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Dipyridamole Bioavailability in Subjects With Reduced Gastric Acidity
Author(s) -
Derendorf Hartmut,
VanderMaelen Cam P.,
Brickl RolfStefan,
MacGregor Tom R.,
Eisert Wolfgang
Publication year - 2005
Publication title -
the journal of clinical pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.92
H-Index - 116
eISSN - 1552-4604
pISSN - 0091-2700
DOI - 10.1177/0091270005276738
Subject(s) - bioavailability , aspirin , dipyridamole , crossover study , oral administration , chemistry , pharmacology , capsule , antacid , dosage form , lansoprazole , medicine , omeprazole , biochemistry , placebo , botany , alternative medicine , pathology , biology
Dipyridamole (DP) is an antiplatelet agent that shows decreased oral bioavailability with increased gastric pH that occurs with commonly prescribed antacids. An extended‐release (ER) formulation of DP that employs tartaric acid to improve bioavailability of DP in the presence of elevated gastric pH was developed as a combination antiplatelet product with immediate‐release aspirin. This crossover‐designed study examined the relative bioavailability of DP from the composite product compared to conventional DP tablets during reduced gastric acidity. Gastric pH was increased (pH > 4.0) in 20 healthy subjects with lansoprazole (30 mg/d for 5 days). Dipyridamole systemic exposure over 12 hours was compared after oral administration of a single composite ER capsule (200 mg DP ± 25 mg aspirin) versus two 100‐mg conventional DP tablets given 6 hours apart combined with 81 mg aspirin. DP relative bioavailability was reduced 53% with conventional tablets compared to the composite buffered ER capsule in reduced gastric acid conditions. Peak DP plasma concentrations were 57% lower with immediate‐release tablets compared to the composite formulation with high stomach pH. Substituting generic DP plus low‐dose aspirin may be less effective than the buffered DP composite product in patients with concomitant antacid therapies.