What is a drug like Phenytoin? Instructions for use, analogues of drugs with the same active ingredient will be presented below.
Chemical properties and release form
"Phenytoin" with the same active ingredient is an antiepileptic drug. It is a derivative of hydantoin, very close to barbituric acid (in its chemical structure).
The substance in question is included in the list of important medicines of the WHO, as well as in the list of essential medicines.
Phenytoin (instructions for using the drug with this component will be presented later) was synthesized in 1908. And only by 1937 were its anticonvulsant properties discovered.
This substance is a powder (crystalline) of white color, which practically does not dissolve in water. This compound can be dissolved only in 1% caustic alkali solutions.
Phenytoin oral tablets, as well as an agent for parenteral administration, are currently available.
Pharmacology
How does the phenytoin medication work? Instructions for use indicate that this drug has anticonvulsant, antiarrhythmic, antiepileptic and muscle relaxant properties.
The anticonvulsant activity of this drug is quite high. However, its reception does not cause drowsiness or lethargy.
Phenytoin is called an effective biological-electric stabilizer. When taking high doses of the substance, it can lead to a violation of the coordination of human movement.
The drug in question activates the central nervous system, increases the threshold of excitability, has an antiarrhythmic effect on the heart, and also reduces the speed of impulses along the His bundle and Purkinje fibers.
The mechanism of action of the drug
What is the effect of the phenytoin medicine based on? The instruction says that the principle of its effect on the human body has not yet been fully studied. However, experts argue that the fundamental property of this tool is its ability to stabilize the membranes (neuronal) of synaptic connections and the body of nerve cells.
Due to this effect, taking the drug can limit the spread of neuronal excitation, as well as reduce convulsive activity.
Features of the tool
What is remarkable phenytoin medicine? The instruction for use reports that its active substance acts on the autonomous ganglia, brain and spinal cord tissues, the heart, including its conduction system, peripheral nerves and smooth muscles of the intestines and blood vessels of the heart.
Taking this drug can reduce the concentration of sodium in neurons, facilitate the transport of sodium ions from cells, and also reduce the intracellular movement of calcium.
It should be noted that the drug in question affects the functioning of fibroblasts, neuroglia and endocrine cells. It was also discovered its ability to accelerate wound healing, suppress the activity of receptors (glutamate), improve the supply of oxygen to cells, tissues and organs in conditions of poisoning with toxins and hypoxia.
Taking the drug in therapeutic doses has a moderate tonic effect and calms, and also does not cause addiction.
Kinetics
Is phenytoin absorbed? Instructions for use (the form of release of the same drug was named above) states that with oral administration of the drug, this component is quite easily absorbed by the patient's body. However, the pharmacokinetic parameters of the drug in question can vary significantly in different groups of patients.
The highest concentration of the drug in the blood is achieved within 5-14 hours (up to 28 hours for the tablet form). The effect of oral administration of the drug is observed after about an hour, and after intravenous administration, after a few minutes.
Almost 80% of the active substance binds to plasma blood proteins. In people suffering from kidney disease, this figure can reach 43%.
According to the instructions, the drug in question quite quickly overcomes the blood-brain barrier. Moreover, it is distributed over almost all tissues and organs.
About 5% of phenytoin is excreted through the kidneys. As for the remaining compound, it is metabolized in the liver, being converted into inactive paraoxyphenyls and glucuronides, which then leave the body along with bile.
How should I use Phenytoin? The use of this drug is indicated along with phenobarbital, vitamins D and K, as well as other antiepileptics. Only in this case will it be most effective.
Indications
When do you use drugs with an active ingredient like phenytoin? Instructions for use (tablets and solution should be recommended only by an experienced doctor) indicates the following indications:
- epilepsy;
- the period after surgery and trauma (as a preventive drug);
- ventricular and supraventricular arrhythmias, which were caused by an overdose of antidepressants and cardiac glycosides;
- epileptic status with partial complex seizures and tonic-clonic seizures;
- Meniere's syndrome;
- trigeminal neuralgia, including with resistance to carbamazepine;
- ulcerative colitis or IBS (with the ineffectiveness of another therapy);
- disturbances in mental processes, mental disorders, behavioral disorders;
- strabismus and glaucoma;
- disturbed regeneration process (burns, caries, ulcers and scleroderma);
- relapsing fever and hypothalamic syndrome.
Contraindications
The drug in question is prohibited for use with:
- cachexia or leukopenia;
- lactation;
- severe diseases of the kidneys and liver;
- heart failure, AV blockade of the 2nd or 3rd degree, bradycardia;
- hypersensitivity to the active active substance;
- porphyria;
- Morgagni-Adams-Stokes syndrome;
- pregnancy.
Caution should also be exercised in patients with diabetes mellitus, alcoholism, with lupus erythematosus or hyperthermia.
The medicine "Phenytoin": instructions for use
The dosage of this drug is selected individually, depending on the age of the patient and the disease.
With non-epileptic diseases, the dose should be several times lower than with epilepsy. The medicine in the form of tablets is taken only with meals.
The daily dose of the drug for adult patients is 1-3 tablets (divided into 2-3 doses). If necessary, this amount can be increased to 4 tablets per day.
The maximum dosage of the drug per day is 8 tablets. At the same time, the patient can take only 3 tablets at a time.
When treating children under 5 years of age, they are prescribed ¼ tablets twice a day. Babies 5-8 years old - in the same amount, but 3 or 4 times a day.
Children who have already reached the age of 8 are recommended to give 1-2 tablets in 2 divided doses.
The duration of treatment with this agent is determined only by a specialist.
Side effects
Taking medication with phenytoin can cause the following undesirable effects:
- Skin allergy, measles-like rash (the drug should be discontinued until the symptom is eliminated).
- Severe allergic reactions (rare), fever, extensive skin rashes, Stevens-Johnson syndrome, erythema angioedema, hepatitis.
- Gingival hyperplasia, macrocytosis, osteomalacia, megaplastic anemia, thrombocytopenia, pancytopenia, hirsutism, hemolytic anemia, lymphadenopathy.
- Dose-dependent disorders of the central nervous system, nystagmus, lip and eyelid fibrillation, anxiety, ataxia, dizziness, tremor, insomnia, increased irritability, sensory neuropathy (develop with prolonged use of large doses).
- Hypertrichosis, coarsening of facial features, hyperpigmentation, weight loss, polyarthritis.
It should also be noted that when taking the first dose, the patient may develop the following side effects: gastrointestinal disorders, increased levels of liver enzymes, nausea, dyspepsia, gastralgia and gastritis. The appearance of such effects can be avoided if you take pills only during the meal.
Overdose cases
The use of the drug in high doses for a long time can lead to the development of ataxia, nystagmus, hyperkinesis, sensory neuropathy and diplopia. Also, the patient may manifest an increase in epilepsy attacks, hyperglycemia and stupor.
It should be especially noted that this substance does not have a specific antidote. Therapy should be carried out according to the manifest signs.
Special information
The drug in question cannot be abruptly canceled by patients with epilepsy, since this can cause the development of withdrawal syndrome. If it is necessary to refuse to take it (for example, with allergies or hypersensitivity), then another kind of anticonvulsant drugs should be used.
Treatment with the agent in question affects cholesterol, bilirubin, alkaline phosphatase, liver enzymes, glucose, calcium in the blood serum, and also the thyroxine hormone.
As mentioned above, the substance phenytoin is metabolized in the liver, therefore, during its administration, special care should be taken for people with liver failure.
If a person has previously observed increased sensitivity to hydantoin anticonvulsants, then this substance is also allergic.
During treatment, the patient is forbidden to drive a car, as well as perform dangerous types of work.
Analogs and reviews
What can replace the phenytoin antiepileptic drug? Analogues of this tool contain the same active substance. These drugs include the following: "Diphenin", "Diphenylhydantoin" and "Dilantin".
Most patient reviews about the drug in question are good. They claim that this drug is tolerated quite easily. In addition, it has a low cost and does not lose its anticonvulsant properties even with prolonged use.
It should also be noted that there are many positive opinions about this remedy, which were left by patients who took it as part of complex therapy.