Antivenoms

Dr. CC LauConsultant & Chief of Service

A&E DepartmentPYNEH

Agkistrodon halys antivenom

• 6000u/vial (HK$1000)• Dosage: 6000u1. Agkistrodon halys 蝮蛇

Trimersures Monticola Gunther or Mountain pit Viper 山區蝮蛇 , 山烙鐵

2. Trimeresurus mucrosquamatus or Chinese Habu, Tortoise Snake, Laotie Tou 烙鐵頭

3. Trimeresurus albolabris: white-lipped green pit viper 青竹蛇 , 白唇竹葉青(Trimeresurus stejnegeri, Chinese Bamboo Viper) * Green pit viper antivenin (Thailand Red Cross Society) for 0.7mg venom, 3 vials (HK$1000)

Agkistrodon acutus antivenom

• 2000u/vial (HK$1000)

• Dosage 8000u

• Agkistrodon acutus, Hundred Pacer

五步蛇

Naja Naja antivenom

• 1000u/vial (HK$1000)

• Dosage: 2000u

• Naja Naja 飯鏟頭 眼鏡蛇* Cobra Antivenin (Thailand Red Cross

Society)

for 0.8mg venom, 2 vials (HK$1000)

Bungarus Multicinctus antivenom

• 10000u/vial (HK$450)

• Dosage: 10000u

1. Bungarus Multicinctus 銀腳帶2. Ophiophages Hannah (Cantor) or King

Cobra 過山烏* King Cobra Antivenin (Thailand Red Cross

Society)

for 0.8mg venom, 5 vials (HK$900)

Tiger Snake antivenom

• Common tiger snake Notechis scutatus• Black tiger snake Notechis ater• Rough scaled snake Tropidechis carinatus• Common copperhead Austrelaps superbus• Highland copperhead Austrelaps ramsayi• Pygmy copperhead Austrelaps labialis• Broad-headed snake Hoplocephalus bungaroides• Pale-headed snake Hoplocephalus bitorquatus• Stephen's banded snake Hoplocephalus stephensi• Red bellied black snake Pseudechis porphyriacus• Spotted black snake Pseudechis guttatus

• Suction

• Pressure immobilization

• Fab antivenom

Suction

Michael B. Alberts et al. Suction for venomous snakebite: A study of “mock

venom” extraction in a human model. Ann Emerg Med. 2004;43:181-186

Conclusion: The Sawyer Extractor pump removed bloody fluid from our stimulated snakebite wounds but removed virtually no mock venom, which suggests that suction is unlikely to be an effective treatment for reducing the total body venom burden after a venomous snakebite.

Pressure Immobilization

• Sean P. Bush, et al. Pressure immobilization delays mortality and increases intracompartmental pressure after artificial intramuscular rattlesnake envenomation in a porcine model. Ann Emerg Med. 2004;44:599-604

• Conclusion: Compared with control animals without treatment, the pressure immobilization group had longer survival, less swelling, and higher intracompartmental pressures after artificial, intramuscular C atrox envenomation in our porcine model.

Pressure Immobilization

• In the 20 pigs studied, application of the pressure immobilization bandage prolonged survival slightly, but increased compartmental pressure greatly.

• Pressure immobilization should be discouraged for bites that involve venoms that produce substantial local injury, such as the rattlesnake, copperhead, and cottonmouth snakes of the United States.

Fab Antivenom

Crotalidae Polyvaent Immune Lab (Ovine) (FabAV)• From Sheep• 5.2 times as potent as Antivenom (Crotalidae) Polyvalent

(ACP)• Less acute reaction (14% c.f. 23-56%)• Less serum sickness (16% c.f. 18-86%)• Recurrence of venom effects after therapy >> dosing

schedule of loading dose and maintenance doses• (smaller molecular weight, larger volume of distribution,

efficient binding of venom, enhanced renal clearance, recurrence of symptoms as FabAV level drops)

Stonefish Injury

Peter Fenner. Emergency Medicine. 2000;12: 295-302• World confirmed death rare and difficult to

confirm (5 in poor details)• Hot water treatment• Parenteral opiods• Local nerve block• Antivenom for intractable pain or systemic

symptoms (some recommend infusion of diluted antivenom for severe cases)

Stingray Injury

Peter Fenner.

Emergency Medicine. 2000;12: 295-302• Immerse wounded area in hot water (43°C)• During penetration of the integument of the

victim, the barb sheath ruptures, leaving tissue and venom in wound, necrosis and infection >> whole tract should be explored and even excised, if possible to remove remaining foreign material

Scorpion Sting

Emergency Medicine Clinics of N. America. May 2004 Vol 22 No. 2

• Estimated 5000 death / year• Dry stings are common• Venom

– mixture of single chain ploypeptides containing neurotoxins blocking Na / K channels with secondary effects of pronunced Ach and catecholamine release

– Hyaluronidase >> spread of toxin

Scorpion Sting

Emergency Medicine Clinics of N. America. May 2004 Vol 22 No. 2

• Sting >> pain and paraesthesia with minimal local redness or oedema

• Systemic envenomation – usually within 6 hours peak at 12 hours and pain / paraesthesia may last for 2 weeks

• Initial transient Ach tone (SLUDGE)• Subsequent Noradrenaline effects >> can be

fatal• Also CNS, hyperglycaemia, pancreatitis….

Scorpion Sting

Foex Bernard et al. Scorpion envenomation: does antivenom reduce serum venom concentrations?. Emergency Medicine Journal. 22(3):195-197, March 2005.

A short cut review. A clinical bottom line is stated.- in an adult who has been stung by a scorpion, there is very little evidence that giving antivenom will improve clinical outcome.

Scorpion Sting

Antivenom – University of Arizona (goat serum), not FDA approved

May be useful for local pain & paraesthesia

Not effective for systemic complications

Scorpion Sting• Nugent, Jeffrey S. et al.Cross-reactivity between allergens in the venom of

the common striped scorpion and the imported fire ant.[Miscellaneous Article]. Journal of Allergy & Clinical Immunology. 114(2):383-386, August 2004.

• Conclusion: Significant cross-reactivity exists between the venom of C vittatus and IFA WBE. The high sensitization rate to IFA venom in endemic areas may therefore be a risk factor for subsequent immediate reactions to an initial scorpion sting. Patients with immediate hypersensitivity reactions to scorpion stings may potentially benefit from immunotherapy with IFA WBE.