![]() Table 3 Infants and Small (< 20 Kg) Children Dose Estimates of DIGIFAB (in mg) from Steady State Serum Digoxin Concentration * dilution of reconstituted vial to 1 mg/mL may be desirableĬalculation Based on Steady-State Digitoxin Concentrations: For very small doses, a reconstituted vial can be diluted with 36 mL of sterile isotonic saline to achieve a concentration of 1 mg/mL.ĭose (in mg) = (Dose in # of vials) (40 mg/vial).Administer smaller doses in children The dose of DIGIFAB represented in Table 3 can be estimated by multiplying the dose (in number of vials) calculated from Formula 2 by the amount of DIGIFAB contained in a vial (40 mg/vial) (see Formula 3).Table 3 gives dosage estimates in milligrams for infants and small (Table 2 Adult Dose Estimate of DIGIFAB (in # of vials) from Steady-State Serum Digoxin Concentration v = vials (in # of vials) 0.5 mg of digitalis bound/vial The dose of DIGIFAB (in number of vials) represented in Table 1 can be approximated using the following formula: Table 1 gives dosage estimates in number of vials for adults and children who have ingested a single large dose of digoxin and for whom the approximate number of tablets or capsules is known. In case of digoxin tablet ingestion, the total body load will be approximately equal to the amount ingested (in mg) multiplied by the bioavailability of the tablet preparation, which is 0.8.Following an acute ingestion, total body load will be approximately equal to the amount ingested in milligrams for either digoxin capsules or digitoxin.The total number of vials required can be calculated by dividing the total body load of digoxin in milligrams (mg) by 0.5 mg per vial (see Formula 1).Each vial of DIGIFAB (40 mg of purified digoxin-specific Fab) binds approximately 0.5 mg of digoxin.If there is no response to an adequate dose of DIGIFAB, the diagnosis of digitalis toxicity should be questioned.Ĭalculation for Ingestion of Known Amount: Failure of a patient to respond to DIGIFAB treatment may indicate that the clinical problem is not caused by digitalis intoxication.If a patient is in need of re-administration of DIGIFAB due to recurrent toxicity, or to a new toxic episode that occurs soon after the first episode, measurement of free (unbound) serum digitalis concentrations should be considered since Fab may still be present in the body. If toxicity has not adequately reversed after several hours, or appears to recur, re-administration of DIGIFAB, at a dose guided by clinical judgment, may be necessary.Many patients may require higher doses for complete neutralization and doses should usually be rounded up to the nearest whole vial. The volume of distribution is a population average and may vary among individuals. Dosage calculations are based on a steady state volume of distribution of approximately 5 L/kg for digoxin, which is used to convert serum digoxin concentrations to total body burden of digoxin in milligrams.Monitor for volume overload in small (<20kg) children. If needed an additional 10 vials may be administered, to avoid a febrile reaction. Up to 20 vials of Digifab® can be administered.Ĭonsider giving 10 vials, which is usually adequate to treat most life threatening ingestions and observe the patient’s response. (In absence of a serum digitalis concentration or estimated ingestion amount.) Dosage for acute ingestion of unknown amount: IMPORTANT: Multiply amount ingested in mg by 0.80 if digoxin tablets involved to account for incomplete absorption – as opposed to the injection. Dosage for acute ingestion of known amount:Įach vial of Digifab® (40mg of purified digoxin-specific Fab) binds approx 0.5mg of digoxin.ĭose (# of vials) = / 0.5mg of digitalis bound/vial Patient wt (kg)ġ microgram per litre = 1 nanogram per ml These must be converted to nanograms per ml to calculate the dose of Digifab® required. NB The biochemistry results in CUH report digoxin levels in microgram per litre. Calculation based on steady-state serum digoxin concentration:ĭose (# of vials) = / 100 Note: Doses should ordinarily be rounded up to the next whole vial.
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