Radioimmunoassay for flupenthixol in plasma

Area of Science:

• Pharmacology
• Analytical Chemistry
• Clinical Chemistry

Background:

• Neuroleptic drug flupenthixol requires routine blood concentration monitoring.
• Existing methods may lack sensitivity or specificity for flupenthixol.
• Accurate quantification is essential for therapeutic drug monitoring.

Purpose of the Study:

• To develop and validate a radioimmunoassay (RIA) for flupenthixol.
• To enable routine monitoring of flupenthixol plasma concentrations.
• To assess the assay's performance characteristics.

Main Methods:

• Antibodies were generated against a 7-carboxyflupenthixol/ovalbumin conjugate.
• A radioimmunoassay using [3H] flupenthixol as the label was developed.
• Assay sensitivity, specificity, and cross-reactivity were evaluated.

Main Results:

• The RIA can detect 2.0 µg/L of flupenthixol in 100 µL plasma.
• The antiserum demonstrated no cross-reactivity with tricyclic drugs.
• Low interference was observed from major flupenthixol metabolites.
• Plasma concentrations were monitored after oral and intramuscular depot administration.

Conclusions:

• A sensitive and specific radioimmunoassay for flupenthixol has been established.
• This assay is suitable for routine therapeutic drug monitoring of flupenthixol.
• The method allows for tracking flupenthixol pharmacokinetics after different administration routes.