Bioavailability of quinidine in slow-release form. A comparison between two preparations containing quinidine bisulphate as the active constituent.
Two different slow-release preparations of quinidine bisulphate (A and B) have been tested. The in vitro dissolution rate of preparation B was substantially lower in intestinal than in gastric juice, whereas the release rate of quinidine from preparation A was virtually unaffected by the pH of the dissolution medium. After a single dose of two tablets of each of the preparations to 6 healthy volunteers, corresponding to 386 mg (B) and 320 mg of quinidine base (A), the maximum plasma concentration was attained after about 4.5 h. The peak concentration was 5.2 +/- 0.5 mumol/l for preparation A and 4.1 +/- 0.4 mumol/l for B. A similar difference was found in the area under the plasma concentration curve (AUC), which was 68 +/- 10 mumol-h/l and 54 +/- 5 mumol-h/l, respectively. Taking into consideration that preparation B contained 20.6% more active drug per tablet these values indicate that the extent of bioavailability is about 50% higher for tablet A than for tablet B.
D000284:Administration, Oral; D000328:Adult; D001682:Biological Availability; D001702:Biopharmaceutics; D001711:Biotransformation / Q000187:drug effects; D003692:Delayed-Action Preparations; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007419:Intestinal Secretions / Q000378:metabolism; D011802:Quinidine / Q000008:administration & dosage / Q000097:blood* / Q000494:pharmacology; D012995:Solubility; D013607:Tablets
D003692:Delayed-Action Preparations; D013607:Tablets; D011802:Quinidine