UG under my supervision.

1. Under the guidance of
Mr. Raja Chakraborty
Assistant Professor
Bengal College of Pharmaceutical Sciences and Research
Durgapur-12. West Bengal.
Amit Samanta.
4th Year B. Pharm
Roll. No. : 24201910002
1

2. Aim: Evaluation of the synergistic effect of a
combination of opioid and non opioid analgesics in
experimental models of pain
Objectives:
To evaluate the analgesic activity of an opioid
analgesic employing suitable animal models.
To evaluate the analgesic activity of a non-opioid
analgesic employing suitable animal models.
To evaluate the analgesic synergism of a opioid-nonopioid fixed dose combination employing suitable
animal models.
2

3. Background
 Definition of Pain ( Algesia): Pain is defined as an unpleasant
sensory & emotional experience associated with actual or potential
tissue damage or described in terms of such damage.
 Cause of pain: Pain may occur due to many reasons like
inflammation, infection, tissue necrosis, stretching of tissue, chemical
or burn. In skeletal muscle, it may result from ischemia or
hemorrhage.
3

4. Classification of Analgesics
Analgesics
OPIOIDS
(Strong
Analgesics)
NSAIDs
(Mild analgesics)
Aspirin
Nimesulide
(COX-2 )
Acetaminophen
Morphine
Pethidine
Codeine
4

5. Material and Methods
Instruments:
 Analgesiometer (Tail-flick)
 Hot plate
Chemicals and drugs:
 Nimesulide powder
(General Import Company India Pvt. Ltd)
 Pethidine (100mg/2ml)
(Bengal Chemicals & Pharmaceutical works Ltd.)
 Acetic acid (1%v/v solution).
Fig 1: Pethidine.
Animals:
 Swiss albino mice ( Mus musculus )[Body wt. 20-40gms]
5

6. Methods
1.
Tail-flick method: 6 mice weighing between 20-40 grams, of either sex were
used for the experiment. Then the basal reaction time is taken by placing the
tip (last 1-2 cm) of the tail on the radiant heat source. The tail withdrawal from
the heat (flicking response) is taken as the end point.
2.
Eddy’s hot plate method: 6 mice weighing between 20-40 grams, of either
sex were used for the experiment. Then the basal reaction time is taken by
placing on the hot plate which is the heat source. The paw licking or jump
response from the heat is taken as the end point. A cut off period of 10-12 sec
was observed to prevent damage to the paw.
3.
Acetic acid induced Writhing test: 6 mice weighing between 20-40 grams, of
either sex were used for the experiment. Then they were divided into two
groups, consisting of three animals in control group (only acetic acid) and
three animals in test group (acetic acid + drug) each, where the i.p. dose is
given. Then the onset of wriths is noted down i.e. the number of abdominal
contractions (AC), trunk twist response (TT) and hind limb extension (HLE)
up to 10 minutes.
6

7. RESULTS
7

8. Tail-flick test - Pethidine:
Sl. No.
BW of
mice
(gm)
Dose
(mg/ kg)
Mean
basal
reading
time
(sec)
After 10
mins
(sec)
After 20
mins
(sec)
After 30
mins
(sec)
After 40
mins (sec)
After 50mins
(sec)
1
35
10
1.83
2.73
7.15
12.09
5.09
1.62
2
24
10
1.84
1.24
5.23
10.45
6.55
1.09
3
25
10
1.96
1.08
6.45
11.59
5.34
1.23
4
30
10
1.42
0.97
5.39
9.54
6.59
1.18
5
31
10
1.25
1.17
7.25
10.43
5.45
1.07
6
38
10
2.04
0.89
6.23
12.86
7.54
1.34
Tail-flick test - Nimesulide:
Sl.
No.
BW of mice
(gm)
Dose (mg/
kg)
1
25
26
2
34
26
3
35
4
Mean
basal
reading
time (sec)
After 10
mins
After 20
mins
After 30
mins
After 40
mins
After 50
mins
2.05
4.35
8.55
5.23
1.13
2.07
4.55
7.13
10.04
6.12
2.12
26
3
2.12
6.23
9.45
4.25
2.12
29
26
0.81
1.12
4.45
10.07
7.23
2.04
5
33
26
0.96
0.96
3.56
7.34
4.55
1.39
6
30
26
0.85
1.55
4.19
8.34
5.27
1.07
0.79
8

9. Tail-flick test of Pethidine + Nimesulide:
Sl.
No.
BW of
mice (gm)
Dose (mg/
kg)
Mean
basal
reading
time (sec)
After 10
mins (sec)
After 20
mins (sec)
After 30
mins (sec)
After 40
mins (sec)
After
50mins
(sec)
1
30
(5+13)
0.84
2.72
8.15
19.09
7.67
1.62
2
26
(5+13)
0.92
1.45
7.76
19.24
6.78
1.45
3
36
(5+13)
0.89
1.98
6.85
18.77
6.30
1.34
4
22
(5+13)
0.78
0.97
7.38
19.25
5.81
1.23
5
39
(5+13)
0.57
1.89
7.98
17.95
6.46
1.57
6
27
(5+13)
0.95
2.38
8.67
19.78
7.56
1.84
9

10. Eddy’s Hot plate - Nimesulide
Sl.
No.
Body
Weight
of mice
(gm)
Dos
e
(mg/
kg)
Mean
besal
readi
ng
time
(sec)
After 10 mins
1
32
26
1.38
1.19
1.51
2.72
1.48
1.12
2
25
26
1.47
1.23
1.97
2.13
1.72
1.08
3
30
26
1.96
1.93
2.07
2.98
1.58
0.82
4
33
26
1.42
0.89
1.24
2.95
1.20
0.95
5
35
26
1.25
1.03
2.31
2.60
1.18
0.97
6
39
26
2.04
0.81
2.02
2.97
1.81
1.04
Paw
liking
(Sec)
After 20
mins
Jump
respon
se (sec)
Paw
likin
g
(sec)
After 30 mins
Jum
p
respo
nse
(sec)
After 40 mins
After 50 mins
Paw
liking
(Sec)
Paw
liking
(Sec)
Paw
liking
(Sec)
Jump
respo
nse
(sec)
Jump
respo
nse
(sec)
Jump
respo
nse
(sec)
Eddy’s Hot plate - Pethidine
Sl.
No.
Body
Weight
of mice
(gm)
Dose
(mg/
kg)
Mean
basal
reading
time
(sec)
After 10 mins
Paw
liking
(Sec)
Jump
respons
e (sec)
After 20 mins
Paw
liking
(Sec)
Jump
respon
se (sec)
After 30 mins
Paw
liking
(Sec)
Jump
respons
e (sec)
After 40 mins
Paw
liking
(Sec)
Jump
respons
e (sec)
After 50 mins
Paw liking
(Sec)
Jump
response
(sec)
1
35
10
2.70
3.96
6.89
10.23
8.57
2.59
2
24
10
1.50
2.38
4.99
9.39
3.76
2.12
3
25
10
2.54
1.98
5.79
10.03
4.81
2.45
4
30
10
2.39
2.78
6.86
11.86
9.58
3.94
5
31
10
1.09
2.47
6.35
2.13
6
39
10
2.87
1.74
6.10
1.90
5.97
8.84
5.72
9.78
10

11. Eddy’s Hot plate : Pethidine + Nimesulide
Sl.
No.
Body
Weight of
mice (gm)
Dose
(mg/
kg)
Mean
basal
readin
g time
(sec)
After 10
mins
Pa
w
liki
ng
(Se
c)
Jump
respo
nce
(sec)
After 20 mins
After 30 mins
After 40 mins
After 50 mins
Paw
liking
(Sec)
Paw
liking
(Sec)
Paw
liking
(Sec)
Paw
liking
(Sec)
Jump
respo
nce
(sec)
Jump
respon
ce
(sec)
Jump
respon
ce
(sec)
Jump
respo
nce
(sec)
1
30
(5+13)
1.07
2.95
8.25
15.24
7.52
2.27
2
26
(5+13)
1.12
3.19
8.53
14.68
6.94
2.49
3
36
(5+13)
1.24
9.13
18.59
8.86
4
22
(5+13)
2.39
1.95
7.38
15.14
6.75
2.18
5
39
(5+13)
1.09
2.39
8.43
15.97
7.17
2.08
6
27
(5+13)
2.48
16.33
6.16
2.25
2.7
8
2.9
4
7.84
2.26
11

12. Writhing test -Nimesulide
Sl.
No.
Dose [acetic
acid/drug]
Treatment
No. of writhings in
10 mins
Mean
1
2
3
4
BW of
mice
(gm)
28
26
23
40
1% soln.
1% soln.
1% soln.
1% soln. + 26mg/kg
CONTROL
{acetic
acid}
78
74
87
60
79.666
5
30
1% soln. + 26mg/kg
6
39
1% soln. + 26mg/kg
TEST
{acetic acid
+ drug}
60.333
59
62
Writhing test- Pethidine
Sl. No.
BW of mice (gm)
1
23
Dose [acetic
acid/drug]
1% soln.
2
26
1% soln.
3
39
1% soln.
4
28
1% soln. + 10mg/kg
5
40
1% soln. +10mg/kg
6
38
1% soln. +10mg/kg
Sl. No.
Treatment
CONTROL
{acetic acid}
Mean
90
97
84
TEST {acetic
acid + drug}
61
57.666
59
53
1
BW of
mice (gm)
23
Dose [acetic
acid/drug]
1% soln.
2
Writhing test : Pethidine + Nimesulide
No. of writings in
10 mins
89
26
1% soln.
3
39
1% soln.
4
28
5
40
6
38
1% soln. +
(5+13)mg/kg
1% soln. +
(5+13)mg/kg
1% soln. +
(5+13)mg/kg
Treatment
CONTROL
{acetic acid}
No. of writings’
in 10 mins
89
Mean
88.333
86
90
TEST {acetic
acid + drug}
38
38
36
40
12

13. Discussions & Conclusions
The combination group of Nimesulide and Pethidine exhibited
significantly enhanced analgesic activity in the aforesaid models
of pain in Swiss albino mice while compared to the individual
drug groups.
The results of the present study indicates that the combination
of an opioid and non-opioid analgesic exhibits significant
synergism in the animal models of pain using animal models of
pain such as Eddy’s hot plate method, Tail flick method using
the Analgesiometer and the findings from the acetic acid
induced writhing appears to corroborate this hypothesis.
13

14. Future Scope of Work
Future studies with more species of animals and a
larger sample size needs to be conducted to establish
and corroborate the hypothesis of this present pilot
study with the underlying aim of better
understanding the mechanism and innate utility of
such a synergism of opioids in the realm of preclinical
research and a part of future for its
utility
therapeutics.
14

15. References
 Susanne Abdulla, Regina Eckhardt,Ute Netter and Walied Abdulla. Efficacy of
three IV non-opioid-analgesicson opioid consumption for postoperative
painrelief after total thyroidectomy:a randomised, double-blind trial M.E.J.
ANESTH 21 (4), 2012.
 Howard S. Smith, Combination Opioid Analgesics Pain Physician 2008;
11:201-214 • ISSN 1533-3159.
 Paul F. White, PhD, MD, FANZCA. The Role of Non-Opioid Analgesic
Techniques in the Management of Pain After Ambulatory Surgery, Anesth
Analg 2002;94:577–85.
 Mark J. Edlund a,b, Diane Steffick a,b,c, Teresa Hudson a,b,Katherine M.
Harris d, Mark Sullivan. the Risk factors for clinically recognized opioid abuse
and dependence among veterans using opioids for chronic non-cancer pain,
Pain 129 (2007) 355–362
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