Terfenadine

Chemical name

альфа-[4-(1,1-Диметилэти��)фенил]-4-(гидроксидиф��нилметил)-1-пиперидин��утанол

Gross

C32-H41-N-O2

Characteristics

Derived piperidine. White or belovaty crystalline powder. Poor soluble in water, easily soluble in chloroform, soluble in alcohol.

Of drugs

The drugs-antigistaminnoe, противоаллергическое . Yes blocks peripheral gistaminove H_1-retseptora, warns caused gistaminom cramps smooth muscles, incl. bronhokonstricciu in patients with asthma, the expansion of capillaries and their permeability development angioneuroticeski nasal tissue eritema, itching. The effect is manifested in 1-2 h after administration, reaches a maximum for 3-4 h and remains more than 12 hours In allergicescom rinite facilitates and reduces the frequency chihanya, rinoreu, itching and slezotechenie. And weak holinoliticski effect, the ability to block potassium channels cardiomyocytes and is not oppressive actions in the central nervous system. Ters severity bronchospasm caused by the physical stress and giperventilaciei lungs. The terfenadina level in the blood (in liver diseases, while others use drugs overdose, etc.) can be extended QT interval and the development of complications from Famagusta experimental studies have been detected cancer and mutagennogo actions, as well as the impact on fertility. In doses much higher than recommended for humans that causes birth defects in the fruit Kras.posle intake of rats around 70% (absorption is not affected by meal); Determined in the blood plasma in 30 minutes. T_max-1 p.m. Associated with the plasma protein by 97% (the active metabolite by 70%). Actively metabolised (99%), with the participation of specific izofermenta CYP3A4 system zitohroma R450 already in the "first pass" through the liver with the formation of two major metabolites-active carboksilno-kislogo counterpart (with 1 / 3 terfenadina activity) and low desalkilirovannogo derivative. After one reception inside the dose of 60 mg C_max active metabolita plasma achieved through 2.5 h of 263 ng / ml, T_1/2 distribution, 3-4 pm Therapeutic drug level and its active metabolita plasma maintained for a period of 12-24 hours Netting active metabolita dwuhfazna : T_1/2 initial phase, 3.5 h, the final-6 pm 60% of the dose is displayed with faeces (50%, in the form of active metabolita, 2% in unaltered, the remainder in the form of unidentified metabolites), and about 40% of kidney (16% active metabolite, 12% ethyl desalkilirovanny and 12% unidentified derivatives). T_1/2 terfenadina-8.5 hours Active metabolite in small quantities secretiruetsa in breast milk. If any liver lowered speed education and Cl active metabolita increases content in the blood terfenadina unchanged, with the reintroduction of the possible accumulation. Older patients at the dose of 120 mg Cl active metabolita may be decreased by 25%.

Indications

Seasonal allergic rhinitis, allergic conjunctivitis, chronic idiopathic urticaria, atopical eczema, contact dermatitis, skin rashes; Itch caused by liver failure; Angioneuroticeski swelling; Allergic reactions caused by drugs, food, insect bites; Bronchial asthma and colds disease (composed of combination therapy), preventing allergic reactions to the introduction of rentgencontrastnykh drugs.

Restrictions on the use of

Pregnancy, breast-feeding.

Pregnancy and lactation

Perhaps if the effect of therapy outweighs the potential risk to the fetus and newborn.

Contraindications

Hypersensitivity, gipokaliemia, gipomagniemia lengthening the QT interval on the ECG expressed by the human liver, a children's age (pill until 6 years suspension of up to 3 years).

Side-Effects

From the nervous system and sensory organs : weakness, headache, dizziness, insomnia, drowsiness, anxiety, depression, fear, convulsions, parestesia deterioration Zrenia.so the circulatory system and blood : cord lengthening the QT interval, ventricular tahiaritmia, torsades de pointes, arrythmia, fibrillace testing, cardiac arrest, gipotenzia breach of blood (fatigue or weakness, sore throat increased body temperature, bleeding or hemorrhage), Trombozitopenia.so part of the intestine : dry mucous membranes of the oral cavity, increased appetite, diarrhoea phenomenon, nausea, vomiting, discomfort in the abdomen, changing frequency chair holetaz, jaundice, Gepatit.so the respiratory system : dry mucous membranes nose and throat, cough, sore throat, bronchial spasm, bow Krovotechenie.so the urogenital system : frequent urination, Dismenorea.so the skin : skin rashes, eczema, thinning hair, alopecia, �отосенсибилизация.Ал лергические reactions : urticaria, angioneuroticeski swelling, Anaphylaccia.prochie : tremor, galactorea, sweating, increased levels transaminaz.

Patient interaction

Inhibitors of zitohroma R450 can increase terfenadina concentration in the blood and cause prolonged QT interval of the risk life jeludockovh tachiarrhythmia. Macrolides (erythromycin, klaritromicin, jozamitsin, etc.) inhibitors neironalnogo takeover serotonin (fluvoksamin, zitalopram, paroxetin etc.), mibefradil, and containing imidazole funds (ketokonazol, Itraconazole, miconazole, etc.) drove metabolism and increase the level of plasma (joint application is not recommended). Blockers calcium channel drugs antiaritmicescie I and III class antihistamines drugs adding QT interval, quinine, trimethoprim, sparfloksacin, cizaprid, Tricyclic antidepressants, neiroleptiki, drugs lithium protease inhibitors HIV (indinavir, ritonavir, saquinavir, nelfinavir), dioretiki, mineralokortikoida, probukol, Antiviral agents (ritonavir, indinavir and others) increase the risk of fracture QT interval and increasing toxicity. It reinforces dampening effect of benzodiazepines and alcohol on the central nervous system. Compatible with bronholitikami.

Overdosing

Symptoms : dry mouth, nausea, vomiting, headache, dizziness sputannosti consciousness; Dose of 360 mg and above-gipotenzia, fear, jeludockove keep lengthening the QT interval, ekstrasistolia, began testing, stopping Serdza.lechenie : washing stomach, vomiting induction, the appointment of absorbent of salt laxatives, monitoring heart activity to the control QT intervals (not less than 24 hours), symptomatic and supportive therapy. If necessary, the introduction of the liquid (in / in), complications preparations not udlinath QT interval, gipertenziveh of oxygen; In the case of a heavy human heartbeat rhythm is to install the driver rhythm (temporary). We do not recommend the use of adrenaline and analeptikov. Haemodialysis ineffective.

Precautions

Do not take medication at night. Avoid drinking grapefruit juice in the treatment period (may inhibit metabolism).

Dosing and Administration

Inside, adults and children over 12 years of age-60 mg twice or 120 mg once a day. The maximum daily dose was 480 mg (in bronchial asthma, and 540 mg / day). When expressed as human kidney (Cl creatinine less than 40 ml / min), it is recommended to use half the dose. Children from 6 to 12 years - to 30 mg twice a day, from 3 to 5 years to a suspension in the dose of 15 mg twice a day. Daily dose for children 2 mg / kg

Literature

J. Slater, D. Zechnich, Haxby D.J. Second-antihistamines. A comparative review / / Drugs - 1999 .- V. 57-N-1 P. 31-47.

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