Compound 64716, a new synthetic antibacterial agent.

Compound 64716, 1-ethyl-4 (1H)-oxo-[1,3]dioxolo[4,5-g]cinnoline-3-carboxylic acid, is a new synthetic antibacterial agent. The antibacterial spectrum of this compound includes gram-negative bacteria that are most frequently isolated from urinary tract infections. Minimal inhibitory concentration values of 64716 for isolates of Escherichia coli and Proteus sp. ranged from 2 to 4 and 2 to 8 mug/ml, respectively, and the compound was bactericidal at concentrations close to the minimal inhibitory concentration values. In vivo, doses required for successful therapy of experimental mouse infections were comparable to those for nalidixic acid. After oral administration of 40 mg/kg, peak concentrations of this compound in mouse blood reached 19.2 mug/ml. Within 30 min after doses of 20 mg/kg, bacteriologically active drug concentrations of 64716, nalidixic acid, and oxolinic acid in mouse urine were >1,000, 170, and <1.5 mug/ml, respectively. Resistant bacteria were not selected when bacteria were exposed to 500 mug/ml of 64716. Compound 64716 was less bound by human serum proteins than was nalidixic acid. Equivalent antibacterial activity along with superior pharmacological properties of 64716 when compared with nalidixic acid lead to the conclusion that this new compound is a promising antibacterial agent.