Asian Journal of Pharmaceutical and Clinical Research Vol.2 Issue 3, July-September 2009 ISSN 0974-2441 92 Research Article CHARACTERIZATION AND IN VITRO EVALUATION OF PIROXICAM SUPPOSITORIES ESKANDAR MOGHIMIPOUR * , MOHAMMAD ALI DABBAGH, FATEMEH ZARIF Department of Pharmaceutics, College of Pharmacy, Jundishapur University of Medical Sciences, Ahwaz, Iran E-mail: moghimipour@yahoo.com ABSTRACT Piroxicam is an effective anti- inflammatory agent; it is an inhibitor of prostaglandin biosynthesis. The Principal advantage of prioxicam is its long half-life, which permits the administration of a single daily dose. Piroxicam is approved in the United States for the treatment of rheumatoid arthritis and osteoarthritis. It also has been used in the treatment of Ankylosing Spondylitis, acute musculoskeletal disorders, dysmenorrhea, postoperative pain and acute gout. Therefore, patients with gastrointestinal disorders or after surgery often have difficulties taking drugs by mouth. Rectal administration may be a good alternative to oral administration in these types of situations. Therefore in the present research attempt has been done to formulate piroxicam suppository dosage form in witepsol base. In the present study, the effectiveness of different agents on dissolution and release rate of piroxicam from its suppository base has been studied. Also, the effect of propylene glycol as cosolvent, polysorbate 80 as increasing solubility and colloidal silicon dioxide as suspending agent on the release behavior were investigated. Finally, the best formulation was chosen regarding their release profile, the time needed for 75% release of the drug (t 75 ), and uniformity of formulations. KEYWORDS Piroxicam, Suppository, Witepsol INTRODUCTION Piroxicam is a weakly acidic and highly lipophilic anti- inflammatory drug (FIG 1) available for oral, parenteral and topical administration. The drug inhibits the synthesis of prostaglandins in inflammation 1,2 . The pharmacokinetics of piroxicam is characterized by a high oral absorption, and a long biological half-life (50-60 h), which makes possible single daily dose administration of the drug 3,4 . Currently, several systemic and topical formulations are available as capsules, solutions for injection and gels of piroxicam. In some circumstances such as during nausea and vomiting or in uncooperative patients, oral route becomes impractical. The drug also has gastrointestinal side effects that limits oral rout of administration 1 . Limitations with the oral rout and potential hazards and unacceptability of parenteral formulations prompted the need for formulation, development and evaluation of suppository formulations of the drug, with the goal of introducing a new formulation to enhance the rate of release of the drug. FIG 1. Chemical structure of piroxicam. The clinical benefits of rectal piroxicam formulation in children have been demonstrated by Dix et al., 2004 5 , and Labrousse et al., 1989 6 . Also, it has been shown that piroxicam has a lower rate of side effects in lower gastrointestinal tract when compared with indomethacin, and no serious complication occurred 7 . The objective