PHARMACOKINETICS AND SUCTION BLISTER FLUID PENETRATION OF A SEMISYNTHETIC INJECTABLE STREPTOGRAMIN RP-59500 (RP-57669 RP-54476)

RP 59500 is a new semisynthetic injectable streptogramin with excellen t activity against most gram-positive bacteria. In order to assess its potential for the treatment of tissue infections, the pharmacokinetic s and penetration into suction blister fluid were studied in a pilot p hase I study in six male volunteers following a single infusion of 12 mg/kg over 1 h. Plasma and suction blister fluid concentrations were d etermined by microbiological assay. The mean peak concentration in pla sma was 8.65 mg/l at the end of infusion. The mean plasma elimination half-life was 1.48 h. The mean peak concentration in interstitial flui d was 2.41 mg/l and was reached after Ih in two volunteers and after 2 h in the other four. The mean percentage penetration for the interval 0-6 h was 82.5 %. RP 59500 was still detectable in interstitial fluid at 6 h at a mean concentration of 0.92 +/- 0.25 mg/l. The data of thi s pilot study demonstrate good penetration of RP 59500 into non-inflam matory interstitial fluid.