الفهرس 
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Abstract
This work was devoted for evaluation of the efficacy of simvastatin and l-carnitine in dexamethasone induced osteoporosis either separately or in combination, and to compare it with a standard antiosteoporotic agent; risedronate. Also, to evaluate the efficacy of l-carnitine to abolish simvastatin induced adverse effects as statin induced myopathy and hepatotoxicity.
In the first set of our experiment, we evaluated the efficacy of oral simvastatin (10mg/kg) and l-carnitine (100mg/kg) separately in dexamethasone induced osteoporosis in rats and we compared it to an antiosteoporotic agent risedronate (1mg/kg). The results demonstrated that simvastatin as well as l-carnitine were as effective as risedronate as antiosteoporotic agent. As, they induced highly significant improvement in calcium, phosphorous, ALP, total antioxidant, OPG, femur weight, BMD and BMC in dexamethasone induced osteoporotic rats.
In addition, we evaluated the efficacy of l-carnitine to overcome the simvastatin induced myotoxicity and hepatotoxicity by measuring serum CK level and liver enzymes (ALT and ALP). Our results showed that simvastatin induced highly significant increase in serum CK level as well as ALT and AST in comparison to both dexamethasone treated group and control group. In addition, risedronate administration induced highly significant reduction in CK, ALT and AST levels in comparison to dexamethasone treated group but still significantly higher than control group. L- carnitine administration induced highly significant reduction in CK, ALT and AST levels in comparison to dexamethasone treated group.
In the second set of our experiment, we evaluated the efficacy of combination of simvastatin with l-carnitine and their combination to risedronate. We divided the dexamethasone treated animals randomly to equal groups. The first group; received risedronate simultaneously with simvastatin for 4weeks. The second group; received risedronate simultaneously with l-carnitine for 4 weeks. The third group; received simvastatin simultaneously with l-carnitine for 4 weeks. The fourth group; received combination of risedronate simultaneously with both simvastatin and l-carnitine for 4 weeks. The doses and routes of administration as the first set.
We observed that the best results were obtained in groups treated by their combination specifically when risedronate was included in this combination, as shown in the histopathological examination. Despite that there was insignificant difference between treated groups.
Furthermore, our results showed that concurrent administration of l-carnitine with either simvastatin or risedronate showed highly significant reduction in both CK as well as ALT and AST levels in comparison to dexamethasone treated group.
from our study we suggest that simvastatin is effective antiosteoporotic agent either separately or in combination with risedronate to decrease the duration and combining adverse effects. In addition, concurrent administration of l-carnitine with simvastatin are effective agents in treatment of osteoporosis owing to their antioxidant, bone anabolic and antiresorptive effects. Furthermore, addition of l-carnitine to the treatment regimen protects against statin induced myopathy and hepatotoxicity.