General information:
Substance group: Antiepileptic drugs ATC: N03AB02
Trade names: Phenhydan®, Phenytoin*®
doses available: tablets 100 mg, solution for injection 250 mg
Reference ranges:
10 – 20 mg/L
Toxic Plasma levels: 25 mg/L
Sampling:
Material: Serum (Monovette brown) Minimum volume for analysis: 500µL
Recommendation: trough level (directly before the next intake)
Requirement (internal): … requirement (external):
Pharmacology:
Test principle: High-performance liquid chromatography with UV detection (HPLC-UV)
Liquid-liquid extraction with ether, chromatographic separation, absorption measurement
Analysis system: HPLC
Findings communication: on the day of submission, via LIMS
Pharmacokinetics:
T1⁄2 : 20 – 60 h
Tmax : 3 – 12 h
Bioavailability: 70 – 90%
Protein retention: 83 – 94%
Clearance: …
Excretion: urine >> Faeces
Metabolism: hepatic
Therapeutic range: 10 – 20 mg/L
toxic concentrations: > 25 mg/L
Distribution volume: 0.6 L/kg
Time to steady state: 5 – 10 days
Indication:
Level 1: TDM strongly recommended
TDM monthly after initial drugtherapy for three months, then every 6 months or more frequently in case of dose titration, suspected non-adherence, dose changes, altered comedication, adverse drug effects, intoxication, pregnancy, change in kidney function or simultaneous use of liver-enzyme inducing drugs.
DrugBank: https://go.drugbank.com/drugs/DB00252