Abstract
A specific and sensitive radioimmunoassay for 4-OHA, a new anti-breast cancer agent, has been developed The assay uses a specific antisera to 4-OHA which can be used directly for the analysis of this drug in plasma samples. A series of chemical reactions were carried out to prepare suitable haptens for this purpose. The antibodies were raised against two immunogens; first, 4-OHT-17β-hemisuccinate-17-ovalbumin and second 4-OHA-7α-carboxy-ethyl-thioether-7-ov-albumin. The assay was successfully validated against a published 'indirect' RIA method for the measurement of 4-OHA. Pharmacokinetic studies on 4-OHA were carried out in two animal species, rat (male and female) and rabbit. These studies were designed firstly to assess the pharmacokinetic differences between male and female rats using the direct RIA and secondly to investigate plasma 4-OHA levels in male rats at various doses of the drug. The RIA of 4-OHA should prove useful in more extensive experimental and clinical studies of 4-OHA.