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Magnetic resonance spectroscopy of fluorine (19F) has been used to noninvasively study the in vivo pharmacokinetics of a model drug, fleroxacin (a fluoroquinolone antibiotic agent), in healthy human subjects. After oral administration, fleroxacin was detected in 19F magnetic resonance spectra from both liver and calf muscle and four magnetic resonance examinations were undertaken during a 24-hour period. By combining plasma analysis by high performance liquid chromatography with the magnetic resonance data, the following pharmacokinetic parameters (mean values) were obtained: tmax, 1.4, 4.6, and 5.6 hours in liver, plasma, and muscle, respectively; Cmax, 53, about 250, and about 60 mumol/L in plasma, liver, and muscle, respectively; t1/2, 4.4 hours (fast phase) and 10.8 hours (slow phase) in liver and 14.2 hours in plasma. The study documents for the first time the potential use of 19F magnetic resonance spectroscopy to noninvasively observe the time-related changes of a fluorine-containing drug in human tissues after oral administration.

The use of nuclear magnetic resonance (N M R) in cement and concrete research has been reviewed and the potential oj the technique Jor Juture research has been elucidated. The most important nuclei Jor cement and concrete research are IH, l3C, 27AI and 29Si, and representative examples are given Jor each oj them. N M R can be utilized to study the degree oj hydration, the reactivity of pozzolanic materials, clinker composition, interaction oJorganic admixtures with cement minerals, the different states oj-water in concrete, etc.

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