KemPharm, Inc. announced the results of its exploratory Phase 1, double-blind, single-dose, 2-treatment, 2-period, randomized, crossover study (Study KP511.A01) intended to assess the pharmacokinetics, safety and intranasal abuse potential of KP511 Active Pharmaceutical Ingredient (API) compared to equivalent doses of hydromorphone hydrochloride (HM API). KP511 is KemPharm’s investigational prodrug of hydromorphone for the treatment of pain. The results of the study indicated that KP511 demonstrated statistically significant reduction in peak and overall hydromorphone exposure with KP511 API versus HM API. The improved pharmacokinetics of KP511 resulted in meaningful, statistically lower scores in the exploratory pharmacodynamic measures of “Drug Liking,” “Feeling High,” “Overall Drug Liking” and “Take Drug Again” when compared to HM API. Preliminary Results from Study KP511.A01: Study KP511.A01 was a Phase 1, double-blind, single-dose, 2-treatment, 2-period, randomized, crossover study intended to assess the pharmacokinetics, safety and exploratory intranasal abuse potential of KP511 API compared to hydromorphone API after intranasal administration in twenty-six nondependent recreational opioid users who reported prior insufflation experience. The primary endpoint was pharmacokinetic evaluation of hydromorphone released from KP511 API and HM API. The secondary endpoint was safety. The exploratory endpoint was the intranasal abuse potential. Mean peak hydromorphone exposure (Cmax) was reduced by approximately 63% and median Tmax for hydromorphone was delayed by 30 minutes after insufflation of KP511 API when compared to HM API. Mean overall hydromorphone exposure with KP511 API was approximately 58% and 48% lower as measured by AUClast and AUCinf, respectively. In addition, mean cumulative hydromorphone exposures at time points following intranasal administration of KP511 were decreased from approximately 56% to 100% (higher reduction at earlier time points) with negligible hydromorphone plasma concentration prior to the 30-minute time point. The results demonstrated that KP511 prodrug may release hydromorphone at a significantly slower rate and lower extent after intranasal administration when compared to HM API. KemPharm believes the statistically significant reduction in hydromorphone exposure translated into statistically significant differences in the exploratory pharmacodynamic measures. Mean maximum scores (Emax) of “Drug Liking” and “Feeling High” for KP511 were approximately 11.4 and 23.4 points lower, respectively. Additionally, mean “Overall Drug Liking” and “Take Drug Again” scores collected at 24 hours post-dose were approximately 16.0 and 13.3 points lower, respectively. Abuse measures were assessed on bipolar and unipolar (“Feeling High” only) visual analog scales.