Clinafloxacin is a broad-spectrum fluoroquinolone antibiotic that was originally developed and subsequently abandoned in the late 1990s as a human health antibiotic for respiratory diseases. Clinafloxacin displays broad-spectrum antibacterial activity against Gram-positive, Gram-negative, and anaerobic pathogens by inhibiting the bacterial regulatory enzyme DNA gyrase (IC50 = 0.92 ug/ml) as well as topoisomerase IV (IC50 = 1.62 ug/ml).

Espatropate (UK 88060) is an antagonist of M3 muscarinic receptors. Espatropate is a bronchodilator with anticholinergic activity. It was undergoing preclinical development with Pfizer for the treatment of asthma.

Evatanepag (CP-533,536) is a prostaglandin E2 EP2 receptor agonist. It stimulates new bone formation on trabecular, endocortical, and periosteal surfaces and enhances fracture healing. Evatanepag was under development with Pfizer as a bone formation stimulant for therapeutic use in the healing of fractures.

Darbufelone mesylate is a dual inhibitor of cellular prostaglandin and leukotriene production. Darbufelone potently inhibits PGHS-2 (IC50 = 0.19 uM) but is much less potent with PGHS-1 (IC50= 20 uM). Darbufelone is a dual inhibitor of cellular PGF2R and LTB4 production. Darbufelone is orally active and nonulcerogenic in animal models of inflammation and arthritis. Darbufelone mesylate was in phase III clinical trials by Pfizer and Zhuhai United Laboratories for the treatment of rheumatoid arthritis.

Pirbenicillin is a broad-spectrum semisynthetic penicillin with activity against both gram-positive cocci and gram-negative bacilli. Pirbenicillin is less active than either carbenicillin or ticarcillin against Proteus spp. It is as active as carbenicillin against Serratia spp. and Enterobacter spp. Pirbenicillin demonstrated eight- and fourfold better minimal bactericidal concentration values towards Pseudomonas isolates than those of carbenicillin and ticarcillin, respectively. Pirbenicillin binds to and inactivates penicillin-binding proteins (PBPs) located on the inner membrane of the bacterial cell wall. The drug is somewhat more stable in serum than carbenicillin. Pirbenicillin does not appear to inactivate gentamicin as rapidly as carbenicillin.

Alitame [l-α-aspartyl-N-(2,2,4,4-tetramethyl-3-thioethanyl)-d-alaninamide] is an amino acid-based sweetener developed by Pfizer Central Research from l-aspartic acid, d-alanine, and 2,2,4,4-tetraethylthioethanyl amine. A terminal amide group instead of the methyl ester constituent of aspartame was used to improve the hydrolytic stability. The incorporation of d-alanine as a second amino acid in place of l-phenylalanine has resulted in optimum sweetness. The increased steric and lipophilic bulk on a small ring with a sulfur derivative has provided a very sweet product and good taste qualities. Alitame is noncariogenic. From an oral intake, 7–22% is unabsorbed and excreted in the feces. The remainder is hydrolyzed to aspartic acid and alanine amide. The aspartic acid is normally metabolized, and the alanine amide is excreted in the urine as a sulfoxide isomer, sulfone, or conjugated with glucuronic acid. U.S. Food and Drug Administration has approved alitame for use as per acceptable daily intake (ADI) value.

Fanetizole is a derivative of 2-aminothiazole. It is an anti-inflammatory agent. This drug is reported to have some cyclooxygenase inhibiting activity. Production of superoxide in response to the chemotactic factor formyl-methionyl-leucyl-phenylalanine (f-Met-Leu-Phe) was markedly inhibited by fanetizole. Suppression of neutrophil production of toxic oxygen metabolites may partially explain the antiarthritic effect of fanetizole. Fanetizole was shown to restore depressed E-rosetting activity in adult thymectomized mice, as well as enhance in in vitro proliferation of murine thymic cells to mitogen and synergistically acted with the monokine interleukin-1. It displays anti-arthritic activity in viva in the rat adjuvant arthritis model, inhibiting the development of disease in the non-infected foot. This drug has less side effects than levamisole in animals.

Englitazone is a thiazolidinedione antidiabetic agent. It has insulinomimetic and insulin-enhancing actions in vitro and glucose-, insulin-, triglyceride-, and cholesterol-lowering properties in an animal model of non-insulin-dependent diabetes mellitus. It acts as a peroxisome-proliferator-activated receptor-gamma ligand. Englitazone inhibits ATP-sensitive potassium and calcium-activated non-selective cation channels in a voltage-independent manner.

Torcetrapib is a CETP inhibitor which was developed by Pfizer for the treatment of diseases associated with elevated level of cholesterol. The drug was tested in phase III (in combination with atorvastatin) of clinical trials in coronary heart disease patients as well as in patients with hyperlipoproteinemia, hypertriglyceridemia, hypercholesterolemia, hyperlipidemia, however its development was terminated due to the high risk of death and heart problems.

Besonprodil (also known as CI-1041), an NR2B subunit specific NMDA receptor antagonist, has been developed for the treatment of certain inflammatory and neuropathic pain, however, these studies were discontinued. Besides, besonprodil was investigated as a supplemental medication for Parkinson's disease. Experiments on animals have shown that this drug could be effective in counteracting the dyskinesia associated with long-term treatment with levodopa and related drugs.