Background: Alendronate sodium (ALD) is used orally but it is poorly absorbed from the
gastrointestinal (GI) tract. For this reason, microemulsion system was chosen to evaluate ALD from the
GI tract after oral delivery.
Objective: This study was aimed to prepare water-in-oil (w/o) microemulsion formulation of ALD and
evaluate the permeability of ALD microemulsion from Caco-2 cell lines with radioactive and nonradioactive
Method: The ALD microemulsion was developed by using pseudo-ternary phase diagram and composed
of Soybean oil, Colliphor EL, Tween 80, Transcutol and distilled water. The prepared ALD microemulsion
was characterized by physical appearance, droplet size, viscosity, pH, electrical conductivity
and refractive index. The stability of the formulation was investigated for 6 months at
25±2°C/60±5% of relative humidity (RH) as well as at 40±2°C/75±5% RH. After that 1 mg of ALD was
radiolabeled with 99mTc and added to microemulsion. The permeability studies were performed with
both 99mTc-ALD microemulsion and ALD microemulsion.
Results: The experimental results suggested that ALD microemulsion presented adequate stability with
droplet size varying from 37.8±0.9 to 39.9±1.2 nm during incubation time. In addition, ALD microemulsion
was radiolabeled with high labeling efficiency (>95%). In a non-radioactive study, ALD permeability
was found to be 45 µg.mL-1 and microemulsion has high permeability percentage when compared
to another study.
Conclusion: The novel w/o microemulsion formulation has been developed for oral delivery of ALD.
Based on the results, permeability of ALD could be significantly improved by the microemulsion formulation.
In addition, 99mTc-ALD microemulsion in capsule can be used for bone disease treatment and