| Budget Amount *help |
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 1993: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 1992: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 1991: ¥1,600,000 (Direct Cost: ¥1,600,000)
|
|---|
| Research Abstract |
Nifedipine, calcium antagonist, is known to induce gingival overgrowth as an adverse effect, but the pathogenesis has not been elucidated yet. Using an experimental model which we established in rats, this study was aimed to clarify whether serum levels of nifedipine, duration of the drug administration, aging, or differences of sex affect the nifedipine-induced gingival overgrowth. Gingival overgrowth was not appreciable till the serum level reached to the maximum level, about 800 ng/ml, however, once the concentration is increased to the level, a marked gingival overgrowth occurred. Time course experiments revealed that a duration of 30 day's oral administration of the drug was enough to induce the overgrowth, but longer periods of the administration did not result in any further increase of the overgrowth. Withdrawal of nifedipine resulted in spontaneous recession of the induced-gingival overgrowth to normal gingival in a time-dependent manner. When the administration was started at different ages, 20, 50 and 90 day-old, respectively, for 55 days, gingival overgrowth was induced only in youngest rats, but not in others. The plasma levels in female rats showed significantly high of the maximum levels in male rats at the same concentrations of nifedipine in diet, but essetially no differences in the magnitude between male and female rats were found. These result suggest that there exists a threshold plasma concentration, preference for younger ages, no preference for either sex on the nifedipin-induced gingival overgroeth in rats.
|
