| Abstrakt: |
Progress in the development of radioimmunoassay techniques for reserpine and related compounds is reported. A conjugate of reserpine with human serum albumin was prepared, involving linkage at the indole nitrogen atom of reserpine. Injection of the purified conjugate into sheep elicited antibodies of high titer, which bound reserpine selectively. Tritiated reserpine was employed in the procedure, and dextran-coated charcoal was utilized to separate free and bound forms of the drug. Antibodies exhibited a selectivity for reserpine and did not cross-react significantly with major human metabolites. Cross-reactivity of antibodies with other reserpine derivatives (i.e., syrosingopine, deserpidine, and rescinnamine) also was investigated. A stable tritiated or radioiodinated reserpine derivative of high specific activity is being sought to improve assay sensitivity for use in bioequivalence and bio-availability studies. In the absence of any extraction or concentration procedures, at least a 10-fold increase in immunoassay sensitivity would lie required to follow reserpine levels in humans given normal doses of the drug. The methods show promise also for the assay of reserpine derivatives such as deserpidine, which exhibits cross-reactivity to reserpine antibodies. |
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