Elimination kinetic of high polar metabolites pool of quinidine from human serum.

The elimination half-life of high polar metabolites pool of quinidine (t1/2 beta = 6.1 h) has been determined in a quinidine phenobarbiturate intoxicated patient after the complete elimination of quinidine (its precursor) from blood. It is equivalent to the generally accepted t1/2 beta of quinidine (6.1 +/- 1.8 h) but substantially different from the t1/2 beta "hybrid" of 3-hydroxyquinidine (10.0 h) determined in therapeutic conditions in which 3-hydroxyquinidine coexists with quinidine in blood. With regard to the low serum level of quinidine and strong ECG impairments, it is speculated that high polar metabolites of quinidine taken as a whole could be involved in this life threatening intoxication.