Abstract
Background: Levodropropizine is non-opioid agent whose peripheral antitussive action may result from its modulation of sensory neuropeptide levels. Currently, levodropropizine 60 mg is taken three-times daily. A controlled release formulation of levodropropizine (levodropropizine CR) 90 mg was developed, which can be taken twice daily. The aim of this study was to evaluate the safety and pharmacokinetic characteristics after multiple oral administrations of levodropropizine CR 90 mg tablets in healthy male volunteers. Methods: A randomized, open-label, cross-over study was conducted in 24 healthy male volunteers. Each subject received levodropropizine syrup 60 mg three times daily or levodropropizine CR 90 mg twice daily for 3 days. Blood samples for pharmacokinetic analysis were collected pre-dose and up to 24 hours on day 4. Pharmacokinetic analysis was conducted by non-compartmental method. Safety assessments including monitoring adverse events, laboratory tests, vital signs, physical examinations and ECGs were performed throughout the study. Results: A total of 20 male volunteers completed the study. The maximum steady-state plasma concentration ($C_{ss,max}$) of levodropropizine syrup and levodropropizine CR were 313.28 ng/mL and 285.31 ng/mL and time to reach $C_{ss,max}$ ($T_{max,ss}$) were 0.48 hr and 0.88 hr, respectively. The area under the concentration-time curve to the last measured concentration of two groups were 2345.36 $hr{\times}ng/mL$ and 2553.81 $hr{\times}ng/mL$, respectively. There was no serious adverse event. Conclusion: Levodropropizine CR 90 mg tablet was safe and well-tolerated when administered twice daily for 3 days. No statistically significant differences were seen in $C_{ss,max}$ and $AUC_{ss,24hr}$ between the two formulations. This study provided pharmacokinetic evidences that the twice-daily dosing regimen of levodropropizine 90 mg may substitute the conventional 3-times-daily regimen of levodropropizine 60 mg.
