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

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Showing 531 - 540 of 42705 results

Prazosin (trade names Minipress, Vasoflex, Lentopres, and Hypovase) is a selective α-1-adrenergic receptor antagonist used to treat hypertension. Prazosin acts by inhibiting the postsynaptic alpha-1-adrenoceptors on vascular smooth muscle. This inhibits the vasoconstrictor effect of circulating and locally released catecholamines (epinephrine and norepinephrine), resulting in peripheral vasodilation. Prazosin is orally active and has a minimal effect on cardiac function due to its alpha-1 receptor selectivity. However, when prazosin is started, heart rate and contractility go up in order to maintain the pre-treatment blood pressures because the body has reached homeostasis at its abnormally high blood pressure. The blood pressure lowering effect becomes apparent when prazosin is taken for longer periods of time. The heart rate and contractility go back down over time and blood pressure decreases. The antihypertensive characteristics of prazosin make it a second-line choice for the treatment of high blood pressure. Prazosin is also useful in treating urinary hesitancy associated with prostatic hyperplasia, blocking alpha-1 receptors, which control constriction of both the prostate and urethra. Although not a first line choice for either hypertension or prostatic hyperplasia, it is a choice for patients who present with both problems concomitantly. Common (4–10% frequency) side effects of prazosin include dizziness, headache, drowsiness, lack of energy, weakness, palpitations, and nausea. Less frequent (1–4%) side effects include vomiting, diarrhea, constipation, edema, orthostatic hypotension, dyspnea, syncope, vertigo, depression, nervousness, and rash.

Class (Stereo):
CHEMICAL (ACHIRAL)

Targets:


Lomustine is used in the treatment of certain neoplastic diseases. Although it is generally agreed that lomustine alkylates DNA and RNA, it is not cross resistant with other alkylators. As with other nitrosoureas, it may also inhibit several key enzymatic processes by carbamoylation of amino acids in proteins. Common adverse reactions include delayed myelosupression, nausea, vomiting, stomatitis, and alopecia.
Status:
First approved in 1976

Class (Stereo):
CHEMICAL (RACEMIC)



Fenoprofen is a propionic acid derivative with analgesic, antiinflammatory and antipyretic properties. Fenoprofen inhibits prostaglandin synthesis by decreasing the enzyme needed for biosynthesis. In patients with rheumatoid arthritis, the anti-inflammatory action of fenoprofen has been evidenced by relief of pain, increase in grip strength, and reductions in joint swelling, duration of morning stiffness, and disease activity (as assessed by both the investigator and the patient). In patients with osteoarthritis, the anti-inflammatory and analgesic effects of fenoprofen have been demonstrated by reduction in tenderness as a response to pressure and reductions in night pain, stiffness, swelling, and overall disease activity (as assessed by both the patient and the investigator). These effects have also been demonstrated by relief of pain with motion and at rest and increased range of motion in involved joints. In patients with rheumatoid arthritis and osteoarthritis, clinical studies have shown fenoprofen to be comparable to aspirin in controlling the aforementioned measures of disease activity, but mild gastrointestinal reactions (nausea, dyspepsia) and tinnitus occurred less frequently in patients treated with fenoprofen than in aspirin-treated patients. It is not known whether fenoprofen causes less peptic ulceration than does aspirin. In patients with pain, the analgesic action of fenoprofen has produced a reduction in pain intensity, an increase in pain relief, improvement in total analgesia scores, and a sustained analgesic effect. Indicated for relief of the signs and symptoms of rheumatoid arthritis and osteoarthritis. Also for the relief of mild to moderate pain.
Vidarabine or 9-β-D-arabinofuranosyladenine (ara-A, trade name Vira-A) is a synthetic purine nucleoside analog with in vitro and in vivo inhibitory activity against herpes simplex virus types 1 (HSV-1), 2 (HSV-2), and varicella-zoster virus (VZV). The inhibitory activity of Vidarabine is highly selective due to its affinity for the enzyme thymidine kinase (TK) encoded by HSV and VZV. This viral enzyme converts Vidarabine into Vidarabine monophosphate, a nucleotide analog. The monophosphate is further converted into diphosphate by cellular guanylate kinase and into triphosphate by a number of cellular enzymes. in vitro, Vidarabine triphosphate stops replication of herpes viral DNA. When used as a substrate for viral DNA polymerase, Vidarabine triphosphate competitively inhibits dATP leading to the formation of 'faulty' DNA. This is where Vidarabine triphosphate is incorporated into the DNA strand replacing many of the adenosine bases. This results in the prevention of DNA synthesis, as phosphodiester bridges can longer to be built, destabilizing the strand.
Status:
First approved in 1976

Class (Stereo):
CHEMICAL (ACHIRAL)



Tolmetin is a nonsteroidal anti-inflammatory agent. It was marketed as Tolectin in USA. TOLECTIN (tolmetin sodium) is indicated for the relief of signs and symptoms of rheumatoid arthritis and osteoarthritis. TOLECTIN is indicated in the treatment of acute flares and the long-term management of the chronic disease. TOLECTIN is also indicated for treatment of juvenile rheumatoid arthritis. The mode of action of tolmetin is not known. However, studies in laboratory animals and man have demonstrated that the anti-inflammatory action of tolmetin is not due to pituitary-adrenal stimulation. Tolmetin inhibits prostaglandin synthetase in vitro and lowers the plasma level of prostaglandin E in man. This reduction in prostaglandin synthesis may be responsible for the anti-inflammatory action.
Amikacin, USP (as the sulfate) is a semi-synthetic aminoglycoside antibiotic derived from kanamycin. Amikacin "irreversibly" binds to specific 30S-subunit proteins and 16S rRNA. Amikacin inhibits protein synthesis by binding to the 30S ribosomal subunit to prevent the formation of an initiation complex with messenger RNA. Specifically Amikacin binds to four nucleotides of 16S rRNA and a single amino acid of protein S12. This interferes with decoding site in the vicinity of nucleotide 1400 in 16S rRNA of 30S subunit. This region interacts with the wobble base in the anticodon of tRNA. This leads to interference with the initiation complex, misreading of mRNA so incorrect amino acids are inserted into the polypeptide leading to nonfunctional or toxic peptides and the breakup of polysomes into nonfunctional monosomes. Amikacin is used for short-term treatment of serious infections due to susceptible strains of Gram-negative bacteria, including Pseudomonas species, Escherichia coli, species of indole-positive and indole-negative Proteus, Providencia species, Klebsiella-Enterobacter-Serratia species, and Acinetobacter (Mima-Herellea) species. Amikacin may also be used to treat Mycobacterium avium and Mycobacterium tuberculosis infections. Amikacin was used for the treatment of gram-negative pneumonia.
Oxybutynin is an antispasmodic, anticholinergic agent indicated for the treatment of overactive bladder with symptoms of urge urinary incontinence, urgency, and frequency. Oxybutynin relaxes bladder smooth muscle. Oxybutynin exhibits only one-fifth of the anticholinergic activity of atropine on the rabbit detrusor muscle, but four to ten times the antispasmodic activity. Antimuscarinic activity resides predominantly in the R-isomer. Oxybutynin exerts a direct antispasmodic effect on smooth muscle and inhibits the muscarinic action of acetylcholine on smooth muscle. No blocking effects occur at skeletal neuromuscular junctions or autonomic ganglia (antinicotinic effects). By inhibiting particularily the M1 and M2 receptors of the bladder, detrusor activity is markedly decreased.
Loxapine is a dibenzoxazepine tricyclic antipsychotic agent, available for oral and inhalatory administration, classified as a typical antipsychotic. Loxapine acts as an antagonist at central serotonin and dopamine receptors. Adasuve (loxapine inhalation powder) is a prescription medicine that is used to treat acute agitation in adults with schizophrenia or bipolar I disorder.
Status:
First approved in 1975

Class (Stereo):
CHEMICAL (ACHIRAL)

Targets:


Dacarbazine (DTIC), also known as imidazole carboxamide, is an antineoplastic agent, which is used in the treatment of metastatic malignant melanoma. In addition, this drug also is indicated for Hodgkin’s disease as a second-line therapy when used in combination with other effective agents. Dacarbazine works by methylating guanine at the O-6 and N-7 positions. Guanine is one of the four nucleotides that makes up DNA. The alkylated DNA strands stick together such that cell division becomes impossible. This affects cancer cells more than healthy cells because cancer cells divide faster. Dacarbazine is bioactivated in liver by demethylation to "MTIC" and then to diazomethane, which is an alkylating agent. Symptoms of anorexia, nausea, and vomiting are the most frequently noted of all toxic reactions. Over 90% of patients are affected with the initial few doses.

Class (Stereo):
CHEMICAL (ABSOLUTE)



Carbidopa is a competitive inhibitor of aromatic L-amino acid decarboxylase that does not cross the blood-brain barrier, is routinely administered with levodopa (LD) for the treatment of the symptoms of idiopathic Parkinson’s disease (paralysis agitans), postencephalitic parkinsonism, and symptomatic parkinsonism, which may follow injury to the nervous system by carbon monoxide intoxication and/or manganese intoxication. Current evidence indicates that symptoms of Parkinson’s disease are related to depletion of dopamine in the corpus striatum. Administration of dopamine is ineffective in the treatment of Parkinson’s disease apparently because it does not cross the blood-brain barrier. However, levodopa, the metabolic precursor of dopamine, does cross the blood- brain barrier, and presumably is converted to dopamine in the brain. When levodopa is administered orally it is rapidly decarboxylated to dopamine in extracerebral tissues so that only a small portion of a given dose is transported unchanged to the central nervous system. For this reason, large doses of levodopa are required for adequate therapeutic effect and these may often be accompanied by nausea and other adverse reactions, some of which are attributable to dopamine formed in extracerebral tissues. Carbidopa inhibits decarboxylation of peripheral levodopa. Carbidopa has not been demonstrated to have any overt pharmacodynamic actions in the recommended doses.