What is the pharmacokinetics of phenytoin?

What is the pharmacokinetics of phenytoin?

Phenytoin metabolism is dose dependent. Elimination follows first-order kinetics (fixed percentage of drug metabolized during a per unit time) at the low drug concentrations and zero-order kinetics (fixed amount of drug metabolized per unit time) at higher drug concentrations.

What is the difference between Fosphenytoin and phenytoin?

Fosphenytoin is a parenterally administered prodrug of phenytoin, used in the treatment of patients with seizures. Advantages of fosphenytoin over phenytoin include more rapid intravenous administration, no need for an intravenous filter, and a lower potential for local tissue and cardiac toxicity.

What is mechanism of phenytoin?

Mechanism of action Phenytoin is believed to protect against seizures by causing voltage-dependent block of voltage gated sodium channels. This blocks sustained high frequency repetitive firing of action potentials.

What class of drug is Fosphenytoin?

Fosphenytoin is a medication used in the management and prevention of seizures. It is a water-soluble phenytoin prodrug with the capability to be used in situations where phenytoin is unadvised. It is in the hydantoin anticonvulsant class of medications.

What is non linear pharmacokinetics?

Nonlinear pharmacokinetics (in other words, time or dose dependences in pharmacokinetic parameters) can arise from factors associated with absorption, first-pass metabolism, binding, excretion and biotransformation.

Does phenytoin bind to albumin?

Phenytoin is mainly bound to albumin, the percentage of bound drug being constant over a wide range of total drug concentrations.

What is fosphenytoin used for?

Fosphenytoin injection is used to control certain types of seizures (convulsions) in the treatment of epilepsy. It is also used to prevent and treat seizures that occur during brain surgery. This medicine is an anticonvulsant that works in the brain tissue to stop seizures.

How is fosphenytoin administered?

Intravenous: When fosphenytoin is administered by IV infusion, maximum plasma fosphenytoin concentrations are achieved at the end of the infusion. Fosphenytoin has a half-life of approximately 15 minutes. Intramuscular: Fosphenytoin is completely bioavailable following IM administration of fosphenytoin.

What is pharmacokinetics Mcq?

Non-linear pharmacokinetics is also known as…………

Q. What does “pharmacokinetics” includes?
B. Influence of drugs on metabolism processes
C. Influence of drugs on genes
D. Complications of drug therapy
Answer» a. Drug biotransformation in the organism

What is the Iupac name for phenytoin?


How is Fosphenytoin metabolized?

Fosphenytoin is metabolized, likely by phosphatases, to phenytoin, phosphate, and formaldehyde; the formaldehyde is subsequently converted into formate. The phenytoin produced is metabolized hepatically by CYP2C9 and, to a lesser extent, by CYP2C19.

How do you convert Fosphenytoin to phenytoin?

Dose conversion from fosphenytoin to phenytoin is a 1:1 ratio, with 1mg PE fosphenytoin = 1 mg phenytoin. Pediatrics: Loading dose: 18 to 20 mg/kg IV Maintenance dose: 2 to 3 mg/kg/ IV dose two times daily (4 to 6 mg/kg/day), though significantly higher dosing may be needed based upon levels.

How much phenytoin is in fosphenytoin sodium?

Characteristic Fosphenytoin Sodium Dose (Based on TBW) Fosphenytoin is dosed in phenytoin equivalents (PE) 1 PE fosphenytoin = 1 mg phenytoin sodium = 1.5 mg fosphenytoin sodium

What are the administration characteristics of injectable fosphenytoin?

Table 1. Administration Characteristics of Injectable Fosphenytoin 2 Characteristic Fosphenytoin Sodium Dose (Based on TBW) Fosphenytoin is dosed in phenytoin equivalents (PE) 1 PE fosphenytoin = 1 mg phenytoin sodium = 1.5 mg fosphenytoin sodium Adults:

What is the half-life of fosphenytoin?

Fosphenytoin is entirely eliminated through metabolism to phenytoin by blood and tissue phosphatases. The bioavailability of the derived phenytoin relative to intravenous phenytoin is approximately 100% following intravenous or intramuscular administration. The half-life for conversion of fosphenytoin to phenytoin ranges from 7-15 minutes.

Who should not take phenytoin/fosphenytoin?

All adult and pediatric inpatients requiring treatment of new onset or previously controlled seizures, including status epilepticus. Avoid phenytoin/fosphenytoin in the neonatal population. In the rare case that phenytoin would be used in a neonate, it should be considered only on an individual basis.