|Dilantin 100 mg|
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Pharmacology of Dilantin
Pharmacological action - antiepileptic, anticonvulsant, antiarrhythmic, muscle relaxant.
It has anticonvulsant activity (without a pronounced sedative and hypnotic effect), manifested in generalized and partial seizures. In high doses, it disrupts the coordination of movements. It has an activating effect on the central nervous system (shortens the period of immobility in the "despair" test and reduces ptosis caused by reserpine), antiarrhythmic effect on the heart (reduces the maximum depolarization rate, increases the threshold of excitability, slows down conduction along the His bundle and Purkinje fibers). Suppresses vestibular reflexes, reduces the manifestations of some forms of Meniere's syndrome. Influences the active and passive transport of sodium and calcium ions through the cellular and subcellular membranes of nerve cells. It significantly reduces the level of sodium in the neuron, since it reduces its intake, blocking the Na+-K+-ATPase of the brain and facilitates active transport from the cell. Changes the calcium-phospholipid interaction in the cell membrane and reduces the active transport of potassium and calcium, inhibits the release of neurotransmitter amino acids (glutamate, aspartate) from nerve endings, thereby providing an anticonvulsant effect. Has the ability to suppress glutamate receptors. Antiarrhythmic activity is realized through a decrease in central adrenergic effects on the heart, stabilization of cardiomyocyte membranes with an increase in their permeability to potassium ions.
When taken orally, it is easily absorbed. The absorption rate is different in different patients, so the time to reach Cmax is very variable - 3-15 hours. It is bound by 70-90% with plasma proteins (in renal failure - 43%). Freely passes histohematogenous barriers and is quickly distributed to organs and tissues (including brain). Less than 5% is excreted in the urine unchanged, the rest is transformed by liver enzymes to inactive metabolites - mainly glucuronides (excreted by the kidneys) and paraoxyphenyl derivatives; the latter are partially excreted in the bile. T1/2 in plasma with intravenous administration - 9-14 hours, after oral administration - 22-28 hours. Children (especially during growth) are recommended to prescribe phenytoin in combination with vitamins D and K, because development of osteopathies such as rickets, hypocalcemia, blood coagulation disorders is possible. If the effect is insufficient, phenobarbital or another antiepileptic drug should be additionally used. It is also used in cases of resistance to carbamazepine in the treatment of trigeminal neuralgia. Eliminates (50 - 90%) supraventricular and ventricular arrhythmias caused by an overdose of cardiac glycosides, but is ineffective in supraventricular arrhythmias of other genesis. A distinct effect is observed in rhythm disturbances during anesthesia, cardiac catheterization, after heart surgery, i.e. when the function of the central structures that regulate the activity of the sympathetic nervous system is impaired.
Application of the substance Phenytoin
Epilepsy (large convulsive seizures), prevention of post-traumatic and post-neurosurgical epilepsy, ventricular arrhythmias, incl. with intoxication with cardiac glycosides, some forms of Meniere's syndrome, trigeminal neuralgia.
Dilantin Dosage Information
Usual Adult Dose for Seizures:
Oral (excluding suspension) Loading Dose: Only when indicated for inpatients.
1 g orally divided into 3 doses (400 mg, 300 mg, 300 mg) with an interval of 2 hours. Then the normal maintenance dose was started 24 hours after loading the dose.
Initial dose: 100 mg of extended supply orally 3 times a day.
Maintenance dose: 100 mg orally 3 to 4 times a day. If set control is established with divided doses of three 100 mg capsules daily, a single dose of 300 mg extended release phenytoin sodium may be considered. Alternatively, the dose may need to be increased to 200 mg orally 3 times a day if needed.
Suspension: Patients who have not received any previous treatment can be started on 125 mg (one teaspoonful) suspension three times a day, and then the dose is adjusted according to individual requirements. Up to five teaspoons per day can be produced as needed.
IV: Do not exceed the infusion rate of 50 mg / min.
Loading Dose: 10-15 mg / kg IV slowly.
Maintenance dose: 100 mg IV every 6 to 8 hours.
IM: Avoid the IM route due to intermittent absorption.
Usual Adult Dose for Arrhythmias:
1.25 mg / kg IV every 5 minutes. May be repeated until loading doses of 15 mg / kg or
250 mg orally 4 times a day for 1 day, then 250 mg twice a day for 2 days
300-400 mg / day orally in 1-4 divided doses once a day
Usual Adult Dose for Status Epilepticus:
Loading Dose: Manufacturer recommends 10 to 15 mg / kg IV slowly (at a rate not exceeding 50 mg / min). Alternatively, generally accepted guidelines suggest 15 to 20 mg / kg by slow IV administration (at a rate not exceeding 50 mg / min).
Maintenance cost: 100 mg orally or IV every 6-8 hours
Maximum rate: 50 mg / min
Maintenance dose: IV or oral: 100 mg every 6-8 hours
Usual adult dose for neurosurgery:
Neurosurgery (prophylactic): 100 to 200 mg IM at intervals of about 4 hours during surgery and immediate postoperative period. (Note: Although the manufacturer recommends IM administration, this route can lead to severe local tissue destruction and necrosis. Some clinicians recommend the use of fophenytoin if IM administration is necessary.) If IM administration is not necessary, the protocol adopted is 100 to 200 mg IV at intervals of about 4 hours during surgery and immediate postoperative period.
Usual Pediatric Dose for Seizures:
Condition Epilepsy: Dose loading:
Infants, children: 15 to 20 mg / kg IV in single or divided doses
Anticonvulsant: Dose loading:
All ages: 15 to 20 mg / kg orally (based on concentration phenytoin serum and recent dosing history). The oral dose should be given in 3 divided doses, every 2-4 hours.
Anticonvulsant: Maintenance dose:
(IV or oral) (Note: Initially, the daily dose was initially divided into 3 doses / day and then adjusted to individual requirements).
Less than or equal to 4 weeks: Initial: 5 mg / kg / day in 2 divided doses
Typical: 5 to 8 mg / kg / day IV in 2 divided doses (may require a dose every 8 hours).
Greater than or equal to 4 weeks: Initial: 5 mg / kg / day in doses 2 to 3
Typical: (may require up to 8 hours of dosing)
6 months to 3 years: 8 to 10 mg / kg / day
4 to 6 years: 7.5 to 9 mg / kg / day
7 to 9 years: 7 to 8 mg / kg / day
10 to 16 years: 6 to 7 mg / kg / day
Usual Pediatric Dose for Arrhythmias:
More 1 year:
Dose for loading: 1.25 mg / kg IV every 5 minutes. A dose of 15 mg / kg may be repeated up to loading.
Maintenance dose: 5 to 10 mg / kg / day orally or IV in doses 2 to 3
Hypersensitivity, impaired liver and kidney function, heart failure, cachexia, porphyria.
If phenytoin is used during pregnancy or in case of pregnancy during phenytoin treatment, the patient should be informed of the potential hazard to the fetus.
Intrauterine exposure to phenytoin may increase the risk of birth defects. An increased incidence of major malformations (such as heart defects), minor anomalies (such as dysmorphic features of the face, nails, and finger hypoplasia), impaired growth (including microcephaly) and mental retardation have been reported in children born to women with epilepsy. who took phenytoin during pregnancy alone or in combination with other antiepileptic drugs. Several cases of malignant neoplasms have also been reported, incl. neuroblastoma, in children whose mothers received phenytoin during pregnancy. The total incidence of malformations in children born to women with epilepsy and receiving antiepileptic drugs (phenytoin and / or others) during pregnancy is about 10%, which is 2-3 times higher than in the general population. However, the relative contribution of antiepileptic drugs and other factors associated with epilepsy to increased risk is unknown and in most cases it is impossible to attribute specific developmental abnormalities to specific antiepileptic drugs.
In preclinical animal studies, an increase in resorption and the incidence of malformations was recorded after administration of phenytoin to pregnant rabbits at doses of 75 mg / kg and higher (about 120% of the maximum loading dose for humans).
Accelerate biotransformation of phenobarbital and carbamazepine, slow down (may increase side effects) - isoniazid and its derivatives, chloramphenicol, coumarins, acetylsalicylic acid, disulfiram.
Symptoms: if the concentration in the blood in children is more than 20 mg / l, the development of acute intoxication is possible - nystagmus, ataxia, mental disorders, pain in the joints; in more severe cases, bradycardia, ventricular fibrillation, atrial flutter, asystole, and coma.
Treatment: symptomatic. There is no specific antidote.
Precautions for the substance Phenytoin
Careful selection of doses is necessary (in case of epilepsy, the concentration in the blood is determined on the 7-10th day of treatment), because elimination is a saturable process and an increase in dose may be accompanied by a disproportionate increase in plasma levels. In case of severe side effects, it is necessary to reduce the dose or cancel the drug.
Dilantin side effects
Get emergency medical help if you have signs of an allergic reaction to Dilantin: hives; labored breathing; Swelling of the face, lips, tongue, or throat. You may have a more severe allergic reaction if you are African American.
In rare cases, phenytoin can cause a severe drug reaction that can affect many parts of the body. This type of reaction may start several weeks after you start using this medicine.
Get medical help if you develop new or worsening symptoms of fever, sore throat, mouth sores, facial swelling, red or blistering skin rash, flu symptoms, swollen glands, feeling weak or tired, easy bruising, unusual bleeding, Nausea, vomiting, loss of appetite, jaundice (yellowing of the skin or eyes), weight loss, pain or burning sensation when urinating, back pain, swelling in the legs or feet, coughing, chest pain, or difficulty breathing.
Report any new or worsening symptoms to your doctor, such as: mood or behavior changes, anxiety, panic attacks, trouble sleeping or if you feel impulsive, irritable, agitated, hostile, aggressive, restless, hyperactive (mentally or physically), more In depression or thoughts of suicide or self-harm.
Call your doctor at once if you have:
fever, swollen glands, sore throat, trouble breathing, painful mouths, sores around the eyes;
Skin rash, easy bruising or bleeding, severe weakness;
Severe muscle pain;
Nausea, vomiting, upper stomach pain, loss of appetite, dark urine, jaundice (yellowing of the skin or eyes);
Bone pain (especially in the hips, legs, or lower back), trouble walking; or
Severe skin reaction - fever, sore throat, swelling on the face or tongue, burning eyes, skin pain accompanied by red or purple skin
Severe muscle pain;
Sh, which spreads (especially in the face or upper body) and causes blistering and flaking.
Common Dilantin side effects may include:
Dizziness, drowsiness, confusion, nervousness;
Tremors, slurred speech, loss of balance or coordination;
Abnormal eye movement;
Sleep problems (insomnia).