Amoxicillin entry into human cerebrospinal fluid: comparison with ampicillin.

Area of Science:

• Pharmacology
• Infectious Diseases
• Neuroscience

Background:

• Penicillin antibiotics like amoxicillin and ampicillin are crucial for treating bacterial infections.
• Understanding their penetration into the central nervous system, specifically cerebrospinal fluid (CSF), is vital for effective treatment, especially in non-inflamed states.

Purpose of the Study:

• To quantify the entry of amoxicillin and ampicillin into human CSF.
• To compare the CSF penetration and serum concentrations of amoxicillin and ampicillin in healthy volunteers.

Main Methods:

• A pharmacokinetic study involving intravenous administration of amoxicillin (33 mg/kg) to 12 volunteers and ampicillin (33 mg/kg) to 9 volunteers.
• Serial sampling of CSF and blood over several hours post-infusion to determine drug concentrations.

Main Results:

• Both amoxicillin and ampicillin were detected in the CSF of all participants.
• Ampicillin demonstrated a trend towards higher CSF concentrations compared to amoxicillin, though the difference was not statistically significant.
• Achieved serum concentrations for ampicillin were comparable to those of amoxicillin.

Conclusions:

• Amoxicillin and ampicillin exhibit penetration into the human CSF even in the absence of meningeal inflammation.
• Ampicillin may offer a slight advantage in CSF penetration over amoxicillin under these conditions.
• These findings have implications for antibiotic selection in CNS infections where blood-brain barrier integrity is a consideration.