Cardiac glycosides Flashcards
digoxin pharmacokinetics
large Vd so in myocardium
long half life
renal elimination
low protein binding
antibiotic effects on digoxin
digoxin is metabolized by gut microflora so absorption can be altered by antibiotics
increased in potential toxicity
cardiac effects of dig
increased inotropy increased automaticity decreased rate of conduction shortened repolarization intervals QT shortened scooping of the ST segment
dig effects on autonomic nervous system
parasym = increased release of acetylcholine sym = increased efferent sympathetic discharge
digoxin toxic dose
1mg in a child
3mg in an adult
>10mg in healthy subject = cardiac arrest
>3mg in child = cardiac arrest
digoxin toxic levels
> 2ng/mL
drug interactions
amiodarone (inhibits tubular secretion)
antibiotics
quinidine
verapamil
risk factors for toxicity
drug interactons renal failure MI electrolyte imbalance elderly
symptoms and signs of acute overdose
vomit hyperkalemia sinus bradycardia sinoatrial arrest second or third degree av block ventricular tachycardia/fibrillation intracellular myocardial hypercalcemia
symptoms and signs of chronic toxicity
visual disturbance - dychromatopsia weakness sinus bradycardia afib ventricular arrhythmia junctional tachycardia paroxymal atrial tachycardia hypokalemia and hypomagnesemia from the use of diuretics
supportive measures for dig
protect airways, assist ventilation
treat hyperkalemia - insulin and glucose
bradycardia or heart block - atropine
treat ventricular tachyarrhythmias - lidocaine
management of intoxicated patient
gastric emptying
activated charcoal
MDAC
digoxin specific antibody fragments
monitoring of digoxin levels
monitor before giving antibodies bc thats what makes you decide you need to use them
dont monitor levels bc they will be increased due to presence of complexes redistributes drug from heart into plasma
when do you use digoxin specific antibody fragments
toxicity related to digoxin, digitoxin, natural cardiac glycosides
how does digifab work
bind to intravascular free digoxin
affinity for digifab greater than the affinity for the atpase