Relative absorption of gastroresistant risedronate taken with food or fasted vs immediate-release

All the gastro-resistant 35 mg risedronate formulations were safe and well-tolerated under fasted and fed conditions, without any severe side effects.

Osteoporosis people often consume oral bisphosphonates with food that renders these medications inefficient. An open-label randomized study was carried out to compare the relative absorption of 4 formulations of gastro-resistant 35 mg risedronate versus 35 mg immediate-release risedronate taken fasted.

In this study, the relative absorption of gastro-resistant formulations administered fasted and fed was compared along with the assessment of the disintegration site. A total of 160 healthy subjects were randomly divided into 1 of 9 intervention groups. In group A, immediate-release risedronate was taken fasted and in group B-I, formulations 1-4 were taken fasted or fed. The fasted group fasted for eight hours before the dose and four hours after the dose.

The Fed groups fasted for seven and a half hours and then received risedronate with breakfast. Urine collection was done until 72 hours after the dose and was assessed utilizing liquid chromatography. To evaluate tablet disintegration, around 7 subjects underwent scintigraphic monitoring from each group.

For group A, the percentage of the total dose recovered in urine (A'e) was ~0.5%. In this study, the A'e of formulations 1-4 administered fasted was found to be 0.220%, 0.298%, 0.154%, and 0.108% respectively. Compared with the A'e of formulations 2 (-73%), 3 (-80%), and 4 (-65%), the A'e of formulation 1 with food reduced least versus fasted (-27%). Formulation 4 disintegrated closer to the large intestine and 1-3 disintegrated in the small intestine.

All the gastro-resistant formulations showed good tolerability with the known safety profile for immediate-release risedronate. When taken fasted, formulation 2 had the greatest absorption.  Formulation 1 absorption was minimally influenced by food.