15 Questions
What is the usual initial dose of phenytoin for acute indications?
150-300 mg/day PO
What is the therapeutic range of total phenytoin in blood samples?
10-20 mg/L
What is a common chronic adverse effect of phenytoin, occurring in 20% of patients?
Gingival hyperplasia
At what phenytoin level can drug-induced seizures occur?
50 mg/L
What is the therapeutic range of free phenytoin concentration in saliva samples?
1-2 mg/L
What is the recommended action if a patient develops symptoms such as fever, rash, mouth ulcers, bruising, or bleeding while taking phenytoin?
Seek immediate medical attention
Why is it important to maintain a patient on a specific manufacturer's product when treating epilepsy with phenytoin?
To ensure bioequivalence
What is the approximate therapeutic equivalent of 100 mg of phenytoin sodium?
92 mg phenytoin base
What is the recommended timing for taking a phenytoin level after initiating therapy?
At 7 days
What is the indication for the use of intravenous phenytoin formulation?
Status epilepticus
What is the percentage of plasma protein binding of phenytoin?
90%
What is the effect of a decrease in protein binding on phenytoin's therapeutic activity?
Increased therapeutic activity
What is the formula for calculating Cp adjusted, the adjusted phenytoin concentration?
Cp adjusted = Cp measured / (1 - a) * (albumin measured / albumin normal) + alpha
What is the quoted half-life of phenytoin?
22 hours
Why is it necessary to monitor plasma-phenytoin concentration?
Due to the narrow therapeutic index of phenytoin
Test your knowledge of Phenytoin, a medication used to treat seizures, including its therapeutic indications, dosing, and adverse effects. Learn about the usual initial dose, maintenance dose, and therapeutic ranges of Phenytoin. Evaluate your understanding of the potential side effects of Phenytoin.
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