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Chapter N/A

PAT 20A/B Chapter Notes - Chapter N/A: Hyponatremia, Nephrotoxicity, Aminoglycoside


Department
Pathotherapeutics
Course Code
PAT 20A/B
Professor
Audrey Kenmir
Chapter
N/A

Page:
of 7
(2)PAT20 Fall Week 10 Drug Classifications (Heart Failure)
1. Inotropic *Cardiovascular Agent* (Anti- irregular contraction)
Inotropic drugs: digoxin (Lanoxin)
Action: increase force of myocardial contraction (positive action); increase refractory
period of AV and SA nodes (positive action); decrease conductivity of AV node, bundle of
His, heart rate (negative action).
Use: treats heart failure, atrial fibrillation, atrial flutter, paroxysmal atrial tachycardia
Pharmacokinetics (Digoxin):
Onset- PO: 50 mins-2 hrs, IV: 5-30 min
Peak- PO: 2-6 hrs; IV: 1-4 hrs
Duration- PO & IV: 2-4 days
Side/Adverse Effects:
CNS: fatigue, headache, weakness, psychosis (rare)
CV: AV block, SV block, conduction disturbance, PVCs, bradycardia
EENT: blurred, yellow/red/green vision
GI: nausea, vomiting, diarrhea, anorexia
HEM: thrombocytopenia
OTHER: diaphoresis, gynecomastia, fatigue, electrolyte imbalance with acute digoxin
toxicity.
Contraindications/Precautions:
Hypersensitivity, uncontrolled ventricular arrhythmias, AV block (in absence of
pacemaker), idiopathic hypertrophic subaortic stenosis, constrictive pericarditis, known
alcohol intolerance (elixir only), hypokalemia, hypercalcemia, hypomagnesemia,
concurrent use of diuretics increase risk for hypokalemia and hypomagnesemia;
hypothyroidism, myocardial infarction, renal impairment, obesity, pregnancy.
Interactions:
- Acetazolamide, amphotericin B, chlorthalidone, ethacrynic acid, furosemide,
laxatives, thiazides, other potassium- reducing drugs increase digoxin toxicity by
inducing hypokalemia.
- Parenteral calcium administration can produce serious arrhythmias.
- Antacids, antidiarrheals, ion-exchange resins decrease oral digoxin absorption.
- Barbiturates, hydantoins, phenylbutazone decreases digoxin activity by enzyme
induction.
- Use cautiously with adrenergics, beta blockers, quinidine, procainamide.
- Excessive consumption of licorice can increase digoxin toxicity.
Dosages (Digoxin):
Capsules = 0.05, 0.1, 0.2 mg; Elixir = 0.05 mg/mL; Pediatric injection = 0.1 mg/mL;
Injection = 0.25 mg/mL; Tablets = 0.125, 0.25 mg
Nursing Management Proprieties:
Assess: history of hypersensitivity, renal function, apical pulse.
Dietary management: diet that is high in potassium and low in sodium.
Lab test evaluation: serum electrolyte (potassium, calcium, magnesium).
2. Diuretics
a) Loop Diuretics "semide”*Cardiovascular Agent* (Anti-ascending limb of loop of
Henle reabsorption)
Loop diuretic drugs: furosemide (Lasix), bumetanide (Burinex), ethacrynic acid
(Edecrin)
Action: promotes excreting of water, sodium, chloride, and other electrolytes, by
inhibiting tubular reabsorption (medullary, cortical portions of ascending limb of loop
of Henle), decreased peripheral vascular resistance.
Use: treats hypertension, edema caused by CHF, renal dysfunction, cirrhosis, or
hepatic dysfunction, edema, hyperaldosteronism.
Pharmacokinetics (Furosemide):
Onset- PO: 30-60 mins, IV: 5 mins, IM: 10-30 mins
Peak- PO: 1-2 hrs, IV: 30 mins, IM: unknown
Duration- PO: 6-8 hrs, IV: 2 hrs, IM: 4-8 hrs
Side/Adverse Effects:
CNS: dizziness, vertigo, paresthesia, headache, encephalopathy
DERM; purpura, urticarial, photosensitivity,
EENT: blurry vision, xanthopsia, hearing loss (loop diuretics), tinnitus
GI: anorexia, nausea, vomiting, watery diarrhea, jaundice
HEM: bleeding (etharynic acid), agranulocytosis, aplastic anemia (furosemide),
leukopenia, thrombocytopenia
MET: hypokalemia, glycosuria, hyperglycemia, hyperperuricemia, hypochloremic
alkalosis
MS: fatigue, leg cramps
RESP: respiratory distress
OTHER: necrotizing angiitis, arthritic pain (bumetanide)
Contraindications/Precautions:
Hypersensitivity due to any thiazide or other sulfonamide derivative, anuria, renal or
liver impairment.
Interactions:
-Risk for digoxin toxicity increase with concurrent use of diuretics.
-Use with corticosteroids increases risk of hypokalemia.
-Antidiabetic, and antihypertensive drugs may require dose adjustment.
-Use with diazoxide can produce significant diabetogenic effects
-Use with neurotoxic drugs (aminoglycosides, chloroquine, vancomycin, can result
in significant toxicity.
-Induced hypokalemia, increased digoxin toxicity.
-Avoid use with indomethacin, lithium, nephrotoxic drugs, probenecid.