Prostatic tissue and secretion concentrations of rosamicin and erythromycin. Experimental studies in the dog.

In dogs with normal and infected prostate glands, a new antibacterial substance, rosamicin, chemically a lipid soluble basic macrolide similar to erythromycin but with a better activity against Gram-negative bacteria, was tested, and compared to erythromycin in normal dogs. The two antibiotics were administered by constant intravenous infusion for 4 hr and their concentrations in plasma, urine, prostatic tissue, and secretion were determined by bioassay technique. Rosamicin was highly concentrated in the secretion of both the normal and the infected prostate gland, although in the latter the antibiotic levels were significantly lower. Erythromycin was significantly less concentrated than rosamicin in the prostatic secretion from normal prostates and was also less concentrated in normal prostatic tissue. Inasmuch as rosamicin has an improved antibacterial spectrum, which is well suited for the treatment of bacterial prostatitis, it should be investigated in this respect.