Is phenytoin contraindicated in liver disease?
Drugs such as valproic acid, phenytoin, and felbamate, have a well-recognized association with liver toxicity.
What are the doses of phenytoin?
Phenytoin typical doses are 3–5mg/kg/day. The first dose should be given 12–24 hours after the loading dose. Oral or nasogastric administration should be used, whenever possible. Only use intravenous administration when these options are not feasible and where cardiac monitoring is available.
What is the administration rate for phenytoin?
In adults, intravenous administration should not exceed a rate of 50mg per minute. In neonates, phenytoin should be administered at a rate of 1 – 3mg/kg/min. Hypotension usually occurs with rapid administration of phenytoin by the intravenous route.
What is the therapeutic drug level for phenytoin?
Obtain a serum phenytoin level. The therapeutic range is 10-20 mcg/mL.
How does phenytoin affect the liver?
Phenytoin is an anticonvulsant that in rare cases can cause acute idiosyncratic drug-induced liver disease that can be severe or even fatal. The liver injury caused by phenytoin appears to be due to a hypersensitivity reaction and resembles cases of immunoallergic hepatotoxicity.
Does Dilantin affect liver function?
Dilantin (phenytoin) can cause liver damage shortly after you start taking it, which is why you will need regular lab tests to monitor your liver functioning. Carbamazepine and lamotrigine can also cause liver injury, which may show up after you’ve been taking either for weeks to months.
How many mg is phenytoin?
Usual Adult Dose for Seizures: 1 g orally divided in 3 doses (400 mg, 300 mg, 300 mg) given at 2 hour intervals. Then normal maintenance dosage started 24 hours after loading dose. Initial dose: 100 mg extended release orally 3 times a day. Maintenance dose: 100 mg orally 3 to 4 times a day.
How do you calculate phenytoin?
If clcr < 20 mL/min then Corrected Phenytoin = Total Phenytoin Level / ( (0.1 x albumin) + 0.1) This is so cool!
How do you monitor phenytoin levels?
Laboratories often report the value in g/L instead (g/dL = g/L x 0.1). After a patient has received a loading dose of intravenous phenytoin, levels can be checked one hour after the dose. If loading is achieved by oral dosing, phenytoin levels can be checked 24 hours after the last dose10.
What is phenytoin level for?
Assessing phenytoin levels is useful in prophylaxis of seizures in patients with intracranial pathology, management of epileptic patients, and evaluation of patients with potential phenytoin overdose/toxicity.
How do you calculate phenytoin levels?
Can antiepileptic drugs affect the liver?
Though relatively rare, when compared with other consistently known hepatotoxic drugs, the hepatotoxicity induced by antiepileptic drug can lead to death or an acute liver failure which could imperatively require liver transplantation.
How many mg of phenytoin should I take per minute?
Loading Dose: A loading dose of parenteral Phenytoin Sodium Injection should be injected slowly, not exceeding 50 mg per minute in adults and 1 to 3 mg/kg/min (or 50 mg per minute, whichever is slower) in pediatric patients.
How much phenytoin is needed to treat grand mal epilepsy?
Therapeutic effect without clinical signs of toxicity occurs more often with serum total concentrations between 10 to 20 mcg/mL (unbound phenytoin concentrations of 1 to 2 mcg/mL), although some mild cases of tonic-clonic (grand mal) epilepsy may be controlled with lower serum levels of phenytoin.
Can you substitute phenytoin for an IV dose?
When treatment with oral phenytoin is not possible, IV phenytoin can be substituted for oral phenytoin at the same total daily dose. Phenytoin capsules are approximately 90% bioavailable by the oral route. Phenytoin is 100% bioavailable by the IV route.
What’s the half life of phenytoin for men?
The plasma half-life in man after oral administration of phenytoin averages 22 hours, with a range of 7 to 42 hours. Steady-state therapeutic levels are achieved at least 7 to 10 days (5–7 half-lives) after initiation of therapy with recommended doses of 300 mg/day.