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

We prospectively compared the ability of antivenom 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<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.