How is phenytoin absorbed?
The absorption of phenytoin was studied in man. It is concluded that phenytoin absorbed from the intestine is recirculated via the bile, so that blood levels do not accurately reflect absorption. Phenytoin is loosely bound to serum proteins and is found in red cells in concentrations similar to those in plasma.
How do you administer phenytoin IV?
Phenytoin Injection BP should be injected slowly and directly into a large vein through a large-gauge needle or intravenous catheter. It must be administered slowly. Intravenous administration should not exceed 50 mg/minute in adults.
How do you give Dilantin suspension orally?
Swallow the tablet whole or chew it thoroughly before swallowing it together with a glass of water. Measure the oral suspension with a marked measuring spoon, oral syringe, or medicine cup. Rinse the dosing spoon or cup with water after each use.
How is phenytoin metabolised?
Phenytoin is metabolized by cytochrome P450 (P450) enzymes primarily to 5-(p-hydroxyphenyl-),5-phenylhydantoin (HPPH), which may be further metabolized to a catechol that spontaneously oxidizes to semiquinone and quinone species that covalently modify proteins.
Is phenytoin a water soluble drug?
Phenytoin is a white, odorless powder at room temperature (Ak- ron 2009). It is practically insoluble in water, but it is soluble in ace- tone, ethanol, and alkali hydroxides (IARC 1996).
Why is phenytoin zero order kinetics?
Phenytoin follows nonlinear (or zero-order) kinetics at therapeutic concentrations, because the rate of metabolism is close to the maximum capacity of the enzymes involved. In nonlinear kinetics, clearance and half-life fluctuate with plasma concentration.
How is phenytoin diluted?
For administration by intravenous infusion phenytoin injection should be diluted in 50 – 100 ml of normal saline, and the final concentration of phenytoin in the solution should not exceed 10 mg/ml, the infusion mixture should not be refrigerated.
What IV fluid is compatible with phenytoin?
It is concluded that 0.9% sodium chloride and lactated Ringer’s injections are suitable diluents for the intravenous administration of phenytoin.
How do you dilute phenytoin?
Does phenytoin come in liquid form?
DILANTIN-125 is available as a 125 mg phenytoin/5 mL oral suspension of orange color with an orange-vanilla flavor. DILANTIN-125 Suspension (phenytoin oral suspension, USP), 125 mg phenytoin/5 mL contains a maximum alcohol content not greater than 0.6 percent in an orange suspension with an orange-vanilla flavor.
What enzyme breaks down phenytoin?
Metabolizing enzymes Phenytoin is primarily metabolized to the inactive hydroxyphenytoin, 5-(4′-hydroxyphenyl)-5-phenylhydantoin or p-HPPH [Article:9798756]. Up to 90% of phenytoin is metabolized to p-HPPH and then glucuronidated and excreted into urine [17576806].
Is phenytoin lipophilic or hydrophilic?
Typically, more hydrophobic drugs are transformed into a more polar, water-soluble compound that is readily eliminated. As an example, the anti-epileptic drug phenytoin is a highly lipophilic compound.
How to prove the bioequivalence of phenytoin versus epamin?
To prove the bioequivalence of Phenytoin versus Epamin by measuring; Area under the curve (AUC), Maximum Concentration (Cmax), Time maximum concentration (tmax), Constant of elimination (ke), Elimination half life (t1/2) [ Time Frame: April 2010 – May 2010 ] Choosing to participate in a study is an important personal decision.
What is the bioavailability of phenytoin?
When based on the comparison of the AUC for multiple oral dosing with the single iv dose area, average bioavailability was 85.9% (71.8 to 106.3). Since the variation in the bioavailability and elimination of phenytoin does not allow accurate prediction of the steady-state plasma concentration, monitoring plasma levels may be of special importance.
What is the pharmacokinetics of phenytoin 300 mg?
Phenytoin: pharmacokinetics and bioavailability The pharmacokinetics of a single 300-mg oral and intravenous and 14 daily 300-mg oral doses of phenytoin were studied in 6 healthy volunteers. The mean plasma elimination t1/2 was the same following intravenous (16.8 +/- 1.3 hr) and oral (17.1 +/- 1.5 hr) doses of phenytoin; however, following chron …