Novel approach for attenuation of pirfenidone-induced digestive symptoms: a respirable powder formulation of pirfenidone.

Aim: Orally taken pirfenidone (PFD) often causes digestive symptoms. A respirable powder formulation of PFD (PFD-RP) was previously developed, and this study aimed to verify the risk of digestive symptoms after insufflation of PFD-RP. Materials & methods: Intestinal motility and gastrointestinal exposure levels was evaluated in PFD-RP (0.3-mg PFD/rat: a pharmacologically effective dose) and orally taken PFD (10-100 mg/kg) groups. Results & conclusion: Orally taken PFD at doses above 30 mg/kg significantly inhibited intestinal motility. In contrast, insufflated PFD-RP led to comparable intestinal motility in control group, and gastrointestinal exposure levels in PFD-RP group were markedly lower than those in orally taken PFD groups. Inhalation therapy using PFD-RP may be efficacious to reduce the risk of digestive symptoms frequently induced by orally taken PFD.