Fig. 2.

Rifampicin concentrations in the blood and pericardial fluid.

The p-values shown throughout are for the Mann–Whitney test, and compared the total drug concentrations in plasma versus pericardial fluid, and not the free drug.

A. The concentration–time profiles of rifampicin in pericardium and in the blood over a 24 h dosing interval. The time to maximum concentration was longer in pericardial fluid, while the peak concentrations were blunted.

B. Clearance of rifampicin from pericardial fluid (PF) and plasma for each patient. The median clearance from the blood was 7.82 (range: 7.79–7.84) L/h while that in pericardial fluid was 9.49 (range: 6.30–13.14) L/h.

C. The 0–24 h AUC for total drug concentrations was lower in pericardial fluid than in plasma; the free drug concentrations were even lower.

D. Total rifampicin peak concentrations achieved in pericardial fluid are lower than in plasma; free concentrations are substantially lower.

E.  Comparison of free rifampicin peak concentrations to MICs demonstrates that the maximum concentrations achieved in pericardial fluid are lower than MICs. Thus, as the concentrations are cleared from the pericardium the gap between drug concentration and MIC rapidly widens.