Optimization of Orally Bioavailable Antileishmanial 2,4,5-Trisubstituted Benzamides.

Leishmaniasis, a neglected tropical disease caused by Leishmania species parasites, annually affects over 1 million individuals worldwide. Treatment options for leishmaniasis are limited due to high cost, severe adverse effects, poor efficacy, difficulty of use, and emerging drug resistance to all approved therapies. We discovered 2,4,5-trisubstituted benzamides (4) that possess potent antileishmanial activity but poor aqueous solubility. Herein, we disclose our optimization of the physicochemical and metabolic properties of 2,4,5-trisubstituted benzamide that retains potency. Extensive structure-activity and structure-property relationship studies allowed selection of early leads with suitable potency, microsomal stability, and improved solubility for progression. Early lead 79 exhibited an 80% oral bioavailability and potently blocked proliferation of Leishmania in murine models. These benzamide early leads are suitable for development as orally available antileishmanial drugs.

Amino-Substituted 3-Aryl- and 3-Heteroarylquinolines as Potential Antileishmanial Agents.

Leishmaniasis, a disease caused by protozoa of the Leishmania species, afflicts roughly 12 million individuals worldwide. Most existing drugs for leishmaniasis are toxic, expensive, difficult to administer, and subject to drug resistance. We report a new class of antileishmanial leads, the 3-arylquinolines, that potently block proliferation of the intramacrophage amastigote form of Leishmania parasites with good selectivity relative to the host macrophages. Early lead 34 was rapidly acting and possessed good potency against L. mexicana (EC50 = 120 nM), 30-fold selectivity for the parasite relative to the macrophage (EC50 = 3.7 µM), and also blocked proliferation of Leishmania donovani parasites resistant to antimonial drugs. Finally, another early lead, 27, which exhibited reasonable in vivo tolerability, impaired disease progression during the dosing period in a murine model of cutaneous leishmaniasis. These results suggest that the arylquinolines provide a fruitful departure point for the development of new antileishmanial drugs.

Antimalarial activity of 2,6-dibenzylidenecyclohexanone derivatives.

Malaria remains one of the deadliest infectious diseases worldwide and continues to infect hundreds of millions of individuals each year. Here we report the discovery and derivatization of a series of 2,6-dibenzylidenecyclohexanones targeting the chloroquine-sensitive 3D7 strain of Plasmodium falciparum . While the initial lead compound displayed significant toxicity in a human cell proliferation assay, we were able to identify a derivative with no detectable toxicity and sub-micromolar potency.

Improvement of Oral Bioavailability of Pyrazolo-Pyridone Inhibitors of the Interaction of DCN1/2 and UBE2M.

The cullin-RING ubiquitin ligases (CRLs) are ubiquitin E3 enzymes that play a key role in controlling proteasomal degradation and are activated by neddylation. We previously reported inhibitors that target CRL activation by disrupting the interaction of defective in cullin neddylation 1 (DCN1), a CRL neddylation co-E3, and UBE2M, a neddylation E2. Our first-generation inhibitors possessed poor oral bioavailability and fairly rapid clearance that hindered the study of acute inhibition of DCN-controlled CRL activity in vivo. Herein, we report studies to improve the pharmacokinetic performance of the pyrazolo-pyridone inhibitors. The current best inhibitor, 40, inhibits the interaction of DCN1 and UBE2M, blocks NEDD8 transfer in biochemical assays, thermally stabilizes cellular DCN1, and inhibits anchorage-independent growth in a DCN1 amplified squamous cell carcinoma cell line. Additionally, we demonstrate that a single oral 50 mg/kg dose sustains plasma exposures above the biochemical IC90 for 24 h in mice.

Identification of Plasmodium falciparum heat shock 90 inhibitors via molecular docking.

A virtual screen was performed to identify anti-malarial compounds targeting Plasmodium falciparum heat shock 90 protein by applying a series of drug-like and commercial availability filters to compounds in the ZINC database, resulting in a virtual library of more than 13 million candidates. The goal of the virtual screen was to identify novel compounds which could serve as a starting point for the development of antimalarials with a mode of action different from anything currently used in the clinic. The screen targeted the ATP binding pocket of the highly conserved Plasmodium heat shock 90 protein, as this protein is critical to the survival of the parasite and has several significant structural differences from the human homolog. The top twelve compounds from the virtual screen were tested in vitro, with all twelve showing no antiproliferative activity against the human fibroblast cell line and three compounds exhibiting single digit or better micromolar antiproliferative activity against the chloroquine-sensitive P. falciparum 3D7 strain.

Evaluation of 1,1-cyclopropylidene as a thioether isostere in the 4-thio-thienopyrimidine (TTP) series of antimalarials.

The 4-(heteroarylthio)thieno[2,3-d]pyrimidine (TTP) series of antimalarials, represented by 1 and 17, potently inhibit proliferation of the 3D7 strain of P. falciparum (EC50 70-100 nM), but suffer from oxidative metabolism. The 1,1-cyclopropylidene isosteres 6 and 16 were designed to obviate this drawback. They were prepared by a short route that features a combined Peterson methylenation / cyclopropanation transformation of, e. g., ketone 7. Isosteres 6 and 16 possess significantly attenuated antimalarial potency relative to parents 1 and 17. This outcome can be rationalized based on the increased out-of-plane steric demands of the latter two. In support of this hypothesis, the relatively flat ketone 7 retains some of the potency of 1, even though it appears to be a comparatively inferior mimic with respect to electronics and bond lengths and angles. We also demonstrate crystallographically and computationally an apparent increase in the strength of the intramolecular sulfur hole interaction of 1 upon protonation.

Synthesis and Structure-Activity Relationship of Dual-Stage Antimalarial Pyrazolo[3,4-b]pyridines.

Malaria remains one of the most deadly infectious diseases, causing hundreds of thousands of deaths each year, primarily in young children and pregnant mothers. Here, we report the discovery and derivatization of a series of pyrazolo[3,4-b]pyridines targeting Plasmodium falciparum, the deadliest species of the malaria parasite. Hit compounds in this series display sub-micromolar in vitro activity against the intraerythrocytic stage of the parasite as well as little to no toxicity against the human fibroblast BJ and liver HepG2 cell lines. In addition, our hit compounds show good activity against the liver stage of the parasite but little activity against the gametocyte stage. Parasitological profiles, including rate of killing, docking, and molecular dynamics studies, suggest that our compounds may target the Qo binding site of cytochrome bc1.

Antimalarial activity of tetrahydro-ß-carbolines targeting the ATP binding pocket of the Plasmodium falciparum heat shock 90 protein.

A series of tetrahydro-ß-carboline derivatives of a lead compound known to target the heat shock 90 protein of Plasmodium falciparum were synthesized and assayed for both potency against the parasite and toxicity against a human cell line. Using a rationalized structure based design strategy, a new lead compound with a potency two orders of magnitude greater than the original lead compound was found. Additional modeling of this new lead compound suggests multiple avenues to further increase potency against this target, potentially paving the path for a therapeutic with a mode of action different than any current clinical treatment.

Gastric emptying of milk in infants and children up to 5 years of age: normative data and influencing factors.

BACKGROUND: Gastric emptying scintigraphy is widely used in infants and children, but there is a lack of age-specific normative data. OBJECTIVE: The objectives of this retrospective study were: 1) to establish a range of gastric emptying of milk or formula as a surrogate for normal gastric emptying in infants and young children ≤5 years of age, and 2) to investigate the effects of patient age, feeding volume, feeding route and gastroesophageal reflux on gastric emptying. MATERIALS AND METHODS: The reports of 5,136 gastric emptying studies of children ≤5 years of age performed at Children's National Medical Center from January 1990 to August 2012 were reviewed. Demographic data, 1-h and 3-h gastric emptying values and gastroesophageal reflux status of all patients were stored in a database. Using stringent inclusion and exclusion criteria, the studies of patients as similar to healthy children as possible were selected for this study. RESULTS: The study group included 2,273 children (57% male) ages 0-59 months (median: 4.6 months). The median 1-h gastric emptying was 43% (interquartile range [IQR] 34-54%). The median 3-h gastric emptying was 91% (IQR 79-98%). Sixty-one percent of patients with 1-h gastric emptying value of <50% had 3-h gastric emptying ≥80%. Gastric emptying was significantly faster in children ≤6 months as compared with all older age groups. In each age group, the median gastric emptying decreased with increasing feeding volume. Gastric emptying was significantly faster in patients fed via combined nasogastric tube and oral routes as compared with those fed exclusively orally. There was no significant difference in gastric emptying of children with and without gastroesophageal reflux. CONCLUSION: Although there are statistically significant differences in gastric emptying based on age, volume and route of feeding, the data suggest that overall normal liquid gastric emptying in infants and children ≤5 years of age is ≥80% at 3 h. One-hour emptying measurements are not reliable for detecting delayed gastric emptying.

Patient characteristics affect the response to ketamine and opioids during the treatment of vaso-occlusive episode-related pain in sickle cell disease.

BackgroundN-methyl-D-aspartate receptor activation has been implicated in the pathobiology of inflammatory, nociceptive and neuropathic pain, opioid tolerance, opioid-induced hyperalgesia, and central sensitization. Some of those mechanisms underlie sickle cell disease(SCD)-associated pain.MethodsWe conducted an exploratory cohort study of SCD patients who during vaso-occlusive episodes (VOEs) received subanesthetic doses of the N-methyl-D-aspartate receptor antagonist, ketamine, as an adjunct to opioids. We sought to identify predictors of changes in pain scores and of the percentage of ketamine infusions associated with meaningful changes (≥20% reduction) in pain and opioid consumption.ResultsEight-five patients received 181 ketamine infusions for VOE-associated pain. Combined with opioids, ketamine yielded significant decrease in pain scores and opioid consumption. Ketamine administered to males and to younger patients yielded greater pain score decrease compared with females (P=0.013) and older patients (P=0.018). Fifty-four percent of infusions yielded meaningful reductions in pain scores, and in multivariate analysis, sex, age group, pain location, and infusion duration independently predicted pain score changes.ConclusionThis study suggests that in SCD patients admitted with VOE-associated pain, ketamine has age- and sex-dependent effects. These data can inform sample and effect size calculations for controlled trials to determine which SCD patients would benefit most from ketamine.

Subanesthetic ketamine for pain management in hospitalized children, adolescents, and young adults: a single-center cohort study.

BACKGROUND: Subanesthetic doses of ketamine, an N-methyl-d-aspartate receptor antagonist used as an adjuvant to opioid for the treatment of pain in adults with acute and chronic pain, have been shown, in some instances, to improve pain intensity and to decrease opioid intake. However, less is known about the role of ketamine in pain management in children, adolescents, and young adults. PURPOSE: We examined the effects of subanesthetic ketamine on pain intensity and opioid intake in children, adolescents, and young adults with acute and chronic pain syndromes treated in an inpatient setting. METHODS: This is a longitudinal cohort study of patients treated with subanesthetic ketamine infusions in regular patient care units in a tertiary pediatric hospital. Primary outcomes included changes in pain scores and morphine-equivalent intake. RESULTS: The study cohort included 230 different patients who during 360 separate hospital admissions received subanesthetic ketamine infusions for pain management. Overall, ketamine infusions were associated with significant reductions in mean pain scores from baseline (mean pain scores 6.64 [95% CI: 6.38-6.90]) to those recorded on the day after discontinuation of ketamine (mean pain scores 4.38 [95% CI: 4.06-4.69]), p<0.001. Importantly, the effect of ketamine on pain scores varied according to clinical diagnosis (p=0.011), infusion duration (p=0.004), and pain location (p=0.004). Interestingly, greater reductions in pain scores were observed in patients with cancer pain and patients with pain associated with pancreatitis and Crohn's disease. There were no records of psychotomimetic side effects requiring therapy. CONCLUSION: These data suggest that administration of subanesthetic ketamine for pain management is feasible and safe in regular inpatient care units and may benefit children, adolescents, and young adults with acute and chronic pain. This study is informative and can be helpful in determining sample and effect sizes when planning clinical trials to determine the role of subanesthetic ketamine infusions for pain management in pediatric patients.

Retrospective comparison of the Low Risk Ankle Rules and the Ottawa Ankle Rules in a pediatric population.

BACKGROUND: A recent multicenter prospective Canadian study presented prospective evidence supporting the Low Risk Ankle Rules (LRAR) as a means of reducing the number of ankle radiographs ordered for children presenting with an ankle injury while maintaining nearly 100% sensitivity. This is in contrast to a previous prospective study which showed that this rule yielded only 87% sensitivity. OBJECTIVE: It is important to further investigate the LRAR and compare them with the already validated Ottawa Ankle Rules (OAR) to potentially curb healthcare costs and decrease unnecessary radiation exposure without compromising diagnostic accuracy. METHODS: We conducted a retrospective chart review of 980 qualifying patients ages 12months to 18years presenting with ankle injury to a commonly staffed 310 bed children's hospital and auxiliary site pediatric emergency department. RESULTS: There were 28 high-risk fractures identified. The Ottawa Ankle Rules had a sensitivity of 100% (95% CI 87.7-100), specificity of 33.1% (95% CI 30.1-36.2), and would have reduced the number of ankle radiographs ordered by 32.1%. The Low Risk Ankle Rules had a sensitivity of 85.7% (95% CI 85.7-96), specificity of 64.9% (95% CI 61.8-68), and would have reduced the number of ankle radiographs ordered by 63.1%. The latter rule missed 4 high-risk fractures. CONCLUSION: The Low Risk Ankle Rules may not be sensitive enough for use in Pediatric Emergency Departments, while the Ottawa Ankle Rules again demonstrated 100% sensitivity. Further research on ways to implement the Ottawa Ankle Rules and maximize its ability to decrease wait times, healthcare costs, and improve patient satisfaction are needed.

Moving from efficacy to effectiveness: red palm oil's role in preventing vitamin A deficiency.

Vitamin A deficiency is one of the most widespread nutritional deficiencies worldwide. Hundreds of millions of children and tens of millions of women living in Sub-Saharan Africa and Southeast Asia are at particularly high risk of the adverse health consequences associated with this largely preventable condition. Red palm oil comes from oil palms that are traditionally grown in tropical regions of West Africa and are now cultivated on a large-scale commercial basis in Southeast Asia. Red palm oil is the richest naturally occurring source of beta-carotene, a carotenoid that the human body can convert into usable vitamin A (retinol). This paper reviews a series of key intervention studies designed to investigate the impact of using red palm oil-based interventions to improve vitamin A status. These included studies from Africa, Asia, and Latin America in which red palm oil was used (or proposed for use) (1) as a dietary supplement, (2) as an in-home fortificant, (3) to fortify foods used for distribution in targeted supplementary feeding programs, and (4) to fortify staple food products. Overall, the results suggest that red palm oil is highly efficacious in improving vitamin A status among populations at risk of vitamin A deficiency. The time has come to move beyond trials of biological efficacy and focus on conducting operational research projects, effectiveness trials, and cost-benefit analyses that will help expand the use of red palm oil in areas where it is likely to be well accepted but remains underutilized as a dietary source of provitamin A.

Is the exclusion of children under 24 months from anthelmintic treatment justifiable?

There are no reports documenting toxicity or adverse effects after treatment of children aged < 24 months with benzimidazole derivatives and there is an urgent need to clarify this point in light of the potential detrimental effect that soil-transmitted helminthiasis has on this age-group. A total of 653 treatments (317 mebendazole 500 mg; 336 placebo) were administered in 1996/97 to 212 children aged < 24 months as part of a 1-year anthelmintic drug study conducted among preschool-age children in Tanzania. Data on fever, cough, diarrhoea, dysentery and acute respiratory illness were collected 1 week following the treatment. No differences between the occurrence of adverse effects in the 2 groups were observed. In light of the potential nutritional benefit achieved by regular deworming in this young age-group, the policy that excludes children aged < 24 months from treatment should be re-considered.