Conventional modified release preparations of tamsulosin HCl have been linked to increased incidence of cardiovascular adverse events, possibly due to rapid drug peaks soon after ingestion. A ‘flattened’ absorption profile has been shown to reduce the occurrence of these unwanted effects while improving symptom control.
The potential of a novel triple-layered tablet to effect prolonged release and continuous absorption of tamsulosin HCl in the gastrointestinal tract was investigated in this clinical study. Gastrointestinal (GI) transit behaviour was monitored by scintigraphic imaging of technetium-labelled tablets. Drug absorption levels were simultaneously determined through pharmacokinetic analysis of blood samples.
A mean Cmax of 6 ± 3 ng/nL was achieved after 324 ± 184 min (mean tmax). The mean AUC0-24 was noted as 4359 ± 1880 ng/mL min. The mean gastric emptying and colon arrival times of the tablets were 105.2 ± 68.9 and 270.1 ± 32.0 min post-dose; giving a mean small intestine transit time of 164.9 ± 83.6 min. Variations in gastrointestinal transit did not appear to influence drug absorption.
Correlation of scintigraphic and PK data indicated that tamsulosin HCl is released steadily throughout the entire GI tract, suggesting that the mechanism of drug release is independent of GI site allowing drug release even in the low moisture environment of the colon.