digitoxin (Crystodigin)
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Introduction
Tradename: Crystodigin.
Dosage
Tabs: 0.05, 0.1, 0.15, 0.2 mg.
Pharmacokinetics
- undergoes significant enterohepatic circulation
- 1/2 life of 8 days
elimination via liver
elimination via kidney
1/2life = 8 days
protein binding = 90 %
elimination by hemodialysis = -
elimination by peritoneal dialysis = -
Adverse effects
- gastrointestinal
- blurred vision
- cardiac
- arrhythmias
- AV conduction defects
- impaired conduction in the atria
- multifocal PVCs
- ventricular tachycardia
- sinus bracycardia
- SA nodal block
- atrial fibrillation
- accelerated AV junctional rhythms
- eosinophilia
- thrombocytopenia
Drug interactions
- agents which increase metabolism of digitoxin
- coadministration increases digitoxin levels
- agents which decrease digitoxin enterohepatic circulation thus decreasing 1/2life
- agents which decrease digitoxin absorption
Laboratory
- specimen:
- serum, plasma (heparin, EDTA)
- collect at least 8 hours after last dose
- digitoxin in serum/plasma
- methods: RIA, EIA, FPIA, TLC
- interferences:
- metabolites may interfere with some RIA procedures
- digitoxin cannot be accurately measured by immunoassay in patients switched from digoxin
- labs with Loincs