Evaluation of Amlodipine Inhibition and Antimicrobial Effects

Antibiotic resistant pathogens is the an urgent challenge of the medicine field. To counter these pathogens, the antibiotic assisting drugs is an ideal choice. Assisting drugs can improve the efficiency of the treatment without further induce of antibiotic resistance. Amlodipine (AML) is one of the most common generic cardiovascular drug for lowering blood pressure. In previous studies, amlodipine was suggested to have some antibiotic properties. The MIC is not very low for amlodipine against these pathogens. However, the findings imply amlodipine potential to be repurposed as assisting drug and its inhibition of β-lactamase. To further discover and verify its potential of antimicrobial drug, amlodipine was tested for β-lactamase inhibition, and its synergistic effects were investigated against methicillin-resistant Staphylococcus aureus (MRSA). The compound was found to inhibit β-lactamase mixture (3 distinct species) in broad spectrum. Cephalosporins requires high concentration (>=64 ug/ml) to inhibit MRSA; combine both amlodipine and cephalosporins, the MIC only requires 8ug/ml (4 ug/ml amlodipine + 4 ug/ml Cefuroxime) in total, with FIC lower than 0.1 for strong synergistic effect. Both enzyme assay and bacterial tests indicate amlodipine as an ideal assisting drug for antibiotics; one of the mechanism is β-lactamase inhibition.