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

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Showing 4671 - 4680 of 8583 results

Tamoxifen (brand name Nolvadex), is selective estrogen receptor modulators (SERM) with tissue-specific activities for the treatment and prevention of estrogen receptor positive breast cancer. Tamoxifen itself is a prodrug, having relatively little affinity for its target protein, the estrogen receptor (ER). It is metabolized in the liver by the cytochrome P450 isoform CYP2D6 and CYP3A4 into active metabolites such as 4-hydroxytamoxifen (4-OHT) (afimoxifene) and N-desmethyl-4-hydroxytamoxifen (endoxifen) which have 30–100 times more affinity with the ER than tamoxifen itself. These active metabolites compete with estrogen in the body for binding to the ER. In breast tissue, 4-OHT acts as an ER antagonist so that transcription of estrogen-responsive genes is inhibited. Tamoxifen has 7% and 6% of the affinity of estradiol for the ERα and ERβ, respectively, whereas 4-OHT has 178% and 338% of the affinity of estradiol for the ERα and ERβ. The prolonged binding of tamoxifen to the nuclear chromatin of these results in reduced DNA polymerase activity, impaired thymidine utilization, blockade of estradiol uptake, and decreased estrogen response. It is likely that tamoxifen interacts with other coactivators or corepressors in the tissue and binds with different estrogen receptors, ER-alpha or ER-beta, producing both estrogenic and antiestrogenic effects. Tamoxifen is currently used for the treatment of both early and advanced estrogen receptor (ER)-positive (ER+) breast cancer in pre- and post-menopausal women. Additionally, it is the most common hormone treatment for male breast cancer. Patients with variant forms of the gene CYP2D6 (also called simply 2D6) may not receive full benefit from tamoxifen because of too slow metabolism of the tamoxifen prodrug into its active metabolites. Tamoxifen is used as a research tool to trigger tissue-specific gene expression in many conditional expression constructs in genetically modified animals including a version of the Cre-Lox recombination technique. Tamoxifen has been shown to be effective in the treatment of mania in patients with bipolar disorder by blocking protein kinase C (PKC), an enzyme that regulates neuron activity in the brain. Researchers believe PKC is over-active during the mania in bipolar patients.
Status:
First approved in 1977
Source:
Colestid by Upjohn
Source URL:

Class (Stereo):
CHEMICAL (ACHIRAL)



Tetraethylenepentamine (TEPA) is a low-molecular-weight linear polyamine exerting metal-chelating properties. TEPA is widely used in industrial applications. The principal hazards that arise in working with TEPA are those associated with similar organic amines; namely, a corrosive action on skin and eyes. TEPA biological activity was attributed to its effect on cellular Cu levels as (a) treatment with TEPA resulted in reduction of cellular Cu, and (b) excess of Cu reversed TEPA's activity and accelerated differentiation. TEPA was shown to attenuate the differentiation of ex vivo cultured hematopoietic cells resulting in preferential expansion of early progenitors. A phase I/II trial was performed to test the feasibility and safety of transplantation of CD133+ cord blood (CB) hematopoietic progenitors cultured in media containing stem cell factor, FLT-3 ligand, interleukin-6, thrombopoietin and TEPA. Transplanting a population of CD133+ CB cells which were expanded ex vivo for 21 days using SCF, FLT3, IL-6, TPO and the copper chelator TEPA (StemEx) was feasible. The expanded cells were well tolerated, with no infusion-related adverse events observed.
Disopyramide is an antiarrhythmic drug indicated for the treatment of documented ventricular arrhythmias, such as sustained ventricular tachycardia that are life-threatening. In man, Disopyramide at therapeutic plasma levels shortens the sinus node recovery time, lengthens the effective refractory period of the atrium, and has a minimal effect on the effective refractory period of the AV node. Little effect has been shown on AV-nodal and His-Purkinje conduction times or QRS duration. However, prolongation of conduction in accessory pathways occurs. Disopyramide is a Type 1A antiarrhythmic drug (ie, similar to procainamide and quinidine). It inhibits the fast sodium channels. In animal studies Disopyramide decreases the rate of diastolic depolarization (phase 4) in cells with augmented automaticity, decreases the upstroke velocity (phase 0) and increases the action potential duration of normal cardiac cells, decreases the disparity in refractoriness between infarcted and adjacent normally perfused myocardium, and has no effect on alpha- or beta-adrenergic receptors. It is used for the treatment of documented ventricular arrhythmias, such as sustained ventricular tachycardia, ventricular pre-excitation and cardiac dysrhythmias. It is a Class Ia antiarrhythmic drug.
Status:
First approved in 1977

Class (Stereo):
CHEMICAL (RACEMIC)


Conditions:

Baclofen (brand names Kemstro, Lioresal, and Gablofen) is a derivative of gamma-aminobutyric acid (GABA). Baclofen is a muscle relaxer and an antispastic agent and is used to treat muscle symptoms caused by multiple sclerosis, including spasm, pain, and stiffness. It is primarily used to treat spasticity and is under investigation for the treatment of alcoholism. Although baclofen is an analog of the putative inhibitory neurotransmitter gamma-aminobutyric acid (GABA), there is no conclusive evidence that actions on GABA systems are involved in the production of its clinical effects. Baclofen is rapidly and extensively absorbed and eliminated. Absorption may be dose-dependent, being reduced with increasing doses. Baclofen is excreted primarily by the kidney in unchanged form and there is relatively large intersubjective variation in absorption and/or elimination. Baclofen is a direct agonist at GABA-B receptors. The precise mechanism of action of baclofen is not fully known. It is capable of inhibiting both monosynaptic and polysynaptic reflexes at the spinal level, possibly by hyperpolarization of afferent terminals, although actions at supraspinal sites may also occur and contribute to its clinical effect.
Clocortolone (used in form of pivalate prodrug) is a topical glucocorticoid that was approved by FDA for the treatment of corticosteroid-responsive skin disorders. The drug exerts its anti-inflammatory action by binding to glucocorticoid receptor which results in regulation of the expression of proinflammatory cytokines and further antiproliferative, immunosuppressive, and initial vasoconstrictive effects.
Clocortolone (used in form of pivalate prodrug) is a topical glucocorticoid that was approved by FDA for the treatment of corticosteroid-responsive skin disorders. The drug exerts its anti-inflammatory action by binding to glucocorticoid receptor which results in regulation of the expression of proinflammatory cytokines and further antiproliferative, immunosuppressive, and initial vasoconstrictive effects.
Cimetidine is a histamine H2-receptor antagonist. It reduces basal and nocturnal gastric acid secretion and a reduction in gastric volume, acidity, and amount of gastric acid released in response to stimuli including food, caffeine, insulin, betazole, or pentagastrin. It is used to treat gastrointestinal disorders such as gastric or duodenal ulcer, gastroesophageal reflux disease, and pathological hypersecretory conditions. Cimetidine inhibits many of the isoenzymes of the hepatic CYP450 enzyme system. Other actions of Cimetidine include an increase in gastric bacterial flora such as nitrate-reducing organisms. Cimetidine binds to an H2-receptor located on the basolateral membrane of the gastric parietal cell, blocking histamine effects. This competitive inhibition results in reduced gastric acid secretion and a reduction in gastric volume and acidity.
Clocortolone (used in form of pivalate prodrug) is a topical glucocorticoid that was approved by FDA for the treatment of corticosteroid-responsive skin disorders. The drug exerts its anti-inflammatory action by binding to glucocorticoid receptor which results in regulation of the expression of proinflammatory cytokines and further antiproliferative, immunosuppressive, and initial vasoconstrictive effects.
Status:
First approved in 1977
Source:
THALLOUS CHLORIDE TL 201 by LANTHEUS MEDCL
Source URL:

Class (Stereo):
CHEMICAL (ACHIRAL)


Thallous chloride (also known as Thallium(I) chloride) is a chemical compound with the formula TlCl. Thallous Chloride Tl 201 Injection is a diagnostic radiopharmaceutical indicated for: Myocardial perfusion imaging with planar scintigraphy or single-photon emission computed tomography (SPECT) for the diagnosis of coronary artery disease by localization of: Non-reversible defects (myocardial infarction) which may have prognostic value regarding survival. Reversible defects (myocardial ischemia) when used in conjunction with exercise or pharmacologic stress. Localization of sites of parathyroid hyperactivity pre- and post-operatively in patients with elevated serum calcium and parathyroid hormone levels.
Cyclobenzaprine is a centrally-acting muscle relaxant which boosts levels of norepinephrine and binds to serotonin receptors in the brain to reduce spasm. Cytochromes P-450 3A4, 1A2, and, to a lesser extent, 2D6, mediate N-demethylation, one of the oxidative pathways for cyclobenzaprine. Cyclobenzaprine relieves skeletal muscle spasm of local origin without interfering with muscle function. Drowsiness, fatigue and sedation (up to 40%) is the most common side effect of Cyclobenzaprine. It may have life-threatening interactions with monoamine oxidase (MAO) inhibitors. Postmarketing cases of serotonin syndrome have been reported during combined use of cyclobenzaprine and other drugs such as selective serotonin reuptake inhibitors (SSRIs), serotonin norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), tramadol, bupropion, meperidine, verapamil, or MAO inhibitors.

Showing 4671 - 4680 of 8583 results