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

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Showing 48741 - 48750 of 55039 results

Quinidine is a pharmaceutical agent that acts as a class I antiarrhythmic agent (Ia) in the heart. It is a stereoisomer of quinine, originally derived from the bark of the cinchona tree. The drug causes increased action potential duration, as well as a prolonged QT interval. Like all other class I antiarrhythmic agents, quinidine primarily works by blocking the fast inward sodium current (INa). Quinidine's effect on INa is known as a 'use-dependent block'. This means at higher heart rates, the block increases, while at lower heart rates, the block decreases. The effect of blocking the fast inward sodium current causes the phase 0 depolarization of the cardiac action potential to decrease (decreased Vmax). Quinidine also blocks the slowly inactivating, tetrodotoxin-sensitive Na current, the slow inward calcium current (ICA), the rapid (IKr) and slow (IKs) components of the delayed potassium rectifier current, the inward potassium rectifier current (IKI), the ATP-sensitive potassium channel (IKATP) and Ito. Quinidine is also an inhibitor of the cytochrome P450 enzyme 2D6 and can lead to increased blood levels of lidocaine, beta blockers, opioids, and some antidepressants. Quinidine also inhibits the transport protein P-glycoprotein and so can cause some peripherally acting drugs such as loperamide to have central nervous system side effects, such as respiratory depression if the two drugs are coadministered. Quinidine can cause thrombocytopenia, granulomatous hepatitis, myasthenia gravis, and torsades de pointes, so is not used much today. Torsades can occur after the first dose. Quinidine-induced thrombocytopenia (low platelet count) is mediated by the immune system and may lead to thrombocytic purpura. A combination of dextromethorphan and quinidine has been shown to alleviate symptoms of easy laughing and crying (pseudobulbar affect) in patients with amyotrophic lateral sclerosis and multiple sclerosis. This drug is marketed as Nuedexta in the United States. Intravenous quinidine is also indicated for the treatment of Plasmodium falciparum malaria. However, quinidine is not considered the first-line therapy for P. falciparum. The recommended treatments for P. falciparum malaria, according to the Toronto Notes 2008, are a combination of either quinine and doxycycline or atovaquone and proguanil (Malarone). The drug is also effective for the treatment of atrial fibrillation in horses.
Status:
First marketed in 1921
Source:
Sodium Nitrite U.S.P.
Source URL:

Class (Stereo):
CHEMICAL (ACHIRAL)



Nitrite Ion is a symmetric anion with equal N–O bond lengths. Nitrite is important in biochemistry as a source of the potent vasodilator nitric oxide. Nitrate or nitrite (ingested) under conditions that result in endogenous nitrosation has been classified as "Probably carcinogenic to humans" (Group 2A) by International Agency for Research on Cancer (IARC), the specialized cancer agency of the World Health Organization (WHO) of the United Nations. Sodium nitrite is used for the curing of meat because it prevents bacterial growth and, as it is a reducing agent (opposite of oxidation agent), in a reaction with the meat's myoglobin, gives the product a desirable pink-red "fresh" color, such as with corned beef. This use of nitrite goes back to the Middle Ages, and in the US has been formally used since 1925. Because of the relatively high toxicity of nitrite (the lethal dose in humans is about 22 milligrams per kilogram of body weight), the maximum allowed nitrite concentration in meat products is 200 ppm. At these levels, some 80 to 90% of the nitrite in the average U.S. diet is not from cured meat products, but from natural nitrite production from vegetable nitrate intake. Under certain conditions – especially during cooking – nitrites in meat can react with degradation products of amino acids, forming nitrosamines, which are known carcinogens. However, the role of nitrites (and to some extent nitrates) in preventing botulism by preventing C. botulinum endospores from germinating have prevented the complete removal of nitrites from cured meat, and indeed by definition in the U.S., meat cannot be labeled as "cured" without nitrite addition. They are considered irreplaceable in the prevention of botulinum poisoning from consumption of cured dry sausages by preventing spore germination. Nitrite is a member of the drug class antidotes and is used to treat Cyanide Poisoning.
Status:
First marketed in 1921
Source:
Emulsion of Cod Liver Oil with Calcium Phosphate N.F.
Source URL:

Class (Stereo):
CHEMICAL (ACHIRAL)


Phosphate is a major intracellular anion in mammals. Hydrogen phopshate is a protonated form of phosphate. In serum, phosphate exists in two forms, dihydrogen phosphate (H2PO4) and its salt, mono-hydrogen phosphate (HPO4). At the physiologic pH of 7.40, the pK of H2PO4 is 6.8 and the ratio of HPO4 to H2PO4 is 4:1. Altered level of phosphate can be an indicator of various disorders, such as chronic renal failure, hypoparathyroidism, familial intermittent hyperphosphatemia, endocrine disorders, hyperthyroidism, acromegaly, juvenile hypogonadism, etc. These disorders may lead to either hyper- or hypophosphatemia, which can be caused by cellular shifts of phosphate. Patients with hypophosphatemia can be treated with dietary phosphate supplements (potassium phosphate, for example).
Methylene blue, also known as methylthioninium chloride, is a medication from WHO's list of essential medicines. Upon administration, methylene blue is converted to leukomethylene blue by erythrocyte methemoblobin reductase in the presence of NADPH. Leukomethylene blue than reduces methemoglobin to oxyhemoglobin, thus restoring oxygen carrying capacity of the blood. Methylene blue is also used as a dye for various diagnostic procedures, for treatment of ifosfamide toxicity and for in vitro staining. Historically, it was used as a photosensitizer for photodynamic therapy for topical treatment of dermatologic or mucocutaneous infections, as an antidote for cyanide poisoning, but these applications are no longer approved. Methylene blue is investigated in clinical trials for treatment of septic shock and Alzheimer's disease.
Status:
First marketed in 1921
Source:
Emulsion of Cod Liver Oil with Calcium Phosphate N.F.
Source URL:

Class (Stereo):
CHEMICAL (ACHIRAL)


Phosphate is a major intracellular anion in mammals. Hydrogen phopshate is a protonated form of phosphate. In serum, phosphate exists in two forms, dihydrogen phosphate (H2PO4) and its salt, mono-hydrogen phosphate (HPO4). At the physiologic pH of 7.40, the pK of H2PO4 is 6.8 and the ratio of HPO4 to H2PO4 is 4:1. Altered level of phosphate can be an indicator of various disorders, such as chronic renal failure, hypoparathyroidism, familial intermittent hyperphosphatemia, endocrine disorders, hyperthyroidism, acromegaly, juvenile hypogonadism, etc. These disorders may lead to either hyper- or hypophosphatemia, which can be caused by cellular shifts of phosphate. Patients with hypophosphatemia can be treated with dietary phosphate supplements (potassium phosphate, for example).
There is no information about biological and pharmacological application of Iron(II) fluoride (also known as ferrous fluoride). It is known, that this substance is used to catalyze some organic reactions.
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.
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.
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.
Status:
First marketed in 1921
Source:
Quinine Dihydrochloride U.S.P.
Source URL:

Class (Stereo):
CHEMICAL (ABSOLUTE)



Quinine soluble salts possess the extremely bitter taste, that may have a perplexing problem especially to children. That is why the most common combinations which are administered in this way are the sulphate, salicylate, tannate and certain esters. Quinine tannate, an insoluble quinine salt has been known in medicine for a very long time. However, many experiments have revealed that quinine tannate was practically inert as a medicinal substance.

Showing 48741 - 48750 of 55039 results