Elvucitabine (ACH-126443 or beta-L-Fd4C) is a reverse transcriptase inhibitor exerting antiviral properties. Elvucitabine, an L-cytosine nucleoside analog, is intracellularly phosphorylated to its active 5′-triphosphate metabolite, which has an intracellular half-life of at least 20 hours. Elvucitabine triphosphate inhibits the activity of HIV reverse transcriptase by competing with natural substrates and by causing DNA chain termination after incorporation into viral DNA. Elvucitabine has also demonstrated in vitro and in vivo activity against HBV. Achillion, under license from Vion is developing elvucitabine for the potential treatment of HIV and hepatitis B virus (HBV) infection.

Palifosfamide or ZIO-201 (isophosphoramide mustard; IPM), a bi-functional DNA alkylator, is the active metabolite of ifosfamide (IFOS). IFOS and the related drug cyclophosphamide (CPA) are widely used anti-cancer drugs. Both are pro-drugs and need to be metabolized to be active. Their clinical use is limited by the toxicity associated with some of their metabolites. Palifosfamide has shown efficacy in diverse cancer models. ZIOPHARM Oncology Inc, under license from Dekk-Tec Inc, was developing palifosfamide, a formulation of isophosphoramide mustard with tris(hydroxymethyl)aminomethane salt-stabilization (palifosfamide-tris) and previously with lysine-stabilization (palifosfamide-lys). Preclinical studies and phase I and I/II clinical trials demonstrated that palifosfamide-tris had an antitumor efficiency comparable or superior to that of ifosfamide. To date ZIO-201 is not present in ZIOPHARM pipeline.

Atilmotin (also known as BAX-ACC-1638), a motilin receptor agonist, is short acting, with t1/2 less than 10 min. It was shown that at doses of 6, 30 or 60 mg intravenously, it affected esophageal, lower esophageal sphincter (LES), and gastric motility. LES and gastric pressures were increased, whereas there was disruption of esophageal peristalsis characterized by lower amplitude and failed contractions. The drug can have the clinical implementation for stomach motility disorders but is needed further study.

Napactadine is a bicyclic antidepressant agent. It is a histamine-H1 receptor antagonist. Preliminary results indicated a marked improvement in depressive symptomalology within 7 days of treatment, as measured by the Hamilton depression scale. However, clinical studies were discontinued after chronic administration of napactadine because an elevation in liver enzyme levels was observed in some patients.

Disoxaril is the antipicornavirus drug. It is an isoxazole heterocyclic compound and a member of the antiviral series commonly referred to as WIN compounds. Disoxaril inhibits enterovirus replication by binding to the hydrophobic pocket within the VP1 coat protein, thus stabilizing the virion and blocking its uncoating. The amino acid sequence of a large VP1 196-258 peptide (disoxaril-binding region) of CVB1/RESISTANT was significantly different from that of the CVB1/SOF (sensitive). Crucially important changes in CVB1/RES were two point mutations, M213H and F237L, both in the ligand-binding pocket. Treatment with disoxaril in newborn mice infected with Coxsackie B1 virus, for 10 days post virus inoculation decreased the virus titer in the mouse brain till day 7.

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.