Pharmacokinetics of a high dose of amikacin administered at extended intervals to neonatal foals.

The research studied the effects of high doses of the antibiotic, amikacin, given at extended intervals to newborn foals. The study found that the once-daily dosage resulted in high peak amikacin concentrations in plasma, suggesting a potentially heightened antibacterial activity. The study also observed an enhancement in the clearance of amikacin, reflecting an improvement in renal function as the foals matured.

Research Methodology

• The study was conducted on 7 newborn foals.
• These foals were administered with Amikacin, an antibiotic, at a dosage of 21 mg/kg intravenously, every 24 hours, for a period of 10 days.
• Plasma samples were taken from the foals on days 1, 5, and 10. These samples were then used for the measurement of amikacin concentrations and the determination of amikacin’s pharmacokinetics – the study of how the body interacts with the drug including absorption, distribution, metabolism, and excretion.

Research Findings

• The researchers recorded the mean peak plasma concentrations of amikacin at different time intervals – immediately (time 0), and at 1-hour intervals. The study found peak plasma concentrations of 103.1, 102.9, and 120.7 microgram/mL on days 1, 5, and 10 respectively.
• The area under the curve (AUC), a pharmacokinetic measurement depicting the total drug exposure over time, was also calculated. The AUC values were found to decrease from 293.0 to 180.9 (microgram x hour)/mL from day 1 to day 10.
• The half-life of the drug, which is the time taken for the drug to reduce to half its initial amount in the body, was found to decrease from 5.33 to 3.85 hours by day 10.
• The clearance of the drug, which is the volume of plasma from which the drug is completely eliminated per unit time, significantly increased from 1.3 to 2.0 mL/(min x kg) from day 1 to day 10.
• Thus, the study found significant increases in amikacin clearance and decreases in its half-life, AUC, mean residence time and plasma concentrations at various hours as the foals aged.

Research Conclusion

• The research concluded that high doses of amikacin, when given once daily, resulted in large peak plasma concentrations and AUC values, suggesting potentially enhanced bactericidal (bacteria-killing) activity.
• The observation of increased clearance of amikacin indicates the maturation of renal function during early life, which enhances the body’s ability to eliminate the drug.
• The researchers note that the use of high-dose, extended-interval amikacin regimens seems logical for neonatal foals, although actual clinical use needs further confirmation.