Phenytoin

Chemical name

5,5-Дифенил-2,4-имидазол��диндион (in the form of sodium salt)

Gross

C15-H12-N2-O2

Characteristics

The white crystalline powder. Virtually nerastvorim in water, soluble in 1% solution caustic alkalis.

Of drugs

The drugs-protevoepilepticescoe, protivosudorozhnoe, antiaritmicescoe, miorelaksirutee. And protivosudorojna activity (without express sedative and hypnotic effect), manifested in Generalized and partial pripadkah. In high doses violates coordinated movements. Provides aguirutee influence on the central nervous system (shorter period stiffness correct "despair" and reduces ptoz due rezerpinom) antiaritmicescoe at heart (reduces the maximum speed depolarization, increases the threshold of anxiety, slows conductivity to lift Guisa and Purkinje fibers). Suppress vestibular reflexes, reduces a certain forms of Ménière syndrome. Affects active and passive transport of ions of sodium and calcium across cell and cellular membranes of nerve cells. Significantly reduces the level of sodium in neirone because it reduces the flow by blocking the Na ^ + K ^ + -atfazu brain and facilitates active transport of cells. Changes кальций-фосфолипидно�� interactions in the cell membrane and reduces the active transport of potassium and calcium inhibits release neiromediatornah amino acids (glutamate, aspartata) from the nerve endings than the protivosudorozhny effect. Has the ability to suppress glutamatne receptors. Protiwaritmical activity is reflected in the decline of central adrenergicakih effects on the heart, stabilize membranes in cardiomyocytes uveliceniie its permeability to ions Kalia.pri ingestion readily absorbed. The speed of absorption varies in the different patients, and thus the time for C_max very variabelno - 3-15 hours Related to the 70-90% of the plasma proteins (with kidney failure-43%). Free passes gistagematicalkie barriers and quickly spread to organs and tissues (including the brain). Less than 5% shall be provided with urine in an unmodified form, the remainder transformed liver enzymes to inactive metabolites, mainly glukuronidov (excretiruyutza kidney) and paraoksifenilnykh derivatives; The last part is made with jelchew. T_1/2 plasma with in / in a 14-hour, after receiving oral-22-28 hours Children (especially in a period of growth), it is advisable to appoint phenytoin in combination with vitamins D and K, as Evolution osteopati of rickets, gipocalziemii, human blood clotting. If the effect should be further applied phenobarbital, etc. противоэпилептически й product. Used in addition, in cases of resistance to carbamazepino to treat neuralgia troinicnogo nerve. Alleviate (50-90%) and supraventrikuliarnae jeludockove arrhythmia caused by the overdose of cardiac glycosides, but with little supraventrikuliarnah aritmiah etc. genesis. Pronounced effect on the human heart at the time of narcosis, catheterization, after operations on the heart, or disrupted when the central function of regulating the activity of the sympathetic nervous system.

Indications

Epilepsy (big apnoea seizures), the prevention of trauma and постнейрохирургическ ой epilepsy, jeludockove adults, including intoxicated with cardiac glycosides, some forms of Ménière syndrome, nevralgia troinicnogo nerve.

Restrictions on the use of

During pregnancy is only for health reasons.

Contraindications

Hypersensitivity, disruption of the liver and kidney failure, heart failure, cachexia, porphyria.

Side-Effects

Vertigo, causing tremor, ataxy, eye, fever, nausea, vomiting, changes in connective tissue (brutalization lines, the contracture Dupuitrena), allergic skin reaction (rash, itching of the skin); In the long-term use (especially in children), neuralgia, giperplazia gums, osteopathy, gipocalziemia, megaloblastnaya anaemia lesser limfoadenopatia, girsutizm.

Patient interaction

Accelerate biotransformatia phenobarbital and carbamazepine, and slow (may exacerbate side effects), isoniazid and its derivatives levomicetin, cumarins, acetylsalicylic acid, teturam.

Overdosing

If the concentration in the blood of the children of more than 20 mg / l may develop acute intoxication - eye, ataxy, mental disorder, pain in joints; In more severe cases, aetiology, began testing, predserdy fibrillation, asistolia and coma. Treatment of symptomatic (specific antidote no).

Precautions

A careful selection of doses (with epilepsy determine concentration in the blood at day 10 of treatment), because off-nassyshchaemy process and the increase in dose may be accompanied by a disproportionate increase in the plasma. When expressed by events, it is necessary to reduce the dosage or stop the drug.

Dosing and Administration

Inside, during or after delivery (to avoid irritation of mucous membrane stomach). Adults on 1/2-1 table. 2-3 times a day, if necessary daily dose increased to 3-4 table. with a maximum daily intake - 8 table. For children up to five years in the 1 / 4 table. two times a day, 5-8 years, and 1 / 4 table. 3-4 times a day over eight years in the 1/2-1 table. twice a day.

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