An Active control, double blind, two-armed, randomized (1:1), phase 3 clinical trial for non-inferiority evaluation of efficacy and safety of ScoFab (Padra Serum Alborz Co. production) vs RVSRI antiscorpion venom serum, was conducted in the treatment of scorpion sting victimsIntroduction

Introduction: Scorpion sting is neglected tropical disease (NTD) which are responsible for enormous suffering, disability and premature death on every continent. Communicable disease control center of Iranian MOH reports more than 50,000 scorpion stings in 2018. Padra Serum Alborz (a knowledge-based company in Iran) has developed a new method for producing equine F(ab’)2 antivenoms complies the cGMP and WHO standards (TRS 1004). The progress is conducted in three steps. 1. Changing the antigen and immunization process (using the 3rd generation of antigen preparations). 2. Purification method, which eventuates in improving the production yield and purity. 3. Viral inactivation and removal method. Study Design: An Active control, double blind, two-armed, randomized (1:1), phase 3 clinical trial for efficacy and safety evaluation of ScoFab (Padra Serum Alborz Co. production) vs Razi Vaccine and Serum Research Institute (RVSRI) antiscorpion venom serum, was conducted. 98 victims with age of 2 to 60 , signs of systemic scorpion envenomation or having the indication for antivenom infusion were enrolled between 2019-03-08 and 2019-04-16 in Razi Hospital. According to randomization master sheet the antiscorpion venom serum was infused intravenously. The victims were assessed 2, 6, 12, 24 hours and 7, 14 days following the antivenom administration. Result: 94.1% and 86% of victims in ScoFab and RSVRI antiscorpion venom serum group exhibited the alleviation signs 12 hours after antivenom infusion, respectively. The proportion of responders is 8.1% more in ScoFab group (95% CI: -5.7– 21.9). 33victims (66%) vs 29 victims (61%) reported at least one adverse events (AEs) (PV=0.57), 14 victims (28%) vs 17 victims (35.4%) had 2 or 3 AEs (PV=0.43) and 1 victim vs 3 victims exhibited more than 3 AEs (PV=0.29) in ScoFab (n=50) vs RSVRI antiscorpion venom serum (n=48) group, respectively. The reported AEs were rash, headache, flushing, fever, malaise, polyarthralgya, face edema, dermatitis, vertigo, urine discoloration, foot edema, itching and cellulitis. There were no life-threatening anaphylactic reactions in the present study. One victim in RSVRI antiscorpion venom serum group with severe malaise, face edema and itching were hospitalized 2 days in ICU with diagnosis of severe serum sickness that considered as a Serious AE (SAE). Conclusion: The study showed that there are no significant statistical differences in two groups, so ScoFab could considered as a reliable replacement for RSVRI antiscorpion venom serum and according to other unmeasurable concerns like virus contaminations and environmental issues, it seems that this replacement is unavoidable.