Updated: 2/25/2018

Cardiac Glycosides (Digoxin)

Topic
Review Topic
0
0
Questions
7
0
0
Evidence
9
0
0
Snapshot
  • A 28-year-old man presents to the emergency room after ingesting an unknown amount of his grandfather’s digoxin medication. He reports feeling depressed and ingested a handful of the drug about 1 hour ago. Since then, he states having abdominal pain, nausea, and vomiting. He also discloses that his vision is becoming blurry with yellow halos around objects. He is found to have a K+ of 6.5 mEq/L. He is quickly administered activated charcoal, given the recent ingestion, and started on digoxin antibodies. (Digoxin poisoning)
Introduction
  • Drug
    • a cardiac glycoside derived from the foxglove plant, digitalis purpurea
  • Mechanism of action
    • direct reversible inhibitor of Na+/K+-ATPase
      • causing ↑ in intracellular Na+ and ↓ in intracellular K+
    • indirectly inhibits Na+/Ca2+-exchanger
      • the increased intracellular Na+ prevents expulsion of Ca2+ from the cell and increases intracellular Ca2+
    • this results in
      • ↑ free Ca2+ ions
      • ↑ inotropy and contractility
      • ↑ vagal tone
        • ↓ conduction through sinoatrial and atrioventricular nodes
        • ↓ heart rate
  • Clinical use
    • heart failure
    • left ventricular dysfunction
    • atrial fibrillation
Toxicity
  • Toxicity can be fatal
  • Clinical manifestations
    • gastrointestinal symptoms (most common)
      • nausea
      • vomiting
      • abdominal pain
      • diarrhea
    • vision changes
      • yellow halos around objects
      • blurry vision
    • arrhythmias
    • hyperkalemia
  • Risk factors for severe toxicity
    • renal failure
    • hypokalemia
      • K+ competes with digoxin for binding sites and excretion
      • low K+ allows digoxin to bind at K+ binding sites on Na+/K+-ATPase 
  • Evaluation
    • serum digoxin concentration
    • serum potassium
    • serial electrocardiograms
  • Treatment
    • digoxin antibodies (anti-digoxin Fab fragments)
    • Mg2+
    • activated charcoal
      • for those who present within 1-2 hours of ingestion

 


 

Please rate topic.

Average 4.8 of 8 Ratings

Thank you for rating! Please vote below and help us build the most advanced adaptive learning platform in medicine

The complexity of this topic is appropriate for?
How important is this topic for board examinations?
How important is this topic for clinical practice?
Questions (7)
Lab Values
Blood, Plasma, Serum Reference Range
ALT 8-20 U/L
Amylase, serum 25-125 U/L
AST 8-20 U/L
Bilirubin, serum (adult) Total // Direct 0.1-1.0 mg/dL // 0.0-0.3 mg/dL
Calcium, serum (Ca2+) 8.4-10.2 mg/dL
Cholesterol, serum Rec: < 200 mg/dL
Cortisol, serum 0800 h: 5-23 μg/dL //1600 h:
3-15 μg/dL
2000 h: ≤ 50% of 0800 h
Creatine kinase, serum Male: 25-90 U/L
Female: 10-70 U/L
Creatinine, serum 0.6-1.2 mg/dL
Electrolytes, serum  
Sodium (Na+) 136-145 mEq/L
Chloride (Cl-) 95-105 mEq/L
Potassium (K+) 3.5-5.0 mEq/L
Bicarbonate (HCO3-) 22-28 mEq/L
Magnesium (Mg2+) 1.5-2.0 mEq/L
Estriol, total, serum (in pregnancy)  
24-28 wks // 32-36 wks 30-170 ng/mL // 60-280 ng/mL
28-32 wk // 36-40 wks 40-220 ng/mL // 80-350 ng/mL
Ferritin, serum Male: 15-200 ng/mL
Female: 12-150 ng/mL
Follicle-stimulating hormone, serum/plasma Male: 4-25 mIU/mL
Female: premenopause: 4-30 mIU/mL
midcycle peak: 10-90 mIU/mL
postmenopause: 40-250
pH 7.35-7.45
PCO2 33-45 mmHg
PO2 75-105 mmHg
Glucose, serum Fasting: 70-110 mg/dL
2-h postprandial:<120 mg/dL
Growth hormone - arginine stimulation Fasting: <5 ng/mL
Provocative stimuli: > 7ng/mL
Immunoglobulins, serum  
IgA 76-390 mg/dL
IgE 0-380 IU/mL
IgG 650-1500 mg/dL
IgM 40-345 mg/dL
Iron 50-170 μg/dL
Lactate dehydrogenase, serum 45-90 U/L
Luteinizing hormone, serum/plasma Male: 6-23 mIU/mL
Female: follicular phase: 5-30 mIU/mL
midcycle: 75-150 mIU/mL
postmenopause 30-200 mIU/mL
Osmolality, serum 275-295 mOsmol/kd H2O
Parathyroid hormone, serume, N-terminal 230-630 pg/mL
Phosphatase (alkaline), serum (p-NPP at 30° C) 20-70 U/L
Phosphorus (inorganic), serum 3.0-4.5 mg/dL
Prolactin, serum (hPRL) < 20 ng/mL
Proteins, serum  
Total (recumbent) 6.0-7.8 g/dL
Albumin 3.5-5.5 g/dL
Globulin 2.3-3.5 g/dL
Thyroid-stimulating hormone, serum or plasma .5-5.0 μU/mL
Thyroidal iodine (123I) uptake 8%-30% of administered dose/24h
Thyroxine (T4), serum 5-12 μg/dL
Triglycerides, serum 35-160 mg/dL
Triiodothyronine (T3), serum (RIA) 115-190 ng/dL
Triiodothyronine (T3) resin uptake 25%-35%
Urea nitrogen, serum 7-18 mg/dL
Uric acid, serum 3.0-8.2 mg/dL
Hematologic Reference Range
Bleeding time 2-7 minutes
Erythrocyte count Male: 4.3-5.9 million/mm3
Female: 3.5-5.5 million mm3
Erythrocyte sedimentation rate (Westergren) Male: 0-15 mm/h
Female: 0-20 mm/h
Hematocrit Male: 41%-53%
Female: 36%-46%
Hemoglobin A1c ≤ 6 %
Hemoglobin, blood Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hemoglobin, plasma 1-4 mg/dL
Leukocyte count and differential  
Leukocyte count 4,500-11,000/mm3
Segmented neutrophils 54%-62%
Bands 3%-5%
Eosinophils 1%-3%
Basophils 0%-0.75%
Lymphocytes 25%-33%
Monocytes 3%-7%
Mean corpuscular hemoglobin 25.4-34.6 pg/cell
Mean corpuscular hemoglobin concentration 31%-36% Hb/cell
Mean corpuscular volume 80-100 μm3
Partial thromboplastin time (activated) 25-40 seconds
Platelet count 150,000-400,000/mm3
Prothrombin time 11-15 seconds
Reticulocyte count 0.5%-1.5% of red cells
Thrombin time < 2 seconds deviation from control
Volume  
Plasma Male: 25-43 mL/kg
Female: 28-45 mL/kg
Red cell Male: 20-36 mL/kg
Female: 19-31 mL/kg
Cerebrospinal Fluid Reference Range
Cell count 0-5/mm3
Chloride 118-132 mEq/L
Gamma globulin 3%-12% total proteins
Glucose 40-70 mg/dL
Pressure 70-180 mm H2O
Proteins, total < 40 mg/dL
Sweat Reference Range
Chloride 0-35 mmol/L
Urine  
Calcium 100-300 mg/24 h
Chloride Varies with intake
Creatinine clearance Male: 97-137 mL/min
Female: 88-128 mL/min
Estriol, total (in pregnancy)  
30 wks 6-18 mg/24 h
35 wks 9-28 mg/24 h
40 wks 13-42 mg/24 h
17-Hydroxycorticosteroids Male: 3.0-10.0 mg/24 h
Female: 2.0-8.0 mg/24 h
17-Ketosteroids, total Male: 8-20 mg/24 h
Female: 6-15 mg/24 h
Osmolality 50-1400 mOsmol/kg H2O
Oxalate 8-40 μg/mL
Potassium Varies with diet
Proteins, total < 150 mg/24 h
Sodium Varies with diet
Uric acid Varies with diet
Body Mass Index (BMI) Adult: 19-25 kg/m2
Calculator

Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK

(M1.CV.19) A 58-year-old African-American man with a history of congestive heart failure presents to the emergency room with headache, frequent vomiting, diarrhea, anorexia, and heart palpitations. He is taking a drug that binds the sodium-potassium pump in myocytes. EKG reveals ventricular dysrhythmia. Which of the following is likely also present in the patient? Review Topic

QID: 100535
1

Angioedema

0%

(0/10)

2

Bronchoconstriction

0%

(0/10)

3

Changes in color vision

80%

(8/10)

4

Decreased PR interval

10%

(1/10)

5

Cough

0%

(0/10)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 3

(M1.CV.111) An 82-year-old male with a history of congestive heart failure presented with new-onset atrial fibrillation. He was initially started on carvedilol, but he now requires an additional agent for rate control. He is started on a medicine and is warned by his physician of the following potential side effects associated with this therapy: nausea, vomiting, confusion, blurry yellow vision, electrolyte abnormalities, and potentially fatal arrhythmia. Which of the following is most likely to increase this patient's susceptibility to the toxic effects associated with this medication? Review Topic

QID: 100627
1

Hyponatremia

2%

(2/82)

2

Elevated AST and ALT

16%

(13/82)

3

Hypokalemia

43%

(35/82)

4

Increased GFR with normal creatinine

2%

(2/82)

5

Hyperkalemia

32%

(26/82)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 3

(M1.CV.202) A 55-year-old male presents to the emergency department with dyspnea and palpitations. He does not smoke cigarettes or consume alcohol, and past medical history is insignificant. Blood pressure is 115/75 mmHG and heart rate is 125/min. Heart rhythm is irregularly irregular. After initial treatment with IV digoxin the patient's heart rate drops to 85/min and remains irregular. Which of the following best explains the effect of digoxin in this patient? Review Topic

QID: 100718
1

Blockade of beta-adrenergic receptors

0%

(0/3)

2

Calcium channel blockade

0%

(0/3)

3

Blockade of Na-K-ATPase on cardiac myocytes

100%

(3/3)

4

Vagal stimulation

0%

(0/3)

5

Increased ventricular contractility

0%

(0/3)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 4

(M1.CV.9) An 81-year-old man being treated for congestive heart failure and atrial fibrillation develops nausea, vomiting, and blurry yellow vision. Which of the following pathologic states would best explain this patient's presentation? Review Topic

QID: 100963
1

Hypernatremia

0%

(0/8)

2

Hyperkalemia

38%

(3/8)

3

Hepatic insufficiency

12%

(1/8)

4

Renal insufficiency

25%

(2/8)

5

Metabolic acidosis

25%

(2/8)

M1

Select Answer to see Preferred Response

PREFERRED RESPONSE 4
Question locked
Sorry, this question is for
PEAK Premium Subscribers only
Upgrade to PEAK
ARTICLES (9)
Topic COMMENTS (8)
Private Note