Piridronic acid is pyridinyl bisphosphonate. It is the bone calcium metabolism regulator. Piridronic acid was used for the treatment of osteoporosis. It is the human farnesyl pyrophosphate synthase inhibitor. When expressed on an actual or anticipated clinical dose basis for osteoporosis piridronic acid may have a greater potential for inducing gastric damage than do pyridinyl bisphosphonates. Piridronic acid induced significantly more antral damage than risedronate and a greater number of lesions compared to pamidronate and risedronate.

Fantofarone (SR 33557) is a non-dihydropyridine calcium antagonist with a novel site of action in the L-type Ca2+ channel. Fantofarone is capable of significantly modifying the cardiovascular function without increasing heart rate. Fantofarone was being developed for the treatment of angina pectoris, arrhythmias and hypertension.

Nifuradene (NF-246), a chemotherapeutic nitrofuran, was first synthesized and reported in 1956. Nifuradene, a 5-Nitorofuran derivative, is an antibacterial drug. Early in vitro testing found it an effective chemotherapeutic agent against most of the common urinary pathogens. Subsequent in vivo studies found that this compound is well absorbed after oral administration in both animals and humans. Nifuradene was used for the treatment of urinary tract infections. The over-all cure rate was found to be best at doses exceeding 600 mg a day.

Linarotene is arotinoid derivative. It is an antikeratolytic agent. Linarotene had been in preclinical phase by Ortho Pharmaceutical (Johnson & Johnson) and BASF Pharma for the treatment of skin disorders. However, this research was discontinued.

ABT-751 is an orally bioavailable antimitotic sulfonamide, which binds to the colchicine-binding site on beta-tubulin and inhibits the polymerization of microtubules, leads to a block in the cell cycle at the G2M phase, resulting in cellular apoptosis. ABT-751 had been in phase Ⅱ clinical studies for the treatment of breast cancer; colorectal cancer; non-small cell lung cancer; renal cancer, prostate cancer, but these researches have been discontinued.

Premafloxacin is an 8-methoxy fluoroquinolone derivative patented by American pharmaceutical company Warner-Lambert Co. as an antibacterial agent. In preclinical studied. Premafloxacin was equivalent to ciprofloxacin, enrofloxacin, and danofloxacin in activity against the gram-negative bacilli but was much more active than the comparison antimicrobial agents (against the staphylococci, streptococci, and anaerobes. Premafloxacin acts as a topoisomerase IV inhibitor with enhanced activity against Staphylococcus aureus.

Deferitrin is a desferrithiocin-derived hexadentate iron chelator, developed by Genzyme Corp. for the treatment of severe iron overload in people who require repeated erythrocyte transfusion for the management of chronic anemia such as beta-thalassemia major. Development of the drug was halted after phase 1/2 clinical trial due to nephrotoxicity.

Axelopran (previously known as TD-1211), a peripherally selective, multivalent µ-opioid receptor antagonist that is under development by Theravance Biopharma. This drug participated in phase II clinical trials in subjects with opioid-induced constipation. The most common adverse events were abdominal pain, nausea, and diarrhea. There were no indications of opioid withdrawal effects or reductions in opioid analgesia in patients treated with axelopran.