Capillary gas chromatography of trihexyphenidyl, procyclidine and cycrimine in biological fluids.

A sensitive (50-100 pg/ml) method is described for the analysis of the anticholinergic drugs cycrimine, procyclidine and trihexyphenidyl by capillary gas chromatography with flame thermionic detection. Since these anticholinergic drugs are frequently administered in combination with antipsychotic medication for the treatment of mental illness, the potential interference by antipsychotic drugs in this assay was examined. No interference was observed from a series of antipsychotic drugs in the quantitation of cycrimine, procyclidine or trihexyphenidyl. The use of this technique to study trihexyphenidyl pharmacokinetics in man is described.