Pharmacokinetics of fazadinium in man

The disposition of fazadinium was studied in 10 patients with normal hepatic and renal function undergoing abdominal surgery. The serum and urinary concentrations were determined fluorimetrically. A single dose of fazadinium 1.5 mg kg-1 was administered i.v. The plasma decay curve for fazadinium was found to be diphasic and the data were interpreted according to a two-compartment open model. The half-lives of the distribution and elimination phases were 12.3 and 76.4 min respectively. The total apparent volume of distribution averaged 234 ml kg-1 and the plasma clearance 132 ml min-1. From these results it is suggested that fazadinium should have a shorter duration of action than other non-depolarizing agents because of the more rapid decline of the serum concentration corresponding mainly to the short half-life of the beta phase. This rapid elimination phase of fazadinium did not correspond to an extensive biotransformation because fazadinium was excreted almost unchanged in the urine and this excretion accounted for 50% of the injected dose within 24 h.