Fexofenadine¿¡ ´ëÇÑ Mechanism_Of_Action Á¤º¸ Like other H1-blockers, Fexofenadine competes with free histamine for binding at H1-receptors in the GI tract, large blood vessels, and bronchial smooth muscle. This blocks the action of endogenous histamine, which subsequently leads to temporary relief of the negative symptoms brought on by histamine. Fexofenadine exhibits no anticholinergic, alpha1-adrenergic or beta-adrenergic-receptor blocking effects. 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
Fexofenadine¿¡ ´ëÇÑ Pharmacology Á¤º¸ Fexofenadine is a second-generation, long lasting H1-receptor antagonist (antihistamine) which has a selective and peripheral H1-antagonist action. Histamine is a chemical that causes many of the signs that are part of allergic reactions, for example, swelling of tissues. Histamine is released from histamine-storing cells (mast cells) and attaches to other cells that have receptors for histamine. The attachment of the histamine to the receptors causes the cell to be "activated," releasing other chemicals which produce the effects that we associate with allergy. Fexofenadine blocks one type of receptor for histamine (the H1 receptor) and thus prevents activation of cells by histamine. Unlike most other antihistamines, Fexofenadine does not enter the brain from the blood and, therefore, does not cause drowsiness. Fexofenadine lacks the cardiotoxic potential, since it does not block the potassium channel involved in repolarization of cardiac cells. 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).
Metabolism
Fexofenadine¿¡ ´ëÇÑ Metabolism Á¤º¸ # Phase_1_Metabolizing_Enzyme:Cytochrome P450 3A4 (CYP3A4) Pseudoephedrine¿¡ ´ëÇÑ Metabolism Á¤º¸ # Phase_1_Metabolizing_Enzyme:Monoamine oxidase type A (MAO-A)
Protein Binding
Fexofenadine¿¡ ´ëÇÑ ´Ü¹é°áÇÕ Á¤º¸ 60%-70% Pseudoephedrine¿¡ ´ëÇÑ ´Ü¹é°áÇÕ Á¤º¸ Pseudoephedrine does not bind to human plasma proteins over the concentration range of 50 to 2000 ng/mL
Fexofenadine¿¡ ´ëÇÑ Absorption Á¤º¸ 33% 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.
Fexofenadine¿¡ ´ëÇÑ Biotransformation Á¤º¸ Approximately 5% of the total dose is metabolized, by cytochrome P450 3A4 and by intestinal microflora. Pseudoephedrine¿¡ ´ëÇÑ Biotransformation Á¤º¸ Hepatic.
Toxicity
Fexofenadine¿¡ ´ëÇÑ Toxicity Á¤º¸ Side effects include dizziness, drowsiness, and dry mouth. 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
Fexofenadine¿¡ ´ëÇÑ Drug_Interactions Á¤º¸ Cisapride Increased risk of cardiotoxicity and arrhythmias 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
Fexofenadine¿¡ ´ëÇÑ Food Interaction Á¤º¸ Take without regard to meals.Grapefruit and grapefruit juice should be avoided throughout treatment as grapefruit can significantly decrease serum levels of this product. Pseudoephedrine¿¡ ´ëÇÑ Food Interaction Á¤º¸ Take without regard to meals.
Fexofenadine¿¡ ´ëÇÑ Description Á¤º¸ Fexofenadine hydrochloride (Allegra) is an antihistamine drug used in the treatment of hayfever and similar allergy symptoms. It was developed as a successor of and alternative to terfenadine. Fexofenadine, like other second and third-generation antihistamines, does not readily pass through the blood-brain barrier, and so causes less drowsiness than first-generation histamine-receptor antagonists. 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]