Indian Journal of Pharmacology Home 

[Download PDF]
Year : 2012  |  Volume : 44  |  Issue : 4  |  Page : 475--479

Experimental evaluation of analgesic and anti-inflammatory activity of simvastatin and atorvastatin

Swapnil R Jaiswal, Smita D Sontakke 
 Department of Pharmacology, Government Medical College, Nagpur, Maharashtra, India

Correspondence Address:
Smita D Sontakke
Department of Pharmacology, Government Medical College, Nagpur, Maharashtra


Aim: The aim of this study is to evaluate the analgesic and anti-inflammatory activities of atorvastatin and simvastatin in different experimental models in mice and rats. Materials and Methods: Analgesic activity of simvastatin and atorvastatin was assessed in tail flick model in rats (n = 6), where it was compared with aspirin and tramadol and in acetic acid induced writhing in mice (n = 6), where it was compared with aspirin. Anti-inflammatory activity of statins was evaluated using carrageenin induced paw edema and formalin induced arthritis in rats. Results: In the tail flick method, analgesic effect of tramadol was significantly more than the other drugs except at two observation times, when it was comparable to simvastatin and atorvastatin. Effect of simvastatin was found to be comparable to aspirin. In acetic acid induced writhing method, analgesic activity of simvastatin was comparable to that of aspirin while that of atorvastatin was significantly less. In carrageenin induced paw edema in rats, both simvastatin and atorvastatin showed anti-inflammatory activity which was comparable to aspirin. Both the statins exhibited significant anti-inflammatory activity (P < 0.01) in formalin induced arthritis model though less than aspirin (P < 0.05). Conclusion: The results of this study if substantiated by further experimental and clinical research suggest that simvastatin and atorvastatin may play an adjuvant role, which may be particularly beneficial in the treatment of inflammatory disorders, especially when there is coexisting dyslipidemia.

How to cite this article:
Jaiswal SR, Sontakke SD. Experimental evaluation of analgesic and anti-inflammatory activity of simvastatin and atorvastatin.Indian J Pharmacol 2012;44:475-479

How to cite this URL:
Jaiswal SR, Sontakke SD. Experimental evaluation of analgesic and anti-inflammatory activity of simvastatin and atorvastatin. Indian J Pharmacol [serial online] 2012 [cited 2023 Apr 2 ];44:475-479
Available from:

Full Text


Drugs commonly used in modern medicine for suppression of pain and inflammation like non-steroidal anti-inflammatory drugs and corticosteroids provide only symptomatic relief. Long-term use of these drugs is associated with serious adverse effects. Hence, the search for a new, safe analgesic and anti-inflammatory drug is ongoing. Introduced in 1980, statin group of drugs are most efficacious and well-tolerated in the treatment of hyperlipidemia. Statins are widely used for the prevention of cardiovascular diseases. Although the beneficial effects of statins in preventing cardiovascular diseases may derive from their lipid-lowering activity, these drugs have also been shown to possess anti-inflammatory and immunomodulatory effects. [1] Indeed, several recent studies have demonstrated the ability of diverse statins to prevent chronic inflammation in vivo, and one clinical trial has shown the beneficial effects of atorvastatin in patients with rheumatoid arthritis. [2],[3],[4],[5]

Statins have been shown to decrease the secretion of pro-inflammatory cytokines IL-6 (interleukin-6) and IL-8 (interleukin-8) from macrophages, and inhibit the release of the chemokine CCL2/MCP-1 (macrophage chemotactic protein-1) from these cells. [6],[7] The molecular mechanisms sub serving such anti-inflammatory and/or immunomodulatory activities are unclear. Osteoarthritis is a common disorder that causes severe pain and immobility in the patient. Treatment of osteoarthritis in modern medicine is currently limited to drugs that provide only symptomatic relief, and these drugs are associated with serious adverse effects. Hence, research for finding a better and safe drug for osteoarthritis has been a continuous process. Patients of hyperlipidemia are often overweight and more likely to suffer from osteoarthritis. [8] Considering various reports about anti-inflammatory and analgesic activity of statins, it is worthwhile to further evaluate these activities.

Atorvastatin has also been evaluated for its anti-inflammatory and analgesic activities; however, the results are controversial. [9] During our literature search we did not come across any study that evaluated the analgesic activity of simvastatin. Hence, this study was planned to evaluate and compare the anti-inflammatory and analgesic activities of simvastatin and atorvastatin in different animal models of inflammation and pain.

 Materials and Methods


Adult Wistar albino rats (Rattus norvegicus, weighing between 180 -280 g) and Swiss mice (weighing between 25-30 g) of either gender were used. Animals were kept in cages in temperature-regulated rooms with air-cooling and 12 hours light and dark cycle, and had free access to water and standard laboratory diet. They were allowed to acclimatize to the laboratory conditions for a period of one week, and kept fasting overnight prior to the experiment. The study was approved by the Institutional Animal Ethics Committee and all the experiments were performed as per the Committee for the purpose of control and supervision on experiments on animals (CPCSEA) guidelines.

Drugs and Reagents

Simvastatin pure powdered form (Jubliant Organic Ltd.), atorvastatin pure powdered form (Ind-Swift laboratories ltd.), aspirin in pure powdered form (The Sugars Ltd), Injection tramadol, carrageenin 1% in 0.9% saline, carboxymethyl cellulose, and polyethylene glycol as a solvent were used. Simvastatin, atorvastatin and aspirin in pure powdered form were obtained as gift samples from the companies mentioned in parenthesis. For evaluation of both analgesic and anti-inflammatory activities, animals were divided into the following four groups (n = six in each group):Group 1- control group: Treated with normal saline (2 ml/kg orally) with polyethylene glycol; Group 2- simvastatin group: Treated with simvastatin (40 mg/kg orally) dissolved in polyethylene glycol; Group 3- atorvastatin group: Treated with atorvastatin (10 mg/kg orally), dissolved in polyethylene glycol; Group 4- aspirin group:Treated with aspirin (300 mg/kg orally), dissolved in carboxymethylcellulose. For tail-flick model of analgesia an additional group (n = six) treated with Injection tramadol Dose: 10 mg/kg intraperitoneal (i.p) was included.

Evaluation of analgesic activity

Tail-flick method

Analgesia was measured using modified method of D Amour and Smith [10] called as tail flick method using an analgesiometer. Reaction time in seconds was used as the unit for measurement of pain and an increase in reaction time was indicative of analgesia. Time between placing the tail of the rat on the radiant heat source and sharp withdrawal of the tail was recorded as "reaction time". Cut off time of ten seconds was imposed in all sets of experiments taken as maximum latency so as to rule out thermal injury while noting down the reaction time. Animals that showed a mean reaction time outside the range of five-six seconds, were discarded. In all the groups, tail-flick test was performed prior to drug administration, and at 30, 60, 90 and 120 minutes after drug administration, and the reaction time at each time interval (test latency) was calculated.

Percentage analgesia was calculated using the following formula:

% Analgesia = MPE=TL-BL / ML-BL × 100

Where, M.P.E. = Maximum possible effect, M.L. = Maximum latency or cut off time T.L. = Test latency, B.L. = Basal latency or control latency

Acetic acid induced writhing method

The writhing model represents a chemical nociceptive test based on the induction of peritonitis like condition in animals by injecting irritant substances i.p. After 30 minutes of drug administration, 0.1 ml of 1% acetic acid solution was injected i.p. Mice were placed individually into glass beakers and five minutes were allowed to elapse. They were then observed for a period of ten minutes and the numbers of writhes were recorded in each animal. For scoring purpose, a writhe is indicated by stretching of the abdomen with simultaneous stretching of at least one hind limb. [11]

Percentage inhibition was calculated using the following formula:

% inhibition= { (W c - W t ) × 100 } / Wc

Where, W c = No. of writhes in control group, W t = No. of writhes in test group

Compounds with less than 70% inhibition were considered to have minimal analgesic activity. [11]

Evaluation of anti-inflammatory activity

Acute anti-inflammatory activity

Paw edema was induced by an intradermal injection of 0.1 ml of carrageenin (1% in normal saline solution) into the plantar surface of the right hind paw of rats (method of Winter, Risley and Nuss). [12] The acute phase of inflammatory reaction, i.e. edema volume of right hind paw was determined using a plethysmometer modified by Hardayal Singh and Ghosh, [13] prior to and 30, 60 and 120 minutes after carrageenin injection. All the drugs were administered one hour prior to carrageenin. Percentage inhibition of paw edema was calculated using the following formula:


Chronic anti-inflammatory activity

In this method, a chronic phase of inflammation was induced by subcutaneous injection of 0.1 ml of 2% formalin under the plantar aponeurosis of right hind paw of rats on first and third day of the experiment. [14] Treatment was started on day one and continued daily for ten days. The linear cross section (LCS) immediately below the ankle joint was measured daily with the vernier caliper. The difference in LCS on day one and day ten was calculated for all groups. Percentage anti-inflammatory effect of particular drug was calculated as follows:


Statistical analysis

Results are expressed as mean ± Standard Error of Mean (SEM). Data was analyzed using Graph pad prism software version 5.01. Comparison between different groups was done by One-Way Analysis of Variance (ANOVA) followed by Tukey's test. P value less than 0.05 was considered statistically significant.


Analgesic Activity: Tail-Flick Method

[Table 1] shows that at 30 minutes, the MPE values of simvastatin and tramadol were comparable (P > 0.05) while that of atorvastatin was statistically significantly less than both (P < 0.05). At 60 and 90 minutes, mean MPE of tramadol was maximum, and significantly greater than the other three groups (P < 0.05). At 120 minutes, MPE of atorvastatin and tramadol was comparable and was significantly more when compared to both, simvastatin and aspirin (P < 0.05). Atorvastatin showed the maximum MPE at 120 minutes amongst the different time intervals, which was comparable to that of tramadol (P > 0.05). [Table 1]{Table 1}

Analgesic activity: acetic acid - induced writhing method

[Table 2] illustrates the time to onset of writhing and the number of writhes in ten minutes which were significantly less in simvastatin and aspirin group when compared to control (P < 0.001), while in the atorvastatin group, these were comparable to that of control and were significantly more as compared to aspirin. Percentage analgesia was maximum in aspirin group (85.36%) and lowest in atorvastatin group (36.30%). [Table 2]{Table 2}

Acute anti-inflammatory activity

[Table 3] shows that the basal mean paw volume was comparable in all the groups. At 60 minutes and 120 minutes, the mean paw volume in all the three drug treated groups was statistically significantly lower when compared to control group (P < 0.001). Percentage inhibition of acute inflammation was greater in aspirin group when compared to simvastatin and atorvastatin at all-time intervals. Similarly, the percentage inhibition in simvastatin group was greater than that of atorvastatin at all-time intervals. [Table 4]{Table 3}{Table 4}

Chronic anti-inflammatory activity

The mean difference between LCS on tenth day and first day was calculated for each group. Lower the difference in LCS, higher is the anti-inflammatory action. [Table 5] shows that the mean differences in LCS in all the three drug treated groups were statistically significantly less when compared to control (P < 0.001), though the difference in LCS in simvastatin and atorvastatin groups was more than that in aspirin group (P < 0.05). The least difference in mean LCS was found in the aspirin group. Inhibition of arthritis started from the fifth day in aspirin group, sixth day in atorvastatin group and seventh day in the simvastatin group, and maximum effect was seen on the tenth day in all the groups.{Table 5}


Statins have been widely used in the treatment of dyslipidemia since long. More recently there has been an interest in the analgesic and anti-inflammatory activities of statins following reports about their ability to relieve pain and inflammation. Tail flick method of analgesia is effective in estimating the efficacy and potency of centrally acting analgesics. [14] This was evident in this study wherein the pain threshold increased significantly during the period of observation in all the four drug treated groups, with maximum effect observed in the tramadol group. Though aspirin has a central component of action, it predominantly produces analgesia through a peripheral action; [7],[15] hence, maximum analgesic action of aspirin cannot be evident in this method which may be the reason that analgesic activity of simvastatin was comparable to aspirin. That atorvastatin showed analgesic activity comparable to tramadol at 120 minutes appears to be a significant finding and suggests that this drug has a slow onset of analgesic action.

In acetic acid induced writhing model, compounds with percentage analgesia of less than 70% are considered to have minimal analgesic activity. [14] Percentage analgesia with both simvastatin and atorvastatin was less than 70%, and it was more than 80% only in the aspirin treated animals. The writhing response induced by acetic acid is a sensitive procedure to establish peripherally acting analgesics. This response is thought to involve local peritoneal receptors. As this method mainly evaluates peripherally acting analgesics, maximum analgesic activity of aspirin was observed in this model. Simvastatin also exhibited significant analgesic activity though less than aspirin. Selective analgesic action of statins has not been evaluated in commonly used experimental models of analgesia; hence, we lack comparative data. Published reports are based on their evaluation in inflammatory nociception. In a rat model of adjuvant-induced arthritis, atorvastatin prevented the hypernociception observed in inflamed joints, [7] while orally administered atorvastatin was found to be effective in inhibiting inflammatory hypernociception in a model of mechanical hypernociception in mouse paw with an electronic pressure-meter. [16]

We did not investigate the underlying mechanism by which statins inhibit nociception; however, it has been reported that bradykinin, (BK), tumour necrosis factor-a (TNF- a), interleukin-1b (IL-1b) and the chemokine CXCL induce approximately the same intensity of hypernociception, and pretreatment with atorvastatin reduced each of these hypernociceptive states, to about the same level. [16] Atorvastatin also has been reported to reduce prostaglandin E2 (PGE2)-induced hypernociception. [17],[18]

Though the results of our study show that analgesic activity of simvastatin and atorvastatin is comparable to aspirin and tramadol, respectively, at specific time intervals in the tail-flick model of analgesia, it is less likely that this would be useful in their clinical use as analgesics in the absence of inflammation. Mediators involved in inflammatory nociception are distinct and reports in literature suggest that statins may be more effective in suppressing the release of these mediators; and hence, their clinical utility would be better in these settings.

In the model of acute inflammation, both simvastatin and atorvastatin showed anti-inflammatory activity comparable to aspirin. Similar findings have been reported by Sparrow CP et al.[1] wherein, simvastatin administered orally (10 to 100 mg/kg) to mice significantly reduced the extent of carrageenin-induced foot pad edema.

Carrageenin-induced hind paw edema is the standard experimental model of acute inflammation. Carrageenin is the phlogistic agent of choice for testing anti-inflammatory drugs as it is not known to be antigenic and is devoid of apparent systemic effects. This model exhibits a high degree of reproducibility and has significant predictive value for clinically useful anti-inflammatory drugs. [10] Carrageenin-induced edema is a biphasic response. The first phase is mediated through the release of histamine, serotonin and kinins, whereas the second phase is due to the release of prostaglandin and slow reacting substances. [19] Inhibition of carrageenin induced edema by simvastatin and atorvastatin can therefore be attributed to their ability to inhibit release of various mediators of inflammation.

Both statins showed significant anti-inflammatory activity though less than aspirin in formalin induced arthritis model of chronic inflammation. Though we did not come across any study evaluating the anti-inflammatory activity of statins in a similar experimental model, the same has been done in arthritis induced by other methods. Atorvastatin has been found to have significantly inhibited adjuvant-induced arthritis in rats, and simvastatin had significant efficacy in murine collagen-induced arthritis. [7],[9] Atleast one clinical trial has reported the efficacy of atorvastatin in a randomized, double-blind, placebo-controlled clinical trial in patients of rheumatoid arthritis in whom atorvastatin was used as an adjunct to existing disease-modifying antirheumatic drug therapy. [5]

Various investigators have tried to explore the mechanisms underlying the anti-inflammatory activity of statins. Simvastatin therapy significantly decreased high-sensitivity C-reactive protein (a bio-marker of inflammation) levels in patients of metabolic syndrome compared with placebo, and resulted in a significant reduction in plasma and lipopolysaccharide-activated monocytic release of interleukin 6 (IL-6) and TNF. [20] Hence, it appears that statins can effectively suppress both acute as well as chronic inflammation by inhibiting the release of various mediators of inflammation. In this study, dosages used for evaluation of both analgesic and anti-inflammatory activities were in accordance with those used in previous published studies. [1],[7],[15],[16]

None of the studies evaluating the analgesic and anti-inflammatory activities of statins in different experimental models have compared them with a standard drug. In this study, we used aspirin as a comparator, and observed that the activity of statins though significantly more than control group was less than aspirin. These results supported by already published reports in literature indicate that statins do have an important role to play as analgesics and anti-inflammatory agents. However, considering their current role as hypolipidemics and the safety issues involved with their use, as well as the availability of many other drugs having superior analgesic and anti inflammatory activities, the routine use of statins for these effects cannot be justified. However, these drugs can certainly emerge as useful alternatives in the treatment of diseases characterized by chronic inflammation particularly when there is coexisting dyslipidemia. Further, it appears that they may be particularly effective in the event of inflammatory nociception.


Jubliant Organic Ltd., Ind-Swift laboratories ltd. and The Sugars Ltd for providing drugs in pure powdered form.


1Sparrow CP, Burton CA, Hernandez M, Mundt S, Hassing H, Patel S, et al. Simvastatin has anti-inflammatory and antiatherosclerotic activities independent of plasma cholesterol lowering. Arterioscler Thromb Vasc Biol 2001;21:115-21.
2Youssef S, Stüve O, Patarroyo JC, Rulz PJ, Radosevich JL, Hur EM, et al. The HMG-CoA reductase inhibitor, atorvastatin, promotes a Th2 bias and reverse paralysis in central nervous system autoimmune disease. Nature 2002;420:78-84.
3Jonhson BA, Iacono AT, Zeevi A, McCurry KR, Duncan SR. Statin is associated with improved function and survival of lung allografts. Am J Crit Care Med 2003;167:1271-8.
4McKay A, Leung BP, McInnes IB, Thompson NC, Liew FY. A novel anti-inflammatory role of simvastatin in a murine model of allergic asthma. J Immunol 2004;172:2903-8.
5McCarey DW, McInnes IB, Madhok R, Hampson R, Sherbakova O, Ford I, et al. Trial of atorvastatin in rheumatoid arthritis (TARA): Double-blind, randomised placebo-controlled trial. Lancet 2004;363:2015-21.
6Chen H, Ikeda U, Shimpo M, Shimada K. Direct effects of statins on cell primarily involved in athereosclerosis. Hypertens Res 2000;23:187-92.
7Barsante MM, Roffe E, Yokoro CM, Tafuri WL, Souza DG, Pinho V, et al. Anti-inflammatory and analgesic effects of atorvastatin in a rat model of adjuvant-induced arthritis. Eur J Pharmacol 2005;516:282-9.
8Flier JS. Obesity. In: Harrison's principles of internal medicine, 16 th ed. New York: McGraw-Hill Medical Publishing Division; 2005. p. 422-9.
9Palmer G, Chobaz V, Talabot-Ayer D, Taylor S, Alexander S, Gabay C, et al. Assessment of the efficacy of different statins in murine collagen-induced arthritis. Arthritis Rheum 2004;50:4051-9.
10D'Amour FE, Smith DN. A method for determining loss of pain sensation. J Pharmacol Exp Ther 1941;72:74-9.
11Vogel HG. Analgesic, anti-inflammatory, and anti-pyretic activity. In: Drug Discovery and Evaluation: Pharmacological Assays. 2 nd ed. Vol 2. Germany: Springer-Verlag Berlin Heidelberg 2002. p. 716-7.
12Winter CA, Risley EA, Nuss GW. Carrageenin induced edema in hind paw of the rat as an assay for anti-inflammatory drugs. Proc Soc Exp Biol Med 1962;111:544-7.
13Ghosh MN, Singh H. Modified plethysmometer for measuring foot volume of unanaesthtized rats. J Pharm Pharmacol 1968;20:316-7.
14Brownlee G. Effect of deoxycortone and ascorbic acid on formaldehyde induced arthritis in normal and adrenalectomised rats. The Lancet 1950;28:157-9.
15Leung BP, Sattar N, Crilly A, Prach M, McCarey DW, Payne H, et al. A novel anti-inflammatory role for simvastatin in inflammatory arthritis. J Immunol 2003;170:1524-30.
16Garzo'n TS, Cunha TM, Verri Jr WA, R Vale'rio DA, Parada CA, Poole S, et al. Atorvastatin inhibits inflammatory hypernociception. Br J Pharmacol 2006;149:14-22.
17Nakamura M, Ferreira SH. A peripheral sympathetic component in inflammatory hyperalgesia. Eur J Pharmacol 1987;135:145-53.
18Taiwo YO, Bjerknes LK, Goetzl EJ, Levine JD. Mediation of primary afferent peripheral hyperalgesia by the cAMP second messenger system. Neuroscience 1989;32:577-80.
19Vinegar R, Schreiber W, Hugo R. Biphasic development of carrageenin oedema in rats. J Pharmacol Exp Ther 1969;166:96-103.
20Devaraj S, Chan E, Jialal I. Direct Demonstration of an anti-inflammatory effect of simvastatin in subjects with the metabolic syndrome. Clin Endocrinol Metab 2006;91:4489-96.