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

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Showing 51 - 60 of 311 results

Status:
First approved in 1981
Source:
Isoptin by Knoll
Source URL:

Class (Stereo):
CHEMICAL (ABSOLUTE)



Vecuronium is a neuromuscular blocking agent. Vecuronium operates by competing for the cholinoceptors at the motor end plate thereby exerting its muscle-relaxing properties which are used adjunctively to general anesthesia. Vecuronium is a bisquaternary nitrogen compound that acts by competitively binding to nicotinic cholinergic receptors. The binding of vecuronium decreases the opportunity for acetylcholine to bind to the nicotinic receptor at the postjunctional membrane of the myoneural junction. As a result, depolarization is prevented, calcium ions are not released and muscle contraction does not occur. Vecuronium is indicated as an adjunct to general anesthesia, to facilitate endotracheal intubation and to provide skeletal muscle relaxation during surgery or mechanical ventilation.
Daunorubicin, also known as daunomycin, is a chemotherapy medication used to treat cancer. Specifically, it is used for acute myeloid leukemia (AML), acute lymphocytic leukemia (ALL), chronic myelogenous leukemia (CML), and Kaposi's sarcoma. Similar to doxorubicin, daunorubicin interacts with DNA by intercalation and inhibition of macromolecular biosynthesis. This inhibits the progression of the enzyme topoisomerase II, which relaxes supercoils in DNA for transcription. Daunorubicin stabilizes the topoisomerase II complex after it has broken the DNA chain for replication, preventing the DNA double helix from being resealed and thereby stopping the process of replication. On binding to DNA, daunomycin intercalates, with its daunosamine residue directed toward the minor groove. It has the highest preference for two adjacent G/C base pairs flanked on the 5' side by an A/T base pair. Daunorubicin should only be administered in a rapid intravenous infusion. It should not be administered intramuscularly or subcutaneously, since it may cause extensive tissue necrosis. It should also never be administered intrathecally (into the spinal canal), as this will cause extensive damage to the nervous system and may lead to death.

Class (Stereo):
CHEMICAL (RACEMIC)


Conditions:

Isoflurane (1-chloro-2, 2,2-trifluoroethyl difluoromethyl ether) a nonflammable liquid administered by vaporizing, is a general inhalation anesthetic drug. Isoflurane is a clear, colorless, stable liquid containing no additives or chemical stabilizers. Similar to many general anesthetics, the exact mechanism of the action has not been clearly delineated. Isoflurane reduces pain sensitivity (analgesia) and relaxes muscles. Isoflurane likely potentiates GABA-A and glycine receptor activity, which decreases motor function, inhibits receptor activity in the NMDA glutamate receptor subtypes and binds to glutamate receptors. Isoflurane is always administered in conjunction with air and/or pure oxygen. Often nitrous oxide is also used. Although its physical properties imply that anesthesia can be induced more rapidly than with halothane, its pungency can irritate the respiratory system, negating this theoretical advantage conferred by its physical properties. It is usually used to maintain a state of general anesthesia that has been induced with another drug, such as thiopentone or propofol.
Metoclopramide is a dopamine D2 antagonist that is used as an antiemetic. Metoclopramide inhibits gastric smooth muscle relaxation produced by dopamine, therefore increasing cholinergic response of the gastrointestinal smooth muscle. It accelerates intestinal transit and gastric emptying by preventing relaxation of gastric body and increasing the phasic activity of antrum. Simultaneously, this action is accompanied by relaxation of the upper small intestine, resulting in an improved coordination between the body and antrum of the stomach and the upper small intestine. Metoclopramide also decreases reflux into the esophagus by increasing the resting pressure of the lower esophageal sphincter and improves acid clearance from the esophagus by increasing amplitude of esophageal peristaltic contractions. Metoclopramide's dopamine antagonist action raises the threshold of activity in the chemoreceptor trigger zone and decreases the input from afferent visceral nerves. Studies have also shown that high doses of metoclopramide can antagonize 5-hydroxytryptamine (5-HT) receptors in the peripheral nervous system in animals. Metoclopramide is used for the treatment of gastroesophageal reflux disease (GERD). It is also used in treating nausea and vomiting, and to increase gastric emptying.
Status:
First approved in 1978
Source:
Depakene by Abbott
Source URL:

Class (Stereo):
CHEMICAL (RACEMIC)



Verapamil is a FDA approved drug used to treat high blood pressure and to control chest pain. Verapamil is an L-type calcium channel blocker that also has antiarrythmic activity. The R-enantiomer is more effective at reducing blood pressure compared to the S-enantiomer. However, the S-enantiomer is 20 times more potent than the R-enantiomer at prolonging the PR interval in treating arrhythmias. Verapamil inhibits voltage-dependent calcium channels. Specifically, its effect on L-type calcium channels in the heart causes a reduction in ionotropy and chronotropy, thuis reducing heart rate and blood pressure. Verapamil's mechanism of effect in cluster headache is thought to be linked to its calcium-channel blocker effect, but which channel subtypes are involved is presently not known.
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.

Class (Stereo):
CHEMICAL (RACEMIC)


Conditions:

Lorazepam (brand name Ativan) is indicated for the management of anxiety disorders or for the short-term relief of the symptoms of anxiety or anxiety associated with depressive symptoms. Anxiety or tension associated with the stress of everyday life usually does not require treatment with an anxiolytic. Lorazepam binds to an allosteric site on GABA-A receptors, which are pentameric ionotropic receptors in the CNS. Binding potentiates the effects of the inhibitory neurotransmitter GABA, which upon binding opens the chloride channel in the receptor, allowing chloride influx and causing hyperpolarization of the neuron. Studies in healthy volunteers show that in single high doses Ativan (lorazepam) has a tranquilizing action on the central nervous system with no appreciable effect on the respiratory or cardiovascular systems. Ativan (lorazepam) is readily absorbed with an absolute bioavailability of 90 percent. The mean half-life of unconjugated lorazepam in human plasma is about 12 hours and for its major metabolite, lorazepam glucuronide, about 18 hours. At clinically relevant concentrations, lorazepam is approximately 85% bound to plasma proteins. Lorazepam is rapidly conjugated at its 3-hydroxy group into lorazepam glucuronide which is then excreted in the urine. Lorazepam glucuronide has no demonstrable CNS activity in animal. Most adverse reactions to benzodiazepines, including CNS effects and respiratory depression, are dose dependent, with more severe effects occurring with high doses. Paradoxical reactions, including anxiety, excitation, agitation, hostility, aggression, rage, sleep disturbances/insomnia, sexual arousal, and hallucinations may occur. Small decreases in blood pressure and hypotension may occur but are usually not clinically significant, probably being related to the relief of anxiety produced by lorazepam.
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.
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.
Mebendazole, known as Emverm is a (synthetic) broad-spectrum anthelmintic that acts by interfering with carbohydrate metabolism and inhibiting polymerization of microtubules. The loss of the cytoplasmic microtubules leads to impaired uptake of glucose by the larval and adult stages of the susceptible parasites, and depletes their glycogen stores. Degenerative changes in the endoplasmic reticulum, the mitochondria of the germinal layer, and the subsequent release of lysosomes result in decreased production of adenosine triphosphate (ATP), which is the energy required for the survival of the helminth. Due to diminished energy production, the parasite is immobilized and eventually dies. Emverm tablets are used for the treatment of Enterobius vermicularis (pinworm), Trichuris trichiura (whipworm), Ascaris lumbricoides (common roundworm), Ancylostoma duodenale (common hookworm), Necator americanus (American hookworm) in single or mixed infections. All metabolites are devoid of anthelmintic activity. In man, approximately 2% of administered mebendazole is excreted in urine and the remainder in the feces as unchanged drug or a primary metabolite. Preliminary evidence suggests that cimetidine inhibits mebendazole metabolism and may result in an increase in plasma concentrations drug. Mebendazole sometimes causes diarrhea, abdominal pain, and elevated liver enzymes. In rare cases, it has been associated with a dangerously low white blood cell count, low platelet count, and hair loss, with a risk of agranulocytosis in rare cases