In vitro and in vivo stability of a highly efficient long-acting cocaine hydrolase.

It is recognized as a promising therapeutic strategy for cocaine use disorder to develop an efficient enzyme which can rapidly convert cocaine to physiologically inactive metabolites. We have designed and discovered a series of highly efficient cocaine hydrolases, including CocH5-Fc(M6) which is the currently known as the most efficient cocaine hydrolase with both the highest catalytic activity against (-)-cocaine and the longest biological half-life in rats. In the present study, we characterized the time courses of protein appearance, pH, structural integrity, and catalytic activity against cocaine in vitro and in vivo of a CocH5-Fc(M6) bulk drug substance produced in a bioreactor for its in vitro and in vivo stability after long-time storage under various temperatures (- 80, - 20, 4, 25, or 37 °C). Specifically, all the tested properties of the CocH5-Fc(M6) protein did not significantly change after the protein was stored at any of four temperatures including - 80, - 20, 4, and 25 °C for ~ 18 months. In comparison, at 37 °C, the protein was less stable, with a half-life of ~ 82 days for cocaine hydrolysis activity. Additionally, the in vivo studies further confirmed the linear elimination PK profile of CocH5-Fc(M6) with an elimination half-life of ~ 9 days. All the in vitro and in vivo data on the efficacy and stability of CocH5-Fc(M6) have consistently demonstrated that CocH5-Fc(M6) has the desired in vitro and in vivo stability as a promising therapeutic candidate for treatment of cocaine use disorder.

The αSynuclein half-life conundrum.

αSynuclein (αSyn) misfolding and aggregation frequently precedes neuronal loss associated with Parkinson's Disease (PD) and other Synucleinopathies. The progressive buildup of pathological αSyn species results from alterations on αSyn gene and protein sequence, increased local concentrations, variations in αSyn interactome and protein network. Therefore, under physiological conditions, it is mandatory to regulate αSyn proteostasis as an equilibrium among synthesis, trafficking, degradation and extracellular release. In this frame, a crucial parameter is protein half-life. It provides indications of the turnover of a specific protein and depends on mRNA synthesis and translation regulation, subcellular localization, function and clearance by the designated degradative pathways. For αSyn, the molecular mechanisms regulating its proteostasis in neurons have been extensively investigated in various cellular models, either using biochemical or imaging approaches. Nevertheless, a converging estimate of αSyn half-life has not emerged yet. Here, we discuss the challenges in studying αSyn proteostasis under physiological and pathological conditions, the advantages and disadvantages of the experimental strategies proposed so far, and the relevance of determining αSyn half-life from a translational perspective.

Moss-produced human complement factor H with modified glycans has an extended half-life and improved biological activity.

Most drugs that target the complement system are designed to inhibit the complement pathway at either the proximal or terminal levels. The use of a natural complement regulator such as factor H (FH) could provide a superior treatment option by restoring the balance of an overactive complement system while preserving its normal physiological functions. Until now, the systemic treatment of complement-associated disorders with FH has been deemed unfeasible, primarily due to high production costs, risks related to FH purified from donors' blood, and the challenging expression of recombinant FH in different host systems. We recently demonstrated that a moss-based expression system can produce high yields of properly folded, fully functional, recombinant FH. However, the half-life of the initial variant (CPV-101) was relatively short. Here we show that the same polypeptide with modified glycosylation (CPV-104) achieves a pharmacokinetic profile comparable to that of native FH derived from human serum. The treatment of FH-deficient mice with CPV-104 significantly improved important efficacy parameters such as the normalization of serum C3 levels and the rapid degradation of C3 deposits in the kidney compared to treatment with CPV-101. Furthermore, CPV-104 showed comparable functionality to serum-derived FH in vitro, as well as similar performance in ex vivo assays involving samples from patients with atypical hemolytic uremic syndrome, C3 glomerulopathy and paroxysomal nocturnal hematuria. CPV-104 - the human FH analog expressed in moss - will therefore allow the treatment of complement-associated human diseases by rebalancing instead of inhibiting the complement cascade.

Long-Acting Strategies for Antibody Drugs: Structural Modification, Controlling Release, and Changing the Administration Route.

Because of their high specificity, high affinity, and targeting, antibody drugs have been widely used in the treatment of many diseases and have become the most favored new drugs for research in the world. However, some antibody drugs (such as small-molecule antibody fragments) have a short half-life and need to be administered frequently, and are often associated with injection-site reactions and local toxicities during use. Increasing attention has been paid to the development of antibody drugs that are long-acting and have fewer side effects. This paper reviews existing strategies to achieve long-acting antibody drugs, including modification of the drug structure, the application of drug delivery systems, and changing their administration route. Among these, microspheres have been studied extensively regarding their excellent tolerance at the injection site, controllable loading and release of drugs, and good material safety. Subcutaneous injection is favored by most patients because it can be quickly self-administered. Subcutaneous injection of microspheres is expected to become the focus of developing long-lasting antibody drug strategies in the near future.

Pharmacokinetics of bromoform in dairy heifers.

AIMS: To determine the pharmacokinetics in dairy heifers after oral and IV administration of bromoform, a potential antimethanogenic agent found in red seaweed, Asparagopsis spp. METHODS: Twenty-four dairy heifers with a mean weight of 319 (SD 36.9) kg were used. The study was conducted in two phases, and each cohort of 12 heifers received an escalating dose of bromoform. In the first phase, 12 heifers successively received doses of 200, 400, 800, and 1600 mg of bromoform orally, separated by a 72-hour washout period. In the second phase, a different cohort of 12 dairy heifers was used. Each heifer received a total of four doses of bromoform separated by a wash-out period of 72 hours. Sequentially the treatments were (for each of the 12 heifers) an oral dose of 50 mg, followed by an IV dose of 50 mg, followed by an oral dose of 100 mg and finally an IV dose of 100 mg.Blood samples were assayed by gas chromatography-mass spectrophotometry for bromoform and dibromomethane to estimate the pharmacokinetic parameters using a non-compartmental analysis. RESULTS: Bromoform was rapidly absorbed as indicated by a short time to the maximum observed concentration of 15 minutes. For the routes of administration and dose ranges investigated, the mean terminal half-life ranged from 0.32 (SE 0.03) hours to 5.73 (SE 1.64) hours when administered orally or IV. With values for the mean area under the curve (AUC) to dose ratio ranging from 0.25 (SE 0.04) to 0.82 (SE 0.19) for oral and 1.39 (SE 0.39) to 4.02 (SE 0.37) for IV administration, bromoform appeared to exhibit non-proportional pharmacokinetic behaviour. The mean absolute bioavailability was 39.13 (SE 10.4)% and 3.36 (SE 0.83)% for 50-mg and 100-mg doses, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Bromoform is rapidly absorbed and exhibits dose dependent elimination kinetics.

A crossover study to evaluate the pharmacokinetics and bioequivalence of hydroxychloroquine tablets in healthy Chinese subjects.

AIMS: Hydroxychloroquine (HCQ) has a high variability and a long half-life in the human body. The purpose of this study was to evaluate the bioequivalence of a generic HCQ tablet (test preparation) versus a brand HCQ tablet (reference preparation) under fasting and fed conditions in a crossover design. MATERIALS AND METHODS: This was an open-label, two-period randomized, single-dose, crossover study in 47 healthy Chinese subjects who were sequentially and randomly allocated either to the fed group (high-fat meal; n = 23) or the fasting group (n = 24). Participants in each group were randomized to the two arms to receive either a single 200-mg dose of the test preparation or a 200-mg dose of the reference preparation. The application of the two preparations in each patient was separated by a 28-day washout period, regarded as sufficiently long to avoid significant interference from residual drug in the body. Whole blood samples were collected over 72 hours after drug administration. RESULTS: A total of 23 subjects completed both the fed and the fasting parts of the trial. There were no significant differences in Cmax, AUC0-72h, and T1/2 between the test and reference preparation (p < 0.05). Food had no significant effect on Cmax and T1/2 (p < 0.05), but AUC0-72h values were significantly reduced under fed condition compared to fasting condition (p < 0.05). The 90% confidence intervals (CIs) for the geometric mean ratios (GMRs) of Cmax and AUC0-72h were 0.84 - 1.05 and 0.89 - 0.98 in the fed study, and 0.97 - 1.07 and 0.97 - 1.05 in the fasting study, respectively. The carryover effect due to non-zero blood concentrations resulted in higher AUC0-72h values in the second period for both test and reference formulations and had no effect on the statistical results. No serious adverse events were reported. CONCLUSION: The investigation demonstrated that the test and reference preparations are bioequivalent and well tolerated under both fasting and fed conditions in healthy Chinese subjects.

Design and Biological Evaluation of the Long-Acting C5-Inhibited Ornithodoros moubata Complement Inhibitor (OmCI) Modified with Fatty Acid.

Disorder of complement response is a significant pathogenic factor causing some autoimmune and inflammation diseases. The Ornithodoros moubata Complement Inhibitor (OmCI), a small 17 kDa natural protein, was initially extracted from soft tick salivary glands. The protein was found binding to complement C5 specifically, inhibiting the activation of the complement pathway, which is a successful therapeutic basis of complement-mediated diseases. However, a short half-life due to rapid renal clearance is a common limitation of small proteins for clinical application. In this study, we extended the half-life of OmCI by modifying it with fatty acid, which was a method used to improve the pharmacokinetics of native peptides and proteins. Five OmCI mutants were initially designed, and single-site cysteine mutation was introduced to each of them. After purification, four OmCI mutants were obtained that showed similar in vitro biological activities. Three mutants of them were subsequently coupled with different fatty acids by nucleophilic substitution. In total, 15 modified derivatives were screened and tested for anticomplement activity in vitro. The results showed that coupling with fatty acid would not significantly affect their complement-inhibitory activity (CH50 and AH50). OmCIT90C-CM02 and OmCIT90C-CM05 were validated as the applicable OmCI bioconjugates for further pharmacokinetic assessments, and both showed improved plasma half-life in mice compared with unmodified OmCI (15.86, 17.96 vs 2.57 h). In summary, our data demonstrated that OmCI conjugated with fatty acid could be developed as the potential long-acting C5 complement inhibitor in the clinic.

Predicting Elimination of Small-Molecule Drug Half-Life in Pharmacokinetics Using Ensemble and Consensus Machine Learning Methods.

Half-life is a significant pharmacokinetic parameter included in the excretion phase of absorption, distribution, metabolism, and excretion. It is one of the key factors for the successful marketing of drug candidates. Therefore, predicting half-life is of great significance in drug design. In this study, we employed eXtreme Gradient Boosting (XGboost), randomForest (RF), gradient boosting machine (GBM), and supporting vector machine (SVM) to build quantitative structure-activity relationship (QSAR) models on 3512 compounds and evaluated model performance by using root-mean-square error (RMSE), R2, and mean absolute error (MAE) metrics and interpreted features by SHapley Additive exPlanation (SHAP). Furthermore, we developed consensus models through integrating four individual models and validated their performance using a Y-randomization test and applicability domain analysis. Finally, matched molecular pair analysis was used to extract the transformation rules. Our results revealed that XGboost outperformed other individual models (RMSE = 0.176, R2 = 0.845, MAE = 0.141). The consensus model integrating all four models continued to enhance prediction performance (RMSE = 0.172, R2 = 0.856, MAE = 0.138). We evaluated the reliability, robustness, and generalization ability via Y-randomization test and applicability domain analysis. Meanwhile, we utilized SHAP to interpret features and employed matched molecular pair analysis to extract chemical transformation rules that provide suggestions for optimizing drug structure. In conclusion, we believe that the consensus model developed in this study serve as a reliable tool to evaluate half-life in drug discovery, and the chemical transformation rules concluded in this study could provide valuable suggestions in drug discovery.

SARS-CoV-2 booster vaccine dose significantly extends humoral immune response half-life beyond the primary series.

SARS-CoV-2 lipid nanoparticle mRNA vaccines continue to be administered as the predominant prophylactic measure to reduce COVID-19 disease pathogenesis. Quantifying the kinetics of the secondary immune response from subsequent doses beyond the primary series and understanding how dose-dependent immune waning kinetics vary as a function of age, sex, and various comorbidities remains an important question. We study anti-spike IgG waning kinetics in 152 individuals who received an mRNA-based primary series (first two doses) and a subset of 137 individuals who then received an mRNA-based booster dose. We find the booster dose elicits a 71-84% increase in the median Anti-S half life over that of the primary series. We find the Anti-S half life for both primary series and booster doses decreases with age. However, we stress that although chronological age continues to be a good proxy for vaccine-induced humoral waning, immunosenescence is likely not the mechanism, rather, more likely the mechanism is related to the presence of noncommunicable diseases, which also accumulate with age, that affect immune regulation. We are able to independently reproduce recent observations that those with pre-existing asthma exhibit a stronger primary series humoral response to vaccination than compared to those that do not, and further, we find this result is sustained for the booster dose. Finally, via a single-variate Kruskal-Wallis test we find no difference between male and female humoral decay kinetics, however, a multivariate approach utilizing  Least Absolute Shrinkage and Selection Operator (LASSO) regression for feature selection reveals a statistically significant (p < 1 × 10 - 3 ), albeit small, bias in favour of longer-lasting humoral immunity amongst males.

SINGLE-DOSE, MULTIPLE-DOSE, AND THERAPEUTIC DRUG MONITORING PHARMACOKINETICS OF FIROCOXIB IN ASIAN ELEPHANTS (ELEPHAS MAXIMUS).

Firocoxib is a COX-2-selective nonsteroidal anti-inflammatory drug (NSAID) with limited effects on COX-1, which means it likely has fewer side effects than typically associated with other NSAIDs. This study determined possible doses of firocoxib based on single- and multidose pharmacokinetic trials conducted in 10 Asian elephants (Elephas maximus). Initially, two single oral dose trials (0.01 and 0.1 mg/kg) of a commercially available tablet (n = 6) and paste (n = 4) formulation were used to determine a preferred dose. The 0.1 mg/kg dose was further evaluated via IV single dose (n = 3) and oral multidose trials (tablets n = 6; paste n = 4). Serum peak and trough firocoxib concentrations were also evaluated in Asian elephants (n = 4) that had been being treated for a minimum of 90 consecutive days. Key pharmacokinetic parameters for the 0.1 mg/kg single-dose trials included mean peak serum concentrations of 49 ± 3.3 ng/ml for tablets and 62 ± 14.8 ng/ml for paste, area under the curve (AUC) of 1,332 ± 878 h*mg/ml for tablets and 1,455 ± 634 h*mg/ml for paste, and half-life (T1/2) of 34.3 ± 30.3 h for tablets and 19.9 ± 12.8 h for paste. After 8 d of dosing at 0.1 mg/kg every 24 h, pharmacokinetic parameters stabilized to an AUC of 6,341 ± 3,003 h*mg/ml for tablets and 5,613 ± 2,262 for paste, and T1/2 of 84.4 ± 32.2 h for tablets and 62.9 ± 2.3 h for paste. Serum COX inhibition was evaluated in vitro and ex vivo in untreated elephant plasma, where firocoxib demonstrated preferential inhibition of COX-2. No adverse effects from firocoxib administration were identified in this study. Results suggest administering firocoxib to Asian elephants at a dose of 0.1 mg/kg orally, using either tablet or paste formulations, every 24 h.

Human IgG Fc-engineering for enhanced plasma half-life, mucosal distribution and killing of cancer cells and bacteria.

Monoclonal IgG antibodies constitute the fastest growing class of therapeutics. Thus, there is an intense interest to design more potent antibody formats, where long plasma half-life is a commercially competitive differentiator affecting dosing, frequency of administration and thereby potentially patient compliance. Here, we report on an Fc-engineered variant with three amino acid substitutions Q311R/M428E/N434W (REW), that enhances plasma half-life and mucosal distribution, as well as allows for needle-free delivery across respiratory epithelial barriers in human FcRn transgenic mice. In addition, the Fc-engineered variant improves on-target complement-mediated killing of cancer cells as well as both gram-positive and gram-negative bacteria. Hence, this versatile Fc technology should be broadly applicable in antibody design aiming for long-acting prophylactic or therapeutic interventions.

Moderate- to vigorous-intensity physical activities for hemophilia A patients during low-dose pharmacokinetic-guided extended half-life factor VIII prophylaxis.

BACKGROUND: Low-dose pharmacokinetic (PK)-guided extended half-life (EHL) factor VIII (FVIII) prophylaxis can reduce the bleeding risk in hemophilia A (HA) patients. An increase in physical activities for promoting musculoskeletal health may enhance the benefits of prophylactic therapy. OBJECTIVES: To determine the clinical impact of moderate- to vigorous-intensity physical activities in HA patients during low-dose PK-guided EHL FVIII prophylaxis. PATIENTS/METHODS: This prospective study enrolled patients with moderate/severe HA (baseline FVIII levels ≤ 5 IU/dL) who had received low-dose PK-guided EHL FVIII prophylaxis for ≥ 6 months. An individualized exercise protocol was introduced to each participant, targeting a 65% increase in the maximum predicted heart rate for ≥ 150 min/week, while continuing low-dose PK-guided EHL FVIII prophylaxis for 6 months. Before and after implementing the intervention, annualized bleeding rates (ABR), annualized joint bleeding rates (AJBR), Hemophilia Joint Health Scores (HJHS), skeletal muscle mass, hemophilia-specific quality-of-life (QoL) scores and annualized FVIII consumption were compared. RESULTS: Of 13 participants (mean age ± standard deviation [SD]: 20.1 ± 6.8 years), ABR, AJBR, and HJHS were significantly reduced (mean differences [MD] ± SD: -5.7 ± 2.6 bleeds/year, -4.2 ± 2.6 joint bleeds/year, and -4.3 ± 3.2 marks, respectively; P < 0.05) after applying the 6-month exercise protocol. Skeletal muscle mass and QoL scores had also improved (P = 0.001), while FVIII usage had decreased (MD ± SD: -129.1 ± 208.7 IU/kg/year; P < 0.05). CONCLUSIONS: The combination of moderate- to vigorous-intensity physical activities with low-dose PK-guided EHL FVIII prophylaxis improves bleeding prevention, musculoskeletal status and QoL in patients with moderate/severe HA. By minimizing FVIII consumption, this strategy helps optimize hemophilia care in countries with budget constraints. CLINICALTRIALS: gov NCT05728528.

Dissipation and Risk Assessment of Propaquizafop in Ginseng under Field Conditions.

Propaquizafop is a highly efficient aryloxy phenoxy propionate chiral herbicide. However, the use of propaquizafop, including its safe use methods, residue patterns, dietary risk assessment, and maximum residue limits, for ginseng, a traditional Chinese medicinal plant, has not been studied. An analytical method was established for the simultaneous determination of propaquizafop and its four metabolites in ginseng soil, fresh ginseng, ginseng plant, and dried ginseng using HPLC-MS/MS. This approach showed good linearity (R2 ranging from 0.9827 to 0.9999) and limit of quantification ranging from 0.01 to 0.05 mg/kg. The intra- and interday recovery rates of this method ranged from 71.6 to 107.1% with relative standard deviation ranging from 1.3 to 23.2%. The method was applied to detect residual samples in the field, and it was found that the degradation of propaquizafop in ginseng plants and soil followed a first-order kinetic equation. R2 was between 0.8913 and 0.9666, and the half-life (t1/2) ranged from 5.04 to 8.05 days, indicating that it was an easily degradable pesticide (T1/2 < 30 days). The final propaquizafop residues in ginseng soil, plants, fresh ginseng, and dried ginseng ranged from 0.017 to 0.691 mg/kg. A dietary risk assessment was conducted on the final propaquizafop residue in fresh and dried ginseng. The results showed that the chronic exposure risk quotient values were less than 100% for fresh and dried ginseng (1.15% for fresh ginseng and 1.13% for dried ginseng). This illustrates that the dietary risk associated with the use of 10% propaquizafop emulsifiable concentrate in ginseng is very low. Thus, applying 750 mL/ha of propaquizafop on ginseng could not pose an unacceptable risk to public health. The results of the present study support the registration of propaquizafop in ginseng.

First-in-human trial evaluating safety and pharmacokinetics of AT-752, a novel nucleotide prodrug with pan-serotype activity against dengue virus.

AT-752 is a novel guanosine nucleotide prodrug inhibitor of the dengue virus (DENV) polymerase with sub-micromolar, pan-serotype antiviral activity. This phase 1, double-blind, placebo-controlled, first-in-human study evaluated the safety, tolerability, and pharmacokinetics of ascending single and multiple oral doses of AT-752 in healthy subjects. AT-752 was well tolerated when administered as a single dose up to 1,500 mg or when administered as multiple doses up to 750 mg three times daily (TID). No serious adverse events occurred, and the majority of treatment-emergent adverse events were mild in severity and resolved by the end of the study. In those receiving single ascending doses of AT-752, no pharmacokinetic sensitivity was observed in Asian subjects, and no food effect was observed. Plasma exposure of the guanosine nucleoside metabolite AT-273, the surrogate of the active triphosphate metabolite of the drug, increased with increasing dose levels of AT-752 and exhibited a long half-life of approximately 15-25 h. Administration of AT-752 750 mg TID led to a rapid increase in plasma levels of AT-273 exceeding the target in vitro 90% effective concentration (EC90) of 0.64 µM in inhibiting DENV replication, and maintained this level over the treatment period. The favorable safety and pharmacokinetic results support the evaluation of AT-752 as an antiviral for the treatment of dengue in future clinical studies.Registered at ClinicalTrials.gov (NCT04722627).

Clinical Pharmacokinetics and Pharmacodynamics of Naloxone.

Naloxone is a World Health Organization (WHO)-listed essential medicine and is the first choice for treating the respiratory depression of opioids, also by lay-people witnessing an opioid overdose. Naloxone acts by competitive displacement of opioid agonists at the µ-opioid receptor (MOR). Its effect depends on pharmacological characteristics of the opioid agonist, such as dissociation rate from the MOR receptor and constitution of the victim. Aim of treatment is a balancing act between restoration of respiration (not consciousness) and avoidance of withdrawal, achieved by titration to response after initial doses of 0.4-2 mg. Naloxone is rapidly eliminated [half-life (t1/2) 60-120 min] due to high clearance. Metabolites are inactive. Major routes for administration are intravenous, intramuscular, and intranasal, the latter primarily for take-home naloxone. Nasal bioavailability is about 50%. Nasal uptake [mean time to maximum concentration (Tmax) 15-30 min] is likely slower than intramuscular, as reversal of respiration lag behind intramuscular naloxone in overdose victims. The intraindividual, interindividual and between-study variability in pharmacokinetics in volunteers are large. Variability in the target population is unknown. The duration of action of 1 mg intravenous (IV) is 2 h, possibly longer by intramuscular and intranasal administration. Initial parenteral doses of 0.4-0.8 mg are usually sufficient to restore breathing after heroin overdose. Fentanyl overdoses likely require higher doses of naloxone. Controlled clinical trials are feasible in opioid overdose but are absent in cohorts with synthetic opioids. Modeling studies provide valuable insight in pharmacotherapy but cannot replace clinical trials. Laypeople should always have access to at least two dose kits for their interim intervention.

Classification of recombinant factor VIII products and implications for clinical practice: A systematic literature review.

INTRODUCTION: Consensus over the definition of recombinant factor VIII (rFVIII) product classification in haemophilia A is lacking. rFVIII products are often classified as standard half-life (SHL) or extended half-life (EHL); despite this, no universally accepted definition currently exists. One proposed definition includes half-life, area under the curve, and technology designed to extend half-life; however, the International Society on Thrombosis and Haemostasis defines activity over time as the most intuitive information for building treatment regimens and the World Federation of Hemophilia describes rFVIII product classification in terms of infusion frequency. AIM: To summarise published data on the clinical and pharmacokinetic criteria used to define rFVIII product classification. METHODS: PubMed and EMBASE database searches of English-language articles (2002-2022) were conducted using search strings to identify the relevant population, intervention, and outcomes (e.g., clinical and pharmacokinetic parameters). Articles then underwent title/abstract and full-text screens. RESULTS: Among 1147 identified articles, 62 were included. Half-life was the most widely reported outcome with no clear trends or product groupings observed. No clear groupings emerged among other outcomes, including infusion frequency, consumption, and efficacy. As activity over time was reported in few articles, further investigation of its relevance to rFVIII product classification is warranted. CONCLUSION: The findings of this systematic literature review suggest that parameters other than half-life might be important for the development of a comprehensive and clinically relevant rFVIII product classification definition. There seems to be an opportunity to consider parameters that are clinically meaningful and useful for shared decision-making in haemophilia A treatment.

Population Pharmacokinetics of Cabotegravir Following Oral Administration and Long-Acting Intramuscular Injection in Real-World People with HIV.

Long-acting cabotegravir has been studied mainly in the stringent framework of clinical trials, which does not necessarily reflect the situation of people with HIV (PWH) in routine clinical settings. The present population pharmacokinetic analysis aims to build real-world reference percentile curves of cabotegravir concentrations, accounting for patient-related factors that may affect cabotegravir exposure. The second objective is to simulate whether dosing interval adjustments of cabotegravir could be considered in specific subpopulations. Overall, 238 PWH contributed to 1,038 cabotegravir levels (186 during the initial oral administration phase and 852 after intramuscular injection). Cabotegravir pharmacokinetics was best described using a one-compartment model with distinct first order-absorption for oral and intramuscular administrations, and identical volume and clearance. Our model showed almost 40% faster absorption and 30% higher clearance than previously reported, resulting in a time to steady-state of 8 months and an elimination half-life of 4.6 weeks for long-acting cabotegravir. Sex and body mass index significantly influenced absorption, and bodyweight affected clearance. Model-based simulations showed that cabotegravir trough concentrations in females were 25% lower 4 weeks after the intramuscular loading dose, but 42% higher during the late maintenance phase. Finally, simulations indicated that in females, despite significantly higher cabotegravir concentrations, longer intervals between injections may not consistently ensure levels above the 4-fold protein-adjusted 90% inhibitory target concentration.

PHARMACOKINETICS OF TRAMADOL AND O-DESMETHYLTRAMADOL IN GIANT TORTOISES (CHELONOIDIS VANDENBURGHI, CHELONOIDIS VICINA).

The objective of this study was to determine the pharmacokinetics of two orally administered doses of tramadol (1 mg/kg and 5 mg/kg) and its metabolite, O-desmethyltramadol (M1) in giant tortoises (Chelonoidis vandenburghi, Chelonoidis vicina). Eleven giant tortoises (C. vandenburghi, C. vicina) received two randomly assigned, oral doses of tramadol (either 1 mg/kg or 5 mg/kg), with a washout period of 3 wk between each dose. The half-life (t½) of orally administered tramadol at 1 mg/kg and 5 mg/kg was 11.9 ± 4.6 h and 13.2 ± 6.1 h, respectively. After oral administration of tramadol at 1 mg/kg and 5 mg/kg, the maximum concentration (Cmax) was 125 ± 69 ng/ml and 518 ± 411 ng/ml, respectively. There were not enough data points to determine pharmacokinetic (PK) parameters for the M1 metabolite from either dose. Tramadol administered orally to giant tortoises at both doses provided measurable plasma concentrations of tramadol for approximately 48 h with occasional transient sedation. Oral tramadol at 5 mg/kg, on average, achieves concentrations of >100 ng/ml, the reported human therapeutic threshold, for 24 h. Based on the low levels of M1 seen in this study, M1 may not be a major metabolite in this taxon.

Residue behavior and consumer risk assessment of spirotetramat and chlorpyrifos on cabbage heads and cropped soil.

A field experiment following good agricultural practices was laid out to study the dissipation of spirotetramat (90 g a.i. ha-1 and 180 g a.i. ha-1) and chlorpyrifos (400 g a.i. ha-1 and 800 g a.i. ha-1) on cabbage heads and soil. Samples were processed using quick, easy, cheap, effective, rugged, and safe (QuEChERS) method for residue estimation of spirotetramat and chlorpyrifos, which were further detected using HPLC-PDA and GC-FPD respectively. The residues of spirotetramat on cabbage heads reached below detection limit (BDL) (< 0.05 mg kg-1) on 7th and 10th day and for chlorpyrifos, BDL (< 0.01 mg kg-1) was achieved on 10th and 15th day for X and 2X dose, respectively. On 20th day after second spray, residues in soil were found to be BDL for both the pesticides. Half-life of spirotetramat and chlorpyrifos was found to be 3 and 2 days, respectively while a safe pre-harvest interval (PHI) of 9 days for spirotetramat and 10 days for chlorpyrifos is suggested on cabbage. The dietary risk assessment studies for various age groups of Indian population, ascertained safety of treated cabbage heads for consumption, as current study revealed that hazard quotient (HQ) < 1 and theoretical maximum dietary intake (TMDI) < maximum permissible intake (MPI) for both the pesticides at respective PHI.

Improved RNA stability estimation through Bayesian modeling reveals most Salmonella transcripts have subminute half-lives.

RNA decay is a crucial mechanism for regulating gene expression in response to environmental stresses. In bacteria, RNA-binding proteins (RBPs) are known to be involved in posttranscriptional regulation, but their global impact on RNA half-lives has not been extensively studied. To shed light on the role of the major RBPs ProQ and CspC/E in maintaining RNA stability, we performed RNA sequencing of Salmonella enterica over a time course following treatment with the transcription initiation inhibitor rifampicin (RIF-seq) in the presence and absence of these RBPs. We developed a hierarchical Bayesian model that corrects for confounding factors in rifampicin RNA stability assays and enables us to identify differentially decaying transcripts transcriptome-wide. Our analysis revealed that the median RNA half-life in Salmonella in early stationary phase is less than 1 min, a third of previous estimates. We found that over half of the 500 most long-lived transcripts are bound by at least one major RBP, suggesting a general role for RBPs in shaping the transcriptome. Integrating differential stability estimates with cross-linking and immunoprecipitation followed by RNA sequencing (CLIP-seq) revealed that approximately 30% of transcripts with ProQ binding sites and more than 40% with CspC/E binding sites in coding or 3' untranslated regions decay differentially in the absence of the respective RBP. Analysis of differentially destabilized transcripts identified a role for ProQ in the oxidative stress response. Our findings provide insights into posttranscriptional regulation by ProQ and CspC/E, and the importance of RBPs in regulating gene expression.