Phenytoin Sodium Tablets

[Pharmacology and Toxicology] This product is an anti-epileptic drug and anti-arrhythmic drug. The therapeutic dose does not cause sedation and hypnosis. 1. Animal experiments have shown that this product has a selective antagonistic effect on the tonic phase of super-strong electric shock and convulsion, but is ineffective or even aggravates the spasm phase. Therefore, it has a good effect on grand mal epilepsy, but is ineffective on absence seizures. Its anti-epileptic mechanism has not yet been elucidated. It is generally believed that it increases the outflow of sodium ions from cells and reduces the inflow of sodium ions, thereby stabilizing the nerve cell membrane, increasing the excitation threshold, and reducing the spread of high-frequency discharges of the lesion. 2. In addition, this product shortens the action potential interval and effective refractory period, and can also inhibit the influx of calcium ions, reduce myocardial autonomicity, inhibit the sympathetic center, and have an inhibitory effect on the ectopic rhythm points of the atrium and ventricle, and increase the threshold of atrial fibrillation and ventricular fibrillation. 3. Its stabilizing cell membrane and reducing synaptic transmission have anti-neuralgia and skeletal muscle relaxation effects. 4. This product can inhibit the synthesis (or) secretion of collagenase by skin fibroblasts. It can also accelerate the metabolism of vitamin D, cause lymphadenopathy, have anti-folate effects, inhibit the hematopoietic system, cause allergic reactions, have enzyme induction effects, and intravenous medication can dilate peripheral blood vessels. [Pharmacokinetics] Oral absorption is slow, 85-90% is absorbed by the small intestine, the absorption rate varies greatly from person to person and is affected by food. Newborns absorb very poorly. Oral bioavailability is about 79%, distributed in intracellular and extracellular fluids, and the intracellular volume may be more than the extracellular volume, with an apparent distribution volume of 0.6L/kg. The plasma protein binding rate is 88-92%, mainly bound to albumin, and the protein binding in brain tissue may be higher. The blood concentration reaches its peak 4-12 hours after oral administration. It is mainly metabolized in the liver, and the metabolites are pharmacologically inactive, mainly hydroxyphenytoin (about 50-70%). This metabolism has genetic polymorphism and racial differences. There is an enterohepatic circulation, mainly excreted through the kidneys, and alkaline urine excretion is faster. T1/2 is 7~42 hours. For patients who take phenytoin sodium for a long time, T1/2 can be 15~95 hours, or even longer. After a certain dose of the drug is applied, the liver's metabolic (hydroxylation) capacity reaches saturation. At this time, even if a small dose is increased, the blood drug concentration increases nonlinearly and sharply, and there is a risk of poisoning. The blood drug concentration should be monitored. The effective blood drug concentration is 10~20mg/L. Oral administration of 300mg per day can reach a steady-state concentration in 7~10 days. When the blood drug concentration exceeds 20mg/L, toxic reactions are likely to occur, and nystagmus will occur; when it exceeds 30mg/L, ataxia will occur; when it exceeds 40mg/L, serious toxic effects often occur. It can pass through the placenta and can be secreted into breast milk.

The main ingredient of this product is phenytoin sodium, and its chemical name is: 5,5-diphenyl-2,4-imidazolidinedione sodium salt.

This product is white tablets or film-coated tablets.

It is suitable for the treatment of generalized tonic-clonic seizures, complex partial seizures (psychomotor seizures, temporal lobe epilepsy), simple partial seizures (localized seizures) and status epilepticus. It can also be used to treat trigeminal neuralgia, recessive dystrophic epidermolysis bullosa, paroxysmal choreoathetosis, paroxysmal control disorders (including behavioral disorders such as anger, anxiety and insomnia due to excessive excitement), myotonia and cardiac conduction disorders in case of overdose of tricyclic antidepressants. This product is also suitable for ventricular and supraventricular arrhythmias caused by digitalis poisoning, and has poor efficacy on arrhythmias caused by various other reasons.

Common dosage for anti-epileptic drugs in adults: 250~300 mg per day, 100 mg at the beginning, twice a day, increase to 250~300 mg within 1~3 weeks, divided into three times for oral administration, the maximum is 300 mg once, 500 mg per day. Due to individual differences and saturated pharmacokinetic characteristics, medication needs to be individualized. After the application achieves control of seizures and the blood drug concentration reaches a steady state, a long-acting (controlled release) preparation can be used instead, which is taken at once. If the seizures are frequent, 12~15 mg/kg can be taken in 2~3 times, once every 6 hours, and 100 mg (or 1.5~2 mg/kg according to body weight) can be given from the next day, 3 times a day until the appropriate dose is adjusted. Common dosage for children: 5 mg/kg per day, divided into 2~3 times, adjusted as needed, not exceeding 250 mg per day.

1. Long-term use of acetaminophen in patients may increase the risk of liver poisoning and reduce the efficacy. 2. It is a liver enzyme inducer. When used in combination with corticosteroids, digitalis (including digoxin), oral contraceptives, cyclosporine, estrogen, levodopa, quinidine, oxytetracycline or tricyclic antidepressants, the effects of these drugs may be reduced. 3. Long-term drinking can reduce the concentration and efficacy of this product, but drinking a lot of alcohol while taking the medicine can increase the blood concentration; combined with chloramphenicol, isoniazid, phenylbutazone, and sulfonamides may reduce the metabolism of this product and increase the blood concentration, increasing the toxicity of this product; combined with anticoagulants, the anticoagulant effect will increase at the beginning, and the continuous use will reduce it. 4. When used in combination with magnesium, aluminum or calcium carbonate, the bioavailability of this product may be reduced. The two should be taken 2 to 3 hours apart. 5. When used in combination with hypoglycemic drugs or insulin, because this product can increase blood sugar, the dosage of the latter two needs to be adjusted. 6. In principle, patients who use dopamine should not use this product. 7. This product may enhance the inhibitory effect on the heart when used in combination with lidocaine or propranolol. 8. Although this product consumes folic acid in the body, increasing folic acid can reduce the concentration and effect of this product. 9. The effect of phenobarbital or primidone on this product varies greatly, and the blood concentration should be monitored frequently; when used in combination with valproic acid, there is a protein binding competition, and the blood concentration should be monitored frequently to adjust the dosage of this product. 10. When used in combination with carbamazepine, the latter's blood concentration is reduced. If a large amount of antipsychotics or tricyclic antidepressants are used in combination, epileptic seizures may occur, and the dosage of this product needs to be adjusted.

Contraindications: Patients with a history of allergy to hydantoins or those with heart function impairment such as Ass syndrome, II-III degree atrioventricular block, sinus node block, sinus bradycardia, etc.

Precautions for children: Since the distribution volume and elimination half-life of children change with age, blood drug concentration should be measured frequently. The pharmacokinetics of this product are special for neonates or infants, and it is difficult to clinically assess the symptoms of poisoning. It is generally not used first. Preschool children have strong liver metabolism, and blood drug concentration needs to be monitored multiple times to determine the frequency and dosage of medication. Precautions for pregnancy and lactation: This product can pass through the placenta and may cause teratogenesis, but it is believed that the risk of teratogenesis due to uncontrolled epileptic seizures is greater than the risk of medication. The pros and cons should be weighed. Patients who can control seizures with this product should continue to take it during pregnancy and maintain blood concentration, and then readjust after delivery. Vitamin K should be supplemented one month before delivery, and vitamin K should be injected into the newborn immediately after delivery to reduce the risk of bleeding. This product can be secreted into breast milk, and it is generally recommended that mothers taking phenytoin sodium avoid breastfeeding. Precautions for the elderly: The incidence of chronic hypoproteinemia in the elderly is high, and there are many combined medications in treatment, and the interactions between drugs are complex. Be cautious when using this product, and the dosage should be low. And monitor blood drug levels frequently.

① Long-term use of acetaminophen in patients may increase the risk of liver poisoning and reduce the efficacy of this product; ② It is a liver enzyme inducer. When used in combination with corticosteroids, digitalis (including digoxin), oral contraceptives, cyclosporine, estrogen, levodopa, quinidine, oxytetracycline or tricyclic antidepressants, the effects of these drugs may be reduced; ③ Long-term drinking can reduce the concentration and efficacy of this product, but drinking a lot of alcohol while taking the medicine can increase the blood concentration; combined with chloramphenicol, isoniazid, phenylbutazone, and sulfonamides may reduce the metabolism of this product and increase the blood concentration, increasing the toxicity of this product; when used in combination with anticoagulants, the anticoagulant effect is initially increased, but it is reduced with continuous use; ④ When used in combination with drugs containing magnesium, aluminum or calcium carbonate, the bioavailability of this product may be reduced, and the two should be taken 2 to 3 hours apart; ⑤ When used in combination with hypoglycemic drugs or insulin, because this product can increase blood sugar, the dosage of the latter two needs to be adjusted; ⑥ In principle, patients using dopamine should not use this product; ⑦ When this product is used in combination with lidocaine or propranolol, it may enhance the inhibitory effect on the heart; ⑧ Although this product consumes folic acid in the body, increasing folic acid can reduce the concentration and effect of this product; ⑨ The effects of phenobarbital or primidone on this product vary greatly, and blood drug concentrations should be monitored frequently; when used in combination with valproic acid, there is a protein binding competition, and blood drug concentrations should be monitored frequently to adjust the dosage of this product. ⑩ When used in combination with carbamazepine, the latter has a lower blood concentration. If a large amount of antipsychotics or tricyclic antidepressants are used in combination, epileptic seizures may occur, and the dosage of this product needs to be adjusted.

Keep sealed.

0.1g

38 months

Yunpeng Pharmaceutical Group Co., Ltd.

• Founded in:

  1998-09-15

• Address:

  No. 19, Yunpeng Avenue, Pharmaceutical Industrial Park, Xiangfen County, Linfen City, Shanxi Province

• Tax NO.:

  911410027136140375

• Registered Funds:

  200 million yuan

• Website:

  Log in to view

• Email:

  Log in to view