Effect of dialysis on exogenous dopamine in haemodialysed critically ill patients

A sensitive and specific high performance liquid chromatographic method (HPLC) was developed for measuring dopamine (DA) in human plasma samples. Dihydroxybenzylamine (DHBA) was employed as an internal standard. Following solvent extraction and separation on a C18 ion-pairing reversed phase column, the drug was detected by a fluorescence detector with excitation and emission wavelengths of 233 nm and 345 nm, respectively. This method was employed to evaluate dopamine dialysability in seven haemodialysed patients under continuous infusion of a positive inotropic agent. Results showed a high dialyser extraction ratio averaging 38.3%, but a low dialysis clearance of 67 ml/min. The fraction removed by dialysis is 2.5%. We concluded that haemodialysis has little effect on dopamine blood levels, and consequently on drug pharmacokinetics, when the drug is delivered to haemodialysed patients under intravenous infusion.