Integral University Lucknow Faculty of Pharmacy

1. Topic: General Anaesthesia
Mahatma Gandhi institute of Pharmacy, Lucknow
Presented by:-
Mohammad Afaque
Assistant Professor
Department of Pharmaceutical Chemistry
(M. Pharm)

2. General Anaesthetics:-
Introduction:-
 General anaesthetics are group of drugs that produces loss of
consciouness, and also loss of all sensations.
 The absolute loss of sensation is called anaesthesia.
 General anaesthetics are depressant of the central nervous system.
 These drugs are used in surgical operations to induce unconsciousness
and also abolish the sensation of pain.
History:-
 Horace william, a dentist used N2O (Nitrous oxide) as an anaesthetic
for tooth extraction in 1844.

3.  The first intravenous anaesthetic, thiopentone, was introduced in 1935.
 Mortan, a dentist, demonstrated ether as an anaesthetic agent and it
become popular.
Classification of general anaesthetics:-
There are three types of anaesthetics:-
1. Inhalation anaesthetics or Volatile anaesthetics:-
e.g. Chloroform (CHCl3), Diethyl ether (C2H5OC2H5),
Cyclopropane, Halothane (CF3CHClBr), Enflurane, Isoflurane.
2. Intravenous anaesthetics or Non-volatile:-
e.g. Thiopentone sodium, Methoxital sodium.
3. Gasous anaesthesia:- e.g. N2O (Nitrous oxide).

4. 1. Diethyl ether (C2H5OC2H5):-
Structure of diethyl ether:-
General structure of ether:-
R-O-R
Where, R= alky or phenyl group.
 There are two types of ether one is solvent ether which is used as
organic solvent another one is anaesthetic ether which is used in
surgical procedure.
 Only anaesthetic ether is used as a general anaesthetic.
Physical properties:-
 It is a clear, colourless liquid, volatile and highly flammable.
 It has characteristic odour.
C2H5 O C2 H5

5.  It has a sweet, burning taste.
 It is very volatile at room tempareture.
 It is soluble in water and miscible with alcohol, chloroform, benzene.
Stability and storage:-
 It should be kept in a closed, airtight, dry container, protected from
light.
 It should be stored in a cool place at a temperature of 8-15℃.
Official:- 1. Anaesthetic ether, I.P, B.P
Brand Name:-
1. Ether, 2. Sulphuric ether, 3. Anaesthetic ether, 4. ethyl oxide.

6. Uses:-
1. It is a potent general anaesthetic agent producing good analgesia and
good muscular relaxation.
2. It is also used in the isolation and extraction of many natural
products such as alkaloids.
2. Cyclopropane:-
 Cyclopropne is cyclic trimethylene.
Structure:-
H2
C
H2C CH2

7. Physical properties:-
 Cyclopropane is a colourless gas.
 It has characteristic odour.
 It has pungent taste.
 It is freely soluble in water and very soluble in ethanol, ether and
chloroform.
Stability and Storage:-
 It should be stored under pressure in metal cylinder in a cool place.
Official:- 1. Cyclopropane, I.P.
Uses:- 1. It is used as a general anaesthetic but now no longer used.

8. 3. Halothane:-
 It is a inhalation anaesthetics or volatile anaesthetics.
Structure of halothane:-
Chemistry of halothane:-
 It is a derivative of ethane CH3-CH3. The three hydrogen atoms at the
first carbon atom are replaced by three fluorine atoms.
 Two hydrogen atoms at the second carbon atom are replaced by one
bromine atom and one chlorine atom.
C
H
H
H
C
H
H
H
Ethane
C
F
F
F
C
Br
H
Cl
Halothane
1 2

9.  IUPAC Name 2-bromo-2-chloro-1,1,1-trifluoroethane.
Physical Properties:-
 Halothane is a clear, colourless, heavy, highly volatile liquid.
 It is non-inflammable.
 It has characteristic odour.
 It is slightly soluble in water but miscible with other liquids like
chloroform, alcohol, ether.
Stability and storage:-
 It should be kept in an airtight container which should be protected
from light and kept at a temperature below 25℃.
 It should not be stored in a container which is made of any metal it can
be react.

10. Official:- 1. Halothane, B.P.
Brand Name:- 1. Fluothane, 2. Bromochlorotrifluoroethane.
Uses:-
1. Halothane is a potent anesthetic but a relatively weak analgesic.
2. It is a potent bronchodilator.
3. Halothane relaxes both skeletal and uterine muscles and can be used
in obstetrics when uterine relaxation is indicated.
4. Trichloroethylene:-
 Trichloroethylene is 1,1,2-trichloroethene.
Structure:-
CH2 CH2
Ethene
CH C
Cl
Cl
Cl
1,1,2-Trichloro-ethene
1
2

11. Physical Properties:-
 It is a clear, colourless or pale blue liquid which non-inflammable.
 It’s boils at 88℃.
 It is practically insoluble in water but miscible with alcohol,
chloroform and ether.
 It is decomposed by light especially when moisture is present and
hydrochloric acid is produced.
Chemical Properties:-
 When trichloroethylene and bromine water are shaken together for one
hour in a stoppered glass cylinder at intervals of 15 mints, a white turbid
solution is formed in the lower layer. After that if we will added organic
compound such as chloroform and tetrachloride which will remain clear.

12. Stability and Storage:-
 It should be stored in tightly-closed, light-resistant containers in a cool
place.
Official:- 1. Trichloroethylene, I.P.
Brand Name:-
1. Trilene
2. Gemalgene
3. Trichloran etc.
Uses:- 1. It is used as a general anaesthetic but no longer used.

13. 5. Thiopentone sodium:-
 Thiopentone is a short-acting barbiturate.
 It is used in the formation of thiopentone sodium.
 It is used as a sedative and hypnotic for short-term treatment of
insomnia.
Structure:-
IUPAC Name:- Sodium 5-ethyl-5-(1-methyl)-2-thiobarbiturate
N
HN
O
C2H5
CH
O
NaS
CH3
CH2-CH2-CH3
1
2
3
4
5
6 Butyl group
1 2 3 4
Thiopentone sodium
HN
HN
O
O
1
2
3
4
5
6
O
Barbiturate
IUPAC Name:- 2,4,6 (1H,3H,5H)-Pyrimidinetrione

14. Chemistry:-
 Thiopentone has one ethyl group and one 1-methylbutyl group at the
5th position.
 The oxygen atom at the 2nd position is replaced by sulphur atom.
 Thiopentone is 5-ethyl-5-(1-methylbutyl)-2-thiobarbiturate.
 Thiopentone or thiopental has the same structure of pentobarbitone
 The only difference is that thiopentone has a suphur atom in place in
oxygen atom at position.
Physical Properties:-
 Thiopentone sodium is a white to yellowish-white powder.
 It has garlic odour.

15.  It is hygroscopic.
 It is freely soluble in water, party soluble in ethanol and practically
insoluble in benzene, ether.
Chemical Properties:-
 Thiopentone base may be precipitated by acidifying an aqueous
solution of thiopentone sodium with dilute acetic acid.
 Precipitate may be filtered, recrystallised from water and alcohol at
70℃.
 The crystals metal at about 160℃.
 The thiopentone crystals may be dissolved in dilute sodium hydroxide
solution and to the solution are added sodium prusside and after 15
mints, dilute hydrochloric acid. Yellowish violet colour is produced.

16. Stability and storage:-
 It should be stored in tightly closed, light-resistant containers.
Official:-
1. Thiopentone sodium, I.P, B.P,
2. Thiopentone sodium injection, I.P.
Brand Name:-
1. Pentothal, 2. Intraval sodium, 3. Nesdonal sodium
Uses:-
1. It is used as a simple anaesthetic for painless, short operations.
2. Thiopentone is commonly used as the inducing agent for general
anaesthesia.

17. 6. Methohexital Sodium:-
 Methohexital sodium contains an ally group and a 1-methyl-2-
pentynyl group in the 5th position and a methyl group in the 1st position.
 It is not a thiobarbiturate.
Physical Properties:-
 It is a white, hygroscopic powder without odour.
 It is soluble in water and insoluble in organic solvent.
 It melts at 92-96℃.
 It is affected by moisture, carbon dioxide and light.
Stability and Storage:-
 It is affected by moisture, carbon dioxide and light, so it must be
stored in tightly-closed, light-resistant container.

18. Brand Name:-
1. Brietal sodium, 2. Brevital sodium etc.
Uses:-
 It is used as a general anaesthetic.
 It is like thiopentone but is 3 times more power full and also has
quicker and more brief action.
 It is also used for short surgical operations.
 It is in the form of an intravenous injection and solution is made
carbon-dioxide-free water.