[Gingival hyperplasia induced by calcium channel blockers. Rare or frequent in Norway?]

Sales statistics indicate that the number of Norwegians treated with calcium channel blockers increased from about 50,000 in 1986 to about 83,000 in 1991 (last year: nifedipine 39%, verapamil 27%, amlodipine 21%, diltiazem 10% and felodipine 3%). In spite of widespread use, only one report on gingival hyperplasia induced by calcium channel blockers has been received by the Norwegian Adverse drug reaction committee. The incidence of this adverse reaction is uncertain, but the few controlled studies that have been performed indicate that it may be as high as 15% in patients on long-term treatment, at least with nifedipine. This corresponds to nearly 5,000 cases among the about 32,000 users of nifedipine. Norwegian physicians and dentists are asked to report cases of gingival hyperplasia induced by calcium channel blockers. Although the voluntary report system is fraught with uncertainty, it is hoped that, in a relatively small and surveyable drug market as the Norwegian, the reporting may provide some relevant information, e.g. to allow comparison of the potential of the various calcium channel blockers to induce this adverse effect. A Norwegian controlled study on gingival conditions among long-term users of calcium channel blockers is in its initial stage. It may be of interest to compare the results of this study with the indications obtained from the spontaneous reporting on the incidence of this adverse effect, which is relatively easy to diagnose.