U.S. Department of Health & Human Services Divider Arrow National Institutes of Health Divider Arrow NCATS

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Showing 461 - 470 of 34988 results

Desipramine is a tricyclic antidepressant that was approved by the FDA in 1964. It was derived from imipramine, which was the first tricyclic antidepressant to be manufactured. Desipramine is one of many tricyclic antidepressants, and this type of antidepressant gets its name due to its three-ring chemical structure. Desipramine, a secondary amine tricyclic antidepressant, is structurally related to both the skeletal muscle relaxant cyclobenzaprine and the thioxanthene antipsychotics such as thiothixene. It is the active metabolite of imipramine, a tertiary amine TCA. The acute effects of desipramine include inhibition of noradrenaline re-uptake at noradrenergic nerve endings and inhibition of serotonin (5-hydroxy tryptamine, 5HT) re-uptake at the serotoninergic nerve endings in the central nervous system. Desipramine exhibits greater noradrenergic re-uptake inhibition compared to the tertiary amine TCA imipramine. In addition to inhibiting neurotransmitter re-uptake, desipramine down-regulates beta-adrenergic receptors in the cerebral cortex and sensitizes serotonergic receptors with chronic use. The overall effect is increased serotonergic transmission. Antidepressant effects are typically observed 2 - 4 weeks following the onset of therapy though some patients may require up to 8 weeks of therapy prior to symptom improvement. Patients experiencing more severe depressive episodes may respond quicker than those with mild depressive symptoms. Desipramine is marketed under the trade name Norpramin, indicated for the treatment of depression.
Melphalan, also known as L-phenylalanine mustard, phenylalanine mustard, L-PAM, or L-sarcolysin, is a phenylalanine derivative of nitrogen mustard. Melphalan is a bifunctional alkylating agent which produces a number of DNA adducts with the DNA interstrand crosslink (ICL) considered to be the critical cytotoxic lesion. Melphalan is used to treat different cancers including myeloma, melanoma and ovarian cancer.
Status:
First approved in 1964

Class (Stereo):
CHEMICAL (ACHIRAL)



Pralidoxime is a cholinesterase reactivator used as the antidote to organophosphate pesticides or acetylcholinesterase inhibitors (nerve agents) in conjunction with atropine and diazepam. Organophosphates bind to the esteratic site of acetylcholinesterase, which results initially in reversible inactivation of the enzyme. Acetylcholinesterase inhibition causes acetylcholine to accumulate in synapses, producing continuous stimulation of cholinergic fibers throughout the nervous systems. If given within 24 hours after organophosphate exposure, pralidoxime reactivates the acetylcholinesterase by cleaving the phosphate-ester bond formed between the organophosphate and acetylcholinesterase. Pralidoxime is indicated as an adjunct in the treatment of moderate and severe poisoning caused by organophosphate pesticides that have anticholinesterase activity or by chemicals with anticholinesterase activity such as some chemicals used as nerve agents during chemical warfare. Pralidoxime is also indicated as an adjunct in the management of the overdose of cholinesterase inhibitors, such as ambenonium, neostigmine, and pyridostigmine, used in the treatment of myasthenia gravis. Pralidoxime, used in conjunction with atropine, reverses nicotinic effects, such as muscle weakness and fasciculation, respiratory depression, and central nervous system (CNS) effects, associated with toxic exposure to organophosphate anticholinesterase pesticides and chemicals and with cholinesterase inhibitor overdose. Atropine, by antagonizing the action of cholinesterase inhibitors at muscarinic receptor sites, reverses muscarinic effects, such as tracheobronchial and salivary secretion, bronchoconstriction, bradycardia, and, to a moderate extent, CNS effects.
Lincomycin (LINCOCIN®) is an antibiotic produced by Streptomyces lincolnensis (Streptomycetaceae family). It has been used in the treatment of staphylococcal, streptococcal, and Bacteroides fragilis infections. Lincomycin (LINCOCIN®) inhibits protein synthesis in susceptible bacteria by binding to the 50S subunits of bacterial ribosomes and preventing peptide bond formation upon transcription. It is usually considered bacteriostatic, but may be bactericidal in high concentrations or when used against highly susceptible microorganisms.
Diazepam is a benzodiazepine first discovered at Hoffman-La Roche in the late 1950s. Diazepam was approved by FDA for the treatment of anxiety disorders as well as for such conditions as skeletal muscle spasm, alcohol withdrawal syndrom and convulsions (under the most known brand Valium). The drug acts by binding to GABA-A receptors and potentiating GABA evoked current. Chronic diazepam use is associated with tolerance, dependence, and withdrawal.
Metronidazole was synthesized by France's Rhone-Poulenc laboratories and introduced in the mid-1950s under the brand name Flagel in the US, while Sanofi-Aventis markets metronidazole globally under the same trade name, Flagyl, and also by various generic manufacturers. Metronidazole is one of the rare examples of a drug developed as ant parasitic, which has since gained broad use as an antibacterial agent. Metronidazole, a nitroimidazole, exerts antibacterial effects in an anaerobic environment against most obligate anaerobes. Metronidazole is indicated for the treatment of the following infections due to susceptible strains of sensitive organisms: Trichomoniasis: symptomatic, asymptomatic, asymptomatic consorts; Amebiasis: acute intestinal amebiasis (amebic dysentery) and amebic liver abscess; Anaerobic bacterial infections; Intra-abdominal infections, including peritonitis, intra-abdominal abscess, and liver abscess; Skin and skin structure infections; Gynecologic infections, including endometritis, endomyometritis, tubo-ovarian abscess, and postsurgical vaginal cuff infection; Bacterial septicemia; Bone and joint infections, as adjunctive therapy; Central Nervous System infections, including meningitis and brain abscess; Lower Respiratory Tract infections, including pneumonia, empyema, and lung abscess; Endocarditis. Metronidazole is NOT effective for infections caused by aerobic bacteria that can survive in the presence of oxygen. Metronidazole is only effective against anaerobic bacterial infections because the presence of oxygen will inhibit the nitrogen-reduction process that is crucial to the drug's mechanism of action. Once metronidazole enters the organism by passive diffusion and activated in the cytoplasm of susceptible anaerobic bacteria, it is reduced; this process includes intracellular electron transport proteins such as ferredoxin, transfer of an electron to the nitro group of the metronidazole, and formation of a short-lived nitroso free radical. Because of this alteration of the metronidazole molecule, a concentration gradient is created and maintained which promotes the drug’s intracellular transport. The reduced form of metronidazole and free radicals can interact with DNA leading to inhibition of DNA synthesis and DNA degradation leading to death of the bacteria. The precise mechanism of action of metronidazole is unknown. Metronidazole has a limited spectrum of activity that encompasses various protozoans and most Gram-negative and Gram-positive anaerobic bacteria. Metronidazole has activity against protozoans like Entamoeba histolytica, Giardia lamblia and Trichomonas vaginalis, for which the drug was first approved as an effective treatment.
Oxacillin is a penicillin beta-lactam antibiotic used in the treatment of bacterial infections caused by susceptible, usually gram-positive, organisms. The name "penicillin" can either refer to several variants of penicillin available, or to the group of antibiotics derived from the penicillins. Oxacillin has in vitro activity against gram-positive and gram-negative aerobic and anaerobic bacteria. The bactericidal activity of Oxacillin results from the inhibition of cell wall synthesis and is mediated through Oxacillin binding to penicillin binding proteins (PBPs). Oxacillin is stable against hydrolysis by a variety of beta-lactamases, including penicillinases, and cephalosporinases and extended spectrum beta-lactamases. By binding to specific penicillin-binding proteins (PBPs) located inside the bacterial cell wall, Oxacillin inhibits the third and last stage of bacterial cell wall synthesis. Cell lysis is then mediated by bacterial cell wall autolytic enzymes such as autolysins; it is possible that Oxacillin interferes with an autolysin inhibitor. Oxacillin is used in the treatment of resistant staphylococci infections. Oxacillin sodium was marketed under the trade name Bactocill.
Status:
First approved in 1962

Class (Stereo):
CHEMICAL (RACEMIC)



Metaxalone (marketed by King Pharmaceuticals under the brand name Skelaxin) is a muscle relaxant used to relax muscles and relieve pain caused by strains, sprains, and other musculoskeletal conditions. The mechanism of action of metaxalone in humans has not been established, but may be due to general central nervous system depression. Metaxalone has no direct action on the contractile mechanism of striated muscle, the motor end plate, or the nerve fiber. Skelaxin is available in an 800 mg scored tablet. Metaxalone relatively low incidence of side effects. The most common adverse reactions to Metaxalone tablets include drowsiness, dizziness, headache, and nervousness or “irritability”, nausea, vomiting, gastrointestinal upset.
Tegafur (INN, BAN, USAN) is a chemotherapeutic fluorouracil prodrug used in the treatment of cancers. It is a component of the combination drugs tegafur/uracil and tegafur/gimeracil/oteracil. UFT is an anticancer medication composed of a fixed molar ration (1:4) of tegafur and uracil. This drug is commonly used in the treatment of head and neck cancer, gastric cancer, colorectal cancer, hepatic cancer, gallbladder cancer, bile-duct cancer, pancreatic cancer, lung cancer, breast cancer, bladder cancer, prostatic cancer, or uterine cervical cancer. In the body, tegafur is converted into 5-fluorouracil (5-FU), the active antineoplastic metabolite. The mechanism of cytotoxicity of 5-FU is thought to be derived from the fact that 5-fluoro-deoxyuridine-monophosphate (FdUMP), the active metabolite of 5-FU, competes with deoxyuridine-monophosphate (dUMP), thereby inhibiting thymidylate synthase and subsequently DNA synthesis. Another active metabolite of 5-FU, 5-fluorouridine-triphosphate (FUTP) is integrated into cellular RNA, inhibiting RNA function. Uracil, when combined with tegafur, enhances the antitumor activity of 5-FU due to higher 5-FU concentrations in the tumor tissue versus normal surrounding tissue compared with tegafur alone. Uracil inhibits degradation of the released 5-FU. The combination of these two drugs enhances the antitumor activity of Tegafur.
Thioridazine (Mellaril or Melleril) is a piperidine typical antipsychotic drug belonging to the phenothiazine drug group and was previously widely used in the treatment of schizophrenia and psychosis. Thioridazine blocks postsynaptic mesolimbic dopaminergic D1 and D2 receptors in the brain; blocks alpha-adrenergic effect depresses the release of hypothalamic and hypophyseal hormones and is believed to depress the reticular activating system thus affecting basal metabolism, body temperature, wakefulness, vasomotor tone, and emesis. Thioridazine primary use in medicine was the treatment of schizophrenia. Thioridazine was also tried with some success as a treatment for various psychiatric symptoms seen in people with dementia, but chronic use of thioridazine and other antipsychotics in people with dementia is not recommended. Thioridazine prolongs the QTc interval in a dose-dependent manner. It produces significantly less extrapyramidal side effects than most first-generation antipsychotics. Its use, along with the use of other typical antipsychotics, has been associated with degenerative retinopathies. It has a higher propensity for causing anticholinergic side effects coupled with a lower propensity for causing extrapyramidal side effects and sedation than chlorpromazine but also has a higher incidence of hypotension and cardiotoxicity. It is also known to possess a relatively high liability for causing orthostatic hypotension compared to other antipsychotics. Similarly to other first-generation antipsychotics, it has a relatively high liability for causing prolactin elevation. It is the moderate risk of causing weight gain.