| OBSERVATION'S |
Phenytoin is an anticonvulsant drug used to treat all forms of epilepsy except absence seizures. Phenytoin acts directly on the central nervous system to block seizure activity.1-3 Phenytoin absorption following oral dosing is variable.2,3 Peak plasma concentrations may occur from as early as three hours to as late as twelve hours following drug administration.2 Once absorbed, phenytoin is rapidly distributed into all tissues. The half-life of phenytoin ranges from 20 to 60 hours at therapeutic concentrations. Phenytoin is bound extensively (about 90%0 to plasma proteins, mainly albumin.2 Metabolism of phenytoin occurs primarily in the liver. The major metabolite, the parahydroxyphenyl derivative, is apparently inactive.2-5 Phenytoin exhibits dose-dependent metabolism and at higher serum concentrations small dosage changes can result in large serum concentration changes. Approximately 2-5% of the drug is excreted unchanged in the urine.2 In addition, concomitant medications may increase or decrease serum phenytoin levels.2,3,6 Monitoring serum phenytoin concentrations is recommended to guide dosage and avoid toxicity effects due to patient differences in the absorption, metabolism and clearance of phenytoin.2,3,6,7 |
|
Want more information ? Interested in the hidden information ? Click here and do your request. |