The in vitro and in vivo potential of metal-chelating agents as metallo-beta-lactamase inhibitors against carbapenem-resistant Enterobacterales.

The recent surge in beta-lactamase resistance has created superbugs, which pose a current and significant threat to public healthcare. This has created an urgent need to keep pace with the discovery of inhibitors that can inactivate these beta-lactamase producers. In this study, the in vitro and in vivo activity of 1,4,7-triazacyclononane-1,4,7 triacetic acid (NOTA)-a potential metallo-beta-lactamase (MBL) inhibitor was evaluated in combination with meropenem against MBL producing bacteria. Time-kill studies showed that NOTA restored the efficacy of meropenem against all bacterial strains tested. A murine infection model was then used to study the in vivo pharmacokinetics and efficacy of this metal chelator. The coadministration of NOTA and meropenem (100 mg/kg.bw each) resulted in a significant decrease in the colony-forming units of Klebsiella pneumoniae NDM-1 over an 8-h treatment period (>3 log10 units). The findings suggest that chelators, such as NOTA, hold strong potential for use as a MBL inhibitor in treating carbapenem-resistant Enterobacterale infections.

Mass Spectrometric Imaging of the Brain Demonstrates the Regional Displacement of 6-Monoacetylmorphine by Naloxone.

Overdose is the main cause of mortality among heroin users. Many of these overdose-induced deaths can be prevented through the timely administration of naloxone (NLX), a nonselective mu (µ)-, kappa (κ)-, and delta (δ)-opioid receptor antagonist. NLX competitively inhibits opioid-overdose-induced respiratory depression without eliciting any narcotic effect itself. The aim of this study was to investigate the antagonistic action of NLX by comparing its distribution to that of 6-monacetylmorphine (6-MAM), heroin's major metabolite, in a rodent model using mass spectrometric imaging (MSI) in combination with liquid chromatography-tandem mass spectrometry (LC-MS/MS). Male Sprague-Dawley rats (n = 5) received heroin (10 mg kg-1) intraperitoneally, NLX (10 mg kg-1) intranasally, and NLX injected intranasally 5 min after heroin administration. The animals were sacrificed 15 min after dose and brain tissues were harvested. The MSI image analysis showed a region-specific distribution of 6-MAM in the brain regions including the corpus callosum, hippocampal formation, cerebral cortex, corticospinal tracts, caudate putamen, thalamus, globus pallidus, hypothalamus, and basal forebrain regions of the brain. The antagonist had a similar biodistribution throughout the brain in both groups of animals that received NLX or NLX after heroin administration. The MSI analysis demonstrated that the intensity of 6-MAM in these brain regions was reduced following NLX treatment. The decrease in 6-MAM intensity was caused by its displacement by the antagonist and its binding to these receptors in these specific brain regions, consequently enhancing the opioid elimination. These findings will contribute to the evaluation of other narcotic antagonists that might be considered for use in the treatment of drug overdose via MSI.

Mass spectrometric investigations into the brain delivery of abacavir, stavudine and didanosine in a rodent model.

HIV replication in the brain is unopposed due to reduced antiretroviral drug penetration into the central nervous system (CNS). Prevalence of HIV-associated neurocognitive disorder (HAND) has increased severely in patients living with HIV despite current treatments. The aims of this study were to evaluate the brain bio-distribution of alternative nucleoside reverse transcriptase inhibitors, abacavir, stavudine and didanosine in the CNS and to determine their localization patterns in the brain.Sprague-Dawley rats received 50 mg kg-1 single i.p dose of each drug. Mass spectrometric techniques were then used to investigate the pharmacokinetics and localization patterns of these drugs in the brain using LC-MS/MS and mass spectrometric imaging (MSI), respectively.Abacavir, stavudine and didanosine reached the Brain Cmax with concentration of 831.2, 1300 and 43.37 ngmL-1, respectively. Based on MSI analysis Abacavir and Stavudine were located in brain regions that are strongly implicated in the progression of HAND.Abacavir and Stavudine penetrated into CNS, reaching a Cmax that was above the IC50 for HIV (457.6 and 112.0 ngmL-1, respectively), however, it was noted ddI showed poor entry within the brain, therefore, it is recommended that this drug cannot be considered for treating CNS-HIV.

Mass Spectrometry Imaging Demonstrates the Regional Brain Distribution Patterns of Three First-Line Antiretroviral Drugs.

HIV in the central nervous system (CNS) contributes to the development of HIV-associated neurological disorders (HAND), even with chronic antiretroviral therapy. In order for antiretroviral therapy to be effective in protecting the CNS, these drugs should have the ability to localize in brain areas known to be affected by HIV. Consequently, this study aimed to investigate the localization patterns of three first-line antiretroviral drugs, namely, efavirenz, tenofovir, and emtricitabine, in the rat brain. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) and matrix-assisted laser desorption ionization mass spectrometry imaging (MALDI-MSI) were utilized to assess the pharmacokinetics and brain spatial distribution of the three drugs. Each drug was administered (50 mg/kg) to healthy female Sprague-Dawley rats via intraperitoneal administration. LC-MS/MS results showed that all three drugs could be delivered into the brain, although they varied in blood-brain barrier permeability. MALDI-MSI showed a high degree of efavirenz localization across the entire brain, while tenofovir localized mainly in the cortex. Emtricitabine distributed heterogeneously mainly in the thalamus, corpus callosum, and hypothalamus. This study showed that efavirenz, tenofovir, and emtricitabine might be a potential drug combination antiretroviral therapy for CNS protection against HAND.

Investigating time dependent brain distribution of nevirapine via mass spectrometric imaging.

Central nervous system (CNS) HIV infection causes brain tissue inflammation and tissue deficit that contributes to neuroAIDS. This complication is escalated by the blood-brain barrier (BBB), which prevents easy access to antiretroviral drugs entering the CNS. In this study the aims were to investigate the BBB membrane penetration and brain localization patterns of Nevirapine (NVP) using Imaging Mass Spectrometry (MSI). Sprague-Dawley rats received an intraperitoneal dose of NVP (50 mg kg-1). Plasma and brain samples were harvested, and mass spectrometric methods were then applied to determine the pharmacokinetic properties and localization patterns of NVP in the brain. The pharmacokinetic parameters demonstrated a rapid bio-distribution of NVP in plasma and brain. The plasma Cmax was 6320 ng mL-1 and the brain Cmax was 1923 ng mL-1, both at a Tmax of 0.25 h. MSI of coronal brain sections showed that NVP penetrated and localized in the brain regions implicated with the development of HIV associated neurodegeneration. NVP has great potential to combat neuroAIDS.

Zidovudine and Lamivudine as Potential Agents to Combat HIV-Associated Neurocognitive Disorder.

The central nervous system has been identified as an anatomical reservoir for HIV due the difficulties in delivering therapeutic agents into the brain and this complication results in HIV-associated neurocognitive disorder that persists in infected patients. The brain regions that are potentially exposed to tissue deficits due to HIV have been reported in previous reports; therefore, it is important to determine the drugs that can enter and localize in brain regions that are known to be susceptible to HIV neurodegeneration. Sprague-Dawley rats received intraperitoneal doses of zidovudine and lamivudine (50 mg kg-1). Mass spectrometry methods were used to determine the pharmacokinetics, of zidovudine and lamivudine, in the brain using liquid chromatography tandem mass spectrometry and mass spectrometry imaging (MSI), respectively. Zidovudine and lamivudine displayed complementary pharmacokinetic curves indicating a rapid absorption and blood-brain barrier penetration of both drugs reaching Cmaxat 0.5 h after single dose. MSI of coronal brain sections showed that zidovudine and lamivudine are mostly distributed in corpus callosum, globus pallidus, striatum, and the neocortex region. Mass spectrometry techniques were used to demonstrate that zidovudine and lamivudine drugs are able to reach and localize in brain regions that are targets of HIV neurodegeneration in the brain.

Spatial distribution of elvitegravir and tenofovir in rat brain tissue: Application of matrix-assisted laser desorption/ionization mass spectrometry imaging and liquid chromatography/tandem mass spectrometry.

RATIONALE: The complexity of central nervous system (CNS) drug delivery is the main obstacle with the blood-brain barrier (BBB) known to restrict access of most pharmaceutical drugs into the brain. Mass spectrometry imaging (MSI) offers possibilities for studying drug deposition into the CNS. METHODS: The deposition and spatial distribution of the two antiretroviral drugs elvitegravir and tenofovir in the brain were investigated in healthy female Sprague-Dawley rats following a single intraperitoneal administration (50 mg/kg). This was achieved by the utilization of quantitative liquid chromatography/tandem mass spectrometry (LC/MS/MS) and matrix-assisted laser desorption/ionization (MALDI) MSI. RESULTS: LC/MS/MS showed that elvitegravir has better BBB penetration, reaching maximum concentration in the brain (Cmax brain) of 976.5 ng/g. In contrast, tenofovir displayed relatively lower BBB penetration, reaching Cmax brain of 54.5 ng/g. MALDI-MSI showed the heterogeneous distribution of both drugs in various brain regions including the cerebral cortex. CONCLUSIONS: LC/MS/MS and MALDI-MSI provided valuable information about the relative concentration and the spatial distribution of the two common antiretroviral drugs. This study has also shown the capability of MALDI-MSI for direct visualization of pharmaceutical drugs in situ.

Rilpivirine as a potential candidate for the treatment of HIV-associated neurocognitive disorders (HAND).

As the HIV epidemic continues to contribute to global morbidity and mortality, the prevalence of HIV-associated neurological disorders (HAND) also continues to be a major concern in infected individuals, despite the widespread use of combination antiretroviral therapy. Therefore, current antiretroviral drugs should be able to reach therapeutic levels in the brain for the treatment of HAND. The brain distribution of the next-generation non-nucleoside reverse transcriptase inhibitor, rilpivirine (RPV) was investigated in healthy female Sprague-Dawley (SD) rats. The presented study involves the use of liquid chromatography-tandem mass spectrometry (LC-MS/MS) to estimate the concentrations of RPV in plasma and brain homogenate samples. The use of matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) provided regional spatial distribution of RPV in brain tissue sections. The localization of RPV was found to be relatively high in the hypothalamus, thalamus and corpus callosum, brain regions known to be associated with neurodegeneration during HAND (including the cerebral cortex). This study has shown that RPV has an excellent blood-brain barrier penetrability. Thus, in combination with other antiretroviral drugs, better central nervous system (CNS) protection against HAND can possibly be achieved.

Brain penetration of ketamine: Intranasal delivery VS parenteral routes of administraion.

Ketamine is approved by the FDA to be used as an anesthetic however, recent reports have exhibited its success in the treatment of major depressive disorder (MDD). Studies have suggested that a sub-anesthetic dose produces rapid antidepressant activity providing significant symptomatic relief particularly in patients with a history of treatment resistant depression (TRD). Many reports have been published on the intranasal (IN) efficacy of ketamine in the treatment of depression, however studies that have investigated the effects of the route of administration on drug delivery to the brain appear to be absent in literature. Therefore, in this study, a single dose (15 mg/kg body weight) was administered via different routes of administration [oral (PO), intranasal (IN) and intraperitoneal (IP)] to healthy male Sprague-Dawley rats in order to determine the brain tissue pharmacokinetics of ketamine. A novel validated liquid chromatography-mass spectrometry (LC-MS) method was developed using a fused core column for the determination of ketamine in plasma and brain homogenates. While IP administration resulted in favorable concentrations in the brain and plasma; IN administration, which is supposed to favour drug delivery to the brain, exhibited moderately low drug levels post administration. PO administration produced significantly lower levels due to extensive first-pass metabolism in the liver and intestines. These results have implications for future studies exploring the use of ketamine for the treatment of MDD in order to optimize treatment regimens and suggest that parenteral administration of ketamine should be used in the treatment of depression.

The downfall of TBA-354 - a possible explanation for its neurotoxicity via mass spectrometric imaging.

1. TBA-354 was a promising antitubercular compound with activity against both replicating and static Mycobacterium tuberculosis (M.tb), making it the focal point of many clinical trials conducted by the TB Alliance. However, findings from these trials have shown that TBA-354 results in mild signs of reversible neurotoxicity; this left the TB Alliance with no other choice but to stop the research. 2. In this study, mass spectrometric methods were used to evaluate the pharmacokinetics and spatial distribution of TBA-354 in the brain using a validated liquid chromatography tandem-mass spectrometry (LCMS/MS) and mass spectrometric imaging (MSI), respectively. Healthy female Sprague-Dawley rats received intraperitoneal (i.p.) doses of TBA-354 (20 mg/kg bw). 3. The concentrationtime profiles showed a gradual absorption and tissue penetration of TBA-354 reaching the Cmax at 6 h post dose, followed by a rapid elimination. MSI analysis showed a time-dependent drug distribution, with highest drug concentration mainly in the neocortical regions of the brain. 4. The distribution of TBA-354 provides a possible explanation for the motor dysfunction observed in clinical trials. These results prove the importance of MSI as a potential tool in preclinical evaluations of suspected neurotoxic compounds.

Bedaquiline has potential for targeting tuberculosis reservoirs in the central nervous system.

Bedaquiline (BDQ) is the first-in-class United States Food and Drug Administration (US FDA) approved anti-tuberculosis (anti-TB) drug, which is a novel diarylquinoline antibiotic that has recently been utilized as an effective adjunct to existing therapies for multidrug-resistant tuberculosis (MDR-TB). BDQ is especially promising due to its novel mechanism of action, activity against drug-sensitive and drug-resistant tuberculosis (TB) in addition to having the potential to shorten treatment duration. Drug delivery to the central nervous system (CNS) is a major concern in TB chemotherapy, especially with the increasing cases of CNS-TB. In this study, we investigated the CNS penetration of BDQ in healthy rodent brain. Male Sprague-Dawley rats (n = 27; 100 ± 20 g) received a single 25 mg kg-1 b.w dose of BDQ via intraperitoneal (i.p.) administration, over a 24 h period. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to determine whole tissue drug concentrations and matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI MSI) was utilized to evaluate drug distribution in the brain. BDQ reached peak concentrations (C max) of 134.97 ng mL-1 in the brain at a T max of 4 h, which is within the range required for therapeutic efficacy. BDQ was widely distributed in the brain, with a particularly high intensity in the corpus callosum and associated subcortical white matter including the striatal, globus pallidus, corticofugal pathways, ventricular system, basal forebrain region and hippocampal regions. Using MALDI MSI, this study demonstrates that due to BDQ's distribution in the brain, it has the potential to target TB reservoirs within this organ.