toxicology point of view

1. SNAKE VENOM

2. TOXICOLOGY DETAILS ON
SNAKE VENOM
UNDER SUPERVISION OF DR ALAA

3. • Introduction
• Route of Intoxication
• Sign and symptoms
• Toxicokinetics
• Toxicodynamics
• Management

4. There are enormous species of snake all over the world
Today we will focus on the most famous species in Eygpt
Several species of snakes are found in Egypt, both venomous
and non-venomous.
Snakes in Egypt are found in a wide variety of habitats
ranging from the vast sandy deserts to the fertile Nile delta.

5. Black Desert Cobra
• Walterinnesia aegyptia
• Completely black in color
and has shiny scales
• this species is 0.5 m
Red Spitting Cobra
• Naja pallida
• usually bright salmon-red in
color and has a black band
on the throat
• lengths ranging from 0.7 to
1.2 m
• The venom which is a
mixture of cytotoxins and
neurotoxins can lead to
extreme pain and even the
permanent loss of eyesight.
Egyptian Cobra
• The Naja haje
• most specimens have a
brownish color
• The length of the snake
ranges between 1 and 2 m
• The Egyptian cobra played
an important role in
Egyptian
• believed that Cleopatra
committed suicide by
getting herself intentionally
bitten by this snake.

6. Cobras have several methods for delivering their deadly
venom to their prey.
Some cobras can spit their venom into a victim's eyes,
causing extreme pain and blindness.
However, the most common and well known method of
venom delivery is injection into a victim's body through
their bite

7. • The symptoms of a venomous snakebite depend on the
type of toxin(s) secreted into the bite or puncture wound,
and in part, on how much toxin is present in the tissue.
groups:
Cardiotoxins: act
on heart tissue
Neurotoxins: act
on nervous system
tissue
Cytotoxins: act on
tissue at the site of
the bite or on
tissue that directly
absorbs the toxin
Hemotoxins: act
on the blood
coagulation system
and may cause
internal bleeding

8. A pair of puncture
marks at the
wound
Redness and
swelling around
the bite
Severe pain at
the site of the
bite
Nausea and
vomiting
Labored breathing
(in extreme cases,
breathing may
stop altogether)
Disturbed vision
Increased
salivation and
sweating

9. 3- Body size
2- The amount absorbed.
1- The toxin type
Symptoms from these toxins are somewhat variable and may occur
quickly or they may be delayed for hours, depending on:

10. The absorption of
neurotoxin was
faster than
cardiotoxin and
other venom
components
Furthermore,
cardiotoxin was
found to deposit in
various organs,
kidneys, liver,
spleen and lung
whereas
neurotoxin
accumulated in
kidneys.
The venoms and
α-neurotoxins
exhibited stronger
binding affinity
towards ‘deep’
tissue
compartment
Large Vd

11. Activation Relaxation
Stimulate
the entire
diaphragm
to
contract
and then
relax
Ach
of
diaphragm
muscle
bind to
receptor
sites on the
individual
fibers
acetylcholine
molecules bound
to receptor sites
will break down
and vacate the
receptor sites they
occupied
Normaly

12. Venom prohibits the interaction
of acetylcholine molecules with
the receptor sites on the
diaphragm muscle
It binds to the receptor sites,
blocking them from interacting
with acetylcholine molecules.
In Addition to :
Proteolytic enz: digestive
properties
Phospholipases: degrade lipids
Hyaluronidase: facilitate venom
spread through out the body

13. First Aid
Emergency
care
Antidotal
therapy

14. 1. Note the Snake's
Appearance
Be ready to describe the
snake to emergency
staff.
2. Protect the Person :
While waiting for
medical help:
Move the person
beyond striking distance
of the snake.
Have the person lie
down with wound
below the heart.
Keep the person calm
and at rest, remaining as
still as possible to keep
venom from spreading.
Cover the wound with
loose, sterile bandage.
Remove any jewelry
from the area that was
bitten.

15. 3. Physical examination
During the initial evaluation, the
bite site should be examined for
signs of local envenomation
(edema, petechiae, bullae, oozing
from the wound, etc) and for the
extent of swelling.
The extremity should be placed in
a well-padded splint for at least
24 h.
Serial measurement of
circumference helps in estimating
spread of venom and effect of
antivenom.
Lymph nodes draining the limb
should be palpated and the
presence of lymphangitic lines
noted.

16. 4. Wound management
The bitten part should be
immobilized with a splint or sling.
Tourniquets and compression
bandages are potentially
dangerous as they can cause
gangrene, increased fibrinolysis
and bleeding in the occluded limb
and intensification of local
envenomation.
The only indication for their use is
in case of severe elapid or sea
snake bites where the delay in
reaching a medical centre is likely
to be more than 0.5 hours but less
than 2-3 hours.
Tourniquet should be tight
enough to occlude the
lymphatic and venous
flow but not the arterial
flow.
A useful guide is that it should be
loose enough to permit a
finger to slip under it.
The tourniquet should be released
for 30 seconds every 15
minutes to allow slow
release of venom into
circulation, thereby enabling its
neutralization.
The tourniquet should only be
released after the first dose of
antivenom is given .
In case of incoagulable blood or
oozing from puncture wounds
only use the intravenous route for
medication.

17. When the patient reaches the emergency department, evaluation should begin
with the assessment of the Airway, Breathing, Circulatory status, and
consciousness.(D)
Urgent resuscitation will be needed in those:
- in shock (cardiovascular toxicity)
- respiratory failure (neurotoxin)
- cardiac arrest (due to hypoxia, cardiac toxicity, or hyperkalemia from rhabdomyolysis).
Oxygen should be administered to every envenomed patient and a large-bore intravenous
catheter should be inserted.
A bolus of normal saline or Ringer's lactate should be given to all patients with suspected
envenomation.
Tetanus prophylaxis

18. Specific investigations
(a) The 20-min whole blood clotting test
(20 WBCT)
(b) Enzyme linked immunosorbent assay
(ELISA)
Other nonspecific tests include
1)Serum creatinine
2) creatinine phosphokinase (CPK)
3)Prothrombin time (PT
4)Fibrinogen and fibrin degradation
products (FDPs)
5)Arterial blood gas
6)electrolyte determinations
7)Electrocardiogram (ECG)
8)Electroencephalogram (EEG)

19. Administer antivenin
therapy as soon as
possible if any signs of
systemic involvement are
present because the
antivenin may reverse
coagulopathy.
Furthermore, larger
initial doses should be
considered if severe
envenomation from
multiple bites is evident.
The dose of antivenom
for children should not
be reduced since the
amount of venom
injected by the snake is
independent of the
victim's size.
Before the antivenin is
given, premedicate the
patient with an
antihistamine, and
continue the
antihistamine for 5 days
to prevent anaphylaxis.
Administer
corticosteroids if any
history of previous serum
sickness or allergic
reaction to the antivenin
is present or for
administration of large
doses of antivenin.
Pregnancy is not a
contraindication to giving
antivenin.
Edrophonium,
neostigmine, and
atropine may be given to
temporarily reverse
respiratory weakness
until antivenin is
obtained, but it should
not delay necessary
intubation.

20. Antivenom is the
key treatment for
systemic
envenoming.
Multiple doses may
be required.
Bivalent Naja /
Walterinnesia
Snake
Antivenom
Antivipmyn
Africa
FAV-Afrique
Favirept
Polyvalent
Snake Venom
Antiserum
Polyvalent
Snake
Antivenom