Comparison of the rates of disintegration, gastric emptying, and drug absorption following administration of a new and a conventional paracetamol formulation, using gamma scintigraphy.
OBJECTIVE
To investigate the hypothesis that faster drug absorption from a new paracetamol formulation containing sodium bicarbonate compared to that from a conventional formulation results from a combination of enhanced gastric emptying and disintegration/dissolution.


METHODS
Each formulation was administered in both fasted and fed states to 12 healthy volunteers. Gastric emptying and disintegration times were assessed by gamma scintigraphy, and serum paracetamol concentrations were determined by HPLC.


RESULTS
The mean time to complete disintegration of the new tablets was faster than that for conventional tablets in both fasted (10.2 min vs. 22.5 min) and fed (14.3 min vs. 46.4 min) states, although this difference was statistically significant in the fed state only (p = 0.0053). Mean gastric emptying times for the new tablets, as measured by t50 and t90, were also faster than those for conventional tablets in both fasted (t50 = 22.4 min vs. 47.5 min, t90 = 30.9 min vs. 64.1 min) and fed (t50 = 76.9 min vs. 106.4 min, t90 = 152.7 min vs. 155.5 min) states, although these differences were not statistically significant. Two subjects showed dramatically retarded gastric emptying of the new tablets in the fasted state: if these atypical data are excluded, the differences in both t50 and t90 in the fasted state are significant (p = 0.0110 and 0.0035, respectively). Rate of paracetamol absorption reflected the gastric emptying profiles as shown by significant correlation of emptying times with partial AUC.


CONCLUSIONS
It would seem that a combination of faster disintegration and gastric emptying of the new tablets is responsible for the faster rate of absorption of paracetamol from PA compared to P observed in both this study and in previous studies. The differences in gastric emptying are more pronounced in the fasted state, and the differences in disintegration are more pronounced in the fed state.
Kelly
Kilian
K
Department of Pharmaceutical Sciences, University of Strathclyde, Glasgow G4 0NR, UK. kilian.kelly@strath.ac.uk
O'Mahony
Bridget
B
Lindsay
Blythe
B
Jones
Tamara
T
Grattan
Tim J
TJ
Rostami-Hodjegan
Amin
A
Stevens
Howard N E
HN
Wilson
Clive G
CG
D000082:Acetaminophen / Q000737:chemistry* / Q000493:pharmacokinetics*; D000284:Administration, Oral; D000328:Adult; D002626:Chemistry, Pharmaceutical; D002851:Chromatography, High Pressure Liquid; D018592:Cross-Over Studies; D005079:Excipients; D005260:Female; D005746:Gastric Emptying / Q000187:drug effects*; D005753:Gastric Mucosa / Q000378:metabolism; D006801:Humans; D008297:Male; D011877:Radionuclide Imaging; D017693:Sodium Bicarbonate; D012995:Solubility; D013270:Stomach / Q000000981:diagnostic imaging; D013607:Tablets; D013997:Time Factors
D005079:Excipients; D013607:Tablets; D000082:Acetaminophen; D017693:Sodium Bicarbonate