Tobramycin serum levels and tissue content in children

Area of Science:

• Pharmacology
• Pediatric Medicine
• Clinical Pharmacy

Background:

• Tobramycin is an aminoglycoside antibiotic used to treat bacterial infections.
• Understanding tobramycin distribution in pediatric tissues is crucial for optimizing dosage and efficacy.
• Previous studies have not fully elucidated tobramycin's tissue penetration in children.

Purpose of the Study:

• To determine tobramycin serum and tissue concentrations in children following intramuscular administration.
• To compare tobramycin levels in muscle, fat, spleen, and testis.
• To investigate factors influencing tobramycin tissue distribution.

Main Methods:

• A single intramuscular injection of tobramycin (2.5 mg/kg) was administered to 29 children.
• Serum, muscle, fat, spleen, and testis samples were collected hourly for 8 hours.
• Tobramycin concentrations were quantified using an agar diffusion method.
• Tissue fluid was obtained using a Colworth Stomacher.

Main Results:

• Peak serum tobramycin concentration (4.32 µg/ml) occurred at 1.5 hours, followed by a decline.
• Mean peak concentrations in muscle (0.93 µg/g) and fat (1.16 µg/g) were observed at 1.5 hours.
• Tobramycin levels in fat tissue were significantly higher (24% of serum) than in muscle tissue (17% of serum).
• Spleen and testis tobramycin content did not exceed levels found in muscle or fat.
• By 8 hours, tissue tobramycin levels fell below the limit of detection (0.01 µg/g).

Conclusions:

• Tobramycin distribution varies between tissues in children, with fat tissue accumulating higher concentrations than muscle.
• Tissue blood supply does not appear to be the primary determinant of tobramycin content in various tissues.
• These findings have implications for understanding tobramycin pharmacokinetics and guiding therapeutic strategies in pediatric populations.