Simulated acetaminophen plasma profiles from fixed-dose combination formulations: studies using the flow-through cell dissolution method

Abstract

The aim of this work was to simulate acetaminophen plasma profiles from two fixed-dose combination formulations (acetylsalicylic acid, acetaminophen, and caffeine of generic vs. reference formulation) and in vitro dissolution data generated by the flow-through cell apparatus (laminar flow of 16 ml/min, 22.6 mm cells and 0.1 M phosphate buffer pH 7.4). Results were compared with in vitro release information of USP apparatus type II (paddle at 100 rpm and 900 ml of same dissolution medium). Dissolved drugs until 60 min were determined with a ratio-derivative spectrophotometric method. To compare dissolution profiles of each drug, dissolution efficiency and mean dissolution time were calculated. To predict in vivo behavior a convolution approach as well as acetaminophen published information were used. Peak plasma concentrations and area under the curve (zero time to infinity) were considered and values of predicted error for these pharmacokinetic parameters were established. When comparing dissolution profiles with Student’s t-tests significant differences were found (p < 0.05). All values of predicted error showed satisfactory results since only data generated by the flow-through cell dissolution method achieved < 10% for each pharmacokinetic parameter. It is important to carried out in vivo studies with used formulations to corroborate the obtained results.