates contraction of the urinary bladder via the DETRUSOR MUSCLE
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2
Q

What are the clinical indications of Bethanechol?

A
  • treatment of choice for detrusor muscle atony —> increases detrusor m. Contractility
  • symptomatic tx plan for dysautonomia (degenerative disorder resulting in polyneuropathy)
  • increases GI motility and can aid in tax of equine gastric ulcer syndrome (EGUS)
  • reproduction —> stimulates uterine contraction (less common use)
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3
Q

What are the precautions with Bethanechol?

A
  • SLUDD signs may be seen in higher doses

- can see life threatening cholinergic Chris is in the event of overdose/toxicity (severe bradycardia, bronchospasm)

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4
Q

What are the contraindications of Bethanechol?

A
  • Problematic if paying has urethra obstruction or GI obstruction
  • patient must have patent urethra and intact bladder wall
  • caution with increased GI motility
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5
Q

What is seen in overdose with Bethanechol?

A
  • excessive muscarinic effects like salivation, urination, defication
  • in very high doses will see more life-threatening cholinergic signs (bradycardia, bronchospasm, etc)
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6
Q

What is the mechanism of action for Neostigmine?

A
  • indirect acting parasympathoMIMETIC
  • acetylcholinesterase antagonist
  • relatively short onset (10-30 minutes)
  • duration lasts about 4 hours
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7
Q

What are the clinical indications of Neostigmine?

A
  • reversal agent of choice for reversal of competitive neuromuscular blockers (NMB)
  • tx for rumen atony (initiate peristalsis)
  • stimulate GI motility and increase bladder emptying
  • may aid in the diagnosis and treatment of myasthenia gravis in dogs
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8
Q

What are the precaution for Neostigmine?

A
  • SLUDD signs which may be more dramatic in patients with pre-existing high vagal tone
  • watch in brachycephalic breeds, GI disease, concurrent medications, etc.
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9
Q

What is the mechanism of action of Neostigmine?

A

It is a competitive (reversible) antagonist of acetylcholinesterase

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10
Q

What is the onset and duration of Neostigmine?

A

It kicks in about 10-30 minutes and can last 4 hours

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11
Q

What are the clinical indications of Neostigmine?

A
  • Reversal agent of choice for reversal of competitive neuromuscular blocks (NMB)
  • tx for rumen atony by initiating peristalsis
  • stimulate GI motility and increase bladder emptying
  • aid in dx and tx of myasthenia gravis
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12
Q

What are some precautions for Neostigmine?

A
  • SLUDD signs may be more dramatic with pre-existing vagal tone
  • watch out for brachycephalic breeds, GI disease, concurrent medications
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13
Q

What are some contraindications with Neostigmine?

A
  • peritonitis
  • GI obstruction
  • urinary tract obstruction
  • in late pregnancy you risk abortion due to uterine contractions
  • if you have the presence of other cholinesterase inhibitors then you risk SYNERGISM
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14
Q

What is the mechanism of action for Pyridostigmine?

A

It is a competitive (reversible) antagonist of acetylcholinesterase

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15
Q

What is the onset and duration of Pyridostigmine?

A
  • onset –> 1 hour after oral dose (but faster if given IV)

- duration –> up to 8-12 hours (longer than Neostigmine)

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16
Q

What are the clinical indications of Pyridostigmine?

A

It is the treatment of choice for myasthenia gravis in dogs for long term maintenance therapy

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17
Q

What are some precautions and contraindications of Pyridostigmine?

A
  • SLUDD signs seen with pre-existing high vagal tone
  • dose-related cholinergic effects
    - GI: nausea, vomiting, diarrhea, hyper salivation
    - increase respiratory secretion, bronchospasm,
    pulmonary edema
    - bradycardia, tachycardia, cardiac arrest
    - muscle cramps and weakness
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18
Q

What are the mechanisms of action for Edrophonium?

A

It is a competitive (reversible) acetylcholinesterase antagonist. IV injection is at 10 mg/mL.

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19
Q

What is the onset and duration of Edrophonium?

A
  • onset –> very fast acting (within 1 minute)

- duration –> very short (lasts about 10 minutes)

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20
Q

What are the clinical indications of Edrophonium?

A

It is used for the Tension test which is used for myasthenia gravis. It is a reversal of non-depolarizing neuromuscular blocks (NMB) but not as commonly used as Neostigmine.

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21
Q

What are some precautions and contraindications of Edrophonium?

A
  • SLUDD signs are usually mild

- less commonly but more severe cholinergic crisis (this is dose dependent)

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22
Q

Who has the longest duration of action?

A. Neostigmine
B. Pyridostigmine
C. Edrophonium

A

B. Pyridostigmine

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23
Q

Who has the shortest duration of action?

A. Neostigmine
B. Pyridostigmine
C. Edrophonium

A

C. Edrophonium

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24
Q

What are the mechanisms of action for Atropine sulfate?

A
  • it is a competitive (reversible) antagonist of acetylcholine
  • it is a tertiary compound that can cross the blood brain barrier (poorly @ therapeutic dose)
  • injectable solution is more common and it will ionize in the GI tract
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25
Q

What are some clinical indications for Atropine sulfate?

A
  • treatment of bradycardia/bradyarrythmias especially during anesthesia
  • cardiac arrest (not in all CPR cases)
  • reduces respiratory and GI secretions –> Xerostomia (dry mouth)
  • treatment of acetylcholinesterase inhibitor toxicity (organophosphates and carbamates)
  • treatment of cholinergic chrisis (due to anti cholinesterase overdose)
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26
Q

What are some precautions with Atropine sulfate?

A
  • drops in heart rate seen initially after IV injection and then will see an increase rapidly
  • may cause tachycardia or exacerbate tachyarrhythmias
  • rabbits have endogenous atropinases (break down atropine) so it is not as effective and should use glycopyrrolate
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27
Q

What are some contraindications with Atropine sulfate?

A
  • glaucoma with systemic and ophthalmic use
  • tachycardia/tachyarrhythmias
  • hypothermic bradycardia patients
  • certain GI diseases, obstructive urinary tract, myasthenia gravis
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28
Q

What are the mechanisms of action of Glycopyrrolate?

A

It is a competitive (reversible) antagonist of acetylcholine. It is a quaternary compound that DOES NOT cross the blood brain barrier.

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29
Q

What is the onset and duration of action with Glycopyrrolate?

A
  • onset –> slower( but IV is fast @ about 1 minute)

- duration –> longer than compared to atropine (most vagolytic effects last about 2-3 hours)

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30
Q

What are the clinical indications of Glycopyrrolate?

A
  • same as atropine but slower kinetics may be more favorable depending on the situation
  • can be used as a pre-med for anesthesia
  • reduces respiratory and GI secretions
  • can be used to reduced hypersialism (excessive salivation) which leads to sialocele (accumulation of saliva in surrounding tissue or glands)
  • horses –> great reduction of cholinergic adverse effects of imidocarb
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31
Q

What are some precautions with Glycopyrrolate?

A
  • same as for atropine
  • less likely to cause CNS effects because it does not cross the blood brain barrier
  • less arrythmogenic than atropine
  • since duration of action is longer it may interfere with the ability to assess patient heart rate post-op
32
Q

What are the mechanisms of action for Oxybutynin and Propantheline?

A
  • competitive (reversible) antagonist of acetylcholine
  • GI or urinary antispasmodic agents
  • causes the relaxation of the detrusor muscle and allows the bladder to empty more easily
  • Oxybutynin –> widely distributed and CAN cross the blood brain barrier
  • Propantheline –> does NOT cross the blood brain barrier
33
Q

What are the clinical indications of Oxybutynin and propantheline?

A
  • MAIN USE –> treat detrusor muscle instability (hyperactive bladder) and urinary antispasmodic
  • Propantheline can also be used to treat certain bradyarrythmias
34
Q

What are some precautions and contraindications of propantheline and oxybutynin?

A
  • potential to cause other parasympathetic signs (propantheline can stimulate HR)
  • at normal therapeutic dose bladder and GI seem to be only organs affected
  • avoid in glaucoma, tachycardia and ileus
35
Q

What are the mechanisms of action of epinephrine?

A
  • 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
36
Q

What are the routes of administration of epinephrine?

A
  • IV, IM, SQ, inhaled, IO

- NOT PO

37
Q

What is 1:1000 equivalent to in mg/mL?

38
Q

What are some indications and clinical effects of epinephrine?

A
  • 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
39
Q

What are some precautions and contraindications of epinephrine?

A
  • cause massive sympathetic output which increases myocardial workload, oxygen demand and oxygen consumption (MVO2) –> myocardial ischemia
  • cardiac arrest
40
Q

What is the mechanism of action of Norepinephrine?

A
  • competitive agonist mainly on a-1 (not active on B-2)

- it is a vasopressor

41
Q

What are some indications of Norepinephrine?

A
  • used where vasopressor support is needed like anesthesia

- used in the treatment of hypotension due to inadequate vascular tone (like in septic shock)

42
Q

What are some precautions of Norepinephrine?

A
  • 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
43
Q

What are some clinical effects of Norepinephrine?

A
  • 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
44
Q

What are some contraindications for Norepinephrine?

A
  • contraindicated in hypertensive patients

- extravasation (if administered outside the vein) can cause tissue damage

45
Q

What are the mechanisms of action for Isoproterenol?

A
  • synthetic catecholamine
  • potent non-specific B-agonist (B1 and B2)
  • no a-adrenergic activity
46
Q

What are some precautions and contraindications of Isoproterenol?

A
  • 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
47
Q

What are some indications and clinical effects of Isoproterenol?

A
  • 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
48
Q

What are the mechanisms of action of Dopamine?

A
  • 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
49
Q

What are the dose dependent factors of Dopamine?

A
  • 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
50
Q

What are some indications and clinical effects of Dopamine?

A
  • 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
51
Q

What are some precautions and contraindications of Dopamine?

A
  • IV has potential for necrosis if extravasation occurs
  • contraindicative in hypertensive patients
  • MONITOR ECG AND ARTERIAL BLOOD PRESSURE
  • tachycardia, tachyarrhythmia, fluctuations in blood pressure
52
Q

What are the mechanisms of actions of Dobutamine?

A
  • synthetic B-1 agonist
  • structurally similar to Dopamine
  • No dopamine receptor activity
  • minimal a-1 and B-2 agonism
53
Q

What are some indications and clinical effects of Dobutamine?

A
  • 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
54
Q

What are some precautions and contraindications of Dobutamine?

A
  • 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
55
Q

What are the mechanisms of action of Phenylephrine?

A
  • direct acting a-1 selective agonist (non-catecholamine)
  • vasopressor
  • potent and used more in anesthesia
  • no B-2 effects so vasoconstriction can be severe
56
Q

What are some routes of administration for Phenylephrine?

A
  • IV, ophthalmic drops, oral tablets and liquids (decongestant), intranasal spray (decongestant)
57
Q

What are some indications and clinical effects of Phenylephrine?

A
  • 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
58
Q

What are some precautions and contraindications for Phenylephrine?

A
  • renal and GI vasoconstriction
  • chronic use can rebound nasal congestion
  • contraindicated with hypertension
59
Q

What is the mechanism of action of Ractopamine and Zilpaterol?

A

It is a non-selective agonist of B-1, B-2 and B-3 receptors

60
Q

What are some indications and main effects of Ractopamine and Zilpaterol?

A

it increases the rate of weight gain, feed efficiency and carcass leanness in food animals and can just be added to the food

61
Q

What are some random facts about Albuterol?

A
  • human approved for inhalers
  • Salmeterol and Fluticasone (steroid)
  • most selective B-2 agonist
62
Q

What are some random facts about Terbutaline?

A
  • human approved and in small animal in tablet or injectable form
63
Q

What are some random facts about Clenbuterol?

A
  • veterinary approved oral syrup in equines
  • contraindicated in food animals
  • least affinity to B-2 but more affinity to B-1 (affects heart)
64
Q

What are some precautions and contraindications for Albuterol, Terbutaline, and Clenbuterol?

A
  • 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
65
Q

What are the mechanisms of action of Phenylproanolamine?

A
  • direct –> a-1 receptor agonist
  • indirect –> increase in norepinephrine in bladder neck/urethra
  • used to treat urinary incontinence
66
Q

What are some indications of Phenylproanolamine?

A
  • used in small animals (dogs) to treat urinary incontinece due to urethral sphincter hypotenuse/incompetence
67
Q

What is a drug to drug interactions with Phenylproanolamine?

A

Estrogens can up regulate a-1 receptors in internal urethral sphincter so may see synergisms

68
Q

What are some precautions for Phenylproanolamine?

A
  • urinary retention
  • tachycardia
  • hypertension
  • restlessness
  • occasionally anorexia
  • few side effects at therapeutic doses
69
Q

What are some mechanisms of action of Ephedrine?

A
  • direct –> a-1 and B receptors (mostly B-1) agonist

- indirect –> increase in norepinephrine release (primary mechanism of action)

70
Q

What are some precautions with Ephedrine?

A
  • hypertension

- arrhythmias (less common than with catecholamines)

71
Q

What are some indications and main effects of Ephedrine?

A
  • used as CRI to maintain blood pressure under anesthesia (vasopressor effect)
  • increase blood pressure –> vasoconstriction and direct cardiac stimulation
  • bronchodilator (same B-2 effects)
  • urinary sphincter contraction may cause urinary retention
  • mydriasis
72
Q

What are some indications of Vasopressin?

A
  • vasopressor agent
  • used in adjunct treatment of shock syndromes and cardiopulmonary cerebral resuscitation (CPR or CPCR) –> no evidence its better than epinephrine
  • treatment of central diabetes insipidus (CDI) but Desmopressin is better for this
  • treatment of Von Willebrand Factor deficiency like Desmopressin
73
Q

What are some precautions and adverse effects of Vasopressin?

A
  • GI signs like nausea and cramping
  • extravasation injury and local irritation and injection site (including sterile abscess)
  • water retention (hypovolemia can occur) –> overdoes can lead to water intoxication
74
Q

What are some contraindications to Vasopressin?

A

Chronic nephritis with uncontrolled azotemia

75
Q

What are mechanisms of action of Phenoxybenzamine?

A
  • none specific alpha antagonist (a-1 and a-2)

- noncompetitive (irreversible antagonist that lasts about 3-4 days

76
Q

What are some precautions of Phenoxybenzamine?

A
  • excessive a-blockade which can cause hypotension, reflex tachycardia, mitosis and change in intraocular pressure, GI signs and its expensive AF
77
Q

What are some indications of Phenoxybenzamine?

A
  • used to treat urinary retention due to urethral hypertonicity by relaxing internal sphincter and may be combined with other stuff like diazepam
  • pheochromocytoma (malignant tumor of the adrenal glands) –> prior to surgery treat associated hypertension for a better outcome

PHARMACOLOGY (6 decks)

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