Tenidap ([Z]-5-chloro-2,3-dihydro-3-[hydroxy-2-thienylmethylene]-2-oxo-1H-indole-1-carboxamide) is an oxindole derivative, a COX/5-LOX inhibitor and cytokine-modulating anti-inflammatory drug candidate that was under development by Pfizer as a promising potential treatment for rheumatoid arthritis. Tenidap shows potent inhibition of cyclooxygenase in vitro, that is of several magnitudes greater than 5-lipoxygenase inhibition. Lipoxygenase inhibition, however, has been difficult to document in vivo because Tenidap is highly protein bound and free drug concentrations are below those necessary for 5-lipoxygenase inhibition. However, several in-vitro activities distinguish Tenidap from conventional cyclooxygenase inhibitors. As shown with stimulated human neutrophils, tenidap inhibits activation of collagenase, lysosomal enzyme secretion, and superoxide generation, as well as aggregation and adhesion to endothelium. Furthermore, unlike Non-steroidal anti-inflammatory drugs (NSAIDs), it lowers circulating C-reactive protein (CRP) concentrations by a magnitude equivalent to hydroxychloroquine and auranofin. This result suggests an effect on the synthesis and/or release of the cytokines known to induce the acute-phase protein response-namely, IL-1, IL-6, and TNF-alpha. Tenidap, like existing second-line drugs, lowers serum IL-6 concentrations, a property not shared by NSAIDs The cytokine inhibitory effect also includes reduced in-vitro concentrations of TNF-alpha and IL-1 from both RA synovium and peripheral blood mononuclear cells. There is no immunosuppressive effect of Tenidap in either animal or clinical studies. In clinical studies. The comparisons between tenidap and other second-line agents show that Tenidap produced a faster reduction in CRP than Auranofin. The rate of withdrawal because of inefficacy was similar (18-20%) in Auranofin and Tenidap groups. The quality of life using the arthritis impact measurement scales has also been assessed Scores were better with tenidap than with NSAID monotherapy, but equivalent to the second line plus NSAID combinations. Tenidap is registered in the United States, Netherlands, and Italy but is not marketed because marketing approval was rejected by the FDA in 1996 due to liver and kidney toxicity, which was attributed to metabolites of the drug with a thiophene moiety that caused oxidative damage.

Fenclozic acid emerged in the late 1960s as a promising carboxylic acid non-steroidal anti-inflammatory drug candidate that demonstrated potent anti-inflammatory, anti-pyretic and analgesic properties. Whole body autoradiography showed fenclozic acid distribution into all tissues except the brain, with radioactivity still detectable in blood, kidney and liver at 72 h post-dose. Fenclozic acid was compared with aspirin in a double-blind, crossover trial in patients with rheumatoid arthritis. It was concluded that fenclozic acid afforded symptomatic relief and was comparable to aspirin. Unfortunately, hepatotoxicity was observed in subsequent trials and the drug was withdrawn from the clinic.

Antiinflamatory agent, analgesic, antipyretic, COX inhibitor. Approved in France in 1975, withdrawn in 1976 because of the neuropsychiatric reactions

Butibufen is a non-steroidal anti-inflammatory cyclooxygenase inhibitor with analgesic and antipyretic properties. The drug was investigated for the treatment of osteoarthritis, rheumatoid artritis, and other arthroses. It was marketed under tradenames Mijal and Butilopan but now is withdrawn from the market.

(R)-Sulindac is the (R)-enantiomer of nonsteroidal anti-inflammatory drug (NSAID) Sulindac, that is marketed in the U.S. by Merck as Clinoril. Sulindac is a prodrug, derived from sulfinylindene, that is converted in vivo to an active sulfide compound by liver methionine sulfoxide reductases (Msr). The (Msr) family of enzymes includes two major classes, MsrA and MsrB, that specifically reduce the S- and R-epimers of Sulindac. Reduction of (R)-Sulindac to Sulindac Sulfide catalyzed by methionine sulfoxide reductase (Msr)-B. The oxidation of both epimers to sulindac sulfone is catalyzed primarily by the microsomal cytochrome P450 (P450) system. (S)-Sulindac increases the activity of the P450 system better than (R)-sulindac, but both epimers increase primarily the enzymes that oxidize (R)-sulindac. Both epimers can protect normal lung cells against oxidative damage and enhance the killing of lung cancer cells exposed to oxidative stress.

(S)-Sulindac is the (S)-enantiomer of nonsteroidal anti-inflammatory drug (NSAID) Sulindac, that is marketed in the U.S. by Merck as Clinoril. Sulindac is a prodrug, derived from sulfinyl-indene, that is converted in vivo to an active sulfide compound by liver methionine sulfoxide reductases (Msr). The (Msr) family of enzymes includes two major classes, MsrA and MsrB, that specifically reduce the S- and R-epimers of Sulindac. Reduction of (S)-Sulindac to Sulindac Sulfide catalyzed by methionine sulfoxide reductase (Msr)-A. The oxidation of both epimers to sulindac sulfone is catalyzed primarily by the microsomal cytochrome P450 (P450) system. (S)-Sulindac increases the activity of the P450 system better than (R)-sulindac, but both epimers increase primarily the enzymes that oxidize (R)-sulindac. Both epimers can protect normal lung cells against oxidative damage and enhance the killing of lung cancer cells exposed to oxidative stress.

N,N-Dimethylcarbamoylmethyl alpha,2-dimethyl-5H-[1]- benzopyrano[2,3-b]pyridine-7-acetate (Y-23023/ Tilnoprofen arbamel) is a prodrug developed as a new non-steroidal anti-inflammatory drug (NSAID), by Yoshitomi and Japan Tobacco for treatment pain in Rheumatoid arthritis, but was discontinued. Y-23023 is rapidly hydrolysed to an active metabolite, alpha,2-dimethyl-5H-[1]benzopyrano[2,3-b]pyridine-7-acetic acid (TILNOPROFENIC ACID), cyclo-oxygenase inhibitor.

Cyclovalone is a synthetic curcumin derivative in which the keto-enolic system is replaced by a cyclohexanone ring. Cyclovalone is a choleretic and cholagogic agent which stimulates the formation and secretion of bile, and also has an anti-inflammatory effect.

Kebuzone is a cyclooxygenase inhibitor that was used for the treatment of different inflammatory conditions such as thrombophlebitis and rheumatoid arthritis. The current marketing status of the drug is unknown and supposed to be discontinued.

Ibuproxam is a prodrug which metabolizes into ibuprofen and is therefore indicated for the treatment of pain and inflammation. Administration of oral ibuproxam resulted in a significantly higher plasma concentration than administration of an equal dose of ibuprofen after 45 minutes. Despite showing some promise as a NSAID ibuproxam does not appear to have been approved or marketed.