Under the guidance of

Mr. Raja ChakrabortyAssistant Professor

Bengal College of Pharmaceutical Sciences and ResearchDurgapur-12. West Bengal.

Amit Samanta.4th Year B. Pharm

Roll. No. : 24201910002

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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-non-opioid fixed dose combination employing suitable animal models.

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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.

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Classification of Analgesics

Aspirin Pethidine

Codeine

MorphineNimesulide(COX-2 )

Acetaminophen

NSAIDs(Mild analgesics)

OPIOIDS(Strong

Analgesics)

Analgesics

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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).  Animals: Swiss albino mice ( Mus musculus )[Body wt. 20-40gms]

Fig 1: Pethidine.

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Methods1. 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.

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RESULTS

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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 - Pethidine:

Sl. No.

BW of mice (gm)

Dose (mg/ kg)

Mean basal

reading time (sec)

After 10 mins

After 20 mins

After 30 mins

After 40 mins

After 50 mins

1 25 26 0.79 2.05 4.35 8.55 5.23 1.13

2 34 26 2.07 4.55 7.13 10.04 6.12 2.12

3 35 26 3 2.12 6.23 9.45 4.25 2.12

4 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

Tail-flick test - Nimesulide:

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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

Tail-flick test of Pethidine + Nimesulide:

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Sl. No.

Body Weight of mice (gm)

Dose

(mg/ kg)

Mean besal readi

ng time (sec)

After 10 mins After 20 mins

After 30 mins After 40 mins After 50 mins

Paw liking (Sec)

Jump response (sec)

Paw likin

g (sec)

Jump

response

(sec)

Paw liking (Sec)

Jump response

(sec)

Paw liking (Sec)

Jump response

(sec)

Paw liking (Sec)

Jump response

(sec)

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

Eddy’s Hot plate - Nimesulide

Sl. No.

Body Weight of mice (gm)

Dose (mg/ kg)

Mean basal

reading time (sec)

After 10 mins After 20 mins After 30 mins After 40 mins After 50 mins

Paw liking (Sec)

Jump response (sec)

Paw liking (Sec)

Jump response (sec)

Paw liking (Sec)

Jump response (sec)

Paw liking (Sec)

Jump response (sec)

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 5.97 8.84 6.35 2.13

6 39 10 2.87 1.74 5.72 9.78 6.10 1.90

Eddy’s Hot plate - Pethidine

Sl. No.

Body Weight of mice (gm)

Dose (mg/ kg)

Mean basal

reading time (sec)

After 10 mins

After 20 mins After 30 mins After 40 mins After 50 mins

Paw

liking (Sec)

Jump responce (sec)

Paw liking (Sec)

Jump responce (sec)

Paw liking (Sec)

Jump respon

ce (sec)

Paw liking (Sec)

Jump respon

ce (sec)

Paw liking (Sec)

Jump responce (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 2.78

9.13 18.59 8.86 2.26

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 2.94

7.84 16.33 6.16 2.25

Eddy’s Hot plate : Pethidine + Nimesulide

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Sl. No.

BW of mice (gm)

Dose [acetic acid/drug]

Treatment No. of writhings in 10 mins

Mean

1 28 1% soln. CONTROL {acetic acid}

78 79.666

2 26 1% soln. 74

3 23 1% soln. 87

4 40 1% soln. + 26mg/kg TEST {acetic acid

+ drug}

60 60.333

5 30 1% soln. + 26mg/kg 59

6 39 1% soln. + 26mg/kg 62

Sl. No. BW of mice (gm)

Dose [acetic acid/drug]

Treatment No. of writings in 10 mins

Mean

1 23 1% soln. CONTROL {acetic acid}

89 90

2 26 1% soln. 97

3 39 1% soln. 84

4 28 1% soln. + 10mg/kg TEST {acetic acid + drug}

61 57.666

5 40 1% soln. +10mg/kg 59

6 38 1% soln. +10mg/kg 53

Sl. No. BW of mice (gm)

Dose [acetic acid/drug]

Treatment No. of writings’ in 10 mins

Mean

1 23 1% soln. CONTROL {acetic acid}

89 88.333

2 26 1% soln. 86

3 39 1% soln. 90

4 28 1% soln. + (5+13)mg/kg

TEST {acetic acid + drug}

38 38

5 40 1% soln. + (5+13)mg/kg

36

6 38 1% soln. + (5+13)mg/kg

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Writhing test : Pethidine + Nimesulide

Writhing test- Pethidine

Writhing test -Nimesulide

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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.

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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.

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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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