Comparison of Tensilon and antivenom for the treatment of cobra-bite paralysis

We prospectively compared the ability of anti-venom and edrophonium (Tensilon) to improve paralytic symptoms in 8 patients envenomed by the Philippine cobra (Naja naja philippinensis). Twenty, 50 or 100 ml of Philippine cobra antivenom were administered in a double-blind fashion by constant intravenous infusion over 30 min. Even the largest dose of antivenom failed to produce marked improvement within 2 h, though enzyme-linked immunosorbent assays and neutralization tests demonstrated that it possessed high titres of anti-neurotoxin antibodies. Tensilon given at 2 h was significantly more effective than antivenom at increasing the duration of upward gaze (78 +/- 28 vs 43 +/- 26 sec, P less than 0.001), and either completely reversed or markedly decreased paralysis in every patient. The Tensilon test should be given to all patients with paralytic envenoming by cobras, and anticholinesterases administered to those with a positive response.