Evidence is accumulating that a non-GH dependent insulin-like growth factor-binding protein (IGF-BP) is not only a carrier protein but also has an active role in the growth process. We have measured levels of this IGF-BP, using a specific RIA, over 12 or 24-h periods in 11 adolescents with diabetes mellitus and five normal adults. In each of the normal the IGF-BP was undetectable for most of the day but with a broad nocturnal peak observed, with levels up to 50 micrograms/l. The levels of IGF-BP were unrelated to the secretory pattern for GH but correlated inversely with the concentration of circulating insulin. In the diabetics a very similar pattern was observed, but with detectable levels throughout the day and much higher peak levels seen at night. Peak levels were up to 120 micrograms/l if a long-acting insulin preparation was administered in the evening but were 400-500 micrograms/l if the long-acting preparation was administered in the morning. The IGF-BP was strongly correlated with plasma glucose in this latter group. In a further group of diabetics overnight profiles were obtained on two separate nights, a normal night and a night with euglycaemia maintained with a glucose clamp technique. Euglycaemia failed to affect peak levels of the binding protein, although the shape of the nocturnal peak was altered consistent with the altered pattern of circulating free insulin. In this group a strong inverse correlation was obtained between the IGF-BP and free insulin levels.(ABSTRACT TRUNCATED AT 250 WORDS)

A high throughput mass spectrometry based method is described for the determination of the 5-HT receptor agonist 31100, and its desmethyl metabolite, in human plasma. Samples were extracted using the MicroLutem system of solid phase extraction in the '96 well' format, automated by means of a robotic sample processor. The extracts were analysed by liquid chromatography tandem mass spectrometry (LC/MS/MS) with thermally assisted electrospray ionization (TbrboIonSpray) and selected-reaction monitoring. The LCIMSNS method offers increased sensitivity, selectivity and speed of analysis over an existing high performance liquid chromotographic method using fluorescence detection.Migraine, characterized by a throbbing headache which is usually unilateral and often associated with nausea, vomiting, photophobia and phonophobia, is a debilitating and recurrent disease affecting approximately 9-1696 of the population of the western world.' The neurotransmitter and vasoac tive monoamine 5 -h y drox y tryptamine (5 -HT) , which is widely distributed within both the central nervous system and the periphery, has been identified as having a central role in the pathophysiology of migraine' although its precise pathogenic role remains undefined. The compound 3 11C90 This combination of high potency and an ability to act at central as well as peripheral elements of the trigemino-vascular system may offer a superior antimigraine profile compared to existing oral therapies.The clinical development of 311C90 was initially supported by a high performance liquid chromatographic (HPLC) method with fluorescence detection (FLD). Using a Zorbax TMS column with a run time of approximately 25 min, the solid phase extraction (SPE) of plasma samples was well suited to automation in a sequential 'on-line' mode using a Gilson (Anachem, Luton, UK) ASPEC system. The HPLC-FLD method provided a lower limit of quantitation (LLOQ) of 2 ng/mL for 311C90 and its metabolites. As the clinical development progressed however, it became apparent that pharmacokinetic data would be necessary at oral doses lower than 5mg, and therefore a more sensitive method was required.As for many other pharmacokinetic applications, this increase in sensitivity has been achieved by the use of combined liquid chromatography tandem mass spectrometry (LC/MS/MS). Initially, atmospheric pressure chemical ionisation (APCI) was used to gain a 10-fold increase in sensitivity, providing an LLOQ for both 311C90 and 183C91 of 0.2 ng/mL? Unfortunately, the cycle times of automated sample preparation systems have historically

Sensitive, mass spectrometry based bioanalytical methods are described for the determination of the R- and S-enantiomers of the beta-agonist salbutamol (albuterol) and its 4-O-sulphate metabolite in human plasma and urine. In both methods samples are prepared by 96 well format solid phase extraction using a custom built robotic system. Extracts are then analysed by liquid chromatography tandem mass spectrometry (LC-MS/MS) using a teicoplanin-based chiral stationary phase and selected reaction monitoring. The methods are accurate (bias < +/- 10%), precise (%CV < 11%) and sensitive, providing lower limits of quantitation (LLoQ) in plasma of 100 pg/mL and 5 ng/mL for the enantiomers of salbutamol and its 4-O-sulphate metabolite, respectively. By restricting the chiral method for plasma to the enantiomers of salbutamol only, it was possible to revalidate at an improved LLoQ of 25 pg/mL. A high throughout LC-MS/MS method has also been developed for racemic salbutamol only, which uses a similar extraction procedure but a conventional C8 column. The method has a reduced analysis time of three minutes per sample and using a high sensitivity, triple quadrupole mass spectrometer provides an LLoQ of 5 pg/mL based on extraction of 0.5 mL of plasma.

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