Intramuscular tobramycin pharmacokinetics in geriatric patients

Area of Science:

• Pharmacokinetics
• Geriatric Medicine
• Infectious Diseases

Background:

• Elderly patients often have altered drug absorption and distribution.
• Intramuscular injections are a common route for antibiotic administration in institutionalized patients.
• Tobramycin is an aminoglycoside antibiotic used for serious bacterial infections.

Purpose of the Study:

• To investigate the absorption kinetics of intramuscular tobramycin in elderly institutionalized patients.
• To assess the time to peak concentration and the extent of tobramycin absorption in this population.
• To evaluate day-to-day variability in tobramycin absorption.

Main Methods:

• Twelve elderly patients (mean age 81) with stable renal function and limited mobility received intramuscular tobramycin.
• Blood samples were collected for eight hours post-injection at regular intervals.
• Tobramycin levels were analyzed using an immunofluorescence technique; the procedure was repeated on a subsequent day.

Main Results:

• Tobramycin absorption primarily occurred within two hours post-injection.
• Peak concentrations were sometimes indicative of a sustained plateau, showing intrapatient variability.
• Absorption time to peak concentration appeared extended in geriatric patients compared to younger adults.

Conclusions:

• Intramuscular tobramycin absorption in elderly patients is primarily rapid but may show a slightly delayed peak.
• The extent of tobramycin absorption appears consistent, despite some day-to-day variability.
• These findings are important for optimizing antibiotic dosing strategies in geriatric populations.