Background: Imipenem, first member of the carbapenem class of β-lactams, is an antibiotic
produced by Streptomyces cattleya. It is an N-formimidoyl derivative of thienamycin, co-administered
with cilastatin, a specific and highly active dehydropeptidase I (DHP-I) inhibitor. Imipenem plays a key
role in the treatment of infections not readily treated with other antibiotics, because of its high resistance
to the β-lactamase enzymes produced by drug-resistant Gram-negative bacteria.
Methods: The elaborated method of micellar electrokinetic chromatography (MEKC) followed by UV
absorption detection at 210 nm was used to separate imipenem and cilastatin from its related substances.
The best results were obtained with borate buffer (25 mM) pH 9.2 and sodium dodecyl sulphate (75 mM).
Uncoated capillary (60/50cm; 75μm I.D.) with normal polarity and voltage values of 25 kV, were used
throughout the investigation. The optimised method of imipenem and cilastatin determination was validated
in terms of linearity, accuracy and precision, and provides a detection limit of 0.4 μg/mL and 0.2
μg/mL at S/N=3 for imipenem and cilastatin, respectively.
Results: The repeatability of the method, expressed by relative standard deviations (RSD) in the migration
times, reached 0.60% and 0.78% for imipenem and cilastatin, respectively, whereas for the corrected
peak areas RSD were 1.14% and 1.02%, accordingly. Satisfactory separation of analyzed compounds was
achieved within 7 minutes of electrophoresis.
Conclusion: A comparison of newly proposed MEKC with existing HPLC method was performed and
demonstrated an improvement in analysis time, an increase in theoretical plate number and a lower
amount of both sample and background electrolyte (BGE) required.