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Phenytoin assay

Product Method Size Catalog Price Quantity
Phenytoin assay LEI R1 2 x17ml, R2 2 x 6ml TD3409 $772.22
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  • Format
    Liquid ready to use
  • Assay Range
    2.9 - 44.5ug/ml
  • Working Stability 15-25 °C
  • Working Stability 2-8 °C
    Stable to expiry
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Intended Use

For the quantitative in vitro determination of Phenytoin in human serum. This product is suitable for use on the RX Series instruments which includes the Rx Daytona and Rx Imola.

Clinical Significance

It is essential to maintain a constant concentration of medication in order for treatment to be successful, insufficient levels can mean drugs are not effective and excessive levels in some cases can lead to toxicity.

Often there is little difference between the dosage required for effective treatment and the dosage needed to cause severe side effects and even toxicity. The fact that individuals absorb, metabolize and make use of drugs at different rates means a standard dose cannot be prescribed for everyone. It is therefore extremely important to monitor the use of drugs with a narrow therapeutic range to ensure individuals are receiving the optimum treatment.

Phenytoin is an antiepileptic drug used for the control of generalised motor (grand mal; tonic-clonic) and focal motor seizures. The range of serum concentrations at which Phenytoin toxicity occurs is broad. Toxic effects, such as nystagums and dystaxia may occur at concentrations above 20 ug/ml, ataxia and disorders of eye movements occur at above 30 ug/ml.


Randox Phenytoin assay is a latex-enhanced immunoturbidimetric assay. It is based on the principle of measuring changes in scattered light. The Latex particles are coated with Phenytoin which, in the presence of Phenytoin antibody solution, rapidly agglutinate.

When a sample containing Phenytoin is introduced, the agglutination reaction is partially inhibited, slowing down the agglutination process. The rate of agglutination is inversely dependent upon the concentration of Phenytoin in the sample. By monitoring the change in scattered light, as a change in absorbance, a concentration curve can be obtained. The actual change in absorbance is inversely proportional to the concentration of Phenytoin in the sample.

This assay uses an end point method and multipoint calibration.

Available Applications

  • Various