Levodopa (LD), in combination with a decarboxylase inhibitor, is a mainstay and 
the most effective therapeutic agent in the treatment of Parkinson's disease 
(PD). Unfortunately, during chronic treatment with this agent, ON-OFF phenomena 
and dyskinesia appear. Despite the many medical treatment options available, 
unpredictable OFF episodes can still occur and be severe and disabling. A rescue 
therapy that provides a rapid and predictable ON response for patients with OFF 
periods would be of great value for such patients. Areas covered: CVT-301 is a 
self-administered dry powder aerosol inhaled formulation of LD that is being 
developed as a self-administered treatment for OFF periods. The PK profile of 
CVT-301, the efficacy, and the safety highlighted in randomized clinical trials 
will be reviewed. Expert opinion: CVT-301 may offer several potential advantages 
including increased systemic bioavailability through pulmonary absorption, rapid 
onset of action, avoidance of first-pass drug metabolism and less plasma-level 
variability. List of Abbreviations: PD: Parkinson's disease; LD: Levodopa; CD: 
Carbidopa; AADC: aromatic L-amino acid decarboxylase; IR: immediate-release; 
FPD: fine particle dose; GI: gastrointestinal; PK: pharmacokinetic; CVs: 
coefficient of variation; UPDRS: Unified Parkinson's Disease Rating Scale; AEs: 
adverse events; FEV: forced expiratory volume; FVC: forced vital capacity; DLCO: 
diffuse lung CO ; tmax: time to maximum concentration.