The document discusses drug incompatibility between skeletal muscle relaxants and thiopental sodium due to their differing pH levels, with the muscle relaxants having acidic pH levels between 3.5-5 and thiopental having an alkaline pH of 11-12. This pH difference can cause precipitation when the drugs are mixed or administered together intravenously, particularly during rapid sequence inductions, posing risks to patients. The document provides recommendations to minimize precipitation such as administering the drugs separately, using a free-flowing IV, or altering the combination of drugs used.

1. Drug Incompatibility
skeletal muscle relaxant vs.
thiopental
BY LAITH J. ABDULREDHA

2. Skeletal muscle relaxant :
 Muscle relaxants are medicines that
block cholinergic transmission of
nerve impulses to the muscles.
( motor nerve ending and NM end
plate of skeletal muscle )
 They sometimes are also referred to
as neuromuscular blocking
agents.

3. What are they used for?
 Facilitate intubation of
the trachea
 Optimized surgical
working conditions

4. Skeletal muscle relaxant :
 Atracurium
 Cistracurium
 Pancuronium
 Vecuronium
 Rocuronium
 Mivacurium

5. Thiopental sodium
 Barbiturate used for induction of
anesthesia
 Administered by slow intravenous
injection or continous IV infusion

6. Incompatibility
 There is a chemical incompatibles
between muscle relaxant and
thiopental
 Muscle relaxants are Incompatible
with high pH solutions, must be
administered separately to drugs with
high pH such as thiopental to prevent
precipitation

7.  The issue of precipitation becomes very
important in rapid sequence inductions of
anesthesia when a muscle relaxant is
injected immediately after thiopental.
 Precipitation is more likely to occur
when the IV fluid does not flow freely
and with use of small-bore
angiocatheters (22-gauge or smaller)

8. pH of thiopental and SMR
Drug pH
thiopental 11-12
mivacurium 4 -5
vecuronium 4
Rocuronium
m
4
atracurium 3.5

10. Solution of problem :
 a combination of a free-flowing drip
as well as fluids running through it
can minimize potential difficulties
 When no fluids are being
administered, then a generous saline
flush clear cannula and vessel
 alter the drugs used

11.  Precipitation of Thiopental by Some
Muscle Relaxants/ Chambi, Denis MD;
Omoigui, Sota MD Anesthesia & Analgesia:
November 1995 - Volume 81 - Issue 5 - p 1112
 Mixing medicines: how to ensure
patient safety /The Pharmaceutical
Journal14 APR 2015By John Bentley, Katie
Heard, George Collins, Chris Chung