Sparfosate (PALA) is a stable transition state analogue for an aspartate transcarbamylase- cartalyzed reaction with antineoplastic activity. PALA is a potent inhibitor of aspartate transcarbamylase (Ki about 10(-8) M for ACTases of various origins), which in whole cells blocks the de novo synthesis of pyrimidines. Thus PALA inhibits de novo pyrimidine biosynthesis and increases the extent to which fluorouracil metabolites are incorporated into RNA. In vivo, low doses of PALA inhibit whole body pyrimidine synthesis. While this action is cytotoxic in vitro, extensive human testing demonstrates that PALA alone is devoid of selective antitumor activity. Interest in the therapeutic action of PALA derives from the demonstration that its action potentiates the cytotoxicity of several cytotoxic drugs, notably 5-fluorouracil (5-FU). Development of Sparfosate for cancer and Hepatitis B treatment is assumed to have been discontinued.

Imazodan, a phosphodiesterase III inhibitor was developed by Parke-Davis to treat heart failure and ischemic heart disorders. However, the study of this drug was discontinued.

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.

Levonantradol is a synthetic cannabinoid analogue of delta (9)-tetrahydrocannabinol (delta(9)-THC) administered intramuscularly. It has antiemetic and anti-analgesic properties. Although its precise mechanism of action is unknown, levonantradol appears to bind and activate the cannabinoid receptors CB1 and/or CB2. Antiemetic effect of levonantradol significantly superior to chlorpromazine. However, its adverse central effects limit its utility. The main adverse events are drowsiness and dizziness. Levonantradol, administered intramuscularly to the patients suffering from postoperative pain, manifested significant analgesic efficacy. Analgesia persisted for more than 6 h with the 2.5 and 3 mg doses of levonantradol. Drowsiness was frequent but few other psychoactive effects were reported.

Piroxantrone is one of a series of compounds commonly known as anthrapyrazoles developed in an effort to combine the broad antitumor activity of the anthracyclines with decreased myocardial toxicity. The mechanism of action of piroxantrone and other anthrapyrazoles is incompletely understood but likely involves DNA binding with induction of DNA strand breaks, DNA-protein cross-linking, and inhibition of DNA, RNA, and protein synthesis. Collectively, these findings suggested an interaction with topoisomerase II. Piroxantrone demonstrated antitumor activity in a wide spectrum of experimental systems against breast carcinoma, colon carcinoma, sarcoma, melanoma and leukemia. Piroxantrone is inactive in patients with persistent, progressive, or recurrent ovarian cancer who recently had received a platinum-based regimen. Piroxantrone has detectable but minimal activity against disseminated malignant melanoma. A phase II clinical trial of the piroxantrone administration for the treatment of advanced metastatic or recurrent endometrial cancer was prematurely terminated due to lack of patient accrual.

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.

PHA-543613 was discovered by Pfizer and has been under development primarily as a potential treatment of schizophrenia. PHA-543613 acts as an agonist to the Neuronal acetylcholine receptor protein alpha-7 subunit. A single human trial was conducted in healthy human volunteers, but the compound has been studied extensively in rat models for schizophrenia as well as Parkinson's disease and Alzheimer's disease.

PF 4800567 is a drug developed by Pfizer which acts as a selective potent inhibitor of CK1epsilon (IC(50) = 32 nM) with greater than 20-fold selectivity over CK1delta, and has mainly been used in the study of the casein kinase 1 enzymes in the regulation of circadian rhythm, as well as showing potential neuroprotective effects. PF 4800567 was found in animal studies to enhance responses to certain drugs of abuse such as methamphetamine and fentanyl, which suggests a role for CK1-ε in negative regulation of sensitivity to stimulant and opioid drugs.

MCOPPB trihydrochloride (MCOPPB) is a nonpeptide agonist of the NOP receptor, an anxiolytic agent. MCOPPB has a high affinity for the human NOP receptor (pKi = 10.07 +/- 0.01) and selectivity for the NOP receptor over other members of the opioid receptor family: 12-, 270- and >1000-fold more selective for the NOP receptor than for the micro-, kappa-, and delta-receptor, respectively. In an ex vivo binding study, MCOPPB (10 mg/kg, p.o.) inhibited signaling through the NOP receptor in the mouse brain, suggesting that it penetrated into the brain after it was orally administered. MCOPPB - a compound with few adverse effects on the central nervous system - is a potential therapeutic agent for the treatment of anxiety.

PHA-543613 was discovered by Pfizer and has been under development primarily as a potential treatment of schizophrenia. PHA-543613 acts as an agonist to the Neuronal acetylcholine receptor protein alpha-7 subunit. A single human trial was conducted in healthy human volunteers, but the compound has been studied extensively in rat models for schizophrenia as well as Parkinson's disease and Alzheimer's disease.