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This calculator uses basic pharmacokinetic principles. Actual loading doses should be determined using drug-specific protocols and patient-specific factors. Consult clinical pharmacist for complex cases.
Calculate loading dose based on pharmacokinetic parameters
100% for IV, varies for oral
Fraction of dose that is active drug
LD = (Cptarget - Cpcurrent) × Vd / (F × S)
LD = Loading Dose
Cptarget = Target plasma concentration
Cpcurrent = Current plasma concentration
Vd = Volume of Distribution
F = Bioavailability (1 for IV)
S = Salt factor
| Drug | Vd (L/kg) | Target Level | Typical LD |
|---|---|---|---|
| Vancomycin | 0.5-0.9 | 15-20 mcg/mL (trough) | 25-30 mg/kg |
| Aminoglycosides | 0.25-0.3 | Varies by dosing | 5-7 mg/kg |
| Phenytoin | 0.6-0.8 | 10-20 mcg/mL | 15-20 mg/kg |
| Digoxin | 5-7 | 0.8-2 ng/mL | 8-12 mcg/kg |
| Theophylline | 0.5 | 10-20 mcg/mL | 5-6 mg/kg |
| Valproic Acid | 0.1-0.5 | 50-100 mcg/mL | 15-20 mg/kg |
* Parameters vary by patient factors. Use drug-specific references.