Effects of indomethacin and calcitonin on bone absorption in type II collagen-induced otosclerosis-like lesions in rats

Perspectives of pharmacological treatment in otosclerosis

To review our current knowledge of the pathologic bone metabolism in otosclerosis and to discuss the possibilities of non-surgical, pharmacological intervention. Otosclerosis has been suspected to be associated with defective measles virus infection, local inflammation and consecutive bone deterioration in the human otic capsule. In the early stages of otosclerosis, different pharmacological agents may delay the progression or prevent further deterioration of the disease and consecutive hearing loss. Although effective anti-osteoporotic drugs have become available, the use of sodium fluoride and bisphosphonates in otosclerosis has not yet been successful. Bioflavonoids may relieve tinnitus due to otosclerosis, but there is no data available on long-term application and effects on sensorineural hearing loss. In the initial inflammatory phase, corticosteroids or non-steroidal anti-inflammatory drugs may be effective; however, extended systemic application may lead to serious side effects. Vitamin D administration may have effects on the pathological bone loss, as well as on inflammation. No information has been reported on the use of immunosuppressive drugs. Anti-cytokine targeted biological therapy, however, may be feasible. Indeed, one study on the local administration of infliximab has been reported. Potential targets of future therapy may include osteoprotegerin, RANK ligand, cathepsins and also the Wnt-β-catenin pathway. Finally, anti-measles vaccination may delay the progression of the disease and potentially decrease the number of new cases. In conclusion, stapes surgery remains to be widely accepted treatment of conductive hearing loss due to otosclerosis. Due to lack of solid evidence, the place of pharmacological treatment targeting inflammation and bone metabolism needs to be determined by future studies.

[Possible benefits of calcitonin in the treatment of otosclerosis]

This study shows the results obtained after treatment with intranasal calcitonin in 23 patients (36 ears) suffering from otosclerosis. 19.4% showed a hearing improvement upper of 10 dB. The gain was 32 dB in air conduction thresholds and 23 dB. In bone conduction. Tinnitus disappeared in 25% of cases suffering from tinnitus. Calcitonin tolerance was good, 8.7% of patients reported migraine. Authors recommended additional studies in order to evaluate the efficacy of this drug in the treatment of otosclerosis.

Effects of enzymatic treatments on the biomechanical properties of screws made of bone

Nowadays, bone tissue employed to manufacture screws used as osteosynthesis material is obtained from organ donors. But in different medical fields there is an increasing need to use xenogenic grafts and implants, which still imply risks of transmission of some diseases and antigenicity. Two different autoclaving programs (A1, A2) and an alternative to reduce the antigenicity of screws made of xenogenic bone based on enzymatic treatment are analyzed from a biomechanical point of view. 128 screws made of bovine femur bone were employed. Some of them were partially demineralized with 0.6 N HCl, enzymatically digested with collagenase (specific) and pepsin (nonspecific) and then autoclaved. The specimens were subjected to tension, shear and screw torque tests and histologically evaluated. Compared to A1, A2 sterilization method (134 degrees C but higher vacuum and longer time) considerably reduced the mechanical strength of specimens. The enzymatic digestion, expected to reduce antigenicity, did not affect the screw superficial structure and would not modify the bone biomechanical properties per se, but maybe because of the association with autoclaving and partial demineralization.

Oral vaccine in otosclerosis

Otosclerosis is a genetically based disease in which the development of autoimmune mechanisms can lead to its clinical expression. Anti-type II collagen antibodies have been found in otosclerotic patient serum. The first clinically unexpressive phase of the disease can be diagnosed from a family history and ON-OFF stapedial reflexes with evidence of an autoimmune disorder. The use of antigenic oral hyposensitization is accepted, based on autoimmune pathogenesis. Hyposensitization should be initiated during this subclinical period of otosclerosis with a type II collagen oral vaccine.