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).

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.

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.

Teloxantrone (also known as DuP 937) was developed as an anthrapyrazole intercalator that inhibits DNA synthesis. Teloxantrone interacts with topoisomerase II, thereby inhibiting DNA replication and repair, as well as RNA and protein synthesis. The drug participated in phase II clinical trials in colorectal carcinoma, in non-small cell lung cancer, in metastatic malignant melanoma. However, these studied apparently were discontinued.

Imagabalin is a ligand to the α(2)δ subunit of voltage-sensitive calcium channel and was developed to treat generalized anxiety disorder. Imagabalin was involved in phase III clinical trials when was made a decision to terminate all studies. However, this decision was not based on any safety concerns.

Gisadenafil is a phosphodiesterase V inhibitor in clinical development at Pfizer. It had been in phase II clinical trials for the treatment of Benign prostatic hyperplasia; Chronic obstructive pulmonary disease; Erectile dysfunction; Overactive bladder. Treatment-emergent adverse events were: headache, myalgia, dyspepsia, back pain.

PF-03654746 is a potent, selective antagonist of the human H3 receptor, developed by Pfizer. It was in the clinical trial phase II for the treatment of excessive daytime sleepiness (EDS) associated with narcolepsy, Tourette syndrome as well as potential anti-allergy applications and in phase I of clinical trial for the treatment of Schizophrenia and Alzheimer's disease, but these investigations were discontinued.

Losoxantrone is an anthrapyrazole that induces both single and double strand breaks in DNA and is a potent inhibitor of DNA synthesis. The drug is in clinical trials for the treatment of breast cancer and of prostate cancer that is refractory to androgen ablation. Acute toxicity is negligible. Losoxantrone may be less cardiotoxic than doxorubicin. Up to 40% of patients encounter alopecia. 3% of patients develop congestive heart failure. Losoxantrone had been in phase II clinical trial for the treatment of breast and prostate cancer. However, this development was discontinued.

Ezlopitant (CJ-11974) is a non-peptide neurokinin-1 receptor antagonist. Pfizer was developing ezlopitant for the potential treatment of irritable bowel syndrome and chemotherapy-induced emesis. Development of ezlopitant has been discontinued.

SU-14813 is an oral, multitargeted tyrosine kinase inhibitor (TKI) targeting vascular endothelial growth factor receptors (VEGFR), platelet-derived growth factor receptors (PDGFR), KIT, and fms-like tyrosine kinase 3 (FLT-3). SU-14813 was developed as a next-generation TKI agent following sunitinib (SU-11248) designed to demonstrate optimized pharmacokinetic (PK) and tolerability profiles. SU14813 demonstrated broad and potent antitumor activity equivalent to that of sunitinib, which resulted in tumor regression, growth arrest, growth delay, and prolonged survival in established xenograft cancer models in mice. A phase II trial of SU-14813 in patients with breast cancer was completed. However, according to the Pfizer pipeline development has been discontinued.