Source: FDA, National Drug Code (US) Revision Year: 2020
ANASCORP is composed of venom-specific F(ab')2 fragments of immunoglobulin G (IgG) that bind and neutralize venom toxins, facilitating redistribution away from target tissues and elimination from the body1.
Eight clinically healthy volunteers (6 males and 2 females, age: 17 to 26 years) received a bolus intravenous dose of 47.5 mg of centruroides (scorpion) immune F(ab')2, (equine) injection. Blood samples were collected till 504 hours (21 days) and pharmacokinetic parameters were estimated by noncompartmental analysis which are summarized in Table 23.
Table 2. Pharmacokinetic parameters of s corpion antivenom:
| Parameters | Mean ± sd |
|---|---|
| AUC(0-∞) (µg•hr/mL) | 706 ± 352 |
| Clearance (mL/hr) | 83.5 ± 38.4 |
| Half-life (hrs) | 159 ± 57 |
| Vss (liters) | 13.6 ± 5.4 |
The efficacy of ANASCORP was assessed in a prospective double-blind randomized placebocontrolled study, four open-label studies and one retrospective study in various treatment settings in the United States and Mexico, where scorpion envenomation is common. A total of 1534 patients ranging from less than one month to 90 years old were treated. The majority of patients (78%, 1204/1534) were pediatric, ranging from less than one month to 18.7 years of age. Male (52.3%) and female patients (47.7%) were equally represented. Treatment success was determined by resolution of clinically important signs of scorpion envenomation within four hours of starting infusion. The randomized placebo study enrolled 15 subjects, eight to the ANASCORP treated group and seven to the placebo. The symptom resolution success rate was 100% for the ANASCORP treated and 14.3% for the placebo group.
A retrospective hospital chart review provided historical data from envenomated patients (N=97) who did not receive antivenom but were treated with sedatives and supportive care for symptoms of envenomation. These data were used as a historical control for expected outcomes in the absence of antivenom treatment. The historical controls were pediatric patients admitted to two pediatric intensive care units between 1990 and 2003 for the treatment of scorpion envenomation with supportive care only. The proportion of patients that required intensive care support four hours after intensive care unit admission, and the overall duration of the intensive care support requirement were calculated.
Overall, 95-100% of patients were relieved of systemic signs associated with scorpion envenomation in less than four hours after initiating ANASCORP treatment. In the historical control database, only 3.1% of patients experienced relief of symptoms within 4 hours of hospital admission.
In 1396/1534 patients the mean time from start of ANASCORP infusion to resolution of clinical signs and symptoms of envenomation was 1.42 hours (0.2 to 20.5 hours). Pediatric patients generally experienced a slightly faster time to resolution (1.28 ± 0.8 hours) compared with that of adult patients (1.91 ± 1.4 hours). The time to resolution of symptoms was not affected by use of sedatives (474 patients who received sedatives resolved in 1.49 ± 1.1 hours and 922 patients who did not receive sedatives resolved in 1.38 ± 0.9 hours).
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