Néphrotoxicité des médicaments: veille bibliographique janvier 2003–décembre 2005

In vivo lung deposition and sub-acute inhalation toxicity studies of nano-sized alendronate sodium as an antidote for inhaled toxic substances in Sprague Dawley rats

INTRODUCTION

Alendronate sodium is a bisphosphonate agent used for the treatment of osteoporosis and other bone diseases. It has a strong chelating property to bind or, to some extent, counteract the effects of substances, such as magnesium, calcium citrate, ferrous fumarate, carbonyl iron, as well as the zinc gluconate, sulfate and acetate salts. The objective of the present study was to evaluate lung deposition and sub-acute inhalation toxicity of the alendronate sodium respiratory formulation.

METHODS

Particle dimension of aerosols of alendronate was measured using a particle size analyzer. Alendronate was radiolabeled using Technetium-99m for in vitro and in vivo biodistribution studies. Alendronate at doses, 0.5%, 1.0%, and 1.5% in ethanol-saline respiratory formulation was inhaled twice a day up to 5 weeks for inhalation toxicity investigations. Hematological, biochemical and lung toxicity biomarkers in bronchoalveolar lavage (BAL) fluid were determined at the end of the experiment. Histopathological analysis of lung tissues was carried out to observe any microscopic changes

RESULTS

Particle size analysis revealed the size within 300-500nm. Anderson cascade impactor results showed that the particles exhibited higher respirable fraction (55.52%) with MMAD of 4.66μm. Hematology, serum biochemistry and lung toxicity biomarkers in BAL fluid performed in the sub-acute toxicity studies indicated no adverse effects of alendronate sodium inhalation except for a significant increase in cholesterol levels and marginal increase in BAL fluid protein. At autopsy, no histopathological changes in major organs were observed.

CONCLUSIONS

The lung deposition and safety evaluation data observed from these studies suggested that aerosolized nanosized alendronate sodium by the inhalation route could be a new and promising route of administration as an antidote to radioactive substances through an increase in the bioavailability of the drug as well as a decrease in side effects on systemic delivery.

Formulation and in vivo evaluation of sodium alendronate spray-dried microparticles intended for lung delivery

Spray-dried powders for lung delivery of sodium alendronate (SA) were prepared from hydroalcoholic solutions. Formulations display geometric particle size below to 12 μm and spherical shape associated to a hollow structure. The addition of leucine and ammonium bicarbonate leads to porous particles with rough surfaces. The tapped density ranges from 0.016 to 0.062 g/cm(3), decreasing with the increase of the leucine concentration. For all formulations, the calculated aerodynamic diameters are lower than 5 μm. The in vitro aerodynamic evaluation shows that all powders present a high emitted fraction of 100%, a fine particle fraction ranging from 34.4% to 62.0% and an alveolar fraction ranging from to 23.7% to 42.6%. An optimized sample was evaluated regarding sodium alendronate acute pulmonary toxicity and lung bioavailability. The bronchoalveolar lavage study shows that the intratracheal administration of sodium alendronate dry powder and sodium alendronate aqueous solution do not induce significant increases of lung toxicity indicators as compared with the positive control. Moreover, the intratracheal administration of sodium alendronate dry powder results in a 6.23 ± 0.83% bioavailability, a 3.5-fold increase as compared to oral bioavailability. Finally, these results suggest that sodium alendronate pulmonary delivery could be a new and promising administration route.