The penetration of carumonam into the pleural exudate of rats was compared after intravenous administration of 30 mg kg(-1) of the drug as a bolus dose or by continuous infusion over 60 min. Both methods of administration ensured a good penetration of carumonam in pleural exudate, as measured by the areas under the concentration-time curves (AUC). The mean values of the ratio of AUC in exudate to AUC in serum (1.07 +/- 0.11 and 0.96 +/- 0.13 for bolus injection and continuous infusion, respectively) were not significantly different. Administration as a bolus dose resulted in significantly higher peak concentrations in pleural exudate as well as in shorter peak times, whereas continuous infusion produced carumonam levels above the MIC for consistently longer times. The pharmacokinetic parameters obtained by analysis of serum carumonam concentrations proved to be independent of the mode of administration. The foregoing results suggest that carumonam may constitute an effective therapeutic alternative to existing antibiotics for the treatment of pleurisy caused by susceptible organisms. No clear superiority of either method of administration could be established on the basis of pharmacokinetic data.