Acetaminophen¿¡ ´ëÇÑ Mechanism_Of_Action Á¤º¸ Acetaminophen is thought to act primarily in the CNS, increasing the pain threshold by inhibiting both isoforms of cyclooxygenase, COX-1 and COX-2, enzymes involved in prostaglandin (PG) synthesis. Unlike NSAIDs, acetaminophen does not inhibit cyclooxygenase in peripheral tissues and, thus, has no peripheral anti-inflammatory affects. While aspirin acts as an irreversible inhibitor of COX and directly blocks the enzyme's active site, studies have found that acetaminophen indirectly blocks COX, and that this blockade is ineffective in the presence of peroxides. This might explain why acetaminophen is effective in the central nervous system and in endothelial cells but not in platelets and immune cells which have high levels of peroxides. Studies also report data suggesting that acetaminophen selectively blocks a variant of the COX enzyme that is different from the known variants COX-1 and COX-2. This enzyme is now referred to as COX-3. Its exact mechanism of action is still poorly understood, but future research may provide further insight into how it works. 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. Pseudoephedrine¿¡ ´ëÇÑ Mechanism_Of_Action Á¤º¸ Pseudoephedrine acts directly on both alpha- and, to a lesser degree, beta-adrenergic receptors. Through direct action on alpha-adrenergic receptors in the mucosa of the respiratory tract, pseudoephedrine produces vasoconstriction. Pseudoephedrine relaxes bronchial smooth muscle by stimulating beta2-adrenergic receptors. Like ephedrine, pseudoephedrine releasing norepinephrine from its storage sites, an indirect effect.
Pharmacology
Acetaminophen¿¡ ´ëÇÑ Pharmacology Á¤º¸ Acetaminophen (USAN) or Paracetamol (INN) is a popular analgesic and antipyretic drug that is used for the relief of fever, headaches, and other minor aches and pains. It is a major ingredient in numerous cold and flu medications and many prescription analgesics. It is extremely safe in standard doses, but because of its wide availability, deliberate or accidental overdoses are not uncommon. Acetaminophen, unlike other common analgesics such as aspirin and ibuprofen, has no anti-inflammatory properties or effects on platelet function, and so it is not a member of the class of drugs known as non-steroidal anti-inflammatory drugs or NSAIDs. In normal doses acetaminophen does not irritate the lining of the stomach nor affect blood coagulation, the kidneys, or the fetal ductus arteriosus (as NSAIDs can). Like NSAIDs and unlike opioid analgesics, acetaminophen does not cause euphoria or alter mood in any way. Acetaminophen and NSAIDs have the benefit of being completely free of problems with addiction, dependence, tolerance and withdrawal. Acetaminophen is used on its own or in combination with pseudoephedrine, dextromethorphan, chlorpheniramine, diphenhydramine, doxylamine, codeine, hydrocodone, or oxycodone. 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. Pseudoephedrine¿¡ ´ëÇÑ Pharmacology Á¤º¸ Pseudoephedrine is a sympathomimetic agent, structurally similar to ephedrine, used to relieve nasal and sinus congestion and reduce air-travel-related otalgia in adults. The salts pseudoephedrine hydrochloride and pseudoephedrine sulfate are found in many over-the-counter preparations either as single-ingredient preparations, or more commonly in combination with antihistamines and/or paracetamol/ibuprofen. Unlike antihistamines, which modify the systemic histamine-mediated allergic response, pseudoephedrine only serves to relieve nasal congestion commonly associated with colds or allergies. The advantage of oral pseudoephedrine over topical nasal preparations, such as oxymetazoline, is that it does not cause rebound congestion (rhinitis medicamentosa).
Acetaminophen¿¡ ´ëÇÑ Absorption Á¤º¸ Rapid and almost complete Acetaminophen¿¡ ´ëÇÑ Absorption Á¤º¸ Rapid and almost complete 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. Pseudoephedrine¿¡ ´ëÇÑ Absorption Á¤º¸ Pseudoephedrine is readily and almost completely absorbed from the GI tract and there is no evidence of first-pass metabolism. Pseudoephedrine¿¡ ´ëÇÑ Absorption Á¤º¸ Pseudoephedrine is readily and almost completely absorbed from the GI tract and there is no evidence of first-pass metabolism.
Acetaminophen¿¡ ´ëÇÑ Toxicity Á¤º¸ Oral, mouse: LD50 = 338 mg/kg; Oral, rat: LD50 = 1944 mg/kg. Acetaminophen is metabolized primarily in the liver, where most of it is converted to inactive compounds by conjugation with sulfate and glucuronide, and then excreted by the kidneys. Only a small portion is metabolized via the hepatic cytochrome P450 enzyme system. The toxic effects of acetaminophen are due to a minor alkylating metabolite (N-acetyl-p-benzo-quinone imine), not acetaminophen itself nor any of the major metabolites. This toxic metabolite reacts with sulfhydryl groups. At usual doses, it is quickly detoxified by combining irreversibly with the sulfhydryl group of glutathione to produce a non-toxic conjugate that is eventually excreted by the kidneys. The toxic dose of paracetamol is highly variable. In adults, single doses above 10 grams or 140 mg/kg have a reasonable likelihood of causing toxicity. In adults, single doses of more than 25 grams have a high risk of lethality. Caffeine¿¡ ´ëÇÑ Toxicity Á¤º¸ LD50=127 mg/kg (orally in mice) Pseudoephedrine¿¡ ´ëÇÑ Toxicity Á¤º¸ Common adverse reactions include nervousness, restlessness, and insomnia. Rare adverse reactions include difficult/painful urination, dizziness/lightheadedness, heart palpitations, headache, increased sweating, nausea/vomiting, trembling, troubled breathing, unusual paleness, and weakness.
Drug Interactions
Acetaminophen¿¡ ´ëÇÑ Drug_Interactions Á¤º¸ Anisindione Acetaminophen increases the anticoagulant effectWarfarin Acetaminophen increases the anticoagulant effectImatinib Increased hepatic toxicity of both agentsIsoniazid Risk of hepatotoxicityDicumarol Acetaminophen increases the anticoagulant effectDicumarol Increases the anticoagulant effectAcenocoumarol Increases the anticoagulant effect Caffeine¿¡ ´ëÇÑ Drug_Interactions Á¤º¸ Not Available Pseudoephedrine¿¡ ´ëÇÑ Drug_Interactions Á¤º¸ Alseroxylon Increased arterial pressureIsocarboxazid Increased arterial pressureLinezolid Possible increase of arterial pressureMethyldopa Increased arterial pressureBromocriptine The sympathomimetic increases the toxicity of bromocriptineTranylcypromine Increased arterial pressureMidodrine Increased arterial pressureMoclobemide Moclobemide increases the sympathomimetic effectPargyline Increased arterial pressurePhenelzine Increased arterial pressureRasagiline Increased arterial pressureReserpine Increased arterial pressureTrimipramine The tricyclic increases the sympathomimetic effectProtriptyline The tricyclic increases the sympathomimetic effectNortriptyline The tricyclic increases the sympathomimetic effectAmitriptyline The tricyclic increases the sympathomimetic effectAmoxapine The tricyclic increases the sympathomimetic effectClomipramine The tricyclic increases the sympathomimetic effectImipramine The tricyclic increases the sympathomimetic effectDesipramine The tricyclic increases the sympathomimetic effectDoxepin The tricyclic increases the sympathomimetic effectDeserpidine Increased arterial pressureGuanethidine The agent decreases the effect of guanethidine
Acetaminophen¿¡ ´ëÇÑ Food Interaction Á¤º¸ Take without regard to meals.Avoid alcohol (may increase risk of hepatotoxicity). Pseudoephedrine¿¡ ´ëÇÑ Food Interaction Á¤º¸ Take without regard to meals.
Acetaminophen¿¡ ´ëÇÑ Description Á¤º¸ Analgesic antipyretic derivative of acetanilide. It has weak anti-inflammatory properties and is used as a common analgesic, but may cause liver, blood cell, and kidney damage. [PubChem] Caffeine¿¡ ´ëÇÑ Description Á¤º¸ A methylxanthine naturally occurring in some beverages and also used as a pharmacological agent. Caffeine& Pseudoephedrine¿¡ ´ëÇÑ Description Á¤º¸ An alpha- and beta-adrenergic agonist that may also enhance release of norepinephrine. It has been used in the treatment of several disorders including asthma, heart failure, rhinitis, and urinary incontinence, and for its central nervous system stimulatory effects in the treatment of narcolepsy and depression. It has become less extensively used with the advent of more selective agonists. [PubChem]