There is no FDA approved therapy for the treatment of scorpion envenomation in the United States. Centruroides scorpion envenomation produces a pattern of neurotoxicity with a spectrum of severity ranging from trivial to life threatening. Patients stung by Centruroides scorpions develop a clinical syndrome which may require sedation with benzodiazepines and observation for 6 to 28 hours of intensive care monitoring. A safe therapy is necessary to halt the progression of symptoms early in the clinical course while avoiding the clinical deterioration that can occur en route to a tertiary facility. Alacramyn® is anticipated to be safer and more effective than the present standard of care in the United States, midazolam, and faster-acting thus eliminating the need to transport most rural patients and reducing hospitalization time.

The purpose of this open label, confirmatory, controlled clinical trial in Mexico was to provide additional data safety and efficacy of Alacramyn® for treatment of patients envenomed by scorpion sting.

This study took place at Morelos Children's Hospital in Cuernavaca, Mexico.

Patients who arrived at the emergency department presenting with scorpion sting symptoms were evaluated for treatment with respect to the inclusion/exclusion criteria according to the study procedures. Only patients with clinically important systemic signs of scorpion sting envenomation were included in the study. Baseline measures included severity evaluation of the scorpion sting envenomation. The patient's vital signs, concomitant medication, medical history and demographic data were collected. Blood tests were done for haematology, chemistry, venom and anti-venom levels and urine test.

After informed consent and inclusion/exclusion criteria were obtained and verified, and the baseline measurements completed, three vials of Alacramyn® were administered. At the one hour assessment an additional vial of Alacramyn® was administered if important systemic signs of scorpion envenomation were present. The assessment was repeated at two hours and a final vial of Alacramyn® was administered if deemed necessary. Patient were discharged after the 4 hour assessment if symptoms were resolved. Prior to discharge repeat lab work, physical assessments, and vital signs were done. Those remaining for extended care underwent final study assessments at time of hospital discharge or at 24 hours after study drug infusion if hospitalization continued.

All patients who participated in the study were contacted 7 and 14 days after treatment, looking for symptoms suggestive of ongoing venom effect, delayed serum sickness, as well as for any other adverse event reported by the patient.

Inclusion Criteria:

• Males and females 6 months to 18 years of age
• Presenting for emergency care within 5 hours with clinically important signs of scorpion sting envenomation
• Signed written Informed Consent by parent or legal guardian
• No participation in a clinical drug trial within the last month or concomitantly

Exclusion Criteria:

• Allergy to horse serum
• Use within the past 24 hours of drugs expected to alter immune response
• Use of any antivenom within the last month or concomitantly
• Underlying medical condition that significantly alters immune response
• Concurrent medical condition involving a baseline neurological status mimicking envenomation
• Pregnant and nursing women