Adjuncts 1: catecholamines, noncatecholamines, beta blockers, CCBs, alpha blockers, vasodilators, antiarrythmics Flashcards
Epinephrine: class
Endogenous catecholamine and nonselective adrenergic agonist at a1, a2, b1, b2
Epinephrine: MoA
Binds to adrenergic receptors, stimulating G-coupled proteins, adenylate cyclase, and cAMP.
Low doses = stimulation of beta2 = vasodilation, bronchodilation, decreased histamine release
Higher doses = stimulation of alpha1 = peripheral, renal, splanchnic vasoconstriction and decrease in bronchial secretions
Epinephrine: PK
Onset 1-2 mins IV
DOA 5-10 mins
E 1/2t = 30 secs
Small Vd = poor lipid solubility
Epinephrine: AE
Tachycardia and severe HTN Arrhythmias Cerebral hemorrhage Hyperglycemia Hypokalemia Increased IOP Periph vascular insufficiency
Headache, nervousness, tremor
Epinephrine: CI
Non-anaphylactic shock Cardiac arrhythmias Severe hypertension Pheochromocytoma Active labor Cerebral or coronary artherosclerosis Glaucoma Renal insufficiency
Epinephrine: dosing
2-8mcg IV for hypotension
10mcg/kg for resuscitation
Continuous infusion:
1-2mcg/min beta2
4-5mcg/min beta 1
10-20mcg/min alpha 1 + beta
Norepi class:
Endogenous catecholamine
Direct acting nonselective adrenergic agonist
Alpha and B1»_space;»> B2
Norepi MoA:
Binds to alpha and beta1 adrenergic receptors, stimulating C-coupled proteins, adenylate cyclase, and cAMP.
Low doses = increased CO (inotrophy and chronotrophy) and increased blood pressure.
High doses = potent alpha1 effects outweighs beta –> arterial constriction and decreased vital organ blood flow.
Epinephrine: metabolism
COMT and MAO in the blood, liver, kidneys; metabolites excreted in urine
Norepi: PK
Rapid onset
Limited DOA
E1/2t = 2.5 mins
Norepi: metabolism
COMT and MAO in the blood, liver, kidneys; metabolites excreted in urine
Norepi: AE
Usually a result of intense vasoconstriction…
HTN Severe bradycardia End organ ischemia Hemorrhagic stroke or ischemia of cerebral vessels Renal vasoconstriction + oliguria
Anxiety and headache
Norepi: CI
HTN
Extreme hypovolemia
Mesenteric or PVD
Norepi: dosing
0.01-0.1mcg/kg/min or 4-16mcg/min
Isoproterenol: class
Synthetic catecholamine
Selective beta adrenergic receptor agonist (beta1»_space; beta 2)
Isoproterenol: MoA
Stimulates beta adrenergic receptors, stimulating g-coupled protein receptors, further stimulating adenylate cyclase and cAMP within the cell.
Beta 1 = increases inotropy and chronotropy of the heart
Beta 2 = Vascular, GI, pulmonary and uterine relaxation
Isoproterenol: PK
Immediate onset
DOA 5-10mins
E1/2t = 2.5-5mins
Isoproterenol: metabolism
COMT in liver and lungs
40-50% unchanged in urine
Isoproterenol: AE
Tachycardia, dysrhythmias
MI and increased O2 consumption
Decreased CBF
Peripheral vasodilation and hypotension
Isoproterenol: CI
HAT
Hypersensitivity
Angina/CAD
Tachycardia
Isoproterenol: dosing
0.5 - 10 mcg/min
Dobutamine: class
Synthetic catecholamine (analog of isoproterenol) Direct acting selective beta 1 adrenergic receptor agonist with some beta 2 activity at clinical doses
Dobutamine: MoA
Binds with beta1 adrenergic receptors, stimulating G-coupled proteins, adenylate cyclase, and cAMP within the cell causing influx of Ca+ and promoting cardiac muscle contractility
Dobutamine: PK
Onset 1-2mins
Peak effect in 10 mins
Dobutamine: metabolism
COMT and MAO in blood, liver, kidneys, GI tract
Metabolites excreted in urine
Dobutamine: AE
Dyspnea Tachycardia, SVT Thrombocytopenia and platelet inhibition Phlebitis Down regulation of beta receptors after 3 days of tx = tolerance
Fever, headache, nausea
Paresthesia
TOXICITY = anorexia, NV, tremor, head, SOB, angina, chest pain, anxiety
Dobutamine: CI
Hypersensitivity
Hypovolemia
CAD without CHF
Caution in pregnancy
Dobutamine: dosing
Start at 0.5-1mcg/kg/min; titrate every few minutes to 2-20mcg/kg/min
Max dose 40mcg/kg/min
Dopamine: class
Endogenous catecholamine
Alpha, beta adrenergic, and dopaminergic receptor agonist
Dopamine: MoA
Low doses – agonize dopaminergic 1 receptors in coronary, renal, and mesenteric vascular smooth muscle cells to stimulate G-CP, AC, cAMP
Medium doses – agonize beta 1 adrenergic receptors in cardiac myocytes to increase contractility = +inotrope = ↑CO and HR
High doses – agonize alpha1 in GU, GI, heart, liver and vascular smooth muscle
Dopamine: PK
Rapid onset
Dopamine: metabolism
MAO and COMT
Beta hydroxylated to norepinephrine, then methylated to epinephrine in liver and plasma
Eliminated in urine
Dopamine: AE
Limb ischemia if extravasated Tachycardia, angina, palpitations Dyspnea Increased IOP Hyperglycemia
Headache, N/V
Dopamine: CI
Right heart failure d/t increase pulm art pressure MAOIs Sulfa allergy V-fib Pheochromocytoma Cocaine use (exaggerated response)
Dopamine: dosing
0.5 to 2mcg/kg/min low dose
2-5mcg/kg/min medium dose
>10mcg/kg/min large dose
Vasopressin: class
Exogenous antidiuretic peptide and vasopressor
Vasopressin: MoA
Stimulates V1 receptors on vascular smooth muscle, glomerular mesangial cells, and vasa recta causing potent vasoconstriction
Stimulates V2 receptors on basolateral cell membrane of renal collecting ducts to ↑ water reabsorption and constricts glomerular efferent arteriole to maintain GFR
Vasopressin: PK
Onset = nasal 1hr DOA = nasal 3-8hrs
Vasopressin: metabolism
Metabolized by tissue peptidases
Rapid oral inactivation by trypsin
E1/2t 10-20min
Vasopressin AE:
Coronary artery vasospasm, angina, MI Vasoconstriction and HTN Increased peristalsis, N/V, and abd pain Decreased PLTs Tremor, headache, fever, diaphoresis
Vasopressin: CI
Hypersensitivity
Caution w/ NSAIDs, carbamazepine (inc AVP effect)
Vasopressin: dosing
Refractory cardiac arrest: 40 units IV push
Esophageal varicies: 20 units over 5 mins
Hemorrhagic/septic shock: 0.04 units/min
DI: 100-200mU/hr IV
Ephedrine: class
Synthetic non-catecholamine
Indirect alpha 1 and beta 2 agonist
Direct beta 1 agonist
Ephedrine: MoA
Indirectly: increases NE release from post ganglionic SNS nerve, activating receptors
Directly: binds to receptors and activates G protein, activates or intracellular enzyme adenylate cyclase to cAMP and phospholipase C
Ephedrine: PK
Rapid onset
DOA 1 hr
E1/2 t 3hrs
Ephedrine: metabolism
COMT, though inefficiently; 40% unchanged in the urine
Ephedrine: AE
Tachyphylaxis Arrhythmias HTN MI CNS stim
Ephedrine: CI
Hypersensitivity Severe HTN Arrhythmias CHF Glaucoma MAOIs Cocaine use (be cautious)
Ephedrine: dosing
5-25 mg IV
Phenylephrine: class
Synthetic non-catecholamine
Selective alpha 1 adrenergic agonist
Phenylephrine: MoA
Binding to alpha1 receptor causes direct stimulation of g-protein coupled receptor, increases adenylate cyclase, and cAMP, leading to an influx of calcium on systemic VENOUS vascular smooth muscle and vasoconstriction
Phenylephrine: PK
Onset
Phenylephrine: AE
Reflex bradycardia
Hypertension and decreased CO d/t increased afterload
Decreased renal, splanchnic, cutaneous blood flow
Decreased UO
Metabolic acidosis
Anxiety, HA, nervousness, weakness, paresthesia
Rebound nasal congestion
Phenylephrine: CI
Hypersensitivity Glaucoma Severe HTN and tachycardia Arrythmias Caution in elderly, heart blocks, HTN, bradycardia
Phenylephrine: dosing
50-200mcg IV bolus Q5mins
20-180mcg/min to start with maintenance at 10-60mcg/min
Esmolol: class
Selective beta 1 adrenergic antagonist
Esmolol: MoA
Reversibly binds to beta 1 adrenergic receptor antagonists to inhibit the binding of NE, EPI, and other beta agonist, preventing the stimulation of G-coupled protein receptors, adenylate cyclase, and cAMP
Slows SA rate and conduction through the AV node and decreases contractility, reducing cardiac O2 demand
Esmolol: PK
Onset: 30-60 sec DOA = 10-15mins E1/2t = 9 mins High Vd 55% PB
Esmolol: metabolism
Plasma esterases and excretion in the urine
Esmolol: AE
Severe bradycardia Hypotension Heart block CHF and pulmonary edema POI d/t propylene glycol
Syncope/dizziness
Headache
Esmolol: CI
Hypersensitivity CHF Concurrent CCB (= complete heart block) Sick sinus syndrome Severe hypotension HR dependent Asthma and COPD (in high doses) Pregnancy
Esmolol: dosing
5-10mg IV Q3-5mins to total dose of 80mg
300-500mcg/kg/min
Labetalol: class
Beta 1, beta 2, alpha1 adrenergic antagonist
Labetalol: MoA
Reversibly binds to beta1, beta2, alpha1 adrenergic receptor antagonists to inhibit the binding of NE, EPI, and other beta agonist, preventing the stimulation of G-coupled protein receptors, adenylate cyclase, cAMP.
Slows SA node rate (beta 1), slows conduction through the AV node (beta 1), decreases contractility (beta 1), and causes peripheral, cerebral, and coronary vasodilation (alpha 1)
Labetalol: PK
Onset = 3-5 mins Peak effect 5-10mins (redose 5-10mins) E1/2t = 5-8hrs Vd 7L/kg 50% PB
Labetalol: metabolism
Hepatic microsomal enzymes
Eliminated in urine 50% - fecal 50%
Labetalol: AE
Bronchospasm* Fluid retention* Hypoglycemia* Severe bradycardia Hypotension Heart block
Syncope/dizziness
Headache
Labetalol: CI
Hypersensitivity Asthma/COPD Severe CHF Concurrent CCB use (= complete heart block) Severe hypotension or bradycardia Sick sinus syndrome
Labetalol: dosing
5-10mg IV Q5-10mins up to 300mg total
Metoprolol: class
Selective beta 1 adrenergic antagonist
Metoprolol: MoA
Reversibly binds to beta 1 adrenergic receptor antagonists to inhibit the binding of NE, EPI, and other beta agonist, preventing the stimulation of G-coupled protein receptors, adenylate cyclase, and cAMP
Slows SA rate and conduction through the AV node and decreases contractility, reducing cardiac O2 demand
Metoprolol: PK
Onset Rapid
E1/2 life = 3-7hrs
12% PB
Metoprolol: metabolism
Hepatic metabolism
Renal excretion
Metoprolol: AE
Bradycardia Cardiac failure/asystole Dyspnea Heart block Peripheral edema Arterial insufficiency
Metoprolol: CI
Hypersensitivity Sick sinus syndrome Concurrent CCB use (= complete heart block) Asthma and COPD (in high doses) HR dependent pts
Metoprolol: dosing
1.25-5mg IV Q2-5mins to max of 15mg
Propranolol: class
Beta 1 and beta 2 adrenergic antagonist
Propranolol: MoA
Reversibly binds to beta 1 adrenergic receptor antagonists to inhibit the binding of NE, EPI, and other beta agonist, preventing the stimulation of G-coupled protein receptors, adenylate cyclase, and cAMP.
Slows SA rate and conduction through the AV node and decreases contractility, reducing cardiac O2 demand.
Causes peripheral, cerebral, and coronary vasodilation.
Propranolol: PK
Vd 4L/kg
90%PB
E1/2t = 4hrs
Propranolol: metabolism
1st pass effect & pulmonary uptake
Active metabolite: hydroxypropanolol
Excreted in the urine
Propranolol: AE
Bronchospasm* Hypoglycemia* Severe bradycardia Severe hypotension Heart block Rebound tachycardia with rapid withdrawal
Syncope/dizziness
Propranolol: CI
Hypersensitivity Asthma/COPD Heart block Concurrent CCB (= complete heart block) PVD DM Pregnancy
Propranolol: dosing
0.25-0.5mg IV titrate to 1mg/min IV
Nifedipine: class
Dihydropyridine calcium channel antagonist
Nifedipine: MoA
Competitive binds to calcium channels in vascular smooth muscle to maintain them in the INACTIVATED CLOSED STATE, preventing the influx of calcium through slow L-type voltage gated Ca++ channels , preventing the contraction of vascular smooth muscle cells
Nifedipine: PK
Onset 1-3 mins
Peak 1-3 hrs
E1/2t = 3-7 hrs
90% PB
Nifedipine: metabolism
Hepatic CYP450 metabolism
Renal excretion
Nifedipine: AE
Reflex tachycardia
Hypotension
MI d/t decreased afterload
Skeletal muscle weakness
Flushing
Vertigo
HA
Nifedipine: CI
Hypersensitivity
Heart failure
Hypotension
Concomitant with grapefruit juice
Nifedipine: dosign
5-15mcg/kg
Verapamil: class
Non-dihydropyridine calcium channel antagonist
Class IV antiarrythmic
Verapamil: MoA
Competitively binds to calcium channels in cardiac muscle tissues to maintain them in the INACTIVATED CLOSED STATE, preventing the influx of calcium through slow L-type voltage gated Ca++ channels in cardiac muscle cells.
Primarily inotropic/chronotropic effects, not blood pressure.
Verapamil: PK
Onset
Verapamil: metabolism
CYP 450 enzymes
Active metabolite: norverapamil
70% unchanged in urine
Verapamil: AE
Heart failure
Peripheral edema
Increased K+ with blood products
Gingival hyperplasia
Dizziness
Verapamil: CI
Hypersensitivity Renal failure Wide QRS V-tach Heart failure WPW, SSS, bradycardia, or heart block (conduction abnormalities)
Verapamil: dosing
2.5-5mg IV over 2 mins
Then 5-10mg in 15 to 30 mins as needed
Max 20mg
Diltiazem: class
Benzothiazipine antiarrythmic
Diltiazem: MoA
Competitively binds to calcium channels in cardiac muscle tissues, and ARTERIOLAR vascular smooth muscle tissue maintaining them in INACTIVATE CLOSED STATE, preventing the influx of calcium through slow L-type voltage gated Ca++ channels and preventing the contraction of both vascular smooth muscle and cardiac muscle cells.
Diltiazem: PK
Onset
Diltiazem: metabolism
1st pass effect
CYP450 and 30% unchanged in the urine
Diltiazem: AE
Bradycardia
AV block
Heart failure
Edema
HA, flushing
Dizziness/syncope
Diltiazem: CI
Hypersensitivity
Diltiazem: dosing
SVT 0.25mg/kg over 2 mins + 0.35mg/kg prn
Pheo 3-10mcg/kg/min
Nifedipine: drug interactions
Potentiates NMB
Decreases anesthetic reqs
Use w/ BBs can cause heart block
Verapamil: drug interactions
Decreases anesthetic reqs
Use w/ BBs can cause heart block
Diltiazem: drug interactions
Potentiates NMB
Use w/ BBs can cause heart block
Phenoxybenzamine: class
Long acting, non-selective alpha adrenergic receptor antagonist
Phenoxybenzamine: MoA
Irreversibly binds to the alpha 1 and alpha 2 adrenergic receptors preventing the binding of NE, Epi, and other alpha agonists, preventing the stimulation of G-coupled proteins, adenylate cyclase, and cAMP.
Blocks alpha mediated vasoconstriction.
It also antagonizes Ach, Histamine, 5HT
Phenoxybenzamine: PK
Slow onset – Prodrug
60mins to peak
E1/2t 24 hrs
Phenoxybenzamine: metabolism
Hepatic metabolism
Renal and biliary excretion
Phenoxybenzamine: AE
Reflex tachycardia Hypotension Seizures Palpitations Sedation with chronic use (alpha 2) Hypoglycemia
Flushing/syncope
Impotence
Nasal stuffiness
Dry mouth
Phenoxybenzamine: CI
Hypersensitivity
Hypotension
Hypovolemia
Phenoxybenzamine: dosing
10mg BID up to total 120mg/day oral – started 2-3 weeks pre op
Phentolamine: class
Short acting, non-selective alpha adrenergic receptor antagonist
Phentolamine: MoA
Competitively but REVERSIBLY binds to alpha 1 and alpha 2 adrenergic receptors, preventing the binding of NE, Epi, and other alpha agonists, preventing the stimulation of G-coupled proteins, adenylate cyclase, and cAMP.
Blocks alpha mediated vasoconstriction.
Phentolamine: PK
Onset =2-5 mins
DOA = 10-15 mins
E1/2L = 19 mins
Phentolamine: metabolism
Hepatic metabolism
10% excreted unchanged in urine
Phentolamine: AE
Tachycardia – reflexive Severe hypotension Arrhythmias MI Hypoglycemia
Dizziness Flushing Impotence Nasal stuffiness Abd cramps
Phentolamine: CI
Hypersensitivity CAD, MI Pregnant moms Renal impairment PUD
Phentolamine: dosing
30-70 mcg/kg IV to decrease BP from transient stimulation
Max 20mg
Extravasation = 10mg injected into affected site.
Prazosin: class
Selective alpha 1 adrenergic antagonist
Prazosin: MoA
Competitively binds to alpha 1 adrenergic receptors preventing the stimulation of G-coupled proteins, adenylate cyclase, and cAMP causing vasodilation of arterial and venous vasculature.
Leaves the inhibiting effect of alpha 2 activity on NE release intact = less likely to have reflex tachycardia
Prazosin: PK
Peak 3 hrs
E1/2 t = 3-4 hrs
Prazosin: metabolism
Hepatic metabolism, elimination via bile and feces NON RENALLY!!
Prazosin: AE
Hypotension Fluid retention Anticholinergic effects N/V Palpitations Drug-induced lupus Hepatotoxicty
Flushing/dizziness Syncope HA Dry mouth Nasal congestion
Prazosin: CI
Hypersensitivity
BB use (refractory hypotension)
Pregnant
Prazosin: drug interactions
Additive effects with diuretics/other BP meds
Prazosin: dosing
1mg PO at bedtime (max daily 20mg in divided doses)
Clonidine: class
Selective alpha 2 adrenergic antagonist
Clonidine: MoA
Inhibits sympathetic outflow from the medulla = decreased HR and contractility and vasomotor tone.
Enhance antinociceptive state by inhibiting release of spinal substance P.
Inhibit central thermoregulatory control to decrease vasoconstriction and shivering.
Also affects the function of K+ channels in the CNS = making cell hyperpolarized = decreased anesthetic requirements
Clonidine: PK
Onset 30-60mins Peak 60-9mins DOA 8 hrs PO E1/2t 9-12hrs 30% PB 2L/kg
Clonidine: metabolism
50% metabolized in liver, 50% excreted unchanged
Clonidine: AE
Bradycardia Heart failure Hepatotoxicity Sedation Postural hypotension Rebound hypertension with abrupt withdrawal Sodium and water retention
Dry mouth
Skin rash
Impotence
Clonidine: CI
Pregnant women
Prior to surgery
Hypersensitivity
Clonidine: dosing
0.2mg-0.3mg/day
Epidural and SAB = 150-450mcg
Hydralazine: class
Direct acting vasodilator
Hydralazine: MoA
Activates guanylate cyclase which leads to membrane hyperpolarization, K+ channel activation, inhibition of calcium release from SR in vascular smooth muscle.
Can trigger reflexive tachycardia.
Hydralazine: PK
IV onset 5-20mins Peak 15-20mins E1/2t = 4 hrs (4x in renal dz) E1/2L = 100hrs d/t strong binding to smooth muscle 90% PB
Hydralazine: metabolism
Metabolized in the liver with extensive first pass effect
Hydralazine: AE
Anemias, hepatotoxicity
Increased ICP, head ache, fever, chills, anxiety, disorientation, depression and coma
RA, lupus like syndrome, cramps, weakness, tremors, neuritis
Tachycardia, angina, orthostatic hypotension, dizziness, palpitations,
Nasal congenstion, dyspnea
Anorexia, NV, diarrhea, constipation, ileus
Impotence, difficult micturition
Hydralazine: CI
Hypersensitivity
Dissecting aortic aneurysm
CAD
Mitral valve rheumatic heart disease
Prolonged onset should be considered before redosing
Hydralazine: dosing
2.5 - 20 mg IV Q4hrs
Nitroglycerin: class
Organic nitrate and venodilator
Nitroglycerin: MoA
Generates Nitric Oxide to stimulate production of cGMP to cause peripheral and smooth muscle vasodilation.
Increased venous capacitance decreases the preload to the right side of the heart = decreased right and left end diastolic pressure = decreased myocardial demand.
Nitroglycerin: PK
IV peak
Nitroglycerin: AE
Reflex tachycardia Tachypnea Increase in ICP with decreased intracranial compliance Increased bleeding time Dizziness, lightheadedness, syncope N/V
Nitroglycerin: CI
Hypertrophic obstructive cardiomyopathy Severe aortic stenosis Hypotension, shock or MI with low left ventricular filling pressures Increased ICP Glaucoma Severe anemaia Cardiac tamponade Restrictive cardiomyopathy or pericarditis
Nitroglycerin: metabolism
Metabolism results in nitrate metabolite capable of producing methemoglobin by oxidation of ferrous ion in hgb
Nitroglycerin: dosing
5-200mcg/min IV
Milrinone: class
Phosphodiesterase inhibitor vasodilator
Milrinone: MoA
Selectively inhibits phosphodiesterase III which is a heart specific enzyme responsible for degradation of cAMP, which increases calcium and thus increases contractility and inotropic effects. Increased cAMP also works in vascular smooth muscle to cause vasodilation and decrease peripheral vascular resistance. This all increases cardiac output.
Milrinone: PK
Onset 5-15mins Peak after 5 mins E1/2time = 2.5hrs Vd = 0.4L/kg 70% PB
Milrinone: metabolism
80% unchanged in the urine
Milrinone: AE
Cardiac dysrhythmias, ventricular arrhythmias, and supraventricular arrhythmias Hypotension Angina Headaches Hypokalemia, tremor, thrombocytopenia
Milrinone: CI
Hypersensitivity
Acute MI
Milrinone: dosing
50mcg/kg IV over 10mins + 0.375mcg/kg/min maintenance infusion
Adenosine: class
Antiarrythmic, endogenous nucleoside consisting of adenine and pentose sugar
Adenosine: MoA
Adenosine acts on adenosine A1 receptors in the cardiac conduction system that are linked to acetylcholine activated G-coupled potassium channels (Kach). This leads to slowing of cardiac conduction tissue, slowing SA node conduction, and a delay in AV node conduction.
Adenosine: PK
E1/2 life = 10 sec; immediate onset, must be IV pushed very fast
Adenosine: metabolism
Intracellular enzyme metabolism. No hepatic/renal involvement.
Adenosine: AE
Headache, dizziness, parasthesia Palpitations, chest pain Hypotension Dyspnea Chest pressure Numbness
Adenosine: CI
Hypersensitivity 2nd or 3rd degree heart block SSS without pacer Bronchospastic and restrictive lung disease (not effective in afib, aflutter, VT)
Adenosine: dosing
SVT: 6mg IV, if not effective give 12mg, if not effective give 18mg
Controlled hypotension: 220mcg/kg/min
Amiodarone: class
Class III antiarrhythmic (with Class I, II, IV effects)
Benzofurane derivative containing iodine
Atrial and ventricular dysrhythmic
Amiodarone: MoA
Alters lipid membrane where ion channels are located, particularly the K+ channels responsible for repolarizations
Also blocks Na+ and Ca++ channels, as well as alpha/beta receptors
Amiodarone: PK
Onset – IV is rapid Vd 66L/kg 96% PB E1/2t = 29days Duration after d/c therapy = 7-50days
Amiodarone: metabolism
CYP450 microsomal enzymes with biliary excretion
Active metabolite: DEA
Amiodarone: AE
Hypotension
Bradycardia
AV block, prolonged QTc and VT, torsades,
Decreased response to catecholamines
Pulm fibrosis, alveolar pneumonitis, ARDS (2% of pts)
Hyper/hypothyroidism, photosensitivity
Amiodarone: CI
Hypersensitivity
Cardiogenic shock, bradycardia, 2nd or 3rd degree heart block
Pregnancy
Amiodarone: drug interactions
Inhibits CYP450 enzymes = increased conc of warfarin, procainamide, digoxin
Fentanyl = cardiac arrest, bradycardia, hypotension
Amiodarone: dosing
A-flutter, Stable VT/SVT: 150mg IV over 10 mins, 1 mg/min over next 6 hrs, then 0.5 mg/min over next 18hrs
Pulseless VT/VF: 300mg IVP, then 150mg IVP, then gtt
Digoxin: class
Antiarrythmic
Cardiac glycoside
Digoxin: MoA
Directly inhibits Na+/K+/ATPase pump, which increases Na+ in cardiac myocytes, which decreases Ca++ outflow by Na+/Ca++ pump, which increases available calcium for cardiac muscle contractions.
Also decreases sympathetic tone and increases vagal tone to slow conduction through SA and AV nodes
Digoxin: PK
Onset = 5-30mins IV Peak 1-5 hrs E1/2life = 30-48hrs Vd 7L/kg 25% PB
Digoxin: metabolism
Hepatic metabolism
50% excreted by kidneys unchanged.
Digoxin: AE
EKG changes: prolonged PR interval, ST depression, T wave changes
Dysrhythmias
Heart block
Blurred vision
NV, diarrhea, headache, fatigue
Digoxin: CI
Vfib, v-tach, heart block
IHSS
Renal impairment (decrease dose)
Hypokalemia, hypomagnesemia or hypercalcemia can lead to toxicity
Digoxin: dosing
Loading dose = 0.75-1.5mg PO or 0.5-1.0mg IV
Maint dose = 0.125-0.5mg PO or 0.25mg IV
Therapeutic level 0.5-2.0ng/mL