Caffeine¿¡ ´ëÇÑ Mechanism_Of_Action Á¤º¸ Caffeine stimulates medullary, vagal, vasomotor, and respiratory centers, promoting bradycardia, vasoconstriction, and increased respiratory rate. This action was previously believed to be due primarily to increased intracellular cyclic 3¡Ç,5¡Ç-adenosine monophosphate (cyclic AMP) following inhibition of phosphodiesterase, the enzyme that degrades cyclic AMP. It is now thought that xanthines such as caffeine act as agonists at adenosine-receptors within the plasma membrane of virtually every cell. As adenosine acts as an autocoid, inhibiting the release of neurotransmitters from presynaptic sites but augmenting the actions of norepinephrine or angiotensin, antagonism of adenosine receptors promotes neurotransmitter release. This explains the stimulatory effects of caffeine. Blockade of the adenosine A1 receptor in the heart leads to the accelerated, pronounced "pounding" of the heart upon caffeine intake. Pyridoxine¿¡ ´ëÇÑ Mechanism_Of_Action Á¤º¸ Vitamin B6 is the collective term for a group of three related compounds, pyridoxine (PN), pyridoxal (PL) and pyridoxamine (PM), and their phosphorylated derivatives, pyridoxine 5'-phosphate (PNP), pyridoxal 5'-phosphate (PLP) and pyridoxamine 5'-phosphate (PMP). Although all six of these compounds should technically be referred to as vitamin B6, the term vitamin B6 is commonly used interchangeably with just one of them, pyridoxine. Vitamin B6, principally in the form of the coenzyme pyridoxal 5'-phosphate, is involved in a wide range of biochemical reactions, including the metabolism of amino acids and glycogen, the synthesis of nucleic acids, hemogloblin, sphingomyelin and other sphingolipids, and the synthesis of the neurotransmitters serotonin, dopamine, norepinephrine and gamma-aminobutyric acid (GABA). Scopolamine¿¡ ´ëÇÑ Mechanism_Of_Action Á¤º¸ Scopolamine acts by interfering with the transmission of nerve impulses by acetylcholine in the parasympathetic nervous system (specifically the vomiting center).
Pharmacology
Caffeine¿¡ ´ëÇÑ Pharmacology Á¤º¸ Caffeine, a naturally occurring xanthine derivative like theobromine and the bronchodilator theophylline, is used as a CNS stimulant, mild diuretic, and respiratory stimulant (in neonates with apnea of prematurity). Often combined with analgesics or with ergot alkaloids, caffeine is used to treat migraine and other headache types. Over the counter, caffeine is available to treat drowsiness or mild water-weight gain. Pyridoxine¿¡ ´ëÇÑ Pharmacology Á¤º¸ Vitamin B6 (pyridoxine) is a water-soluble vitamin used in the prophylaxis and treatment of vitamin B6 deficiency and peripheral neuropathy in those receiving isoniazid (isonicotinic acid hydrazide, INH). Vitamin B6 has been found to lower systolic and diastolic blood pressure in a small group of subjects with essential hypertension. Hypertension is another risk factor for atherosclerosis and coronary heart disease. Another study showed pyridoxine hydrochloride to inhibit ADP- or epinephrine-induced platelet aggregation and to lower total cholesterol levels and increase HDL-cholesterol levels, again in a small group of subjects. Vitamin B6, in the form of pyridoxal 5'-phosphate, was found to protect vascular endothelial cells in culture from injury by activated platelets. Endothelial injury and dysfunction are critical initiating events in the pathogenesis of atherosclerosis. Human studies have demonstrated that vitamin B6 deficiency affects cellular and humoral responses of the immune system. Vitamin B6 deficiency results in altered lymphocyte differentiation and maturation, reduced delayed-type hypersensitivity (DTH) responses, impaired antibody production, decreased lymphocyte proliferation and decreased interleukin (IL)-2 production, among other immunologic activities. Scopolamine¿¡ ´ëÇÑ Pharmacology Á¤º¸ Scopolamine is a muscarinic antagonist structurally similar to the neurotransmitter acetylcholine and acts by blocking the muscarinic acetylcholine receptors and is thus classified as an anticholinergic. Scopolamine has many uses including the prevention of motion sickness. It is not clear how Scopolamine prevents nausea and vomiting due to motion sickness. The vestibular part of the ear is very important for balance. When a person becomes disoriented due to motion, the vestibule sends a signal through nerves to the vomiting center in the brain, and vomiting occurs. Acetylcholine is a chemical that nerves use to transmit messages to each other. It is believe that Scopolamine prevents communication between the nerves of the vestibule and the vomiting center in the brain by blocking the action of acetylcholine. Scopolamine also may work directly on the vomiting center. Scopolamine must be taken before the onset of motion sickness to be effective.
Caffeine¿¡ ´ëÇÑ ´Ü¹é°áÇÕ Á¤º¸ Low (25 to 36%). Pyridoxine¿¡ ´ëÇÑ ´Ü¹é°áÇÕ Á¤º¸ 22% Scopolamine¿¡ ´ëÇÑ ´Ü¹é°áÇÕ Á¤º¸ Not Available
Half-life
Caffeine¿¡ ´ëÇÑ ¹Ý°¨±â Á¤º¸ 3 to 7 hours in adults, 65 to 130 hours in neonates Pyridoxine¿¡ ´ëÇÑ ¹Ý°¨±â Á¤º¸ 15-20 days Scopolamine¿¡ ´ëÇÑ ¹Ý°¨±â Á¤º¸ Not Available
Absorption
Caffeine¿¡ ´ëÇÑ Absorption Á¤º¸ Readily absorbed after oral or parenteral administration. The peak plasma level for caffeine range from 6-10mg/L and the mean time to reach peak concentration ranged from 30 minutes to 2 hours. Pyridoxine¿¡ ´ëÇÑ Absorption Á¤º¸ The B vitamins are readily absorbed from the gastrointestinal tract, except in malabsorption syndromes. Pyridoxine is absorbed mainly in the jejunum. Scopolamine¿¡ ´ëÇÑ Absorption Á¤º¸ Not Available
Caffeine¿¡ ´ëÇÑ Biotransformation Á¤º¸ Hepatic cytochrome P450 1A2 (CYP 1A2) is involved in caffeine biotransformation. About 80% of a dose of caffeine is metabolized to paraxanthine (1,7-dimethylxanthine), 10% to theobromine (3,7-dimethylxanthine), and 4% to theophylline (1,3-dimethylxanthine). Scopolamine¿¡ ´ëÇÑ Biotransformation Á¤º¸ Not Available
Toxicity
Caffeine¿¡ ´ëÇÑ Toxicity Á¤º¸ LD50=127 mg/kg (orally in mice) Pyridoxine¿¡ ´ëÇÑ Toxicity Á¤º¸ Oral Rat LD50 = 4 gm/kg. Toxic effects include convulsions, dyspnea, hypermotility, diarrhea, ataxia and muscle weakness. Scopolamine¿¡ ´ëÇÑ Toxicity Á¤º¸ Not Available
Drug Interactions
Caffeine¿¡ ´ëÇÑ Drug_Interactions Á¤º¸ Not Available Pyridoxine¿¡ ´ëÇÑ Drug_Interactions Á¤º¸ Not Available Scopolamine¿¡ ´ëÇÑ Drug_Interactions Á¤º¸ Not Available
Caffeine¿¡ ´ëÇÑ Description Á¤º¸ A methylxanthine naturally occurring in some beverages and also used as a pharmacological agent. Caffeine& Nicotinamide¿¡ ´ëÇÑ Description Á¤º¸ An important compound functioning as a component of the coenzyme NAD. Its primary significance is in the prevention and/or cure of blacktongue and pellagra. Most animals cannot manufacture this compound in amounts sufficient to prevent nutritional deficiency and it therefore must be supplemented through dietary intake. [PubChem] Pyridoxine¿¡ ´ëÇÑ Description Á¤º¸ The 4-methanol form of vitamin B 6 which is converted to pyridoxal phosphate which is a coenzyme for synthesis of amino acids, neurotransmitters (serotonin, norepinephrine), sphingolipids, aminolevulinic acid. Although pyridoxine and Vitamin B 6 are still frequently used as synonyms, especially by medical researchers, this practice is erroneous and sometimes misleading (EE Snell; Ann NY Acad Sci, vol 585 pg 1, 1990). [PubChem] Scopolamine¿¡ ´ëÇÑ Description Á¤º¸ An alkaloid from Solanaceae, especially Datura metel L. and Scopola carniolica. Scopolamine and its quaternary derivatives act as antimuscarinics like atropine, but may have more central nervous system effects. Among the many uses are as an anesthetic premedication, in urinary incontinence, in motion sickness, as an antispasmodic, and as a mydriatic and cycloplegic. [PubChem]