A new approach to drug intravenous compatibility research: the case of obstetric parenteral drugs.

OBJECTIVES: The product information and literature does not provide confirmation of compatibility for co-administration of all commonly used drug pairs in obstetrics. However, there is a need for co-administration of these drugs over one lumen for this group of patients. Therefore, this study focuses on Y-site compatibility. Since different conditions between clinical and laboratory settings can lead to discrepancies in results, a novel approach for drug intravenous compatibility testing was designed to reflect clinical conditions. The aim was to study the compatibility of nine commonly used drug pairs in obstetrics and to evaluate the clinical value of the designed method. METHODS: The clinical situation was reflected by using different temperature ranges (20°C and 37°C), actual Y-site flow ratios, clinically relevant drug pairs and an observation time of 120 min. The clinically relevant drugs pairs include atosiban, nicardipine, amoxicillin/clavulanic acid, oxytocin, remifentanil, labetalol and magnesium sulpfate. Drug pairs were visually assessed according to the European Pharmacopoeia (Ph. Eur.) and pH was measured. When incompatibility of a drug pair seemed likely based on literature review or observed abnormalities during visual assessment, subvisual analysis was performed using a particle counter. Y-site compatibility applied for drug pairs when no visual changes occurred or when no additional particles were formed during the observation time. RESULTS: Eight of the nine combinations showed no visual changes or noticeable changes in pH during the observation time. The amoxicillin/clavulanic-acid-oxytocin combination showed a colour change at 37°C at the actual Y-site flow ratio. However, subvisual particle counting showed no formation of additional particles. CONCLUSIONS: Y-site compatibility was established for all tested drug pairs. The new clinical approach for analysing Y-site compatibility provides a high certainty of outcomes for clinical practice. In this way, clinical complications and use of several additional intravenous catheters can be avoided.

Application of effect-directed analysis to identify mutagenic nitrogenous disinfection by-products of advanced oxidation drinking water treatment.

Advanced oxidation processes are important barriers for organic micropollutants in (drinking) water treatment. It is however known that medium pressure UV/H2O2 treatment may lead to mutagenicity in the Ames test, which is no longer present after granulated activated carbon (GAC) filtration. Many nitrogen-containing disinfection by-products (N-DBPs) result from the reaction of photolysis products of nitrate with (photolysis products of) natural organic material (NOM) during medium pressure UV treatment of water. Identification of the N-DBPs and the application of effect-directed analysis to combine chemical screening results with biological activity would provide more insight into the relation of specific N-DBPs with the observed mutagenicity and was the subject of this study. To this end, fractions of medium pressure UV-treated and untreated water extracts were prepared using preparative HPLC and tested using the Ames fluctuation test. In addition, high-resolution mass spectrometry was performed on all fractions to assess the presence of N-DBPs. Based on toxicity data and read across analysis, we could identify five N-DBPs that are potentially genotoxic and were present in relatively high concentrations in the fractions in which mutagenicity was observed. The results of this study offer opportunities to further evaluate the identity and potential health concern of N-DBPs formed during advanced oxidation UV drinking water treatment.

Active site substitution A82W improves the regioselectivity of steroid hydroxylation by cytochrome P450 BM3 mutants as rationalized by spin relaxation nuclear magnetic resonance studies.

Cytochrome P450 BM3 from Bacillus megaterium is a monooxygenase with great potential for biotechnological applications. In this paper, we present engineered drug-metabolizing P450 BM3 mutants as a novel tool for regioselective hydroxylation of steroids at position 16ß. In particular, we show that by replacing alanine at position 82 with a tryptophan in P450 BM3 mutants M01 and M11, the selectivity toward 16ß-hydroxylation for both testosterone and norethisterone was strongly increased. The A82W mutation led to a ≤42-fold increase in V(max) for 16ß-hydroxylation of these steroids. Moreover, this mutation improves the coupling efficiency of the enzyme, which might be explained by a more efficient exclusion of water from the active site. The substrate affinity for testosterone increased at least 9-fold in M11 with tryptophan at position 82. A change in the orientation of testosterone in the M11 A82W mutant as compared to the orientation in M11 was observed by T(1) paramagnetic relaxation nuclear magnetic resonance. Testosterone is oriented in M11 with both the A- and D-ring protons closest to the heme iron. Substituting alanine at position 82 with tryptophan results in increased A-ring proton-iron distances, consistent with the relative decrease in the level of A-ring hydroxylation at position 2ß.