title: Comparison of the effectiveness of dihydroquinidine and quinidine on ventricular ectopy after acute and chronic administration.
abstract: The aim of this study was to compare the pharmacokinetics and antiarrhythmic activity of dihydroquinidine and quinidine in 14 patients (11 men, 3 women, aged 28 to 67 years) with heart disease and chronic, stable, high-frequency premature ventricular beats (PVB) (greater than 100/hr). A randomized, double-blind, crossover, placebo-controlled protocol was utilized. During Holter monitoring the patients were given either dihydroquinidine or quinidine as the gluconates in an oral solution (600 mg); blood samples were taken 0.5, 1, 1.5, 2, 4, 6, 8, and 12 hours later. The patients were then assigned to three successive treatment periods of 7 days each: dihydroquinidine HCl (900 mg/day), quinidine polygalacturonate (1,650 mg/day), or placebo. At the end of each period 24-hour Holter monitoring was carried out and a blood sample was taken for determination of drug concentration. By comparing the area under the curves dihydroquinidine was 59% as available as quinidine; rates of absorption and elimination were similar. Mean peak blood levels of dihydroquinidine and quinidine were 1.06 +/- 0.34 and 2.15 +/- 0.96 micrograms/ml, respectively. After dihydroquinidine, eight patients had a positive response (greater than 50% reduction in PVB frequency), while seven patients responded to quinidine. During maintenance treatment both dihydroquinidine (233 +/- 330) and quinidine (234 +/- 311) reduced the mean PVB frequency per hour compared to placebo (690 +/- 569). Nine patients (64%) on dihydroquinidine and eight (57%) on quinidine had greater than 70% decrease in mean PVB frequency per hour. Steady-state peak plasma concentrations of dihydroquinidine and quinidine were 1.10 +/- 0.41 and 2.24 +/- 1.13 micrograms/ml, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Internal Medicine, University of Pavia, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Chimienti
authors.forename: M B
authors.initials: MB
authors.lastname: Regazzi
authors.forename: M T
authors.initials: MT
authors.lastname: La Rovere
authors.forename: J A
authors.initials: JA
authors.lastname: Salerno
authors.forename: M
authors.initials: M
authors.lastname: Previtali
authors.forename: V
authors.initials: V
authors.lastname: Montericcio
authors.forename: R
authors.initials: R
authors.lastname: Rondanelli
authors.forename: C
authors.initials: C
authors.lastname: Montemartini
mesh_terms: D000328:Adult; D000368:Aged; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use*; D005117:Cardiac Complexes, Premature / Q000188:drug therapy* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011802:Quinidine / Q000031:analogs & derivatives* / Q000627:therapeutic use*
chemical_list: D000889:Anti-Arrhythmia Agents; C014486:hydroquinidine; D011802:Quinidine