Iraqi J Pharm Sci, Vol.23(2) 2014 Metformin or pioglitazone in treatment of knee osteoarthritis 13 Evaluation of the Clinical use of Metformin or Pioglitazone in Combination with Meloxicam in Patients with Knee Osteoarthritis; using Knee Injury and Osteoarthritis outcome Score Mohammed M. Mohammed *,1 , Kassim J. Al-Shamma ** and Nizar A. Jassim *** * Department of Clinical Pharmacy, College of Pharmacy, University of Al-Mustansiryah, Baghdad, Iraq. ** Department of Therapeutics and Clinical Pharmaceutics, Baghdad College of Pharmacy, Baghdad, Iraq. ***Department of Rheumatology, College of Medicine, University of Baghdad, Baghdad, Iraq. Abstract Osteoarthritis is the most prevalent arthritic disease and a leading cause of disability. The pathogenesis of osteoarthritis involves multiple etiologies, including variable degree of synovial inflammation. Metformin and pioglitazone could potentially reduce the levels and activity of inflammatory mediators. This may consider as a new therapeutic approach added to the current used drugs in an attempt to decrease the pain, inflammation, and improve daily activity and quality of life in patients with knee osteoarthritis. This study designed to evaluate the clinical utility of using metformin or pioglitazone as anti- inflammatory agents in combination with non-steroidal anti-inflammatory drugs (NSAID) of selective type of cyclooxygenase-2 (COX-2) inhibitor, meloxicam, in the treatment of knee osteoarthritis (OA). Randomized, double blinded clinical study was performed on 98 patients who have symptomatic and radiologic evidence of painful OA of the knee (57 patients only completed the study). Patients were allocated into three groups, group (A); 20 patients treated with meloxicam (15mg/day) alone, group (B); 20 patients treated with metformin (1000mg/day) + meloxicam (15mg/day) and group (C); 17 patients treated with pioglitazone (15mg/day) + meloxicam (15mg/day). The treatment was followed for 12 weeks through measurement of the clinical effects of drugs each 7 days, using the Knee Injury and Osteoarthritis Outcome Score (KOOS) system. The results showed that metformin or pioglitazone, when used in combination with NSAID resulted in significant improvement in the components of KOOS, higher than that produced by meloxicam when used alone. In conclusion, administration of metformin or pioglitazone as adjuvant therapy to NSAID, meloxicam, in OA patients produced very well characterized analgesic and anti- inflammatory activities, and improves the therapeutic profile of meloxicam. Keywords: Metformin, Pioglitazone, Osteoarthritis, Knee injury, KOOS. ة للوتفىرهٍي او الباٌىكلٍتازوى كعالج هساًذ للوٍلىكسٍكام فً الورضى تقٍٍن الفعالٍت السرٌري الوصابٍي بالتهاب الركبت غٍر الرثىي، باستخذام ًظام كىز لتقٍٍن حالت الورٌض هحوذ هحوىد هحوذ *،1 ، قاسن جلٍل الشواع ** و ًسار عبذ اللطٍف جاسن *** * .اىؼشاق،تغذاد اىَسرْصشٝح،ظاٍؼح ،ميٞح اىصٞذىح اىصٞذىح اىسشٝشٝح ،فشع ** .اىؼشاق ،تغذاد ، صٞذىحتغذاد ىوميٞح ، اىؼالظاخ ٗاىصٞذىح اىسشٝشٝحفشع *** .ميٞح اىطة ، ظاٍؼح تغذاد ، تغذاد ،اىؼشاق الخالصة ٍشض اىرٖاب اىَفاصو غٞش اىشش٘ٛ ٕ٘ اىَشض االمصش اّرشاسا تِٞ اٍشاض اىَفاصو ٗاىسثة اىشئٞسٜ فٜ ظؼو اىَشٝط غٞش الٝ٘ظذ حٞس, ٍرفاٗذحاه ٓذٖاب اىضىٞيٜ فٜ اىَفاصو تذسظاخهاال ٍِ ظَْٖاأسثاب اىَشض ٍرؼذدج , قادس ػيٚ اىحشمح تص٘سج غثٞؼٞح فٜ اىَقاً االٗه اىٚ اىحذ ٍِ ذٖذف االسرشاذٞعٞاخ اىؼالظٞح اىحاىٞح ىزىل ّعذ اُ, ٍشظٚ اىرٖاب اىَفاصو غٞش اىشش٘ٛه شافٜػالض ػقاس مال ٍِ فاػيٞحاىؼذٝذ ٍِ اىذساساخ اىَصََح ػيٚ اىَْارض اىحٞ٘اّٞح اٗ ػيٚ االّساُ اىٚ أشاسخ .األىٌ ٗذحسِٞ ٗظٞفح اىَفصو ا ّٖعا ػالظٞا ظذٝذا ٝعاف اىٚ ٍعاداخ ًٍَا ٝعؼئ, ٗسطاء االىرٖاب فٜ اىحذ ٍِ ٍسر٘ٝاخ ّٗشاغ صُٗاىَرف٘سٍِٞ ٗػقاس اىثاٝ٘ميٞرا االىرٖاب غٞش اىسرٞشٗٝذٝح اىَسرخذٍح حاىٞا فٜ ٍحاٗىح ىيرقيٞو ٍِ االىٌ ٗاالىرٖاب ٗذحسِٞ اىفؼاىٞح اىٍٞ٘ٞح ّٗ٘ػٞح حٞاج اىَشظٚ اسرخذاً ػقاس ػِ ظَحاىْا ٕزٓ اىذساسح ىرقٌٞٞ اىفائذج اىسشٝشٝح خصٌَ ٙ رىلاء ػوٗتِ. اىَصاتِٞ تاىرٖاب ٍفصو اىشمثح غٞش اىشش٘ٛ فٜ ػالض , اىَٞي٘مسٞناًك -2-اىَصثطح الّضٌٝ االمسذج اىحيقٜ اىسرٞشٗٝذٝح ٍعاداخ االىرٖاب غٞشاحذ ٍغاىثاٝ٘ميٞراصُٗ اىَرف٘سٍِٞ اٗ . اىرٖاب ٍفصو اىشمثح غٞش اىشش٘ٛ أمَو )ٍشٝعا̿ ٍَِ ىذٌٖٝ أػشاض ٗأدىح سشٝشٝح ػيٚ األصاتح تاىرٖاب ٍفصو اىشمثح اىَسثة ىألىٌ 98أظشٝد ٕزٓ اىذساسح ػيٚ ذٌ ػالظٌٖ تؼقاس اىَٞي٘مسٞناً (ٍشٝط 20) -أ-اىَعَ٘ػح : ٗذٌ ذقسٌٞ ٕؤالء اىَشظٚ اىٚ شالز ٍعاٍٞغ(. ٍشٝعا̿ فقػ 57اىذساسح 500)ٳظافح اىٚ ػقاس اىَرف٘سٍِٞ ( ٍيغٌ ٍٝ٘ٞا 15)قاس اىَٞي٘مسٞناً ذٌ ػالظٌٖ تغ( ٍشٝط 20) -ب–اىَعَ٘ػح , (ٍيغٌ ٍٝ٘ٞا 15) ٳظافح اىٚ ػقاس اىثاٝ٘ميٞراصُٗ ( ٍيغٌ ٍٝ٘ٞا 15)ذٌ ػالظٌٖ تؼقاس اىَٞي٘مسٞناً ( ٍشٝط 17) -ض–اىَعَ٘ػح , (ساػح 12ٍيغٌ مو (. ٍيغٌ ٍٝ٘ٞا 15) 1 Corresponding author E-mail: phd_pharm@yahoo.com Received: 11/5/2014 Accepted: 10/6/2014 Iraqi J Pharm Sci, Vol.23(2) 2014 Metformin or pioglitazone in treatment of knee osteoarthritis 14 .KOOSٍشاقثح اىَشظٚ ٗذقٌٞٞ فؼاىٞح االدٗٝح اىَسرخذٍح ٍِ خاله فحص االسرعاتح اىسشٝشٝح ىيؼالض اسث٘ػٞا̿ تاسرخذاً ّظاً ٗذٌ فٜ ٍؼْ٘ٛ ػقاس اىَٞي٘مسٞناً ٝؤدٛ اىٚ ذحسِ ٍغأظٖشخ ّرائط اىذساسح تأُ اسرخذاً ػقاس اىَرف٘سٍِٞ اٗ اىثاٝ٘ميٞراصُٗ . ذيل اىرٜ ٝسثثٖا ػقاس اىَٞي٘مسٞناً ى٘حذٓب ٍقاسّح KOOSٍسر٘ٙ اىَؼاٝٞش اىخاصح تْظاً ػقاس اىَرف٘سٍِٞ أٗ اىثاٝ٘ميٞراصُٗ ىؼقاس اىَٞي٘مسٞناً ٝحذز ذأشٞشا̿ ٗاظحا̿ فٜ اىرقيٞو ٍِ ٍسر٘ٙ ظافَٔٝنِ االسرْراض تأُ ا مَا . ض اىَصاحثح ىٔ مَا ٝحسِ اىفؼاىٞح اىٍٞ٘ٞح ّٗ٘ػٞح حٞاج اىَشٝط ٍِ خاله اىرأشٞش اىَعاد ىالىرٖاب ٗاىَسنِ ىألىٌاالىٌ ٗاالػشا .اىؼالظٞحٝسٌٖ فٜ ذحسِٞ فؼاىٞرٖا اُ اسرخذأٍ ٍغ ٍعاداخ االىرٖاتاخ غٞش اىسرٞشٗٝذٝح .الرثىي، اصابت الركبت، ًظام كىز لتقٍٍن حالت الورٌض اسبىعٍاهتفىرهٍي، باٌىكلٍتازوى، التهاب الركبت غٍر :الكلواث الوفتاحٍت Introduction Osteoarthritis (OA) is a progressive musculoskeletal condition that involves the deterioration of articular cartilage and subsequent subchondral bone erosion (1) . Although the exact pathophysiology of the condition has not been uncovered yet, it is generally considered to be caused by a combination of cumulative mechanical stresses from aging, destructive biochemical changes taking place in the synovial membrane, and apoptosis of chondrocytes (2) . Clinically, there are several classes of treatments for OA, including non- pharmacological , pharma- cological , and surgical treatment modalities. However, these treatments provide largely symptom relief, and do not halt the progression of the disease (3) . Non-steroidal anti-inflammatory drugs (NSAIDs) are the most commonly used medications to treat OA. However, these drugs may elicit adverse effects particularly gastrointestinal ulcerations (4) . Moreover, some of these agents have been reported to disrupt extracellular matrix metabolism, particularly proteoglycans synthesis (5) . Prolonged consumption of these drugs can result in severe adverse effects. Consequently, there is an urgent need for new strategies in OA therapy which can improve symptoms and are safe for clinical use over long periods of time (6) . The ability of metformin and pioglitazone to reduce the intensity of pain and inflammation that contributed to the pathophysiology of OA, with no serious adverse effects, has been reported in many animal model studies (7,8) . This may considered a new therapeutic approach added to the currently used NSAIDs to improve pain, inflammation, and quality of life in patients with knee OA. It has been shown that metformin can serve as potential drug to treat inflammation-related disorders (8) . The specific anti-inflammatory mechanism of metformin is not clearly understood. However , several studies demonstrated that the pharmacological action of metformin goes beyond mere glycemic control , decreasing markers of inflammation and contributing to the reduction of oxidative stress (9,10) . Metformin dose-dependently reduced the production of nitric oxide (NO) and prostaglandin E2 (PGE2) and suppressed the mRNA and protein levels of inducible nitric oxide synthase (iNOS) and COX-2 in lipopolysaccharides- activated macrophages (11) . Pioglitazone is potent and highly selective agonist for the nuclear receptor peroxisome proliferator- activated receptors gamma (PPAR-γ) and to a lesser extent PPAR-α (12) . Through PPAR-γ- mediated effects, pioglitazone improve insulin sensitivity and also have pleiotropic effects on insulin secretion, lipid and adipose tissue metabolism, body fat distribution, and vascular endothelial function (13) .The anti-inflammatory effects of PPARs are mainly mediated by either inhibiting the induction of pro- inflammatory cytokines or stimulating the production of anti-inflammatory molecules (14) . Many in vitro studies have been shown that PPAR-γ is expressed and functionally active in chondrocytes, and those PPAR-γ activators modulate the expression of several genes considered essential in the pathogenesis of OA. PPAR-γ activation inhibits the IL-1- induced expression of iNOS, metalloproteinase-13 (MMP-13), COX-2, and PGE2 in chondrocytes (15- 17) . This study designed to evaluate the clinical utility of using metformin or pioglitazone as anti-inflammatory agents in combination with NSAID of selective type of COX-2 inhibitor, meloxicam, in the treatment of knee osteoarthritis (OA). Patients and Methods A double blind clinical study was carried out on (98) randomly selected patients (29 males and 69 females) with painful osteoarthritis (OA) of the knee, at the outpatients clinic in Baghdad Teaching Hospital with age range 36-71 years (59.2  7.3). All selected patients have symptomatic and radiological evidence of OA in one or both knee joints. They were informed about the nature and the aim of the study. During selection of patients, certain exclusion criteria Iraqi J Pharm Sci, Vol.23(2) 2014 Metformin or pioglitazone in treatment of knee osteoarthritis 15 were followed to exclude unsuitable patients including; 1. Patient with hypertension, ischemic heart diseases or diabetes mellitus. 2. Patient with hepatic or renal impairment and those who are on treatment with drugs, which interfere with the tested drugs. 3. Patients who have active peptic ulcer or damage. 4. Patients with end-stage radiological events of joint destruction. 5. Patients with positive history of bladder cancer. 6. Patients with positive history of allergic reactions to any one of the known tested drugs. 7. Patient who misses one time of blood sampling or treatment assessment indicated in this study and/or his medication for any reason. 8. Pregnant or lactating female patients. The selected patients were randomly allocated into three groups as follow: Group A, includes 32 (11 males and 21 females) patients with negative GIT risk factors, treated with meloxicam tablets (15mg/day) taken at night for 12 weeks (20 patients only completed the study). Group B, includes 36 (9 males and 27 females) patients with negative GIT risk factors, treated with meloxicam tablets (15mg/day) taken at night and metformin (500mg/12 hours) for 12 weeks (20 patients only completed the study). Group C, includes 30 (9 males and 21 females) patients with negative GIT risk factors, treated with meloxicam tablets (15mg/day) taken at night and pioglitazone (15mg/day) for 12 weeks (17 patients only completed the study). Effects of drug treatment were assessed each seven days by clinical evaluation and direct interview with patients through a questionnaire method known as Knee Injury and Osteoarthritis Outcome Score (KOOS) (18) . The results were expressed as mean ± SEM; paired t-test and ANOVA were used to examine the degree of significance; P values less than 0.05 were considered significantly different. Results Effect on pain score Before enrolment in the study (zero time), OA patients demonstrated poor pain control with their previous therapy, manifested by low pain score which indicate severe or extreme symptoms of pain in most of patients (table 1). Treatment with meloxicam alone resulted in significant increase in pain score from the first week (22.11%) compared to pre-treatment value, reaching maximum level at week twelve (88.81%) at the end of the study. However, combination of meloxicam with metformin resulted in significantly higher levels of improvement in the pain score started from the first week of treatment (51%) and remain elevated to the end of the study (170.95%). While addition of pioglitazone to meloxicam resulted in significant increase in pain score started from the first week (30.07%) reaching maximum level at week nine (146.62%), and remain around this level until the last week of the study (twelve weeks) (table 1). The obtained data showed that maximum level of improvement in pain score was gained in patients treated with combination of meloxicam and metformin which was significantly higher than that observed in patients treated with combination of meloxicam and pioglitazone at corresponding durations. However; these two groups demonstrated significant improvement in pain score compared to patients treated with meloxicam alone at corresponding duration. Effects on symptom score At zero time (before starting treatment), all selected OA patients showed poor management of OA symptoms, manifested by low score of symptoms according to the outcome of KOOS (table 2). Treatment with meloxicam alone resulted in significant elevation in symptom score compared to pre- treatment value from the first week (15.57%) with maximum elevation at the last three weeks of the study (54.52%, 56.01%, and 55.03%). Treatment with combination of meloxicam and metformin resulted in significantly higher levels of improvement in the symptom score started from the first week of treatment (21.99%) and maximum score achieved at week eight (113.64%) and remain elevated to the end of the study. However, the combination of pioglitazone and meloxicam resulted in time dependent significant increase in symptom score, reaching maximum level at the last two weeks of the study (87.08%, and 86.52%) relative to pre-treatment value, respectively. Parallel improvement in symptoms score were obtained by using combinations of meloxicam with either metformin or pioglitazone through first seven weeks of treatment. From week eight to the end of study; combination of meloxicam with metformin showed significant improvement compared to that of meloxicam and pioglitazone combination at corresponding duration. Both of these combination groups showed significantly different improvement in symptom score along the study period compared to patients group of meloxicam alone-treatment (table 2). Iraqi J Pharm Sci, Vol.23(2) 2014 Metformin or pioglitazone in treatment of knee osteoarthritis 16 Table(1): Effects of treatment with meloxicam alone, combination of meloxicam + metformin, and meloxicam + pioglitazone on pain score in osteoarthritic patients. Duration (Weeks) Pain Score of KOOS Meloxicam (15 mg/day) No. of Patient=20 Meloxicam(15mg/day)+ Metformin(1000mg/day) No. of Patient=20 Meloxicam (15mg/day)+ Pioglitazone(15mg/day) No. of Patient=17 0 32.07  1.08 29.98  1.08 31.53  1.45 1 39.16  1.14 * a 45.27  1.16 * b 41.01  1.13 * a 2 44.16  1.05 * a 52.08  0.94 * b 49.67  0.89 * c 3 47.24  0.92 * a 56.66  1.02 * b 54.08  1.04 * c 4 49.3  0.85 * a 61.38  1.01 * b 58.17  1.27 * c 5 52.08  0.85 * a 66.11  0.87 * b 61.92  0.91 * c 6 52.91  0.84 * a 71.58  0.83 * b 66.99  0.95 * c 7 55.41  0.79 * a 76.65 0.89 * b 74.01  1.04 * c 8 55.83  0.8 * a 79.42  0.76 * b 75.8  0.85 * c 9 57.49  0.83 * a 80.98  0.72 * b 77.76  1.09 * c 10 59.16  0.73 * a 80.81  0.64 * b 77.76  1.01 * c 11 60.41  0.78 * a 81.09  0.77 * b 77.76  0.82 * c 12 60.55  0.85 * a 81.23  0.8 * b 76.78  0.75 * c - Data are expressed as mean  SEM. - * P>0.05 significant difference compared to pre-treatment value within the same group. - Values with non-identical superscripts (a, b & c) among different groups are significantly different (P>0.05) at corresponding duration. Iraqi J Pharm Sci, Vol.23(2) 2014 Metformin or pioglitazone in treatment of knee osteoarthritis 17 Table (2): Effects of treatment with meloxicam alone, combination of meloxicam + metformin, and meloxicam + pioglitazone on symptoms score in osteoarthritic patients. Duration (Weeks) Symptoms Score of KOOS Meloxicam (15 mg/day) No. of Patient=20 Meloxicam(15mg/day)+ Metformin(1000mg/day) No. of Patient=20 Meloxicam (15mg/day)+ Pioglitazone(15mg/day) No. of Patient=17 0 35.71  1.37 34.1  1.69 37.39  1.37 1 41.27  1.02 * a 41.6  1.01 * a 43.48  0.76 * b 2 44.28  0.91 * a 48.22  0.92 * b 48.1  1.07 * b 3 48.03  0.99 * a 52.32  1.08 * b 52.73  1.13 * b 4 51.07  0.86 * a 56.07  0.74 * b 55.04  0.87 * b 5 51.97  0.71 * a 62.85  0.79 * b 62.6  1.06 * b 6 53.22  0.93 * a 66.23  0.65 * b 66.8  0.96 * b 7 52.5  0.69 * a 69.28  0.75 * b 69.32  0.69 * b 8 52.85  0.88 * a 72.85  0.95 * b 68.69  0.78 * c 9 54.1  0.94 * a 72.14  0.85 * b 68.2  0.92 * c 10 55.18  0.75 * a 70.89  0.83 * b 69.3  0.76 * c 11 55.71  0.79 * a 72.67  0.87 * b 69.95  0.75 * c 12 55.36  0.84 * a 72.49  0.78 * b 69.74  0.54 * c - Data are expressed as mean  SEM. - * P>0.05 significant difference compared to pre-treatment value within the same group. - Values with non-identical superscripts (a, b & c) among different groups are significantly different (P>0.05) at corresponding duration. Effects on Daily Living Activity (ADL) score In table 3, ADL score was found relatively low before starting treatment in all patients (zero time) enrolled in study. In patients group treated with meloxicam, ADL score showed significant increase, started after one week of treatment and reaching maximum score at the end of the study (13.98% and 80.82%) compared to pre-treatment value, respectively, with no significant differences among the mean values of last three weeks of the study. These values are significantly lower than those produced by combination treatment of meloxicam with metformin and meloxicam with pioglitazone at the same period of time. Addition of metformin to meloxicam resulted in significant improvement of ADL score after one week treatment (32.73%) compared to pre-treatment value and reach maximum improvement at the last four weeks of the study. The levels of improvement in ADL score produced by treatment with meloxicam and pioglitazonee combination remained significantly higher than baseline from week one (33.78%) to the end of study (106.53%), with maximum level of improvement recorded at week eight (118.58%) as shown in (table 3). Treatment with combination of meloxicam and metformin showed higher improvement of ADL scores which are significantly different compared to that resulted by treatment with meloxicam alone, and with combination of meloxicam and pioglitazone, particularly at the last five weeks of study. Iraqi J Pharm Sci, Vol.23(2) 2014 Metformin or pioglitazone in treatment of knee osteoarthritis 18 Table (3): Effects of treatment with meloxicam alone, combination of meloxicam + metformin, and meloxicam + pioglitazone on Daily Living Activity (ADL) score in osteoarthritic patients. Duration (Weeks) ADL Score of KOOS Meloxicam (15 mg/day) No. of Patient=20 Meloxicam(15mg/day)+ Metformin(1000mg/day) No. of Patient=20 Meloxicam (15mg/day)+ Pioglitazone(15mg/day) No. of Patient=17 0 34.77  1.72 38.38  1.37 37.36  1.06 1 39.63  0.99 * a 50.94  0.89 * b 49.98  1.04 * b 2 42.35  1.1 * a 57.35  0.93 * b 56.13  1.33 * b 3 45.44  1.12 * a 62.94  0.88 * b 66.17  0.91 * c 4 51.46  0.87 * a 65.88  0.8 * b 70.67  0.86 * c 5 53.22  0.87 * a 75.36  0.99 * b 77.85  0.64 * c 6 54.4  0.93 * a 79.88  0.83 * b 80.45  0.64 * b 7 56.83  0.84 * a 82.19  0.78 * b 81.66  0.78 * b 8 51.82  0.98 * a 84.38  0.73 * b 81.66  0.96 * c 9 60.95  0.66 * a 85.99  0.8 * b 81.35  0.8 * c 10 62.65  0.81 * a 87.46  0.79 * b 78.98  0.84 * c 11 62.57  0.7 * a 86.94  0.72 * b 77.68  0.79 * c 12 62.87  0.8 * a 86.87  0.84 * b 77.16  0.99 * c - Data are expressed as mean  SEM. - * P>0.05 significant difference compared to pre-treatment value within the same group. - Values with non-identical superscripts (a, b and c) among different groups are significantly different (P>0.05) at corresponding duration. Effects on sport/recreation score: Table 4; revealed low sport/recreation score at zero time levels before starting drug treatment with treated drugs. Treatment with meloxicam alone resulted in significant increase in sport/recreation score started after first week (16.19%) compared to pre-treatment value, reaching maximum level (59.05%) at the end of the study (12 weeks). Combination of meloxicam with metformin resulted in significantly higher level of improvement in sport/recreation score after the first week of treatment, which found to be comparable to those produced by combination of meloxicam with pioglitazone (28.7%, 17.04%) compared to pre-treatment values, respectively. At the end of the study; significant difference was achieved between the two combination groups, with preference to meloxicam and metformin group over meloxicam and pioglitazone group in improving sport/recreation score (117.39%, 75% compared to pre-treatment value, respectively) (table 3). Both of combination groups revealed a significant elevation in sport/recreation score compared to patients group treated with meloxicam alone at the same period of study. Iraqi J Pharm Sci, Vol.23(2) 2014 Metformin or pioglitazone in treatment of knee osteoarthritis 19 Table (4): Effects of treatment with meloxicam alone, combination of meloxicam + metformin and, meloxicam + pioglitazone on Sport/Recreation score in osteoarthritic patients. Duration (Weeks) Sport / Recreation Score of KOOS Meloxicam (15 mg/day) No. of Patient=20 Meloxicam(15mg/day)+ Metformin(1000mg/day) No. of Patient=20 Meloxicam (15mg/day)+ Pioglitazone(15mg/day) No. of Patient=17 0 26.25  0.8 28.75  1.35 25.88  1.23 1 30.5  0.8 * a 37  1.11 * b 30.29  1.17 * a 2 32  0.76 * a 44  1.12 * b 35.59  1.04 * c 3 33.75  0.8 * a 46.75  0.98 * b 38.24  1.05 * c 4 34.75  0.68 * a 48.5  0.73 * b 38.82  1.01 * c 5 36.75  0.98 * a 49.75  0.92 * b 40  0.96 * c 6 37  1.05 * a 54.5  1.02 * b 40.88  1.15 * c 7 37.5  0.85 * a 59  0.93 * b 41.76  1.05 * c 8 39.25  0.75 * a 59.75  0.85 * b 43.24  0.73 * c 9 39.5  0.88 * a 62.25  0.68 * b 44.12  0.77 * c 10 39.25  0.83 * a 62.75  0.77 * b 45.59  0.84 * c 11 41.25  0.95 * a 62.5  0.85 * b 45.59  0.95 * c 12 41.75  0.91 * a 62.5  0.93 * b 45.29  0.8 * c - Data are expressed as mean  SEM. - * P>0.05 significant difference compared to pre-treatment value within the same group. Values with non-identical superscripts (a, b & c) among different groups are significantly different (P>0.05) at corresponding duration . Effects on Quality of Life score (QOL) At zero time (before treatment), all patients showed relatively low QOL score. There is a clear evidence for good response to treatment with all used medications concerning QOL score, indicating that drug therapy improves not only the disease state and clinical features, but also the patient's mood. During the first week of treatment , all groups demonstrated time-dependent improvement in QOL score compared to baseline value of each group, with the priority to patients group treated with combination of meloxicam and metformin (28.87%). The presented data also showed that treatment with meloxicam alone resulted in a slower improvement pattern of QOL score compared to that produced by treatment of meloxicam and metformin combination at the end of the study (50%, 89.98%) compared to pre-treatment values, respectively. Addition of pioglitazone to meloxicam resulted in significant improvement in QOL score compared to that of meloxicam alone at corresponding duration, particularly within the last few weeks of study. The presented data, clearly demonstrated the advantage of adding metformin to meloxicam concerning improvement of QOL score in comparison to that produced by meloxicam alone and combination of meloxicam with pioglitazone (table 5). Iraqi J Pharm Sci, Vol.23(2) 2014 Metformin or pioglitazone in treatment of knee osteoarthritis 20 Table (5): Effects of treatment with meloxicam alone, combination of meloxicam + metformin, and meloxicam + pioglitazone on Quality of Life (QOL) score in osteoarthritic patients. Duration (Weeks) QOL Score of KOOS Meloxicam (15 mg/day) No. of Patient=20 Meloxicam(15mg/day)+ Metformin(1000mg/day) No. of Patient=20 Meloxicam (15mg/day)+ Pioglitazone(15mg/day) No. of Patient=17 0 25  1.36 28.13  1.4 25.37  1.56 1 27.81  1.24 * a 36.25  0.86 * b 27.57  1.52 * a 2 32.19  0.94 * a 40.63  0.96 * b 28.31  1.21 * c 3 33.13  0.92 * a 42.78  1.04 * b 30.15  1.23 * c 4 33.75  0.84 * a 44.69  0.82 * b 33.09  0.71 * a 5 34.69  0.85 * a 45.63  0.8 * b 35.29  0.92 * a 6 35.31  0.94 * a 46.88  0.85 * b 35.66  0.89 * a 7 35.94  0.89 * a 47.5  0.95 * b 36.38  0.96 * a 8 35. 63  0.92* a 50.63  1.01 * b 38.97  1.01 * c 9 36.25  0.86 * a 51.88  1.02 * b 39.34  1.04 * c 10 37.49  0.9 * a 53.13  0.85 * b 39.71  0.92 * c 11 37.5 0.78 * a 53.76  0.84 * b 40.44  0.95 * c 12 37.5 0.78 * a 53.44  0.96 * b 41.18  0.94 * c - Data are expressed as mean  SEM. - * P>0.05 significant difference compared to pre-treatment value within the same group. - Values with non-identical superscripts (a, b & c) among different groups are significantly different (P>0.05) at corresponding duration. Discussion Osteoarthritic pain is generally described as a sharp ache or a burning sensation in the associated muscles and tendons. OA can cause a crackling noise (called "crepitus") when the affected joint is moved or touched and patients may experience muscle spasms and contractions in the tendons. Occasionally, some patients reported increased pain with movement, cold weather, high humidity, and/or a drop in barometric pressure (19) . The pain of OA includes both nociceptive and non- nociceptive components and is associated with abnormally excitable pain pathways in the peripheral and central nervous systems (20, 21) . Furthermore; unrelieved pain leads to serious negative consequences, like those observed with poor pain score belong to OA patients before treatment (table 1), with many other physiological effects associated with increased catabolic demands (22) . There is evidence that NSAIDs are superior to paracetamol for pain relief in patients with osteoarthritis (23) , but they are also associated with more adverse effects. The major concern is serious gastrointestinal, renal and cardiovascular complications, with risk increasing with age, concurrent use of other medications and duration of therapy. NSAIDs help relieve pain, swelling and stiffness but they do not alter the progression of osteoarthritis (24) . Since cartilage tissues of osteoarthritic patients contain no pain receptors. So, sensation of pain likely results from inflammatory mediators. Pro-inflammatory agents interleukin-1 (IL-1), tumor necrosis factor alpha (TNF-α), as well as the growth Iraqi J Pharm Sci, Vol.23(2) 2014 Metformin or pioglitazone in treatment of knee osteoarthritis 21 factors have all been shown to induce COX-2 expression which produces measurable quantities of prostaglandins. On the other hand, the anti-inflammatory cytokines IL-4 and IL-13, as well as the immunosuppressive glucocorticoids, were shown to decrease COX- 2 levels (25) . In this respect, the beneficial effects of metformin and pioglitazone in reducing pain and symptoms in patients with OA can be explained according to the nature of the biological activity which can be attributed to many factors including the anti-inflammatory and antioxidant effects. The mechanism by which metformin or pioglitazone regulate the inflammatory response is poorly understood, but many studies on animal models demonstrated their inhibitory effect on the expression of the pro-inflammatory mediators and oxidative stress markers. Metformin, the well-known adenosine monophosphate- activated kinase (AMPK) activator, can suppress COX-2 and iNOS mRNA and protein expression dose dependently (26) . Metformin ability to reduce the intensity of pain, mainly associated with its effects on the profile of inflammatory cytokines (i.e., TNF a, IL-1β, IL-6, and IL-10) and adipokines (27) , it significantly prevented the increased levels of pro-inflammatory mediators like TNF-α, IL- 1β, IL-6, and IL-18 in many inflammatory disorders, Moreover; metformin prevented the expression of COX-2, iNOS, and decreased the levels of NO and PGE2 in cell culture media (28) , an evidence which support the observed effect of reducing the consequence of pain in OA patients. Pioglitazone is potent and highly selective agonist for the nuclear receptor, PPAR-γ. Activation of PPAR-γ has been shown to exhibit anti-inflammatory and anti-catabolic properties and to be protective in animal models of OA (29) . Study by (Mrgenweck, 2013) reported that PPAR-γ could be emerged as a new pharmacotherapeutic target for chronic pain; PPAR-γ activation blocks the development of, and reduces established neuropathic pain (30) , the possible mechanism of neuroprotection by PPAR-γ agonist, pioglitazone, may involve modulation of inflammatory reaction and oxidative stress (31) . Pioglitazone, via PPAR-γ activation, reduce the effects of IL-1β-induced COX-2 expression by interfering with oxidative stress and role of ROS (32) . PPAR-γ agonist, pioglitazone, has been reported to reduce the severity of experimental OA. This effect was associated with a reduction in the levels of MMP-13 and IL-1β, which are known to play an important role in the pathophysiology of OA lesions (33) . The lack of satisfaction of patients and doctors with NSAIDs treatment reflected by that fewer than 20% of patients with hip or knee OA, in whom NSAIDs treatment initiated, are still taking the same drug 12 months later (18) . The typical patient with OA is middle aged or elderly, and complains of knee, hip, hand, or spine pain. In most cases, the patient experience pain and stiffness in and around the affected joint, causing a decrease in function and activity. The onset of these symptoms is mostly insidious, and pain typically worsens with the use of the affected joint, but usually is alleviated with rest, while morning stiffness is lasting less than 30 minutes in common (34) . Osteoarthritis is a common debilitating joint disorder, affecting large sections of the population, which results in high morbidity; significant disability and impaired quality of life (35) . Accordingly, the primary goals of OA treatment are to relief pain, minimizing disability and limit the progression of the disease. Because most patients with OA are elderly people who have co-morbidities and are more susceptible to side effects of chronically used medications, care must be taken to individualize therapy on the bases of a patient's need and to minimize potential drug toxicity (36) . In this study, the high level of improvement in pain score observed with the use of metformin compared to meloxicam alone or in combination with pioglitazone (table 3 and 5) may correspond to the reported improvement in the daily activities and quality of life score, where metformin, and to less extent pioglitazone, improve all parameters in KOOS system when added to meloxicam, compared to using meloxicam alone. According to the results of this study, the addition of either metformin or pioglitazone to NSAIDs could constitute a new promising way to reversing or retarding the progression of degenerative processes that predispose to pain and other consequent symptoms in OA. 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