Full details for "Phenytoin ". | |
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Name |
Phenytoin |
Alternative name/Profile |
Epanutin |
Department |
Biochemistry |
Investigation |
Therapeutic drug monitoring for indications of : Toxicity ; Inadequate therapeutic response: Assessment of patient compliance with a medication regimen; Assess therapy following initiation or a change in dosage regimen. |
Specimen type |
Serum |
Sample type |
|
Sample container & volume |
5ml - Red Tube |
Frequency of analysis |
Daily |
Turnaround time |
1 working days |
Availability |
|
Notes |
Time to Steady State is variable (2 - 4 weeks). Concentrations should be checked several days after starting the drug (to ensure levels are within therapeutic range and are not toxic) and after 2-4 weeks to verify that the concentration is not continuing to increase slowly. If loaded, a sample should be taken 2 - 4 hours post IV loading dose. Ideal Sample Time; Trough or predose samples are the most appropriate to use, however this is not critical. |
Related links |
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Reference range |
Phenytoin Therapeutic Range : 20 - 80 µmol/L Toxic Concentrations : The initial symptoms of toxicity can include nystagmus, ataxia and dysarthria. The risk of toxicity increases at concentrations above 80µmol/L and toxicity occurs particularly at concentratons greater than 100µmol/L ; however some patients can tolerate a plasma phenytoin concentration in excess of 100µmol/L. A plasma concentration below 80µmol/L does not exclude the possibility of toxicity, and if there is good clinical reason for suspecting toxicity then reducing the dosage should be tried. Results should always be interpreted in conjunction with the patient's medical history, clinical presentation and other findings. |
Last updated |
Wed, 16 Jun 2021 12:05:51 IST |