The absorption of (99m)Tc-alendronate given by rectal route in rabbits

Pharm Dev Technol. 2008;13(3):213-20. doi: 10.1080/10837450801949509.


Alendronate sodium (ALD) is a bisphosphonate medication used in the treatment and prevention of osteoporosis. Absorption of ALD as oral formulation is very poor (0.5%-1%). Its bioavailability can decrease with food effect. It has some gastrointestinal adverse effects such as gastritis, gastric ulcer, and esophagitis. The aim of this study was to develop a rectal formulation of ALD as an alternative to oral route and to investigate the absorption of it by using gamma scintigraphy. For this reason, ALD was labeled with Technetium-99m ((99m)Tc) by direct method. The radiochemical characterization of the (99m)Tc-ALD was carried out by paper chromatography, thin layer chromatography, and electrophoresis methods. The labeling efficiency of (99m)Tc-ALD was found 99% without significant changes until 6 h postlabeling at room temperature. The rectal suppositories containing (99m)Tc-ALD were prepared by fusion method using polyethylene glycol (PEG) 1500. The (99m)Tc-labeled ALD suppositories were administrated to rabbits by rectal route. Serial scintigrams over all bodies of the rabbits were obtained at different time intervals using a gamma camera. We found that the rectal absorption of (99m)Tc-ALD from suppository formulation was possible. According to our results, this formulation of ALD can be suggested for the therapy of osteoporosis as an alternative route.

MeSH terms

  • Administration, Oral
  • Administration, Rectal
  • Alendronate / administration & dosage
  • Alendronate / chemistry
  • Alendronate / pharmacokinetics*
  • Animals
  • Biological Availability
  • Bone Density Conservation Agents / administration & dosage
  • Bone Density Conservation Agents / chemistry
  • Bone Density Conservation Agents / pharmacokinetics*
  • Chemical Phenomena
  • Chemistry, Pharmaceutical
  • Chemistry, Physical
  • Diffusion
  • Food-Drug Interactions
  • Intestinal Absorption / physiology*
  • Isotope Labeling
  • Male
  • Rabbits
  • Solubility
  • Technetium / chemistry


  • Bone Density Conservation Agents
  • Technetium
  • Alendronate