Diltiazem improves cyclosporine dosage in cystic fibrosis lung transplant recipients.

Maintenance of therapeutic blood levels of cyclosporine in lung transplant patients with cystic fibrosis can be challenging. In addition, total daily dosage can be high when compared with patients who do not have cystic fibrosis. We report the advantage of adding diltiazem to decrease the cyclosporine dosage and maintain adequate therapeutic levels. Diltiazem 60 mg twice daily was initiated in four patients with cystic fibrosis and in four patients who did not have cystic fibrosis. In patients with cystic fibrosis, mean dosage and mean diltiazem efficacy ratio (dose milligrams per kilograms per day/cyclosporine blood level) were significantly reduced. Dosage was reduced from 13.9 +/- 8 to 8.1 +/- 2.6 mg/kg mean +/- standard deviation). The latter was similar to patients who do not have cystic fibrosis (6.5 +/- 1.8 mg/kg). Diltiazem efficacy ratio was reduced from 85 +/- 22 to 27 +/- 4. In patients who did not have cystic fibrosis, the ratio was significantly reduced from 42 +/- 13 to 19 +/- 3. Resting blood pressure, pulse, and serum creatinine levels remained normal or normalized. Although cyclosporine dosage was not significantly reduced by adding diltiazem in patients who did have cystic fibrosis, adequate cyclosporine blood levels were achieved. We conclude that the addition of diltiazem can be useful in the maintenance of adequate cyclosporine therapy in lung transplant recipients who do or who do not have cystic fibrosis.