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MDL number MFCD00005264. These incidents usually occur within the first 2 months of treatment and may be associated with AHS/DRESS (see section 4.4).Patients with impaired hepatic function, the elderly, or those who are gravely ill may show early signs of toxicity.The clinical course of acute phenytoin hepatotoxicity ranges from prompt recovery to fatal outcomes. The serum level achieved by a given dose is therefore also subject to wide variation.Patients with Renal or Hepatic Disease: see section 4.4.Age: Phenytoin clearance tends to decrease with increasing age (20% less in patients over 70 years of age relative to that in patients 20-30 years of age). Arrhythmias including bradycardia, atrial and ventricular depression and ventricular fibrillation can occur and these have, in some cases, resulted in asystole/ cardiac arrest and death.
Discoloration and pain distal to the site of injection (described as “purple glove syndrome”) have also been reported (see section 4.4). An anticonvulsant that is used in a wide variety of seizures. Patients (and caregivers of patients) should be advised to seek medical advice should signs of suicidal ideation or behaviour emerge.Laboratory tests: It may be necessary to measure serum phenytoin levels to achieve optimal dosage adjustments.This product contains a number of excipients known to have a recognized action or effect. By continuing to browse the site you are agreeing to our policy on the use of cookies.
However, it cannot be stated with certainty that even minor seizures do not pose some hazard to the developing embryo or foetus.There is some evidence that phenytoin may produce congenital abnormalities in the offspring of a small number of patients with epilepsy. Phenytoin sodium is related to the barbiturates in chemical structure, but has a five-membered ring. In neurons, phenytoin decreases sodium and calcium ion influx by prolonging channel inactivation time during generation of nerve impulses. 2017 Sep;264(9):2043-2047. doi: 10.1007/s00415-017-8465-4.
Phenytoin is metabolized by hepatic cytochrome (CYP) P450 enzymes CYP2C9 and CYP2C19 and is particularly susceptible to inhibitory drug interactions because it is subject to saturable metabolism. Administration should commence immediately after the mixture has been prepared and must be completed within one hour (the infusion mixture should not be refrigerated). Limited evidence suggests that HLA-B*1502 may be a risk factor for the development of SJS/TEN in patients of Asian ancestry taking drugs associated with SJS/TEN, including phenytoin. Other physiologic … The loading dose should be followed by maintenance doses of 100mg orally or intravenously every 6 to 8 hours.In neonates, it has been shown that absorption of phenytoin is unreliable after oral administration, but a loading dose of 15-20mg/kg of phenytoin intravenously will usually produce serum concentrations of 10–20 mg/l phenytoin which is within the generally accepted therapeutic range. The drug should be injected slowly intravenously at a rate of 1-3mg/kg/min.Determination of phenytoin serum levels is advised during use in the management of status epilepticus and subsequently whilst establishing maintenance dosage. The initial signs are nystagmus, diplopia, ataxia, and dysarthria. NACRES NA.24
The inducing effect may persist for at least 2 weeks after cessation of treatment with St. John's wort. Alternatively, the dosage may need to be increased up to 200 mg orally 3 times a day, if necessary. Phenytoin may affect blood sugar metabolism tests.It is recommended that serum folate concentrations be measured at least every 6 months, and folic acid supplements given if necessary.The following information should be taken into account when considering the intravenous use of phenytoin in the management of status epilepticus in pregnancy.