The toxic enzymes liberated by the active focus appear to be the mechanism of the sensorineural deterioration. Sodium fluoride acts partly as an enzyme inhibitor and partly to decrease osteoclastic resorption and to increase calcification of the focus, thus arresting its activity. In most cases, between 40 to 60 mg of sodium fluoride a day was administered. The duration of treatment in these studies varied between 6 months to more than 7 years in certain cases with no ill effects to the patients. The side effects most frequently reported were gastrointestinal complaints and musculoskeletal pain.
Sodium fluoride is rapidly and almost completely absorbed from the gastrointestinal tract.
Certain cations such as calcium, magnesium, aluminum and iron retard the absorption of fluoride ion by forming low solubility complexes in the gastrointestinal tract. Fluoride can be detected in all organs and tissues and especially in bones, thyroid, aorta and kidney. Fluoride is predominantly deposited in the skeleton and teeth and the degree of skeletal storage is related to age and intake. In patients where, following surgery, a soft vascular focus is encountered at the oval window or when the patient begins to experience progressive neurosensorial deterioration after successful stapedectomy. Since the safety of sodium fluoride has not been established in pregnant women, in children and adolescents up to 18 years old, the drug should not be used in these patients.