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

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Showing 4031 - 4040 of 8583 results


Class (Stereo):
CHEMICAL (ABSOLUTE)



Atorvastatin calcium (LIPITOR®) is a pyrrole and heptanoic acid derivative, a synthetic lipid-lowering agent. Atorvastatin is a selective, competitive inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase. This enzyme catalyzes the conversion of HMG-CoA to mevalonate, an early and rate-limiting step in cholesterol biosynthesis. Atorvastatin is used to reduce serum levels of LDL(low-density lipoprotein)-cholesterol; apolipoprotein B; and triglycerides and to increase serum levels of HDL(high-density lipoprotein)-cholesterol in the treatment of hyperlipidemias and prevention of cardiovascular disease in patients with multiple risk factors.
Tizanidine is a short-acting drug for the management of spasticity. Tizanidine is an agonist at a2-adrenergic receptor sites and presumably reduces spasticity by increasing presynaptic inhibition of motor neurons. In animal models, tizanidine has no direct effect on skeletal muscle fibers or the neuromuscular junction, and no major effect on monosynaptic spinal reflexes. The effects of tizanidine are greatest on polysynaptic pathways. The overall effect of these actions is thought to reduce facilitation of spinal motor neurons. Side effects include dizziness, drowsiness, weakness, nervousness, hallucinations, depression, vomiting, dry mouth, constipation, diarrhea, stomach pain, heartburn, increased muscle spasms, back pain, rash, sweating, and a tingling sensation in the arms, legs, hands, and feet.
Topotecan, a semi-synthetic derivative of camptothecin (a plant alkaloid obtained from the Camptotheca acuminata tree), is an anti-tumor drug with topoisomerase I-inhibitory activity similar to irinotecan. DNA topoisomerases are enzymes in the cell nucleus that regulate DNA topology (3-dimensional conformation) and facilitate nuclear processes such as DNA replication, recombination, and repair. During these processes, DNA topoisomerase I creates reversible single-stranded breaks in double-stranded DNA, allowing intact single DNA strands to pass through the break and relieve the topologic constraints inherent in supercoiled DNA. The 3'-DNA terminus of the broken DNA strand binds covalently with the topoisomerase enzyme to form a catalytic intermediate called a cleavable complex. After DNA is sufficiently relaxed and the strand passage reaction is complete, DNA topoisomerase reattaches the broken DNA strands to form the unaltered topoisomers that allow transcription to proceed. Topotecan interferes with the growth of cancer cells, which are eventually destroyed. Since the growth of normal cells can be affected by the medicine, other effects may also occur. Unlike irinotecan, topotecan is found predominantly in the inactive carboxylate form at neutral pH and it is not a prodrug. Topotecan has the same mechanism of action as irinotecan and is believed to exert its cytotoxic effects during the S-phase of DNA synthesis. Topoisomerase I relieves torsional strain in DNA by inducing reversible single strand breaks. Topotecan binds to the topoisomerase I-DNA complex and prevents religation of these single strand breaks. This ternary complex interferes with the moving replication fork, which leads to the induction of replication arrest and lethal double-stranded breaks in DNA. As mammalian cells cannot efficiently repair these double strand breaks, the formation of this ternary complex eventually leads to apoptosis (programmed cell death). Topotecan mimics a DNA base pair and binds at the site of DNA cleavage by intercalating between the upstream (−1) and downstream (+1) base pairs. Intercalation displaces the downstream DNA, thus preventing religation of the cleaved strand. By specifically binding to the enzyme–substrate complex, Topotecan acts as an uncompetitive inhibitor. Topotecan is used for the treatment of advanced ovarian cancer in patients with disease that has recurred or progressed following therapy with platinum-based regimens. Also used as a second-line therapy for treatment-sensitive small cell lung cancer, as well as in combination with cisplatin for the treatment of stage IV-B, recurrent, or persistent cervical cancer not amenable to curative treatment with surgery and/or radiation therapy. Topotecan is sold under the trade name Hycamtin.
Docetaxel was protected by patents (U.S. patent and European patent) which were owned by Sanofi-Aventis, and so was available only under the Taxotere brand name internationally. The European patent expired in 2010. Docetaxel is a clinically well-established anti-mitotic chemotherapy medication used for the treatment of patients with locally advanced or metastatic breast cancer after failure of prior chemotherapy. Also used as a single agent in the treatment of patients with locally advanced or metastatic non-small cell lung cancer after failure of prior platinum-based chemotherapy. It is also used in combination with prednisone, in the treatment of patients with androgen independent (hormone refractory) metastatic prostate cancer. Furthermore, docetaxel has uses in the treatment of gastric adenocarcinoma and head and neck cancer. Docetaxel interferes with the normal function of microtubule growth. Whereas drugs like colchicine cause the depolymerization of microtubules in vivo, docetaxel arrests their function by having the opposite effect; it hyper-stabilizes their structure. This destroys the cell's ability to use its cytoskeleton in a flexible manner. Specifically, docetaxel binds to the β-subunit of tubulin. Tubulin is the "building block" of mictotubules, and the binding of docetaxel locks these building blocks in place. The resulting microtubule/docetaxel complex does not have the ability to disassemble. This adversely affects cell function because the shortening and lengthening of microtubules (termed dynamic instability) is necessary for their function as a transportation highway for the cell. Chromosomes, for example, rely upon this property of microtubules during mitosis. Further research has indicated that docetaxel induces programmed cell death (apoptosis) in cancer cells by binding to an apoptosis stopping protein called Bcl-2 (B-cell leukemia 2) and thus arresting its function.
Ropivacaine is a member of the amino amide class of local anesthetics and is supplied as the pure S-(-)-enantiomer. It produces effects similar to other local anesthetics via reversible inhibition of sodium ion influx in nerve fibers. Ropivacaine is less lipophilic than bupivacaine and is less likely to penetrate large myelinated motor fibers, resulting in a relatively reduced motor blockade. Thus, ropivacaine has a greater degree of motor-sensory differentiation, which could be useful when the motor blockade is undesirable. The reduced lipophilicity is also associated with decreased potential for central nervous system toxicity and cardiotoxicity. Ropivacaine is indicated for the production of local or regional anesthesia for surgery and for acute pain management.
Status:
First approved in 1996

Class (Stereo):
CHEMICAL (ACHIRAL)


Conditions:

Acitretin is all-Trans-9-(4-methoxy-2, 3, 6¬ trimethylphenyl)-three, 7-dimethyl-2, 4, 6, 8-nonatetraenoic acid. It is a metabolite of exterminate and is related to both retinoic acid and retinol (vitamin A). It is taken orally, and is typically used for psoriasis. The mechanism of action of is unknown. However it is believed to work by targeting specific receptors (retinoid receptors such as RXR and RAR) in the skin, which help normalize the growth cycle of skin cells. Studies on nuclear retinoic acid receptors have shown that acitretin activates all 3 receptor subtypes (RAR-alpha, -beta, and -gamma) without measurable receptor binding; this paradox remains unexplained.
Olopatadine is an antihistamine (as well as anticholinergic and mast cell stabilizer) used to treat itching associated with allergic conjunctivitis (eye allergies). Olopatadine is a selective histamine H1 antagonist that binds to the histamine H1 receptor. This blocks the action of endogenous histamine, which subsequently leads to temporary relief of the negative symptoms brought on by histamine. Olopatadine is devoid of effects on alpha-adrenergic, dopamine and muscarinic type 1 and 2 receptors. Some known side effects include a headache (7% of occurrence), eye burning and/or stinging (5%), blurred vision, dry eyes, foreign body sensation, hyperemia, keratitis, eyelid edema, pruritus, asthenia, sore throat (pharyngitis), rhinitis, sinusitis, and taste perversion.
There is no information in the literature about pharmacological and biological application of definite isomer of valsatran, R – form (also known as VALSARTAN, D- or CGP-49309). However there were found, that in the tablets of valsartan, which are used to treat high blood pressure and to heart failure, the R-enantiomer was an impurity.
Irinotecan is an antineoplastic enzyme inhibitor primarily used in the treatment of colorectal cancer. Irinotecan is sold under the brand name Camptosar among others. CAMPTOSAR is a topoisomerase inhibitor indicated for: • First-line therapy in combination with 5-fluorouracil and leucovorin for patients with metastatic carcinoma of the colon or rectum. • Patients with metastatic carcinoma of the colon or rectum whose disease has recurred or progressed following initial fluorouracil-based therapy. Irinotecan is a derivative of camptothecin. Camptothecins interact specifically with the enzyme topoisomerase I, which relieves torsional strain in DNA by inducing reversible single-strand breaks. Irinotecan and its active metabolite SN-38 bind to the topoisomerase I-DNA complex and prevent religation of these single-strand breaks. Current research suggests that the cytotoxicity of irinotecan is due to double-strand DNA damage produced during DNA synthesis when replication enzymes interact with the ternary complex formed by topoisomerase I, DNA, and either irinotecan or SN-38. Mammalian cells cannot efficiently repair these double-strand breaks.
Docetaxel was protected by patents (U.S. patent and European patent) which were owned by Sanofi-Aventis, and so was available only under the Taxotere brand name internationally. The European patent expired in 2010. Docetaxel is a clinically well-established anti-mitotic chemotherapy medication used for the treatment of patients with locally advanced or metastatic breast cancer after failure of prior chemotherapy. Also used as a single agent in the treatment of patients with locally advanced or metastatic non-small cell lung cancer after failure of prior platinum-based chemotherapy. It is also used in combination with prednisone, in the treatment of patients with androgen independent (hormone refractory) metastatic prostate cancer. Furthermore, docetaxel has uses in the treatment of gastric adenocarcinoma and head and neck cancer. Docetaxel interferes with the normal function of microtubule growth. Whereas drugs like colchicine cause the depolymerization of microtubules in vivo, docetaxel arrests their function by having the opposite effect; it hyper-stabilizes their structure. This destroys the cell's ability to use its cytoskeleton in a flexible manner. Specifically, docetaxel binds to the β-subunit of tubulin. Tubulin is the "building block" of mictotubules, and the binding of docetaxel locks these building blocks in place. The resulting microtubule/docetaxel complex does not have the ability to disassemble. This adversely affects cell function because the shortening and lengthening of microtubules (termed dynamic instability) is necessary for their function as a transportation highway for the cell. Chromosomes, for example, rely upon this property of microtubules during mitosis. Further research has indicated that docetaxel induces programmed cell death (apoptosis) in cancer cells by binding to an apoptosis stopping protein called Bcl-2 (B-cell leukemia 2) and thus arresting its function.

Showing 4031 - 4040 of 8583 results