2. 
Atropine

Cholinesterase reactivators (Oximes)

3. (a)ATROPINE





Anti cholinergic drug.
Objective : To block the muscarinic receptors until the
organophosphate is metabolised away from the body.
Atropine : Adult dose : 2-5mg i.v. repeated every 5 min
doubling the initial dose.
Children : 0.05-0.1mg/kg
Given till signs of atropinization appear.
Continued treatment: maintenance dose (30% of
atropinization dose) for 1-2 weeks.

4. (b)CHOLINESTERASE REACTIVATORS
 Oximes
are used to restore neuromuscular
transmission.
 If
more reactive OH groups in the form of
oximes (Generic formula R-CH=N-OH) are
provided reactivation occurs more faster.
 Eg:
Pralidoxime ( 2-PAM)

5. Action of Pralidoxime (2-PAM)
 Attaches to the anionic site of the enzyme.
 Oxime end reacts with the phosphorus atom
attached to the esteratic site.
 Oxime-phosphonate form and diffuse away.
 Reactivated ChE remain.
 Treatment should be started within 24 hours
before the phosphorylated enzyme undergoes
‘Aging’ and become resistant to hydrolysis.

6.  It
is ineffective to carbamate poisoning as in
that case the anionic site of the enzyme is not
free.
 It is rather contraindicated because it has
weak anti-ChE activity of its own.

7.  Injected
 Doses
 Use
i.v. slowly in a dose of 1-2g.
may be repeated according to need.
of oximes in OP poisoning is secondary
to that of Atropine.

8. OTHER OXIMES:
 Obidoxime:
more potent than pralidoxime
 Diacetyl-monoxime
(DAM):
Lipophilic; so if the OP poisoning symptoms
are more central DAM is used as it can cross
the blood brain barrier.