5,5-дифенилхидантоин

Описание

The drug was first approved for the treatment of epilepsy by the Food and Drug Administration in 1953 and marketed by Parke-Davis as Dilantin. Its primary mechanism of action appears to block voltage-sensitive sodium channels in the brain (especially in the motor cortex), producing a delay in electrical recovery in neurons and stabilizing the threshold against hyperexcitability.

Химические свойства

white crystals or powder

Использование

5,5-Diphenylhydantoin has been used for phenytoin treatment. It has also been used to slow down or prevent mesoendoderm cell migration.

Определение

ChEBI: A imidazolidine-2,4-dione that consists of hydantoin bearing two phenyl substituents at position 5.

Общее описание

Fine white or almost white crystalline powder. Odorless or almost odorless. Tasteless.

Реакции воздуха и воды

Insoluble in water.

Профиль реактивности

5,5-Diphenylhydantoin is an amide. Amides/imides react with azo and diazo compounds to generate toxic gases. Flammable gases are formed by the reaction of organic amides/imides with strong reducing agents. Amides are very weak bases (weaker than water). Imides are less basic yet and in fact react with strong bases to form salts. That is, they can react as acids. Mixing amides with dehydrating agents such as P2O5 or SOCl2 generates the corresponding nitrile. The combustion of these compounds generates mixed oxides of nitrogen (NOx). 5,5-Diphenylhydantoin is incompatible with strong oxidizers and strong bases.

Пожароопасность

Flash point data for 5,5-Diphenylhydantoin are not available; however, 5,5-Diphenylhydantoin is probably combustible.

Механизм действия

Phenytoin is indicated for initial monotherapy or adjunct treatment of complex partial or tonic-clonic seizures, convulsive status epilepticus, and prophylaxis. It often is selected for initial monotherapy because of its high efficacy and relatively low incidence of side effects. Phenytoin is not used in the treatment of absence seizures, because it may increase their frequency of occurrence. Phenytoin binds to and stabilizes the inactivated state of sodium channels, thus producing a use-dependent blockade of repetitive firing and inhibition of the spread of seizure activity to adjacent cortical areas.

Фармаколо?гия

In terms of its effect on the CNS, phenytoin is considered an excellent antiepileptic drug with insignificant sedative effects. Even in large doses it does not cause hypnosis. It is presumed that phenytoin facilitates secretion of sodium ions from nerve cells, which reduces the stimulation of neurons. This in turn prevents the activation of neurons upon receiving impulses from the epileptogenic center. In addition, phenytoin reduces the incoming flow of potassium ions during repolarization. It is possible that phenytoin significantly slows the distribution of excitation in the brain as a direct result of the redistribution of the ion flow.

Клиническое использование

Phenytoin (Dilantin) was originally introduced for the control of convulsive disorders but has now also been shown to be effective in the treatment of cardiac arrhythmias. Phenytoin appears to be particularly effective in treating ventricular arrhythmias in children.
Phenytoin, like lidocaine, is more effective in the treatment of ventricular than supraventricular arrhythmias. It is particularly effective in treating ventricular arrhythmias associated with digitalis toxicity, acute myocardial infarction, open-heart surgery, anesthesia, cardiac catheterization, cardioversion, and angiographic studies.
Phenytoin finds its most effective use in the treatment of supraventricular and ventricular arrhythmias associated with digitalis intoxication. The ability of phenytoin to improve digitalis-induced depression of A-V conduction is a special feature that contrasts with the actions of other antiarrhythmic agents.

Побочные эффекты

The most common side effect in children receiving long-term therapy is gingival hyperplasia, or overgrowth of the gums (occurs in up to 50% of patients). Although the condition is not serious, it is a cosmetic problem and can be very embarrassing to the patient. Hirsutism also is an annoying side effect of phenytoin, particularly in young females. Thickening of subcutaneous tissue, coarsening of facial features, and enlargement of lips and nose (hydantoin facies) are often seen in patients receiving long-term phenytoin therapy. Peripheral neuropathy and chronic cerebellar degeneration have been reported, but they are rare.
There is evidence that phenytoin is teratogenic in humans, but the mechanism is not clear. However, it is known that phenytoin can produce a folate deficiency, and folate deficiency is associated with teratogenesis. Only a few well-documented drug combinations with phenytoin may necessitate dosage adjustment. Coadministration of the following drugs can result in elevations of plasma phenytoin levels in most patients: cimetidine, chloramphenicol, disulfiram, sulthiame, and isoniazid (in slow acetylators). Phenytoin often causes a decline in plasma carbamazepine levels if these two drugs are given concomitantly.
Ethotoin and mephenytoin are congeners of phenytoin that are marketed as AEDs in the United States. They are not widely used.

Профиль безопасности

Confirmed carcinogen producing lymphoma, Hodgkin's disease, tumors of the skin and appendages. Experimental carcinogenic and tumorigenic data. A human poison by ingestion. Poison experimentally by ingestion, subcutaneous, intravenous, and intraperitoneal routes. Moderately toxic by an unspecified route. Experimental teratogenic and reproductive effects. Human systemic effects by ingestion: dermatitis, change in motor activity (specific assay), ataxia (loss of muscle coordmation), degenerative brain changes, encephalitis, hallucinations, dtstorted perceptions, irritabihty, and jaundice. Human teratogenic effects by ingestion: developmental abnormalities of the central nervous system, carlovascular (circulatory) system, musculoskeletal system, craniofacial area, skin and skin appendages, eye, ear, other developmental abnormalities. Effects on newborn include abnormal growth statistics (e.g., reduced weight gain), physical abnormakties, other postnatal measures or effects, and delayed effects. Human mutation data reported. A drug for the treatment of grand mal and psychomotor seizures. When heated to decomposition it emits toxic fumes of NOx

Возможный контакт

Phenytoin is an amide pharmaceutical used in the treatment of grand mal epilepsy, Parkinson’s syndrome; and in veterinary medicine. Human exposure to phenytoin occurs principally during its use as a drug. Figures on the number of patients using phenytoin are not available, but phenytoin is given to a major segment of those individuals with epilepsy. The oral dose rate is initially 100 mg given 3 times per day and can gradually increase by 100 mg every 2
4 weeks until the desired therapeutic response is obtained. The intravenous dose is 200
350 mg/day.

взаимодействия лекарств

Plasma phenytoin concentrations are increased in the presence of chloramphenicol, disulfiram, and isoniazid, since the latter drugs inhibit the hepatic metabolism of phenytoin. A reduction in phenytoin dose can alleviate the consequences of these drug–drug interactions.

Канцерогенность

Phenytoin and its sodium salt are reasonably anticipated to be human carcinogens based on sufficient evidence from studies in experimental animals.

Экологическая судьба

Routes and Pathways
Exposure is usually oral, but the intravenous route may be used to treat status epilepticus.
Relevant Physicochemical Properties
Appearance: clear, colorless, or slightly yellow in solution Solubility: ethyl alcohol

Растворимость в воде

practically insoluble in water. 1 g dissolves in about 75 ml of ethanol or 30 ml of acetone.

Перевозки

UN2811 Toxic solids, organic, n.o.s., Hazard Class: 6.1; Labels: 6.1-Poisonous materials, Technical Name Required. UN3249 Medicine, solid, toxic, n.o.s., Hazard Class: 6.1; Labels: 6.1-Poisonous materials.

Методы очистки

Crystallise the hydantoin from EtOH. [Beilstein 24 III/IV 1748.]

Несовместимости

Incompatible with oxidizers (chlorates, nitrates, peroxides, permanganates, perchlorates, chlorine, bromine, fluorine, etc.); contact may cause fires or explosions. Keep away from alkaline materials, strong bases, strong acids, oxoacids, epoxides. Similar organic amides react with azo and diazo compounds, releasing toxic gases. Contact with reducing agents can release flammable gases. Amides are very weak bases but they can react as acids, forming salts. Mixing amides with dehydrating agents such as phosphorus pentoxide or thionyl chloride generates the corresponding nitrile.

Меры предосторожности

Phenytoin either should not be used or should be used cautiously in patients with hypotension, severe bradycardia, high-grade A-V block, severe heart failure, or hypersensitivity to the drug.
Because of the increase in A-V transmission observed with phenytoin administration, it should not be given to patients with atrial flutter or atrial fibrillation. Phenytoin will probably not restore normal sinus rhythm and may dangerously accelerate the ventricular rate.