Edoxudine (5-ethyl-2'-deoxyuridine), an antiviral drug, has been clinically studied against the recurrent genital herpes.

ALANOSINE is an antiviral and antitumor antibiotic derived from Streptomyces alanosinicus. It inhibits adenylosuccinate synthetase, which converts inosine monophosphate into adenylosuccinate, an intermediate in purine metabolism. ALANOSINE-induced disruption of de novo purine biosynthesis is potentiated by methylthioadenosine phosphorylase (MTAP) deficiency. In cancer cells that lack MTAP, required in the salvage pathway, ALANOSINE should deprive such cells (but not normal cells) of de novo synthesized adenosine. However, in clinical trials, it was ineffective in patients with advanced MTAP-deficient tumors.

Etofylline [7-(2-hydroxyethyl)theophylline] is a N-7-substituted derivative of theophylline, a smooth muscle relaxant. Etofylline is used to relieve bronchoconstriction. It may act as a phosphodiesterase inhibitor and adenosine receptor antagonist.

Cycloguanil is a dihydrofolate reductase inhibitor and is a metabolite of the antimalarial drug proguanil. The parent drug proguanil was suggested to contribute to the antimalarial activity as well, but the mechanism of action is unknown. Proguanil is a prodrug that is metabolized to its main active metabolite, cycloguanil, mostly via CYP2C19. There is significant variation in proguanil pharmacokinetics.12 CYP2C19 is the predominant enzyme catalyzing the bioactivation of proguanil to cycloguanil. Cycloguanil is one of the few antimalarial drugs that act on both the erythrocytic and on the pre-erythrocytic (hepatic) forms of the malaria parasites. Although cycloguanil is not currently in general use as an antimalarial, the continuing development of resistance to current antimalarial drugs has led to renewed interest in studying the use of cycloguanil in combination with other drugs.

AMFLUTIZOLE is a xanthine oxidase inhibitor used for the treatment of gout.

Acivicin is a modified amino acid and structural analog of glutamine, that irreversibly inhibits glutamine-dependent amidotransferases involved in nucleotide and amino acid biosynthesis. Acivicin is a potent antitumor agent that induces apoptosis in human lymphoblastoid cells. Phase I dose-escalating studies conducted in cancer patients administered acivicin showed reversible, dose-limiting CNS toxicity, characterized by lethargy, confusion and decreased mental status.

Bucladesine is a cyclic nucleotide derivative which mimics the action of endogenous cAMP and is a phosphodiesterase inhibitor. The compound is used in a wide variety of research applications because it mimics cAMP and can induce normal physiological responses when added to cells in experimental conditions. cAMP is only able to elicit minimal responses in these situations. The neurite outgrowth instigated by bucladesine in cell cultures has been shown to be enhanced by nardosinone. Recently, the effect of bucladesine as a cAMP analog has been studied on the pentylenetetrazol-induced seizure in the wild-type mice. The data showed that bucladesine (300nM/mouse) reduced the seizure latency and threshold. In addition they found that combination of bucladesine and pentoxyfillin has additive effect on seizure latency and threshold. Bucladesine is more lipophilic than cAMP and in contrast to cAMP capable of penetrating cell membranes. Bucladesine interferes with different protein kinases which are normally activated by cAMP. Bucladesine has undergone in the past clinical developments as systemic treatment for cardioprotection and as topical treatment to improve wound healing. In Japan, a bucladesine ointment (Actosin® ointment; Daiichi Pharmaceutical Co., Ltd., Tokyo, Japan) was marketed to treat skin ulcers. Clinical studies have shown favourable effects on diabetic foot ulcers or decubitus, but the compound was later withdrawn despite good tolerability. One possible reason for the withdrawal may be the odour of the cream formulation which can be related to the hydrolytic cleavage in aqueous solutions resulting in release of butyric acid.

Enviroxime (LY 122772 or 2-amino-1-(isopropyl sulphonyl)-6-benzimidazole phenyl ketone oxime) is an benzimidazole antiviral agent. Enviroxime inhibits the replication of rhinoviruses and enteroviruses, additionally it impedes the replication of the hepatitis C virus. Enviroxime targets the 3A coding region of rhinovirus and poliovirus. Enviroxime is able to inhibit host phosphatidylinositol 4-kinase III.

Moclobemide ia an antidepressant that acts on the monoaminergic cerebral neurotransmitter system by reversibly inhibiting monoamine oxidase, primarily type A (RIMA). The metabolism of noradrenaline, dopamine and serotonin is thereby reduced, resulting in increased extracellular concentrations of these neurotransmitters. Increase in the level of serotonin is the most pronounced. Moclobemide administration also leads to increased monoamine receptor stimulation, reversal of reserpine induced behavioral effects, selective depression of the rapid eye movement (REM) sleep, down regulation of beta-adrenoceptors and increases in plasma prolactin and growth hormone levels. It reduces scopolamine-induced performance decrement and alcohol induced performance deficit which suggest a neuroprotective role. Moclobemide is indicated for the treatment of major depressive episodes.

Phenoxypropazine is a monoamine oxidase inhibitor. It was used in the treatment of depression. Phenoxypropazine was introduced in 1961 and withdrawn after 5 years on the market due to dose- and time-unrelated liver damage not identified in animal experiments.