Effects of loratadine, a histamine H₁ receptor antagonist, on the skeletal system of young male rats

Abstract

Background

Histamine H₁ receptor antagonists are widely used in the treatment of allergic diseases. H₁ receptors are expressed on bone cells and histamine takes part in regulation of bone metabolism. Loratadine is often prescribed to children.

Purpose

The aim of the present study was to investigate the effects of loratadine on the skeletal system of young rats.

Material and methods

Loratadine (0.5, 5, and 50 mg/kg p.o. daily) was administered for 4 weeks to male Wistar rats, 6-week-old at the start of the experiment. Bone mass, mass of bone mineral, calcium, and phosphorus content in the bone mineral of the tibia, femur, and L-4 vertebra, histomorphometric parameters of the femur, mechanical properties of the proximal tibial metaphysis, femoral diaphysis and femoral neck, and serum levels of bone turnover markers were examined.

Results

Loratadine at 0.5 and 5 mg/kg did not significantly affect the skeletal system of young rats. At 50 mg/kg, loratadine decreased the femoral length, increased content of calcium and phosphorus in the bone mineral of the vertebra, and tended to improve mechanical properties of the tibial metaphysis.

Conclusion

High-dose loratadine slightly but significantly affected development of the skeletal system in rapidly growing rats.

Keywords:

• loratadine
• histamine H₁ receptor antagonists
• bone
• rats

Acknowledgments

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Preliminary results of this paper were presented at the 18th International Congress of the Polish Pharmacological Society as a poster presentation. The poster’s abstract was published in “Conference Abstracts” in Pharmacol. Rep. 2013;65(Suppl.1):44. https://doi.org/10.1016/S1734-1140(13)71323-9. 

Disclosure

The authors report no conflicts of interest in this work.