Correct Methods for Calculating Drug Dosages in Patients, Including Special Situations

Intravenous Drug Dosing Calculations: Bolus vs Continuous Infusion

Accurate drug dosage calculation is critical in medical practice to ensure patient safety and effective treatment. Intravenous (IV) drug administration requires precise calculations, especially when considering bolus versus continuous infusion methods.

Understanding Bolus vs Continuous Infusion

• Bolus Injection: A single, rapid administration of medication, typically used for immediate therapeutic effects.
• Continuous Infusion: A slow, steady administration of medication over a set period, ideal for maintaining constant drug levels.

Key Calculation Methods

Bolus Dosage Calculation

Bolus dosing requires knowledge of the drug’s concentration and the patient’s weight. The formula commonly used:

Dose (mg) = Patient weight (kg) × Recommended dose (mg/kg)

Continuous Infusion Rate Calculation

For continuous infusions, the dose is spread over time. The formula:

Infusion rate (mL/hr) = Total dose (mg) ÷ Duration (hr) ÷ Drug concentration (mg/mL)

Special Considerations

• Renal Impairment: Dosages need adjustment based on creatinine clearance levels.
• Pediatric vs Adult Patients: Dosing varies significantly based on age and metabolism.
• Critically Ill Patients: Require continuous monitoring and dosage modifications.

Conclusion

Intravenous drug dosing is a fundamental practice requiring precision and patient-specific considerations. Understanding the differences between bolus and continuous infusion ensures safe and effective medication administration.