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Bretylium| IV Dose | 5-10 mg by rapid push for VF resistant to DC cardioversion. Dilute in D5W and infuse over 10-20 minutes for treatment of other arrhythmias, to avoid hypotension.
May repeat once after 1/2 to 2 hours.
Drip 15-30 ug/kg/min or 5-10 mg/kg q 6 hours.
Maximum 30 mg/kg/day. | | Oral dose | | | Levels | Therapeutic range undefined | | Kinetics | Actions delayed up to 1 hour after IV dose, because of slow accumulation in myocardium. Elimination half-life 6.3-13.6 hours. Half-life greatly increased in renal failure. | | Cautions | Hypotension, particularly with rapid IV bolus. | | Interactions | Additive AVN blocking effect with quinidine. Antagonizes local anaesthetic effect of quinidine. Worsens digoxin toxic arrhythmias, via release of norepinephrine. Effects are blocked by tricyclic antidepressants. | | Preparations | Bretylol injection: 500 mg/10 ml ampules, vials. | | FDA approval in children | no |
Digoxin| IV Dose | Any IV dose should be 75% of corresponding oral dose (see below) | | Oral dose | Dosing guidelines are largely a theological issue among pediatric cardiologists.
Total oral digitalizing dose (TDD) given over 24 hours:
Prematures: 20 ug/kg
Full term newborns: 30 ug/kg
Infants < 2years: 40-50 ug/kg
Children >2 years: 30-40 ug/kg
Adults: 1.25-1.5 mg total dose.
Maintenance: 25% of TDD, daily divided BID. | | Levels | Life is too short to argue about whether digoxin levels are meaningful, other than in toxicity.
Column-separated levels in infants.
O.7-2.0 nanograms/ml in adults.
Levels up to 3.5 are well tolerated in infants | | Kinetics | Infants and children have high volumes of distribution.
Elimination half-life by age:
Prematures: 61 hours.
Full term newborns: 35 hours
Infants: 18 hours.
Children: 37 hours.
Adults: 35-48 hours. | | Cautions | Most common arrhythmias due to toxicity are PVCs and VT in adults, PAT with block in children | | Interactions | Levels increased by erythromycin, quinidine, amiodarone, verapamil and aldactone. (!)
Levels decreased by phenytoin.
Digoxin toxic arrhythmias exacerbated by bretylium due to initial catechol release from nerve terminals | | Preparations | Lanoxin scored tablets: 0.125, 0.250. 0.500 mg
Lanoxicaps (solution in capsule): 50, 100, 200 ug.
Lanoxin elixir (60 cc dropper bottle): 50 ug/ml.
Lanoxin injection, Adult: 500 ug/2 ml
Pediatric:100 ug/1 ml | | FDA approval in children | One of the few! |
Adenosine| IV Dose | .050 or 0.10 mg/kg IV as initial dose. Double dose every several minutes, up to 0.40 mg/kg or arrhythmia termination. Upper limit 20 mg in adults. Give fast and flush. Works best when given by central line.
"If nothing happens, you didn't give enough"
| | Oral dose | | | Levels | Action too shor to measure | | Kinetics | Serum half-life <10 seconds. All effects gone in 20-30 secs. | | Cautions | Principally effective in SVT utilizing AV node as part of reentrant circuit (AVRT, AVNRT). May be weak bronchoconstrictor, so be cautious in patients with severe asthma. Often causes atrial ectopy, including atrial fibrillation. Use only in setting where immediate electrical cardioversion is possible. | | Interactions | Digoxin, verapamil may potentiate effect | | Preparations | Adenocard 6 mg/cc ampule | | FDA approval in children | no |
Phenylephrine| IV Dose | Adults: 0.2-0.5 mg IV bolus over 30 seconds. May go up to 1.0 mg bolus to raise BP acutely.
Drip: 40-60 ug/min.
Tetralogy spells: 20-100 ug/kg bolus, 1-5 ug/kg/min IV infusion
| | Oral dose | | | Levels | Therapeutic range undefined | | Kinetics | Acute increase in blood pressure within a minute of intravenous administration. Effects last about 20 minutes. | | Cautions | Hypertension | | Interactions | Extreme caution when used with halothane anesthesia. | | Preparations | Neo-synephrine injection, 1% solution: 10 mg/1 ml
vials, 20 mg/2 ml syringes | | FDA approval in children | yes |
Midodrine| IV Dose | | | Oral dose | Adults: 10 mg TID recommended, 3rd dose not later than 6 pm. | | Levels | | | Kinetics | Direct effect of metabolite on alpha receptors. Peak levels of metabolite at 1-2 hours, half-life of 3-4 hours. | | Cautions | Supine and/or sitting hypertension should be checked for after initiation of therapy. Symptoms may include heart pounding, headache, blurred vision. | | Interactions | May potentiate vagal bradycardia with digoxin.
Avoid other vasoconstrictors (e.g. phenylephrine, phenylpropanolamine, dihydroergotamine)
Effects antagonized by prazosin)
| | Preparations | ProAmatine scored tablets, 2.5, 5 mg | | FDA approval in children | no |
Fludrocortisone| IV Dose | | | Oral dose | 0.10 mg orally QD for adults, 0.05 mg QD for children up to 0.15 mg/day | | Levels | | | Kinetics | | | Cautions | Hypertension, hypokalemia, edema | | Interactions | | | Preparations | Florinef acetate scored tablets, 0.10 mg.
Use with salt, 1 Gram sodium tablets TID
| | FDA approval in children | yes |
Bretylium| IV Dose | 5-10 mg by rapid push for VF resistant to DC cardioversion. Dilute in D5W and infuse over 10-20 minutes for treatment of other arrhythmias, to avoid hypotension.
May repeat once after 1/2 to 2 hours.
Drip 15-30 ug/kg/min or 5-10 mg/kg q 6 hours.
Maximum 30 mg/kg/day. | | Oral dose | | | Levels | Therapeutic range undefined | | Kinetics | Actions delayed up to 1 hour after IV dose, because of slow accumulation in myocardium. Elimination half-life 6.3-13.6 hours. Half-life greatly increased in renal failure. | | Cautions | Hypotension, particularly with rapid IV bolus. | | Interactions | Additive AVN blocking effect with quinidine. Antagonizes local anaesthetic effect of quinidine. Worsens digoxin toxic arrhythmias, via release of norepinephrine. Effects are blocked by tricyclic antidepressants. | | Preparations | Bretylol injection: 500 mg/10 ml ampules, vials. | | FDA approval in children | no |
Digoxin| IV Dose | Any IV dose should be 75% of corresponding oral dose (see below) | | Oral dose | Dosing guidelines are largely a theological issue among pediatric cardiologists.
Total oral digitalizing dose (TDD) given over 24 hours:
Prematures: 20 ug/kg
Full term newborns: 30 ug/kg
Infants < 2years: 40-50 ug/kg
Children >2 years: 30-40 ug/kg
Adults: 1.25-1.5 mg total dose.
Maintenance: 25% of TDD, daily divided BID. | | Levels | Life is too short to argue about whether digoxin levels are meaningful, other than in toxicity.
Column-separated levels in infants.
O.7-2.0 nanograms/ml in adults.
Levels up to 3.5 are well tolerated in infants | | Kinetics | Infants and children have high volumes of distribution.
Elimination half-life by age:
Prematures: 61 hours.
Full term newborns: 35 hours
Infants: 18 hours.
Children: 37 hours.
Adults: 35-48 hours. | | Cautions | Most common arrhythmias due to toxicity are PVCs and VT in adults, PAT with block in children | | Interactions | Levels increased by erythromycin, quinidine, amiodarone, verapamil and aldactone. (!)
Levels decreased by phenytoin.
Digoxin toxic arrhythmias exacerbated by bretylium due to initial catechol release from nerve terminals | | Preparations | Lanoxin scored tablets: 0.125, 0.250. 0.500 mg
Lanoxicaps (solution in capsule): 50, 100, 200 ug.
Lanoxin elixir (60 cc dropper bottle): 50 ug/ml.
Lanoxin injection, Adult: 500 ug/2 ml
Pediatric:100 ug/1 ml | | FDA approval in children | One of the few! |
Adenosine| IV Dose | .050 or 0.10 mg/kg IV as initial dose. Double dose every several minutes, up to 0.40 mg/kg or arrhythmia termination. Upper limit 20 mg in adults. Give fast and flush. Works best when given by central line.
"If nothing happens, you didn't give enough"
| | Oral dose | | | Levels | Action too shor to measure | | Kinetics | Serum half-life <10 seconds. All effects gone in 20-30 secs. | | Cautions | Principally effective in SVT utilizing AV node as part of reentrant circuit (AVRT, AVNRT). May be weak bronchoconstrictor, so be cautious in patients with severe asthma. Often causes atrial ectopy, including atrial fibrillation. Use only in setting where immediate electrical cardioversion is possible. | | Interactions | Digoxin, verapamil may potentiate effect | | Preparations | Adenocard 6 mg/cc ampule | | FDA approval in children | no |
Phenylephrine| IV Dose | Adults: 0.2-0.5 mg IV bolus over 30 seconds. May go up to 1.0 mg bolus to raise BP acutely.
Drip: 40-60 ug/min.
Tetralogy spells: 20-100 ug/kg bolus, 1-5 ug/kg/min IV infusion
| | Oral dose | | | Levels | Therapeutic range undefined | | Kinetics | Acute increase in blood pressure within a minute of intravenous administration. Effects last about 20 minutes. | | Cautions | Hypertension | | Interactions | Extreme caution when used with halothane anesthesia. | | Preparations | Neo-synephrine injection, 1% solution: 10 mg/1 ml
vials, 20 mg/2 ml syringes | | FDA approval in children | yes |
Midodrine| IV Dose | | | Oral dose | Adults: 10 mg TID recommended, 3rd dose not later than 6 pm. | | Levels | | | Kinetics | Direct effect of metabolite on alpha receptors. Peak levels of metabolite at 1-2 hours, half-life of 3-4 hours. | | Cautions | Supine and/or sitting hypertension should be checked for after initiation of therapy. Symptoms may include heart pounding, headache, blurred vision. | | Interactions | May potentiate vagal bradycardia with digoxin.
Avoid other vasoconstrictors (e.g. phenylephrine, phenylpropanolamine, dihydroergotamine)
Effects antagonized by prazosin)
| | Preparations | ProAmatine scored tablets, 2.5, 5 mg | | FDA approval in children | no |
Fludrocortisone| IV Dose | | | Oral dose | 0.10 mg orally QD for adults, 0.05 mg QD for children up to 0.15 mg/day | | Levels | | | Kinetics | | | Cautions | Hypertension, hypokalemia, edema | | Interactions | | | Preparations | Florinef acetate scored tablets, 0.10 mg.
Use with salt, 1 Gram sodium tablets TID
| | FDA approval in children | yes |
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