METHOD: The effects of organic modifiers in mobile phase, protein precipitation agent to plasma sample ratio, and light on montelukast stability in unprocessed and processed human plasma, were evaluated. Validation was conducted in accordance with European Medicines Agency Guideline on bioanalytical method validation.
RESULTS: No interference peak was observed when acetonitrile was used as an organic modifier. Acetonitrile to plasma ratio of 4:1 produced clean plasma sample. Approximately 3 % of cis isomer was detected in unprocessed plasma samples while 21 % of cis isomer was detected in processed plasma samples after exposing to fluorescent light for 24h. The standard calibration curve was linear over 3.00-1200.00 ng/mL. All method validation parameters were within the acceptance criteria.
CONCLUSION: The validated method was successfully applied to a bioequivalence study of two montelukast formulations involving 24 healthy Malaysian volunteers. The light stability of a light sensitive drug in unprocessed and processed human plasma samples should be studied prior to pharmacokinetic/bioequivalence studies. Measures could then be taken to protect the analyte in human plasma from light degradation.
RESULTS: Analytes were gradiently separated on a C18 column and detected with a Sciex API 4000 MS/MS with an ESI source operated in the positive ion mode with deuterated PQ as internal standard. The response was linear in the range 3.9-2508nM with a runtime of 7.0min per sample. The method was applied to clinical samples from healthy volunteers.
CONCLUSION: This LC-MS/MS method for the simultaneous quantitation of PQ and two of its metabolites in plasma may prove helpful for assessment of metabolite safety issues in vivo.
METHODS: A total of 71 malaria microscopy positive blood samples collected in blood spots were obtained from the Sarawak State Health Department. Using 18s rRNA as the target gene, nested PCR and SYBR green I LAMP assay were performed following the DNA extraction. The colour changes of LAMP end products were observed by naked eyes.
RESULTS: LAMP assay demonstrated a detection limit of 10 copies/µL in comparison with 100 copies/µL nested PCR. Of 71 P. knowlesi blood samples collected, LAMP detected 69 microscopy-positive samples. LAMP exhibited higher sensitivity than nested PCR assay. The SYBR green I LAMP assay was 97.1% sensitive (95% CI 90.2-99.7%) and 100% specific (95% CI 83.2-100%). Without opening the cap, incorporation of SYBR green I into the inner cap of the tube enabled the direct visualization of results upon completion of amplification. The positives instantaneously turned green while the negatives remained orange.
CONCLUSIONS: These results indicate that SYBR green I LAMP assay is a convenient diagnosis tool for the detection of P. knowlesi in remote settings.