| Abstract|| |
Background: In India, a number of fixed dose drug combinations of non-steroidal anti-inflammatory drugs (NSAID's) are available, often as over-the-counter products. These combinations are being prescribed too. Evidence for efficacy of NSIAD fixed dose combination is lacking.
Objectives: The current study was undertaken to assess the analgesic and anti-inflammatory efficacy of these combinations over their individual components.
Materials and Methods: The study used three NSAIDs viz; paracetamol, ibuprofen and diclofenac sodium, alone or in combination with paracetamol. Animals were divided into six groups with six animals in each group. Analgesic activity was tested by writhing test and paw edema model was used to assess the anti-inflammatory activity. The test drugs were administered orally 30 min prior to injecting 0.6% solution of glacial acetic acid intraperitoneally for writhing test. For paw edema test, after 30 min of drugs administration, animals were injected with 0.1 ml of 1% carrageenan in subplanter region for inducing inflammation. Paw volume was again measured at baseline and after 3 h of subplanter injection of 1% carrageenan.
Results: The analgesic and the anti-inflammatory activity of paracetamol and ibuprofen combination were significantly greater than the individual agents when used alone. However, no significant difference in the analgesic or anti-inflammatory activity was found between diclofenac sodium and its combination with paracetamol. It was observed that diclofenac sodium was the most efficacious of the analgesics tested. Combining paracetamol with diclofenac did not show superior analgesic activity compared to diclofenac alone (P = 0.18).
Conclusion: Combining paracetamol with ibuprofen enhances analgesic/anti-inflammatory activity over their individual component but potentiation of analgesic activity of diclofenac was not seen when paracetamol was added to it.
Keywords: Analgesics, anti-inflammatory, fixed dose combination rat paw edema, Non-steriodal anti-infl ammatory drugs, writhing
|How to cite this article:|
Lahoti A, Kalra BS, Tekur U. Evaluation of the analgesic and anti-inflammatory activity of fixed dose combination: Non-steroidal anti-inflammatory drugs in experimental animals. Indian J Dent Res 2014;25:551-4
Non-steriodal anti-inflammatory drugs (NSAIDs) are among the most commonly prescribed drugs world over. NSAIDs are commonly used for treatment of mild to moderate pain and inflammation. They are prescribed for acute and chronic conditions like fever, headache, rheumatoid arthritis, osteoarthritis, etc., The treatment with NSAIDs can range from one day to a few months or even years depending upon disease condition. The NSAIDs exhibit their analgesic, antipyretic and anti-inflammatory activity by inhibiting the cyclo-oxygenase (COX) enzymes, which are responsible for the production of prostaglandins.
|How to cite this URL:|
Lahoti A, Kalra BS, Tekur U. Evaluation of the analgesic and anti-inflammatory activity of fixed dose combination: Non-steroidal anti-inflammatory drugs in experimental animals. Indian J Dent Res [serial online] 2014 [cited 2019 Jul 19];25:551-4. Available from: http://www.ijdr.in/text.asp?2014/25/5/551/147071
Paracetamol, ibuprofen and diclofenac sodium are some of the most frequently used NSAIDs in clinical practice. In India, a number of fixed dose drug combinations of NSAIDs are available, and are used often as over-the-counter (OTC) products. Fixed dose combination (FDC) of NSAIDs like paracetamol with diclofenac, ibuprofen with paracetamol, etc., are widely prescribed for treating fever, pain or inflammation. These combinations are being extensively marketed by pharmaceutical industry claiming higher efficacy compared to either of the drug used alone. However, there is inadequate documented evidence comparing the efficacy of these FDCs over the individual components.
Clinical trials in the past have compared the efficacy of paracetamol and NSAIDs given alone and in combination, for as varied a condition like dental pain or for the relief of postoperative pain. In a qualitative review, comparing analgesic effect of paracetamol, NSAIDs or their combinations in postoperative pain management, it was observed that the combination of NSAID and paracetamol had superior analgesic efficacy compared to paracetamol administered alone.  A double-blind study in children undergoing tonsillectomy provided evidence to support that, for perioperative analgesia a combination of ibuprofen with paracetamol was more effective than paracetamol alone.  Romsing et al., in a meta-analysis, reported the superiority of the combination of paracetamol with NSAIDs as compared to paracetamol alone, when used as an analgesic. In this report, diclofenac sodium was one of the NSAIDs, among the various NSAIDs studied. However, they also reported that the analgesic activity of the combination of paracetamol and NSAIDs was not superior when compared to NSAIDs alone.  Contrary to this finding, Hiller et al., observed that for postoperative analgesia for tonsillectomy, the combination of diclofenac and paracetamol was only marginally better than paracetamol or diclofenac when used alone.  Thus, the literary search indicates contradictory reports of analgesic activity of NSAIDs when used in combination with paracetamol.
FDCs are advocated if the combination provides an increase in efficacy, decrease in adverse effects or a decrease in dose of the individual drugs. The present study is designed to study the anti-inflammatory and anti-nociceptive activity of three most commonly used NSAIDs viz., paracetamol, ibuprofen and diclofenac sodium used alone or with the latter two in combination with paracetamol in animal models of pain and inflammation.
| Materials and Methods|| |
This study was approved by Institutional Animal Ethical Committee for experiments on small animals, Maulana Azad Medical College, New Delhi.
Wistar rats weighing 150-200 g and albino mice of 20-25 g body weight of either sex were procured from central animal house and were housed in air-conditioned environment. A gap of 1 week was kept for acclimatization of animals. They were provided with normal rat food pellet diet with water ad libitum.
Animals were divided into six groups with six animals in each group. All the animals received drugs through oral route. Drugs and carrageenan were dissolved in 0.5%CMC. For evaluation of analgesic activity, "Writhing Test", was used in swiss-breed albino mice. For evaluation of anti-inflammatory activity, wistar albino rats were used for the "Modified Randall-Selitto Test". Animals in group 1 served as control and received normal saline. Animals in group 2 were administered diclofenac sodium alone in the dose of 10 mg/kg in mice and 15 mg/kg in rats. Group 3 received Ibuprofen at the dose of 7.5 mg/kg in mice and 30 mg/kg in rats. In group 4, rats were pretreated with paracetamol at the dose of 100 mg/kg in mice and 300 mg/kg in rats. Group 5 received combination of diclofenac and paracetamol in the dose as in group 2 and 4. Group 6 was administered a combination of ibuprofen and paracetamol. Ibuprofen in the dose mentioned for group 3 and 4 as above.
Anti-inflammatory activity: Paw edema model (Modified Randall-Selitto Test)
After overnight fasting, on the morning of experiment, rats were weighed and baseline paw volume was measured with the aid of plethysmometer. To ensure uniformity, lateral malleolus of left hind limb was marked in all animals so that same length of paw is dipped in fluid each time. This was followed by oral administration of drugs. After 30 min of drugs administration, animals were injected with 0.1 ml of 1% carrageenan in subplanter region for inducing inflammation.  Paw volume was again measured after 3 h of subplanter injection of 1% carrageenan. The paw volume and percent decrease in paw edema was compared between control group and drug-treated groups.
Analgesic activity: Writhing test
Albino mice weighing 20-25 g were fasted overnight. The test drugs were administered orally 30 min prior to injecting 0.6% solution of glacial acetic acid intraperitoneally. Writhing movements were observed. These are characterized by specific abdominal contractions and are accompanied by elongation of the body with concave arching of the back and/or twisting or turning of the hip together with the hind paw and/or side rolling of the body and circling.  The number of writhes observed over a 10-min period were recorded and percent inhibition of writhing was also calculated and compared among control and drug-treated groups.
All results were expressed as Mean ± Standard Deviation (SD). Statistical significance was determined by One-way ANOVA with post hoc test (Bonferroni) was employed. P <0.05 was considered as significant.
| results|| |
Analgesic activity: Writhing
Writhing was observed in all control animals with 0.1% glacial acetic acid. The average number of writhes in control group was 38.3 ± 5.4. Pretreatment of rats with NSAIDs in all the groups showed statistically significant inhibition of writhes as compared to control [Table 1]. Decrease in mean count of writhes in diclofenac pretreated animals was maximum among single drug groups (38.3 ± 5.4 to 0.8 ± 1.3, P < 0.05). Pretreatment of animals with ibuprofen and paracetamol combination significantly decreased writhing in comparison to control animals (38.3 ± 5.4 to 12.5 ± 3.4, P < 0.05). Decrease in number of writhes were also significant as compared to ibuprofen and paracetamol-alone groups. In the group administered with combination of paracetamol and diclofenac, significant decrease in writhing was observed as compared to control and paracetamol alone group. Mean decrease in number of writhes with combination of paracetamol and diclofenac was not found to be statistically significant as compared to diclofenac alone group (P = 0.18).
|Table 1: Effect of NSAIDs on acetic acid induced writhing response in mice (n=6) |
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Anti-inflammatory activity: Paw edema
Marked edema was produced in rats with sub planter injection of 0.1 ml of 1% carrageenan. Mean paw edema in the control rats was 708.2 ± 108.4 cu.mm [Table 2]. Pretreatment of rats with diclofenac alone showed significant decrease in paw edema as compared to control (708.2 ± 108.4 to 88.6 ± 108.5, P < 0.05). The groups pretreated with ibuprofen and paracetamol alone also showed significant decrease in edema as compared to control but maximum reduction in paw edema was observed with diclofenac [Table 2]. Pretreatment of rats with combination of ibuprofen and paracetamol, significantly inhibited paw edema as compared to control (708.2 ± 108.4 to 155.0 ± 100.0, P < 0.05). Decrease in mean paw edema was also significant in rats pretreated with this combination as compared to NSAID alone (ibuprofen, paracetamol) groups. In the group administered with combination of paracetamol and diclofenac, significant decrease in mean paw edema was observed as compared to control and paracetamol alone group. Mean paw edema reduction with combination of paracetamol and diclofenac was not found to be statistically significant as compared to diclofenac alone group (P = 0.18).
|Table 2: Effect of NSAIDs on carrageenan induced paw edema in rats (n=6) |
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| Discussion|| |
It is a well-documented fact that FDCs should be advocated if each component is necessary for the desired effect and if the advantages outweigh the added risks of using two or more drugs.  Also, FDCs are more likely to be useful when the incidence of adverse reactions is not increased or remains leveled to that of its individual component. FDC of NSAIDs are being aggressively promoted by pharmaceutical industry which leads to excessive prescribing.  There is, however, inadequate experimental or clinical evidence regarding the enhanced efficacy of these FDCs of NSAIDs. Very few clinical studies have demonstrated that the combination of NSAIDs increases analgesic activity. ,,, There is paucity of data comparing the different FDC preparations available for NSAIDs. Hence in the present study, three most commonly prescribed NSAIDs, i.e. diclofenac sodium, ibuprofen and paracetamol were selected to compare the analgesic effect and the anti-inflammatory activity when administered alone or in combination, in experimental animals. 
In the present study, it was observed that diclofenac had the maximum analgesic and anti-inflammatory activity compared to paracetamol and ibuprofen. However, the addition of paracetamol to diclofenac did not increase either the analgesic effect or the anti-inflammatory activity. These findings are similar to those reported in human studies earlier. , In the current study, the paracetamol and diclofenac combination, however, showed a significant decrease in both the analgesic and the anti-inflammatory activity when compared to paracetamol administered alone. The analgesic and anti-inflammatory activity of ibuprofen was found to be greater than that of paracetamol. Consequently the combination of the two drugs was found to be superior to either of the drugs administered alone.
A study conducted on 60 women undergoing elective abdominal gynecological surgery has shown that the combination of paracetamol and diclofenac sodium when administered before the operation, reduced the cumulative dose of morphine required during the intraoperative period.  This was attributed indirectly to a better analgesic effect of the combination of paracetamol and diclofenac sodium. This study, however, did not compare the analgesic effect of diclofenac or paracetamol with each other. . A study by Kalra et al, reported that fixed dose combinations does not possess additional analgesic activity over their individual components. 
In view of the above findings it is felt that detailed studies need to be done comparing the additive or synergistic analgesic, anti-inflammatory and anti-pyretic activity of different NSAIDs available extensively as FDC.
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Bhupinder S Kalra
Department of Pharmacology, Maulana Azad Medical College, New Delhi
Source of Support: None, Conflict of Interest: None
[Table 1], [Table 2]