digitoxin (Crystodigin)

Tradename: Crystodigin. Dosage: 0.05-0.5 mg PO QD. Tabs: 0.05, 0.1, 0.15, 0.2 mg. Pharmacokinetics: 1) undergoes significant enterohepatic circulation 2) 1/2 life of 8 days Adverse effects: 1) gastrointestinal a) anorexia b) nausea/vomiting c) abdominal discomfort & pain 2) blurred vision 3) cardiac a) arrhythmias b) AV conduction defects c) impaired conduction in the atria d) multifocal PVCs e) ventricular tachycardia f) sinus bracycardia g) SA nodal block h) atrial fibrillation i) accelerated AV junctional rhythms 4) eosinophilia 5) thrombocytopenia Drug interactions: 1) agents which increase metabolism of digitoxin a) phenylbutazone b) phenobarbital c) phenytoin d) rifampin 2) coadministration increases digitoxin levels a) amiodarone b) quinidine c) verapamil d) diltiazem 3) agents which decrease digitoxin enterohepatic circulation thus decreasing 1/2life a) cholestyramine b) colestipol 4) agents which decrease digitoxin absorption a) antacids b) cholestyramine c) colestipol d) kaolin-pectin e) metoclopramide f) neomycin g) sulfasalazine Laboratory: 1) specimen: a) serum, plasma (heparin, EDTA) b) collect at least 8 hours after last dose c) digitoxin in serum/plasma 2) methods: RIA, EIA, FPIA, TLC 3) interferences: a) metabolites may interfere with some RIA procedures b) digitoxin cannot be accurately measured by immunoassay in patients switched from digoxin 5) labs with Loincs - digitoxin in body fluid - digitoxin in serum/plasma - digitoxin in urine

General

cardenolide cardiac glycoside (digitalis glycoside)

Properties

MISC-INFO: elimination route LIVER KIDNEY 1/2life 8 DAYS therapeutic-range 20-35 NG/ML toxic-range >45 NG/ML protein-binding 90% elimination by hemodialysis - peritoneal dialysis -