Radioimmunoassay drug testing

The flow of pancreatic juice and bile was tested before and after the experiment by means of an intravenous bolus of 5 pmol/kg secretin. Before the experiment the duodenum was continuously perfused at a rate of 2 ml/min for 435 min with isotonic saline containing phenol red (10 mg/1) as a marker. After drug treatment (intravenous infusion of gastrin-releasing peptide or duodenal HC1 perfusion) pancreatic and hepatic secretions were collected in 15-min periods and the volumes determined by weighing. Duodenal effluents were collected in 15-min periods and phenol red concentrations determined spectrophotometrically. Blood sampled were withdrawn for determination of secretin by radioimmunoassay. 

Immunoassay is an application of the substoichiometric principle ( 9.3.4) developed by Yalow (Nobel laureate in 1977) for protein analysis. In the United States tens of millions radioimmunoassays are made annually in hospitals to measure hormones, enzymes, viruses, serum proteins, drugs, and so forth. Only a drop of the patient s blood is needed, reflecting the versatility and smisitivity of this technique, which can be performed automatically. Commercial RAST-kits (Radio Allergy Sorbent Tests) are used for rapid diagnosis of allergic reactions. 

ECG effects T wave diminished in amplitude or inverted, P-R interval prolonged, Q-T interval shortened. Tests for serum digoxin levels may be altered by electrolyte imbalance, renal impairment, age, thyroid disease, other drugs, or substances in the body which imitate digoxin in radioimmunoassay. 

In the present study the technique of GC-MS has been used as a means of identifying the anabolic drug in samples which have given a positive response to the radioimmunoassay test. These studies have necessitated (2) an investigation into the metabolism of the anabolic steroids most likely to be used in sport, and to establish the most specific and sensitive means of applying GC-MS methods. It has been important to retain in the method the capability of identifying metabolites of previously unencountered drugs. 

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