Post-VX exposure treatment of rats with engineered phosphotriesterases

The biologically stable and highly toxic organophosphorus nerve agent (OP) VX poses a major health threat. Standard medical therapy, consisting of reactivators and competitive muscarinic receptor antagonists, is insufficient. Recently, two engineered mutants of the Brevundimonas diminuta phosphotriesterase (PTE) with enhanced catalytic efficiency (kcat/KM = 21 to 38 × 106 M−1 min−1) towards VX and a preferential hydrolysis of the more toxic P(−) enantiomer were described: PTE-C23(R152E)-PAS(100)-10-2-C3(I106A/C59V/C227V/E71K)-PAS(200) (PTE-2), a single-chain bispecific enzyme with a PAS linker and tag having enlarged substrate spectrum, and 10-2-C3(C59V/C227V)-PAS(200) (PTE-3), a stabilized homodimeric enzyme with a double PASylation tag (PAS-tag) to reduce plasma clearance. To assess in vivo efficacy, these engineered enzymes were tested in an anesthetized rat model post-VX exposure (~ 2LD50) in comparison with the recombinant wild-type PTE (PTE-1), dosed at 1.0 mg kg−1 i.v.: PTE-2 dosed at 1.3 mg kg−1 i.v. (PTE-2.1) and 2.6 mg kg−1 i.v. (PTE-2.2) and PTE-3 at 1.4 mg kg−1 i.v. Injection of the mutants PTE-2.2 and PTE-3, 5 min after s.c. VX exposure, ensured survival and prevented severe signs of a cholinergic crisis. Inhibition of erythrocyte acetylcholinesterase (AChE) could not be prevented. However, medulla oblongata and diaphragm AChE activity was partially preserved. All animals treated with the wild-type enzyme, PTE-1, showed severe cholinergic signs and died during the observation period of 180 min. PTE-2.1 resulted in the survival of all animals, yet accompanied by severe signs of OP poisoning. This study demonstrates for the first time efficient detoxification in vivo achieved with low doses of heterodimeric PTE-2 as well as PTE-3 and indicates the suitability of these engineered enzymes for the development of highly effective catalytic scavengers directed against VX.

Pharmacotherapeutic strategy for COPD patients: focus on dual bronchodilators

For two decades, the GOLD Initiative has consistently identified the use of bronchodilators as a priority in the pharmacotherapeutic strategy for COPD. The authors of international and national clinical guidelines consider fixed combinations of long-acting beta2-agonists (LABAs) and long-acting muscarinic receptor antagonists (LAMAs) as “first-line” drugs in most patients with COPD. Numerous clinical studies have shown that fixed LABAs/LAMAs combinations provide optimal bronchodilation and play a paramount role in preventing exacerbations of COPD. Outperforming placebo and active controls, LABAs, LAMAs, inhaled glucocorticosteroids (ICS)/LABAs combination bronchodilators may differ in their therapeutic potential. The available evidence base currently does not allow to make an unambiguous choice in favor of one or another fixed LABAs/ LAMAs combination. With the appearance of “triple” combinations (ICS/LABAs/LAMAs) on the pharmaceutical market, the issue of their comparison with “dual” bronchodilators has become particularly acute. Currently available data suggest that the use of “triple” therapy is not considered as a starting treatment option for COPD and is appropriate only in a subgroup of patients with a higher baseline risk of exacerbations: in the presence of a history of exacerbations ≥ 1, which required prescription of systemic antibiotics and/or glucocorticosteroids, or necessitated hospitalization during the previous year. Thus, ICS-containing therapy is justified only in cases of recurrent exacerbations of moderate COPD or single episodes of severe exacerbations, despite the continued administration of LABAs/LAMAs, as well as in certain categories of patients whose inflammatory profile suggests a “response” to ICS.

19 Nebulized Tobramycin is Associated with Decreased Pneumonia After Inhalation Injury

Introduction Management of inhalation injury is largely supportive and consists primarily of mechanical ventilation, bronchodilators, muscarinic receptor antagonists, and inhaled mucolytics and anticoagulants. Patients with inhalation injury are at high risk for pneumonia. Nebulized tobramycin is well supported in the use of chronic lung infections in patients with cystic fibrosis (CF). We hypothesize that after inhalation injury patients empirically treated with nebulized tobramycin (NT) have decreased incidence of pneumonia. Methods A protocol for a standardized 7-day course of nebulized treatments with bronchodilators, inhaled mucolytics combined with inhaled anticoagulants and Nebulized tobramycin was developed. Starting in May 2013, all patients that had a clinical diagnosis of inhalation documented by the attending physician were started on the 7-day treatment course. Patients with inhalation injury from 2009–2019 were retrospectively reviewed for treatment of inhalation injury. Univariate analysis and multiple logistic regression were performed using Stata. Results Of 90 patients with inhalation injury, median age was 52 (IQR:31–60) with 27% (n=23) women and median TBSA of 10%(IQR:0.7–35%). The median length of stay was 21 days (IQR:6–47). Median ventilator days were lower in patients treated with NT (8.5, IQR:4–21) compared to patients that did not receive NT (10, IQR:3–23) but was not significant (p=0.85). However, of those that received NT, the presence of pneumonia was significantly lower compared to patients not treated with NT (p=0.032). (Table 1) Patients who were not treated with NT developed pneumonia earlier (day 5, IQR:3–7) than patients treated with NT (day 10, IQR 6–16, p=0.02) After adjusting for grade of inhalation injury, patients who did not receive NT were 2.7 times as likely to get pneumonia compared to patients who received NT (p=0.037). Conclusions NT is a prophylactic strategy for pneumonia in patients with CF, well documented to be safe. It allows for concentrated antibacterial coverage localized to the area of infection without significant systemic absorption. After seeing ~60% incidence of pneumonia in inhalation patients, we developed a strategy that avoided systemic prophylactic treatment. Initial data shows empiric administration of NT in patients with inhalation injury may abrogate the development pneumonia. Additional research and clinical trials are needed to better understand the role of inhaled tobramycin in the management of inhalation injury.

Effectiveness of tolterodine in relief of postoperative symptoms related to urethral catheter in transurethral prostate resection patients: a prospective randomized trial

Background: Urethral catheterisation following surgery causes significant discomfort postoperatively. Use of muscarinic receptor antagonists for relief of these symptoms in transurethral prostate resection (TURP) patients has been studied previously. In this study it is aimed to identify efficacy of toltoredine for relief of bladder overactivity symptoms in the post-operative period following TURP.Methods: In this randomized, prospective, controlled study, results of 95 patients evaluated. Group 1(n=49) received tolterodine 4 mg/day and group 2 (n=45) received no medication. Presence and severity of symptoms together with visual pain scale (VPS) scores were recorded and compared in very early and late postoperative period (0, 4, 8, 12, 24 hours and every 24 hours thereafter). Additional analgesic requirement was also compared and adverse events were recorded.Results: Tolerodine treatment was shown to be associated with low incidence and less severity of symptoms. Symptoms were shown to be present especially in the early postoperative period. VPS scores were also shown to be less in group 1. Treatment was not cessated in any of the patients due to adverse events. Conclusions: Tolterodine 4 mg/day was shown to be effective in relief of symptoms related to urethral catheterisation in the postoperative period following TURP. Treatment was not cessated in any of the patients due to adverse events. Further prospective placebo-controlled studies are needed with tolterodine and other muscarinic receptor antagonists.