| abstract |
A compound of the formula:wherein R<sub>1</sub> stands for n-propyl or isoprppyl; and R<sub>2</sub> stands for n-butyl, isobutyl, n-pentyl, n-hexyl or 2-ethylbutyl, or a pharmaceutically acceptable salt thereof, processes for preparing the same and a pharmaceutical composition thereof are provided. The compound can orally be applied as antibiotics having improved bioavailability. |