Urine drug concentration analysis

Yoo and Porter [67] developed a sensitive immunoassay for the natural Podophyllum lignan, podophyllotoxin. Reverse-phase HPLC separation followed by radioimmunoassay (RIA) for human plasma samples and immunoaffinity extraction (IAE) followed by RIA for human urine samples were used to investigate a lignan-related hypocholesterolemic agent. This analysis proved to be very useful in quantifying extremely low drug concentrations in body fluids [68],... 

As with blood, urine analysis is used in clinical studies, and the relative concentrations of various ionic species are of great importance in both disease diagnostic and drug metabolism studies. For example, IC is used to determine urine oxalate concentrations. Urinary oxalate levels are an important parameter in urolithiasis research (kidney stones). Other anions that can be determined in urine using IC include phosphate, sulfate, bromide, citrate, nitrate, nitrite, and thiosulfate. As with blood and serum samples, both ultrafiltration and centrifugation are often used as sample cleanup steps. 

In biomedical analysis, LC-LC has been used most extensively and successfully in the heart-cut mode for the analysis of drugs and related compounds in matrices Such as plasma, serum or urine. Table 11.1 gives an overview of analytes in biological matrices which have been determined by heart-cut LC-LC systems. A typical example of such an approach is the work of Eklund et al. (16) who determined the free concentration of sameridine, an anaesthetic and analgesic drug, in blood plasma... 

The progress made in interfacingHPLC instruments with mass spectrometry has been a significant development for laboratory analyses in the pharmaceutical industry. The low concentrations of test drugs in extracts of blood, plasmas, serums, and urine are no problem for this highly sensitive HPLC detector. In addition, the analysis is extremely fast. Lots of samples with very low concentrations of the test drugs can thus be analyzed in a very short time. At the MDS Pharma Services facility in Lincoln, Nebraska, for example, a very busy pharmaceutical laboratory houses over 20 LC-MS units, and they are all in heavy use daily. 

Answer to Case C Two types of analysis would have been helpful. An analysis of blood would have been a better indicator of causality than a urine sample. If benzodiazepines were found in the blood, the type of benzodiazepine and its concentration would have helped establish whether or not the driver was impaired. An examination by a DRE might have revealed any drug-related physiological effects, and performance of field sobriety tests might have indicated impairment. 

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