Effect of a short course of rhDNase on cough and mucociliary clearance in patients with cystic fibrosis

The aim of the study was to measure the effect of a short course of recombinant human deoxyribonuclease I (rhDNase) on ciliary and cough clearance in a group of cystic fibrosis patients, using a radioaerosol and gamma camera technique. Patients were initially randomized to receive either rhDNase (2.5 mg qd) or placebo. Following the measurement of baseline clearance, patients were given a 7-day course of either rhDNase or placebo. The patient then returned on the seventh day for follow-up clearance measurements. This was followed by a 2-week washout period before the whole process was repeated with the alternative inhalation solution. On each of the study days, mucociliary clearance was initially measured for a period of 60 min (IC). This was followed by cough clearance (CC) measurements for 30 min, during which patients were requested to cough a total of 120 times. Post-cough clearance (PCC) was then measured for a further 60 min. Thirteen patients completed the study. Patients' age ranged between 18-38 years, and they had baseline values of FEV(1) of 27-103% of predicted values. Following completion of the course of rhDNase, there was a mean percent increase from baseline of 7.5% for FEV(1) and 5.4% for FVC% (P = 0. 03). There was a small, nonsignificant increase in IC (6.2 +/- 3.6%) on the rhDNase arm compared with the placebo arm (-2.3 +/- 2.9%), P = 0.1. No changes were seen in either CC (1.0 +/- 3.2% rhDNase] vs. 1.9 +/- 2.4% placebo], P = 0.9) or PCC (-0.7 +/- 1.5% rhDNase] vs. 0.9 +/- 1.7% placebo], P = 0.3). Patients who achieved a 10% or greater improvement in FEV(1) (n = 5) in response to rhDNase did not show any greater change in clearance than nonresponders. In conclusion, we were unable to demonstrate any improvements in either ciliary or cough clearance in response to a short course of rhDNase. The mechanism of action of this drug in vivo remains uncertain.