Search

Background: Methadone is effective for the treatment of chronic pain, but its unique pharmacology requires additional considerations with dosing and monitoring. Objective: The study objective was to evaluate methadone prescribing for pain and subsequent monitoring. Methods: This retrospective chart review at a single center reviewed patients who received methadone over a two-year period. Results: Of the 100 patients, most were noncancer cases (60%) with unspecified pain (50%). The majority of methadone treatments were initiated by medicine service (37%), followed by burn service (27%), and trauma (10%). Forty-two percent of the patients were being followed by the palliative care team, primarily for the medicine patients (80%). Patients on the burn service had significantly higher oral morphine equivalent ( χ2 = 10.6, p = 0.01) and longest length of stay ( χ2 = 37.9, p = 0.0001). Patients on medicine service were significantly more likely to have an outpatient discharge plan for methadone starts in the hospital (odds ratio = 3.7, confidence interval: 1.4, 9.7). Only 45% of patients had an electrocardiogram (EKG) checked seven days before methadone start and 37% of those have a measured corrected QT (QTc) of greater than 450 milliseconds. Electrolytes (potassium and magnesium) were not consistently checked and, of those that were evaluated, 15-20% were abnormal. There was an average of 2.6 severe or major drug interactions per patient related to methadone, with the most common being related to concomitant sedatives and other medications that prolonged the QTc. Conclusions: Prescribing guidelines for methadone would provide a consistent approach for all practitioners involved in using methadone safely and effectively for chronic pain. [ABSTRACT FROM AUTHOR]

Summary: Selective protein-protein interactions between nonribosomal peptide synthetase (NRPS) proteins, governed by communication-mediating (COM) domains, are responsible for proper translocation of biosynthetic intermediates to produce the natural product. In this study, we developed a crosslinking assay, utilizing bioorthogonal probes compatible with carrier protein modification, for probing the protein interactions between COM domains of NRPS enzymes. Employing the Huisgen 1,3-dipolar cycloaddition of azides and alkynes, we examined crosslinking of cognate NRPS modules within the tyrocidine pathway and demonstrated the sensitivity of our panel of crosslinking probes toward the selective protein interactions of compatible COM domains. These studies indicate that copper-free crosslinking substrates uniquely offer a diagnostic probe for protein-protein interactions. Likewise, these crosslinking probes serve as ideal chemical tools for structural studies between NRPS modules where functional assays are lacking. [Copyright &y& Elsevier]

Many pharmaceuticals on the market today belong to a large class of natural products called nonribosomal peptides (NRPs). Originating from bacteria and fungi, these peptide-based natural products consist not only of the 20 canonical L-amino acids, but also non-proteinogenic amino acids, heterocyclic rings, sugars, and fatty acids, generating tremendous chemical diversity. As a result, these secondary metabolites exhibit a broad array of bioactivity, ranging from antimicrobial to anticancer. The biosynthesis of these complex compounds is carried out by large multimodular megaenzymes called nonribosomal peptide synthetases (NRPSs). Each module is responsible for incorporation of a monomeric unit into the natural product peptide and is composed of individual domains that perform different catalytic reactions. Biochemical and bioinformatic investigations of these enzymes have uncovered the key principles of NRP synthesis, expanding the pharmaceutical potential of their enzymatic processes. Progress has been made in the manipulation of this biosynthetic machinery to develop new chemoenzymatic approaches for synthesizing novel pharmaceutical agents with increased potency. This review focuses on the recent discoveries and breakthroughs in the structural elucidation, molecular mechanism, and chemical biology underlying the discrete domains within NRPSs.

A panel of chimeric carrier proteins was developed and screened for functional activity with essential enzymes involved in carrier protein-mediated biosynthesis. Regions on either side of the recognition helix II within three carrier proteins (CPs) from distinct biosynthetic pathways were swapped in all combinations to generate 24 mutated CPs. This panel of chimeric carrier proteins was tested using two previously established and one novel carrier protein assays. The results suggest a significant contribution from multiple structural units within carrier protein structure, rather than universal recognition helix, is necessary for proper recognition and activity with partner enzymes.