Development and validation of a fast and sensitive UHPLC-DAD assay for the quantification of nitrofurantoin in plasma and urine.

Nitrofurantoin is an antimicrobial drug that has been used in the treatment of lower urinary tract infections for more than 50 years. Despite its long use, surprisingly little is known of the pharmacokinetics of nitrofurantoin, whereas this is essential to optimize patient treatment. We developed a novel analytical method for the quantification of nitrofurantoin in plasma and urine using ultra-high performance liquid chromatography and diode array detection to allow pharmacokinetic studies in these two matrices.

Dried Blood Spot Sampling for Tacrolimus and Mycophenolic Acid in Children: Analytical and Clinical Validation.

Background: Tacrolimus and mycophenolic acid (MPA) are the backbone of immunosuppressive therapy after pediatric kidney transplantation. Dosing of these drugs is individualized by therapeutic drug monitoring. Dried blood spot (DBS) sampling may prove beneficial over conventional venous sampling.

Delayed trough level measurement with the use of prolonged-release tacrolimus.

Trough concentrations of prolonged-release tacrolimus are usually measured at 24 h after taking the drug in the morning. It is impractical to measure these trough concentrations in patients who visit the outpatient clinic in the afternoon. Trough concentrations obtained in the afternoon may also be suitable for estimating the 24-h exposure.

Effect of mild diarrhea on tacrolimus exposure.

Background: Diarrhea is a frequent adverse event in patients treated with the combination of tacrolimus and mycophenolate mofetil (MMF). In case of severe diarrhea, the total exposure to tacrolimus can substantially increase, which is reflected in a rise of the predose trough level (C0). In mild diarrhea (two to three stools per day), an increased exposure might occur without trough levels exceeding the target range, resulting in "silent" chronic tacrolimus overexposure.