Sirolimus is the USAN-assigned generic name for the natural product rapamycin. Sirolimus is produced by a strain of Streptomyces hygroscopicus, isolated from a soil sample collected from Rapa Nui commonly known as Easter Island. Although sirolimus was isolated as an antifungal agent with potent anticandida activity, subsequent studies revealed impressive antitumor and immunosuppressive activities. Sirolimus demonstrates activity against several murine tumors, such as B16 43 melanocarcinoma, Colon 26 tumor, EM ependymoblastoma, and mammary and colon 38 solid tumors. Demonstration of the potent immunosuppressive activity of sirolimus in animal models of organ transplantation led to clinical trials and subsequent approval by regulatory authorities for prophylaxis of renal graft rejection. Interest in sirolimus as an immunosuppressive therapy in organ transplantation derives from its unique mechanism of action, its unique side-effect profile, and its ability to synergize with other immunosuppressive agents. It is used in medicine to prevent organ transplant rejection and to treat lymphangioleiomyomatosis. Sirolimus inhibits T-lymphocyte activation and proliferation that occurs in response to antigenic and cytokine (Interleukin [IL]-2, IL-4, and IL-15) stimulation by a mechanism that is distinct from that of other immunosuppressants. Sirolimus also inhibits antibody production. In cells, sirolimus binds to the immunophilin, FK Binding Protein-12 (FKBP-12), to generate an immunosuppressive complex. This complex blocks the activation of the cell-cycle-specific kinase, TOR. The downstream events that follow the inactivation of TOR result in the blockage of cell-cycle progression at the juncture of G1 and S phase. Rapamycin/FKBP12 efficiently inhibit some, but not all, functions of mTOR and hence much interest has been placed in the development of drugs that target the kinase activity of mTOR directly. Studies in experimental models show that sirolimus prolongs allograft (kidney, heart, skin, islet, small bowel, pancreatico-duodenal, and bone marrow) survival in mice, rats, pigs, and/or primates. Sirolimus reverses acute rejection of heart and kidney allografts in rats and prolongs the graft survival in presensitized rats. In some studies, the immunosuppressive effect of sirolimus lasts up to 6 months after discontinuation of therapy. This tolerization effect is alloantigen-specific. In rodent models of autoimmune disease, sirolimus suppresses immune-mediated events associated with systemic lupus erythematosus, collagen-induced arthritis, autoimmune type I diabetes, autoimmune myocarditis, experimental allergic encephalomyelitis, graft-versus-host disease, and autoimmune uveoretinitis. Lymphangioleiomyomatosis involves lung tissue infiltration with smooth muscle-like cells that harbor inactivating mutations of the tuberous sclerosis complex (TSC) gene (LAM cells). Loss of TSC gene function activates the mTOR signaling pathway, resulting in cellular proliferation and release of lymphangiogenic growth factors. Sirolimus inhibits the activated mTOR pathway and thus the proliferation of LAM cells.

Pioglitazone (brand name Actos) is a prescription drug of the thiazolidinedione class with hypoglycemic action used in the treatment of type 2 diabetes. Pioglitazone selectively stimulates the nuclear receptor peroxisome proliferator-activated receptor gamma (PPAR-γ) and to a lesser extent PPAR-α. It modulates the transcription of the genes involved in the control of glucose and lipid metabolism in the muscle, adipose tissue, and the liver. As a result, pioglitazone reduces insulin resistance in the liver and peripheral tissues, decreases gluconeogenesis in the liver, and reduces the quantity of glucose and glycated hemoglobin in the bloodstream. Pioglitazone is used to lower blood glucose levels in the treatment of diabetes mellitus type 2 (T2DM) either alone or in combination with a sulfonylurea, metformin, or insulin. Pioglitazone cannot be used in patients with a known hypersensitivity to pioglitazone, other thiazolidinediones or any of components of its pharmaceutical forms. It is ineffective and possibly harmful to diabetes mellitus type 1 and diabetic ketoacidosis. Pioglitazone can cause fluid retention and peripheral edema. As a result, it may precipitate congestive heart failure (which worsens with fluid overload in those at risk). It may cause anemia. Mild weight gain is common due to increase in subcutaneous adipose tissue. In studies, patients on pioglitazone had an increased proportion of upper respiratory tract infection, sinusitis, headache, myalgia and tooth problems.

NEO 212 is novel DNA alkylating agent exhibiting superior activity against breast cancer cells in vitro and intracranial triple-negative tumor growth in vivo. NEO212 is a conjugate of temozolomide (TMZ,) with the natural product perillyl alcohol (POH). NEO 212 causes DNA damage and cell death much more efficiently than TMZ because linkage with POH increased it's biological half-life and thus provided greater opportunity for placement of cytotoxic DNA lesions.

Levetiracetam is an anticonvulsant medication used to treat epilepsy. Levetiracetam may selectively prevent hypersynchronization of epileptiform burst firing and propagation of seizure activity. The precise mechanism(s) by which levetiracetam exerts its antiepileptic effect is unknown. The antiepileptic activity of levetiracetam was assessed in a number of animal models of epileptic seizures. Levetiracetam did not inhibit single seizures induced by maximal stimulation with electrical current or different chemoconvulsants and showed only minimal activity in submaximal stimulation and in threshold tests. Levetiracetam also displayed inhibitory properties in the kindling model in rats, another model of human complex partial seizures, both during kindling development and in the fully kindled state. The predictive value of these animal models for specific types of human epilepsy is uncertain. In vitro and in vivo recordings of epileptiform activity from the hippocampus have shown that levetiracetam inhibits burst firing without affecting normal neuronal excitability, suggesting that levetiracetam may selectively prevent hypersynchronization of epileptiform burst firing and propagation of seizure activity. Levetiracetam at concentrations of up to 10 µM did not demonstrate binding affinity for a variety of known receptors, such as those associated with benzodiazepines, GABA (gamma-aminobutyric acid), glycine, NMDA (Nmethyl-D-aspartate), re-uptake sites, and second messenger systems. Furthermore, in vitro studies have failed to find an effect of levetiracetam on neuronal voltage-gated sodium or T-type calcium currents and levetiracetam does not appear to directly facilitate GABAergic neurotransmission. However, in vitro studies have demonstrated that levetiracetam opposes the activity of negative modulators of GABA- and glycine-gated currents and partially inhibits N-type calcium currents in neuronal cells. A saturable and stereoselective neuronal binding site in rat brain tissue has been described for levetiracetam. Experimental data indicate that this binding site is the synaptic vesicle protein SV2A, thought to be involved in the regulation of vesicle exocytosis. Interaction of levetiracetam with the SV2A protein may contribute to the antiepileptic mechanism of action of the drug. Levetiracetam, along with other anti-epileptic drugs, can increase the risk of suicide behavior or thoughts. People taking levetiracetam should be monitored closely for signs of worsening depression, suicidal thoughts or tendencies, or any altered emotional or behavioral states.

Bexarotene (Targretin) is an antineoplastic agent indicated by the FDA for Cutaneous T cell lymphoma. It has been used off-label for lung cancer, breast cancer, and Kaposi's sarcoma. Bexarotene is a member of a subclass of retinoids that selectively activate retinoid X receptors (RXRs). These retinoid receptors have biologic activity distinct from that of retinoic acid receptors (RARs). Bexarotene selectively binds and activates retinoid X receptor subtypes (RXRa, RXRb, RXRg). RXRs can form heterodimers with various receptor partners such as retinoic acid receptors (RARs), vitamin D receptor, thyroid receptor, and peroxisome proliferator activator receptors (PPARs). Once activated, these receptors function as transcription factors that regulate the expression of genes that control cellular differentiation and proliferation. Bexarotene inhibits the growth in vitro of some tumor cell lines of hematopoietic and squamous cell origin. It also induces tumor regression in vivo in some animal models. The exact mechanism of action of bexarotene in the treatment of cutaneous T-cell lymphoma (CTCL) is unknown.

Ketotifen is a cycloheptathiophene blocker of histamine H1 receptors and release of inflammatory mediators. It has been proposed for the treatment of asthma, rhinitis, skin allergies, and anaphylaxis. Ketotifen was developed in 1970 by Sandoz Pharmaceuticals of Switzerland. It is a benzocycloheptathiophene derivative and was initially marketed as an inhibitor of anaphylaxis. The pharmacodynamic properties of ketotifen are many, because it is an inhibitor of the release and/or activity of mast cell and basophil mediators, including histamine, neutrophil, and eosinophil chemotactic factors, arachidonic acid metabolites, prostaglandins, and leukotrienes. Properties of ketotifen which may contribute to its antiallergic activity and its ability to affect the underlying pathology of asthma include inhibition of the development of airway hyper-reactivity associated with activation of platelets by PAF (Platelet Activating Factor), inhibition of PAF-induced accumulation of eosinophils and platelets in the airways, suppression of the priming of eosinophils by human recombinant cytokines and antagonism of bronchoconstriction due to leukotrienes. Ketotifen is marketed under many brand names worldwide. Ketotifen inhibits the release of mediators from mast cells involved in hypersensitivity reactions. Decreased chemotaxis and activation of eosinophils have also been demonstrated. Ketotifen also inhibits cAMP phosphodiesterase.

Tolcapone is a potent, selective, and reversible inhibitor of catechol-O-methyltransferase (COMT). In humans, COMT is distributed throughout various organs. COMT catalyzes the transfer of the methyl group of S-adenosyl-L-methionine to the phenolic group of substrates that contain a catechol structure. Physiological substrates of COMT include dopa, catecholamines (dopamine, norepinephrine, epinephrine) and their hydroxylated metabolites. The function of COMT is the elimination of biologically active catechols and some other hydroxylated metabolites. COMT is responsible for the elimination of biologically active catechols and some other hydroxylated metabolites. In the presence of a decarboxylase inhibitor, COMT becomes the major metabolizing enzyme for levodopa catalyzing it to 3-methoxy-4-hydroxy-L-phenylalanine (3-OMD) in the brain and periphery. When tolcapone is given in conjunction with levodopa and an aromatic amino acid decarboxylase inhibitor, such as carbidopa, plasma levels of levodopa are more sustained than after administration of levodopa and an aromatic amino acid decarboxylase inhibitor alone. It is believed that these sustained plasma levels of levodopa result in more constant dopaminergic stimulation in the brain, leading to greater effects on the signs and symptoms of Parkinson's disease in patients as well as increased levodopa adverse effects, sometimes requiring a decrease in the dose of levodopa. The precise mechanism of action of tolcapone is unknown, but it is believed to be related to its ability to inhibit COMT and alter the plasma pharmacokinetics of levodopa, resulting in an increase in plasma levodopa concentrations. The inhibition of COMT also causes a reduction in circulating 3-OMD as a result of decreased peripheral metabolism of levodopa. This may lead to an increase distribution of levodopa into the CNS through the reduction of its competitive substrate, 3-OMD, for transport mechanisms. Sustained levodopa concentrations presumably result in more consistent dopaminergic stimulation, resulting in greater reduction in the manifestations of parkinsonian syndrome. Tolcapone is used as an adjunct to levodopa/carbidopa therapy for the symptomatic treatment of Parkinson's Disease. This drug is generally reserved for patients with parkinsonian syndrome receiving levodopa/carbidopa who are experiencing symptom fluctuations and are not responding adequately to or are not candidates for other adjunctive therapies. Tolcapone is sold under the brand name Tasmar.

PRIFTIN® (rifapentine) is indicated in adults and children 12 years and older for the treatment of active pulmonary tuberculosis (TB) caused by Mycobacterium tuberculosis. PRIFTIN must always be used in combination with one or more antituberculosis (anti-TB) drugs to which the isolate is susceptible. Rifapentine is an antibiotic that inhibits DNA-dependent RNA polymerase activity in susceptible cells. Specifically, it interacts with bacterial RNA polymerase but does not inhibit the mammalian enzyme. And it acts via the inhibition of DNA-dependent RNA polymerase, leading to a suppression of RNA synthesis and cell death. It is bactericidal and has a very broad spectrum of activity against most gram-positive and gram-negative organisms (including Pseudomonas aeruginosa) and specifically Mycobacterium tuberculosis. Because of rapid emergence of resistant bacteria, use is restricted to treatment of mycobacterial infections and a few other indications. Rifampin is well absorbed when taken orally and is distributed widely in body tissues and fluids, including the CSF. It is metabolized in the liver and eliminated in bile and, to a much lesser extent, in urine, but dose adjustments are unnecessary with renal insufficiency. Rifapentine has shown higher bacteriostatic and bactericidal activities especially against intracellular bacteria growing in human monocyte-derived macrophages.

Eptifibatide is a platelet aggregation inhibitor - an anti-coagulant that selectively blocks the platelet glycoprotein IIb/IIIa receptor. It is a cyclic heptapeptide derived from a protein found in the venom of the southeastern pygmy rattlesnake. It belongs to the class of the so called arginin-glycin-aspartat-mimetics and reversibly binds to platelets. Eptifibatide inhibits platelet aggregation by reversibly binding to the platelet receptor glycoprotein (GP) IIb/IIIa of human platelets, thus preventing the binding of fibrinogen, von Willebrand factor, and other adhesive ligands. Inhibition of platelet aggregation occurs in a dose- and concentration-dependent manner. It is used for treatment of myocardial infarction and acute coronary syndrome.

Thalidomide is an immunomodulatory agent with a spectrum of activity that is not fully characterized. Thalidomide is racemic — it contains both left and right-handed isomers in equal amounts: one enantiomer is effective against morning sickness, and the other is teratogenic. The enantiomers are converted to each other in vivo. That is, if a human is given D-thalidomide or L-thalidomide, both isomers can be found in the serum. Hence, administering only one enantiomer will not prevent the teratogenic effect in humans. In patients with erythema nodosum leprosum (ENL) the mechanism of action is not fully understood. Available data from in vitro studies and preliminary clinical trials suggest that the immunologic effects of this compound can vary substantially under different conditions, but may be related to suppression of excessive tumor necrosis factor-alpha (TNF-a) production and down-modulation of selected cell surface adhesion molecules involved in leukocyte migration. For example, administration of thalidomide has been reported to decrease circulating levels of TNF-a in patients with ENL, however, it has also been shown to increase plasma TNF-a levels in HIV-seropositive patients. As a cancer treatment, the drug may act as a VEGF inhibitor. Thalidomide is used for the acute treatment of the cutaneous manifestations of moderate to severe erythema nodosum leprosum (ENL). Also for use as maintenance therapy for prevention and suppression of the cutaneous manifestations of ENL recurrence. Thalidomide is sold under the brand name Immunoprin, among others.