Clinical pharmacokinetics of amikacin in hypoxic premature foals.

This research study investigated the effects of hypoxia and prematurity on the pharmacokinetics of the antibiotic amikacin in foals. The results revealed a longer drug half-life and slower elimination rate in premature, hypoxic foals, prompting adjustments to dosage schedules.

Research Methodology

• The researchers conducted a comparative study on a specific population of foals – 7 premature, hypoxic (oxygen-deficient) foals and 8 full-term, non-hypoxic foals. Both groups were critically ill upon hospitalization.
• Amikacin, an antibiotic commonly used to treat serious bacterial infections, was given intravenously at a dosage of 7 mg/kg every 8 hours, and its effects were monitored over the first 48 hours of hospitalization.

Data Analysis and Findings

• The statistical evaluation of pharmacokinetics indicated significant changes in premature, hypoxic foals as compared to full-term, non-hypoxic foals.
• Specifically, the half-life, or the time it takes for the concentration of the drug to halve in the body, was increased in premature foals (5.39 ± 3.46 hours), indicating a slower metabolism and elimination of the drug.
• The elimination rate constant, a measure of how quickly the drug is removed from the body, was also lower (0.17 ± 0.09 per hour) in the premature foals.
• These findings led to revisions in dosage schedules. In 6 of 7 premature foals, the dosage had to be increased to 8.5-10.5 mg/kg body weight, and in all 7 foals, the dosage interval needed to be extended to 12-24 hours.

Research Implications

• This research indicates that factors like prematurity and hypoxia impact the pharmacokinetics of amikacin in foals, which can have significant implications on drug dosage and frequency.
• The prolonged half-life of amikacin in premature, hypoxic foals requires particular attention to ensure the dosage schedules maintain effective plasma concentrations without exceeding toxic levels. The target concentration range was between 15-30 micrograms/ml for peak values and less than or equal to 3 micrograms/ml for trough concentrations.
• Although no evidence of amikacin-induced nephrotoxicity (kidney damage) was observed in this study, researchers recommend daily monitoring and individual adjustment of dosage schedules considering the health variables of each foal.