indication

Used as adjunct therapy in the treatment of cystic fibrosis.

pharmacology

Cystic fibrosis (CF) is a disease characterized by the retention of viscous purulent secretions in the airways. These thick secretions contribute both to reduced pulmonary function and to frequent pulmonary infection. Purulent pulmonary secretions of individuals with cystic fibrosis contain very high concentrations of extracellular DNA released by degenerating leukocytes that accumulate in response to these infections. Dornase alfa hydrolyzes the DNA in sputum of CF patients and reduces sputum viscosity and viscoelasticity. The enzyme does not appear to affect sputum in the absence of an inflammatory response to infection, nor does it affect the sputum of healthy individuals.

mechanism of action

Dornase alfa is a biosynthetic form of human DNase I. The enzyme is involved in endonucleolytic cleavage of extracellular DNA to 5´-phosphodinucleotide and 5´-phosphooligonucleotide end products. It has no effect on intracellular DNA. Optimal activity is dependent on the presence of divalent cations such as calcium and magnesium. Extracellular DNA is a viscous anionic polymer and its breakdown appears to improve the viscosity and viscoelasticity of purulent sputum of individuals with CF.

toxicity

Adverse reactions occur at a frequency of < 1/1000 and are usually mild and transient in nature. Reported adverse effects include chest pain (pleuritic/non-cardiac), fever, dyspepsia, voice alteration (hoarseness), pharyngitis, dyspnea, laryngitis, rhinitis, decreased lung function, rash, urticaria, and conjunctivitis.

absorption

Systemic absorption undetectable following administration by inhalation.