Pathogenesis of drug-induced gingival overgrowth. A review of studies in the rat model
Drug-induced gingival overgrowth is a side effect associated primarily with three types of drugs: anticonvulsants (phenytoin), immunosuppressants (cyclosporin A), and various calcium channel blockers (nifedipine, verapamil, diltiazem). The authors chose to evaluate the effect of phenytoin, cyclosporin A, and nifedipine-induced gingival overgrowth in the rat model. They also looked at the onset and severity of these disorders. Features of drug- induced overgrowth were noted as follows: (1) gingival overgrowth is seen more often on the buccal rather than lingual gingiva and is more severe in the mandible than in the maxilla; (2) the severity of the gingival overgrowth is dependent upon blood level of the drug and the most severe gingival overgrowth is seen with cyclosporin A; (3) duration of drug administration is also evaluated, and at 40 days maximal gingival overgrowth will be noted; (4) gingival overgrowth will decrease once the drug is discontinued; (5) plaque plays a role in the severity of gingival overgrowth but is not required for onset of gingival overgrowth; and (6) more severe gingival overgrowth is seen in young versus old rats.
The results of this study suggest that drug-induced overgrowth in rats is dependent upon drug dose, blood level of drug age, and sex. The authors conclude that since these factors are important in human drug- induced gingival overgrowth, the rat model may be useful in obtaining the molecular pathogenesis of this disorder. [I.S.]
Nishikawa, S., T. Nagata, I. Morisaki, T. Oka, and H. Ishida, J Periodont, 67:463, 1996