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

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Prednisolone hemisuccinate is a prodrug of a glucocorticoid agonist prednisolone, which is marketed under trade name Prednisolut in Germany and Austria. Prednisolone hemisuccinate is used in emergency medicine to treate shock due to allergic reaction, insect and snake bites, in neurology to treat brain edema and meningitis, in transplantation medicine to reduce risk of organ refection after kidney transplane, in pneumology to treat acute asthma attack, pulmonary edema, in severe or life-threatening situation in rheumatic diseases.

Class (Stereo):
CHEMICAL (RACEMIC)



Phenoxybenzamin (marketed under the trade name Dibenzyline) is an alpha-adrenergic antagonist with long duration of action. It is indicated in the treatment of pheochromocytoma, to control episodes of hypertension and sweating. If tachycardia is excessive, it may be necessary to use a beta-blocking agent concomitantly. Phenoxybenzamine produces its therapeutic actions by blocking alpha receptors, leading to a muscle relaxation and a widening of the blood vessels. This widening of the blood vessels results in a lowering of blood pressure. Phenoxybenzamine hydrochloride can produce and maintain “chemical sympathectomy” by oral administration. It increases blood flow to the skin, mucosa and abdominal viscera, and lowers both supine and erect blood pressures. It has no effect on the parasympathetic system. Twenty to percent of orally administered phenoxybenzamine appears to be absorbed in the active form. The half-life of orally administered phenoxybenzamine hydrochloride is not known; however, the half-life of intravenously administered drug is approximately 24 hours. Demonstrable effects with intravenous administration persist for at least 3 to 4 days, and the effects of daily administration are cumulative for nearly a week. The following adverse reactions have been observed, but there are insufficient data to support an estimate of their frequency: Postural hypotension, tachycardia, inhibition of ejaculation, nasal congestion, and miosis. These so-called “side effects” are actually evidence of adrenergic blockade and vary according to the degree of blockade. Miscellaneous: Gastrointestinal irritation, drowsiness, fatigue.
Status:
First approved in 1948
Source:
Hexachlorophene by Various Mfrs.
Source URL:

Class (Stereo):
CHEMICAL (ACHIRAL)



Hexachlorophene, also known as Nabac, is an organochlorine compound that was once widely used as a disinfectant. The compound occurs as a white odorless solid, although commercial samples can be off-white and possess a slightly phenolic odor. It is insoluble in water but dissolves in acetone, ethanol, diethyl ether, and chloroform. Exact mechanism(s) of action unknown, but at low concentrations appears to interrupt bacterial electron transport and inhibit membrane-bound enzymes. Higher concentrations rupture bacterial membranes. It induces leakage, causes protoplast lysis, and inhibits respiration. In medicine, hexachlorophene is a useful as a topical anti-infective, anti-bacterial agent, often used in soaps and toothpaste. It is also used in agriculture as a soil fungicide, plant bactericide, and acaricide.
Status:
First approved in 1943
Source:
Aralen by Winthrop
Source URL:

Class (Stereo):
CHEMICAL (RACEMIC)



Chloroquine (brand name Aralen) is indicated for the suppressive treatment and for acute attacks of malaria due to P. vivax, P.malariae, P. ovale, and susceptible strains of P. falciparum. The drug is also indicated for the treatment of extraintestinal amebiasis. In addition, chloroquine is in clinical trials as an investigational antiretroviral in humans with HIV-1/AIDS and as a potential antiviral agent against chikungunya fever. The mechanism of plasmodicidal action of chloroquine is not completely certain. However, is existed theory, that like other quinoline derivatives, it is thought to inhibit heme polymerase activity. The heme moiety consists of a porphyrin ring called Fe(II)-protoporphyrin IX (FP). To avoid destruction by this molecule, the parasite biocrystallizes heme to form hemozoin, a non-toxic molecule. Chloroquine enters the red blood cell, inhabiting parasite cell, and digestive vacuole by simple diffusion. Chloroquine then becomes protonated (to CQ2+), as the digestive vacuole is known to be acidic (pH 4.7); chloroquine then cannot leave by diffusion. Chloroquine caps hemozoin molecules to prevent further biocrystallization of heme, thus leading to heme buildup. Chloroquine binds to heme (or FP) to form what is known as the FP-Chloroquine complex; this complex is highly toxic to the cell and disrupts membrane function.
Status:
First marketed in 1921
Source:
Theophylline U.S.P.
Source URL:

Class (Stereo):
CHEMICAL (ACHIRAL)



Since its discovery as component of the tea leaf by Albert Kossel in 1888, the history of theophylline (CAS 58-55-9) has been a long and successful one. At the turn of the century, theophylline became less expensive due to chemical synthesis and was primarily used as diuretic in subsequent years. It was Samuel Hirsch who discovered the bronchospasmolytic effect of theophylline in 1992, however, despite this pioneering discovery theophylline continued to be used primarily as diuretic and cardiac remedy. The molecular mechanism of bronchodilatation is inhibition of phosphodiesterase(PDE)3 and PDE4, but the anti-inflammatory effect may be due to histone deacetylase (HDAC) activation, resulting in switching off of activated inflammatory genes. Theophylline is indicated for the treatment of acute exacerbations of the symptoms and reversible airflow obstruction associated with asthma and other chronic lung diseases, e.g., emphysema and chronic bronchitis.
Phenobarbital is a barbiturate derivative used to treat insomnia and anxiety, seizures, hyperbilirubinemia in neonates and cholestasis. Phenobarbital promotes binding to inhibitory gamma-aminobutyric acid subtype receptors, and modulates chloride currents through receptor channels.
Status:
US Previously Marketed
First approved in 1952

Class (Stereo):
CHEMICAL (ACHIRAL)



Phenylbutazone is an anti-inflammatory drug, which binds to and inactivates cyclooxygenases and prostacyclin synthase through peroxide (H2O2) mediated deactivation. The reduced production of prostaglandin leads to reduced inflammation of the surrounding tissues. Phenylbutazone was marked under the brand name butazolidin for the treatment rheumatoid arthritis and gout, but then this usage was discontinued. In addition, phenylbutazone is used in UK for the treatment of ankylosing spondylitis, but only in those cases, when other therapies are unsuitable.
Sulfamethazine is a sulfonamide used to treat a variety of bacterial diseases in animals. It inhibits bacterial synthesis of dihydrofolic acid by competing with para-aminobenzoic acid (PABA) for binding to dihydropteroate synthetase (dihydrofolate synthetase).
Diethylstilbestrol is a synthetic non-steroidal estrogen. It is used in the treatment of menopausal and postmenopausal disorders, prostate cancer and in the prevention of miscarriage or premature delivery in pregnant women prone to miscarriage or premature delivery. Diethylstilbestrol is a very potent full agonist of the estrogen receptors. At the cellular level, estrogens increase the synthesis of DNA, RNA, and various proteins in target tissues. Pituitary mass is also increased. Estrogens reduce the release of gonadotropin-releasing hormone from the hypothalamus, leading to a reduction in release of follicle-stimulating hormone and luteinizing hormone from the pituitary. Adverse effects are: breast pain or tenderness, enlargement of breasts, gynecomastia, peripheral edema and others. Estrogens may interfere with the effects of bromocriptine. Dosage adjustment may be needed. Concurrent use with estrogens may alter the metabolism and protein binding of the glucocorticoids, leading to decreased clearance, increased elimination half-life, and increased therapeutic and toxic effects of the glucocorticoids.
Clomiphene (CLOMID®) is a triphenyl ethylene stilbene derivative which is an estrogen agonist or antagonist depending on the target tissue. It is an orally administered, nonsteroidal, ovulatory stimulant. Clomiphene (CLOMID®) is a mixture of two geometric isomers [cis (zuclomiphene) and trans (enclomiphene)] containing between 30% and 50% of the cis-isomer. Clomiphene (CLOMID®) initiates a series of endocrine events culminating in a preovulatory gonadotropin surge and subsequent follicular rupture. The first endocrine event in response to a course of clomiphene therapy is an increase in the release of pituitary gonadotropins. This initiates steroidogenesis and folliculogenesis, resulting in growth of the ovarian follicle and an increase in the circulating level of estradiol. Following ovulation, plasma progesterone and estradiol rise and fall as they would in a normal ovulatory cycle.