Evaluation of UGT1A1 and CYP3A Genotyping and Single-Point Irinotecan and Metabolite Concentrations as Predictors of the Occurrence of Adverse Events in Cancer Treatment.

PURPOSE: The variability on irinotecan (IRI) pharmacokinetics and toxicity has been attributed mostly to genetic variations in the UGT1A1 gene, responsible for conjugation of the active metabolite SN-38. Also, CYP3A mediates the formation of inactive oxidative metabolites of IRI. The association between the occurrence of severe adverse events, pharmacokinetics parameters, and UGT1A1 and CYP3A4 predicted phenotypes was evaluated, as the evaluation of [SN-38]/IRI dose ratio as predictor of severe adverse events. METHODS: Forty-one patients undergoing IRI therapy were enrolled in the study. Blood samples were collected 15 min after the end of drug the infusion, for IRI, SN-38, SN-38G, bilirubin concentrations measurements, and UGT1A1 and CYP3A genotype estimation. Data on adverse event was reported. RESULTS: Fifteen patients (36.5%) developed grade 3/4 adverse events. A total of 9.8% (n = 4) of the patients had UGT1A1 reduced activity phenotype, and 48.7% (n = 20) had UGT1A1 and 63.4% (n = 26) CYP3A intermediary phenotypes. Severe neutropenia and diarrhea were more prevalent in patients with reduced UGT1A1 in comparison with functional metabolism (50% and 75% versus 0% and 13%, respectively). SN-38 levels and its concentrations adjusted by IRI dose were significantly correlated to toxicity (rs = 0.31 (p = 0.05) and rs = 0.425 (p < 0.01)). The [SN-38]/IRI dose ratio had a ROC curve of 0.823 (95% CI 0.69-0.956) to detect any severe adverse event and 0.833 (95% CI 0.694-0.973) to detect severe diarrhea. The cut-off of 0.075 ng mL-1 mg-1 had 100% sensitivity and 65.7% specificity to predict severe diarrhea. CONCLUSION: Our data confirmed the relevance of the pre-emptive genotypic information of UGT1A1. The [SN-38]/IRI ratio, measured 15 min after the end of the IRI infusion, was a strong predictor of severe toxicity and could be applied to minimize the burden of patients after IRI administration.

Sensitive determination of 11-nor-9-carboxy-Δ9-tetrahydrocannabinol and complementary cannabinoids in hair using alkaline digestion and mixed-mode solid phase extraction followed by liquid-chromatography-tandem mass spectrometry.

Hair drug testing can be used for the evaluation of cannabis use with a large detection window, and is required for professional driving license granting in Brazil. A positive hair result for cannabis use requires quantification of the metabolite THC-COOH above the cutoff value of 0.2 ng/g. The achievement of such lower limit of quantification is challenging, particularly with the use of liquid chromatography coupled to triple quadrupole mass spectrometers (LC-MS/MS). In this study, a very sensitive LCMS/ MS assay for the simultaneous quantification of THC-COOH along with THC, CBD, and CBN was developed and validated. Sample preparation was based on hair hydrolysis, followed by selective ion-exchange solid-phase extraction. The extraction yield was 101.5-101.6% for THC-COOH, 92.3-97.4% for THC, 89.7-95.2% for CBN, and 104.9-121.1% for CBD. Internal standard corrected matrix effects were - 2.7 to - 1,1 for THCCOOH and - 11.5 to - 0.1% for the other analytes. The lower limit of quantification was 01 ng/g for THC-COOH and 25 ng/g for THC, CBD, and CBN. The assay fulfilled validation guidelines acceptance criteria. The measurement uncertainties were determined and the assay was ISO17025 accredited, being currently used in routine testing.

Simple determination of valproic acid serum concentrations using BioSPME followed by gas chromatography-mass spectrometric analysis.

Valproic acid (VA) is a drug widely used on the treatment of epilepsy and bipolar affective disorders, with stablished therapeutic concentration ranges in serum. The measurement of VA serum concentrations using chromatographic methods requires a sample preparation step. In this context, this study aims to describe the development and validation of an assay for VA measurement in serum using a new microextraction strategy, known as BioSPME, followed by GC-MS analysis. The extraction procedure was very simple based on direct immersion of the BioSPME tips on acidified serum, followed by agitation and desorption in methanol. The methanolic extracts were directly injected into the chromatograph. Extraction yield was 95.6 to 101.3%. The assay was linear from 10 to 150 mg L-1. Precision, accuracy and stability assays were acceptable according to bioanalytical validation guidelines. The method was applied to 41 clinical serum samples also tested with a previously GC-MS validated assay, which used liquid-liquid extraction as sample preparation. Measurements obtained with both methods were comparable. This study is the first description of the use of BioSPME tips for a therapeutic drug. BioSPME is a promising alternative for the preparation of biological specimens prior to the determination of therapeutic drugs by GC-MS.