Pulmozyme (dornase alfa) is a mucolytic (mucus-thinning agent) developed by Genentech. It is approved by the U.S. Food and Drug Administration (FDA) to improve lung function in patients with cystic fibrosis (CF).

How Pulmozyme works

CF is a serious heritable disease caused by mutations in a gene called CFTR. This gene codes for a protein that channels salts in and out of cells. Mutations in CFTR cause the protein to be made incorrectly, or not at all, which causes thick, sticky mucus to build up in different tissues and organs, interfering with their function. In the lungs, it makes it difficult for patients to breathe, as well as making them more susceptible to infections.

The mucus in CF patients’ lungs contains long strands of DNA that have been shed from cells. Pulmozyme contains an enzyme called a DNase that acts like molecular scissors to cut the long DNA strands into smaller pieces. This makes the mucus thinner and easier to cough up. Thinning the mucus also may make CF patients less susceptible to infections.

Pulmozyme is a medication inhaled through the mouth; patients take Pulmozyme using a measured dose inhaler that delivers a specific amount of medication in a fine spray.

Pulmozyme in clinical trials for CF 

A review of clinical trials looking at the effect of Pulmozyme was published in the Cochrane Database of Systematic Reviews. The authors reviewed 19 clinical trials, which included 2,565 participants in total.

Fifteen trials compared Pulmozyme to placebo (2,447 participants), two trials compared daily Pulmozyme treatments to hypertonic saline (another mucus-thinning treatment — 32 participants), one trial compared daily Pulmozyme to hypertonic saline and alternate day Pulmozyme (48 participants), one trial compared Pulmozyme to mannitol (a CF treatment available in Europe and Australia), and the combination of both therapies (38 participants). Trial durations varied from six days to three years.

The primary outcome measure was forced expiratory volume in 1 second (FEV1, a measure of lung capacity in which patients breathe into a spirometer to assess the volume of their breath). 

Compared to placebo, FEV1 improved in the groups that received Pulmozyme, with significant differences at one, three, and six months, as well as two years. There also was a decrease in pulmonary exacerbations (a worsening of pulmonary symptoms) compared to placebo in trials of longer duration.

The results for the trials, which compared Pulmozyme to other medications (hypertonic saline or mannitol) were mixed, with one trial showing greater improvement in FEV1 for Pulmozyme compared to hypertonic saline, and three trials finding no difference between medications.

In the trial that assessed the combination of Pulmozyme and mannitol compared to Pulmozyme alone, there was no benefit seen with the combination treatment.

Side effects reported for clinical trials were mild and included voice alteration and rash.

The authors concluded that, compared to placebo, Pulmozyme improves lung function in patients with CF in trials lasting longer than one month.

Other information

The most common side effects associated with Pulmozyme are sore or dry throat and hoarseness, though eye redness or irritation also may occur.

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