Gentamicin intravenous infusion rate: effect on interstitial fluid concentration

Area of Science:

• Pharmacokinetics
• Drug delivery
• Antibiotic therapy

Background:

• Understanding drug distribution is crucial for optimizing therapeutic efficacy.
• Interstitial fluid penetration influences antibiotic effectiveness at infection sites.
• Intravenous infusion rates can impact drug pharmacokinetics.

Purpose of the Study:

• To evaluate the influence of intravenous (i.v.) infusion rate on gentamicin's interstitial fluid penetration.
• To compare the degree and rate of gentamicin penetration into interstitial fluid following slow i.v. bolus versus 30-minute i.v. infusion.

Main Methods:

• A crossover study design was employed in six rabbits.
• Gentamicin (1.7 mg/kg) was administered via either a 2.5-minute i.v. bolus or a 30-minute i.v. infusion.
• Antibiotic levels were measured in serum and in fluid from intraperitoneal implanted capsules at various time points.

Main Results:

• Slow i.v. bolus administration resulted in significantly higher peak serum gentamicin levels (17.4 mug/ml) compared to 30-minute infusion (8.3 mug/ml).
• Interstitial fluid antibiotic levels were significantly higher at 30 minutes, 1 hour, and 2 hours post-administration with the slow bolus method.
• No significant differences in capsule levels were observed beyond 2 hours, and peak capsular concentrations were similar between methods.

Conclusions:

• Slow 2.5-minute i.v. bolus administration of gentamicin leads to superior interstitial fluid concentrations within the initial 2 hours of therapy.
• Bolus administration may be the preferred route for gentamicin delivery when rapid extravascular penetration is a therapeutic goal.