Microglia drive APOE-dependent neurodegeneration in a tauopathy mouse model.

Chronic activation of brain innate immunity is a prominent feature of Alzheimer's disease (AD) and primary tauopathies. However, to what degree innate immunity contributes to neurodegeneration as compared with pathological protein-induced neurotoxicity, and the requirement of a particular glial cell type in neurodegeneration, are still unclear. Here we demonstrate that microglia-mediated damage, rather than pathological tau-induced direct neurotoxicity, is the leading force driving neurodegeneration in a tauopathy mouse model. Importantly, the progression of ptau pathology is also driven by microglia. In addition, we found that APOE, the strongest genetic risk factor for AD, regulates neurodegeneration predominantly by modulating microglial activation, although a minor role of apoE in regulating ptau and insoluble tau formation independent of its immunomodulatory function was also identified. Our results suggest that therapeutic strategies targeting microglia may represent an effective approach to prevent disease progression in the setting of tauopathy.

Aphthous ulcer drug inhibits prostate tumor metastasis by targeting IKKɛ/TBK1/NF-κB signaling.

Tumor metastasis is the major cause of death for prostate cancer (PCa) patients. However, the treatment options for metastatic PCa are very limited. Epithelial-mesenchymal transition (EMT) has been reported to be an indispensable step for tumor metastasis and is suggested to associate with acquisition of cancer stem cell (CSC) attributes. We propose that small-molecule compounds that can reverse EMT or induce mesenchymal-epithelial transition (MET) of PCa cells may serve as drug candidates for anti-metastasis therapy. Methods: The promoters of CDH1 and VIM genes were sub-cloned to drive the expression of firefly and renilla luciferase reporter in a lentiviral vector. Mesenchymal-like PCa cells were infected with the luciferase reporter lentivirus and subjected to drug screening from a 1274 approved small-molecule drug library for the identification of agents to reverse EMT. The dosage-dependent effect of candidate compounds was confirmed by luciferase reporter assay and immunoblotting. Wound-healing assay, sphere formation, transwell migration assay, and in vivo intracardiac and orthotopic tumor xenograft experiments were used to evaluate the mobility, metastasis and tumor initiating capacity of PCa cells upon treatment. Possible downstream signaling pathways affected by the candidate compound treatment were analyzed by RNA sequencing and immunoblotting. Results: Drug screening identified Amlexanox, a drug used for recurrent aphthous ulcers, as a strong agent to reverse EMT. Amlexanox induced significant suppression of cell mobility, invasion, serial sphere formation and in vivo metastasis and tumor initiating capacity of PCa cells. Amlexanox treatment led to downregulation of the IKK-ɛ/ TBK1/ NF-κB signaling pathway. The effect of Amlexanox on EMT reversion and cell mobility inhibition can be mimicked by other IKK-ɛ/TBK1 inhibitors and rescued by reconstitution of dominant active NF-κB. Conclusions: Amlexanox can sufficiently suppress PCa metastasis by reversing EMT through downregulating the IKK-ɛ/TBK1/NF-κB signaling axis.

Cost-effectiveness of roflumilast as an add-on to triple inhaled therapy vs triple inhaled therapy in patients with severe and very severe COPD associated with chronic bronchitis in the UK.

Purpose: Patients with severe COPD are at high risk of experiencing disease exacerbations, which require additional treatment and are associated with elevated mortality and increased risk of future exacerbations. Some patients continue to experience exacerbations despite receiving triple inhaled therapy (ICS plus LAMA plus LABA). Roflumilast is recommended by the Global Initiative for Chronic Obstructive Lung Disease as add-on treatment to triple inhaled therapy for these patients. This cost-effectiveness analysis compared costs and quality-adjusted life-years for roflumilast plus triple inhaled therapy vs triple inhaled therapy alone, using data from the REACT and RE2SPOND trials. Patients and methods: Patients included in the analysis had severe to very severe COPD, FEV1 <50% predicted, symptoms of chronic bronchitis and ≥2 exacerbations per year. Our model was adapted from a previously published and validated model, and the analyses conducted from a UK National Health Service perspective. A scenario analysis considered a subset of patients who had experienced at least one COPD-related hospitalization within the previous year. Results: Roflumilast as add-on to triple inhaled therapy was associated with non-significant reductions in rates of both moderate and severe exacerbations compared with triple inhaled therapy alone. The incremental cost-effectiveness ratio (ICER) for roflumilast as add-on to triple inhaled therapy was £24,976. In patients who had experienced previous hospitalization, roflumilast was associated with a non-significant reduction in the rate of moderate exacerbations, and a statistically significant reduction in the rate of severe exacerbations. The ICER for roflumilast in this population was £7,087. Conclusions: Roflumilast is a cost-effective treatment option for patients with severe or very severe COPD, chronic bronchitis, and a history of exacerbations. The availability of roflumilast as add-on treatment addresses an important unmet need in this patient population.

Mini Review: Chronic obstructive pulmonary disease, its new drug treatments and strategies: A review.

COPD is a complicated disease. Current available treatments are just for symptomatic relief and they cannot reverse the damages to lungs tissues due to alveolar destruction in COPD. Research is being conducted to evaluate new treatments and strategies to find specific treatments to minimize the symptoms of COPD. A new mixture of herbal medicine i.e AKL1 has emerged and thought to cure COPD symptoms especially cough related quality of life of COPD patients. Although, the results have showed no significant difference as compared to placebo but researchers recommend further evaluation in a large population (COPD Patients) group. Another medicine Roflumilast, a phosphodiesterase 4 inhibitor, was also found to be effective to treat COPD under specific recommendations with further research needed. Finally another medicine Indacaterol, a novel, once-daily (o.d) inhaled long-acting ß2-agonist proved to be effective clinically to treat COPD related broncho-constriction and also increasing the COPD patient's compliance by reducing the number of doses as compared to other conventional inhaled bronchodilators such as Albuterol.

Preclinical and Clinical Studies of Chidamide (CS055/HBI-8000), An Orally Available Subtype-selective HDAC Inhibitor for Cancer Therapy.

Epigenetic modifications play central roles in cellular differentiation and their deregulations really contribute to tumor development. Histone deacetylase (HDAC) enzymes can exert their functions in the epigenetic regulation of gene expression related to oncogenesis via deacetylating the lysine residues of histones in the chromatin and various non-histone proteins. A majority of HDAC inhibitors (HDACIs) have been in different stages of preclinical and clinical trials with potent anticancer activity recently. Among these agents, chidamide tested as either monotherapeutic agent or in combination regimens for numerous hematological and solid malignancies has shown promising potential as an orally active subtype-selective HDACI. Herein we will highlight the progress of clinical trials of chidamide and rationally analyze those results from both preclinical and clinical studies about chidamide as an epigenetic modulator in cancer therapy.

Sorafenib and DE605, a novel c-Met inhibitor, synergistically suppress hepatocellular carcinoma.

Sorafenib, an oral multikinase inhibitor of Raf, VEGF and PDGF receptor signaling is approved for advanced hepatocellular carcinoma (HCC). One strategy to improve HCC therapy is to combine agents that target key signaling pathways. Aberrant mesenchymal-epithelial transition factor (c-Met) activation is associated with a variety of human malignancies and therefore represents a target for therapy. In this study, we investigated a novel c-Met inhibitor, DE605, together with sorafenib in hepatocellular carcinoma cells in vitro and in vivo. DE605 and sorafenib synergistically induced apoptosis in hepatocellular carcinoma cells. Mechanistically, DE605 activated the FGFR3/Erk pathway, which in turn was inhibited by sorafenib, resulting in synergism. Finally, DE605 and sorafenib significantly inhibited growth of PLC/PRF/5 hepatocellular carcinoma tumor xenografts in athymic nude mice. Importantly, no obvious weight loss (toxicity) was detected. Thus in combination, DE605 and sorafenib target complementary anti-apoptotic pathways and synergistically suppress HCC, providing the rationale for clinical studies with this novel combination.

Increased KIT inhibition enhances therapeutic efficacy in gastrointestinal stromal tumor.

PURPOSE: Gastrointestinal stromal tumor (GIST) is the most common human sarcoma and a model of targeted molecular therapy. GIST depends on oncogenic KIT signaling and responds to the tyrosine kinase inhibitor imatinib. However, imatinib is rarely curative. We hypothesized that PLX3397, which inhibits KIT and colony-stimulating-factor-1 receptor (CSF1R), would be more efficacious than imatinib in GIST by also depleting tumor-associated macrophages, which are generally thought to support tumor growth. EXPERIMENTAL DESIGN: We treated Kit(V558del/+) mice that develop GIST or mice with subcutaneous human GIST xenografts with imatinib or PLX3397 and analyzed tumor weight, cellular composition, histology, molecular signaling, and fibrosis. In vitro assays on human GIST cell lines were also performed. RESULTS: PLX3397 was more effective than imatinib in reducing tumor weight and cellularity in both Kit(V558del)(/+) murine GIST and human GIST xenografts. The superiority of PLX3397 did not depend on depletion of tumor-associated macrophages, because adding CSF1R inhibition did not improve the effects of imatinib. Instead, PLX3397 was a more potent KIT inhibitor than imatinib in vitro. PLX3397 therapy also induced substantial intratumoral fibrosis, which impaired the subsequent delivery of small molecules. CONCLUSIONS: PLX3397 therapy has greater efficacy than imatinib in preclinical GIST models and warrants study in patients with GIST. The resultant intratumoral fibrosis may represent one of the barriers to achieving complete tumor eradication.

Flupirtine enhances the anti-hyperalgesic effects of morphine in a rat model of prostate bone metastasis.

OBJECTIVE: Current treatments for cancer pain are often inadequate, particularly when metastasis to bone is involved. The addition to the treatment regimen of another drug that has a complementary analgesic effect may increase the overall analgesia without the necessity to increase doses, thus avoiding dose-related side effects. This project investigated the synergistic effect of the addition of the potassium channel (KCNQ2-3) modulator flupirtine to morphine treatment in a rat model of prostate cancer-induced bone pain. DESIGN: Syngeneic prostate cancer cells were injected into the right tibia of male Wistar rats under anesthesia. This led to expanding tumor within the bone in 2 weeks, together with the concurrent development of hyperalgesia to noxious heat. Paw withdrawal thresholds from noxious heat were measured before and after the maximum non-sedating doses of morphine and flupirtine given alone and in combinations. Dose-response curves for morphine (0.13-5.0 mg/kg ip) and flupirtine (1.25-10.0 mg/kg ip) given alone and in fixed-dose combinations were plotted and subjected to an isobolographic analysis. RESULTS: Both morphine (ED50 = 0.74 mg/kg) and flupirtine (ED50 = 3.32 mg/kg) caused dose-related anti-hyperalgesia at doses that did not cause sedation. Isobolographic analysis revealed that there was a synergistic interaction between flupirtine and morphine. Addition of flupirtine to morphine treatment improved morphine anti-hyperalgesia, and resulted in the reversal of cancer-induced heat hyperalgesia. CONCLUSIONS: These results suggest that flupirtine in combination with morphine may be useful clinically to provide better analgesia at lower morphine doses in the management of pain caused by tumors growing in bone.

Efficacy of oral E1210, a new broad-spectrum antifungal with a novel mechanism of action, in murine models of candidiasis, aspergillosis, and fusariosis.

E1210 is a first-in-class, broad-spectrum antifungal with a novel mechanism of action-inhibition of fungal glycosylphosphatidylinositol biosynthesis. In this study, the efficacies of E1210 and reference antifungals were evaluated in murine models of oropharyngeal and disseminated candidiasis, pulmonary aspergillosis, and disseminated fusariosis. Oral E1210 demonstrated dose-dependent efficacy in infections caused by Candida species, Aspergillus spp., and Fusarium solani. In the treatment of oropharyngeal candidiasis, E1210 and fluconazole each caused a significantly greater reduction in the number of oral CFU than the control treatment (P < 0.05). In the disseminated candidiasis model, mice treated with E1210, fluconazole, caspofungin, or liposomal amphotericin B showed significantly higher survival rates than the control mice (P < 0.05). E1210 was also highly effective in treating disseminated candidiasis caused by azole-resistant Candida albicans or Candida tropicalis. A 24-h delay in treatment onset minimally affected the efficacy outcome of E1210 in the treatment of disseminated candidiasis. In the Aspergillus flavus pulmonary aspergillosis model, mice treated with E1210, voriconazole, or caspofungin showed significantly higher survival rates than the control mice (P < 0.05). E1210 was also effective in the treatment of Aspergillus fumigatus pulmonary aspergillosis. In contrast to many antifungals, E1210 was also effective against disseminated fusariosis caused by F. solani. In conclusion, E1210 demonstrated consistent efficacy in murine models of oropharyngeal and disseminated candidiasis, pulmonary aspergillosis, and disseminated fusariosis. These data suggest that further studies to determine E1210's potential for the treatment of disseminated fungal infections are indicated.

Memory facilitating effects of agomelatine in the novel object recognition memory paradigm in the rat.

The aim of the present study was to evaluate the effects of agomelatine, an antidepressant with melatonergic agonist and 5-HT(2C) antagonist properties, in the rat novel object recognition (NOR) task, a model of short-term episodic memory. To assess the potential involvement of its chronobiotic activity, single intraperitoneal administration of agomelatine and NOR testing were performed either in the evening or in the morning. In both conditions, using a 24h retention interval, vehicle-treated rats did not discriminate between the novel and the familiar object (recognition index was not different from chance performance) while object memory performance of rats treated with agomelatine either in the evening (10 and 40mg/kg) or in the morning (2.5, 10, and 40mg/kg) was significantly improved. Moreover, the selective 5-HT(2C) antagonist SB 242,084 (0.63, 2.5, and 10mg/kg) and melatonin (2.5, 10, and 40mg/kg) displayed also memory facilitating effects in both administration conditions. Finally, thioperamide used as positive reference compound to validate the experimental conditions, demonstrated a memory facilitating effect. In conclusion, agomelatine was shown to possess memory facilitating effects in the rat NOR task and both melatonergic agonist and 5-HT(2C) antagonist properties could be involved in these effects.

Pharmacokinetics and elucidation of the rates and routes of N-glucuronidation of PF-592379, an oral dopamine 3 agonist in rat, dog, and human.

PF-592379 is a potent, selective agonist of the dopamine 3 receptor, for the treatment of male erectile dysfunction and female sexual dysfunction. In vivo, PF-592379 has low-moderate clearance relative to liver blood flow of 6.3 and 8.5 ml/min/kg in dog and 44.8 and 58.2 ml/min/kg in rat. It has high permeability in Caco-2 cells and was completely absorbed in rat and dog pharmacokinetic studies with an oral bioavailability of 28% in both rats and 61 and 87% in the dogs. These data are consistent with the physicochemical properties of PF-592379, which indicate complete absorption by the transcellular route. Elimination of PF-592379 was predominantly metabolic in nature. In vitro routes of metabolism studies indicate that metabolism in the rat is a combination of P450 mechanisms and N-glucuronidation, whereas in dog and human, N-glucuronidation is the major route. NMR analysis indicates that N-glucuronidation is non-quaternary in nature and occurs on both the pyridyl amine and ring nitrogen. Rates of clearance via N-glucuronidation were predicted to be low in humans compared with acyl or phenolic glucuronidation. PF-592379 was predicted to have complete absorption from the gastrointestinal tract and an oral bioavailability of >60% in the clinic. Clinical data verified that PF-592379 is a low clearance compound in human, with a mean oral clearance of 6.5 ml/min/kg following a 200 mg oral dose. PF-592379 has ideal pharmacokinetic properties for an oral D3 agonist, intended for on demand dosing.

Reduced ghrelin secretion in the hypothalamus of rats due to cisplatin-induced anorexia.

Although chemotherapy with cisplatin is a widely used and effective cancer treatment, the undesirable gastrointestinal side effects associated with it, such as nausea, vomiting, and anorexia, markedly decrease patients' quality of life. To elucidate the mechanism underlying chemotherapy-induced anorexia, focusing on the hypothalamic ghrelin secretion-anorexia association, we measured hypothalamic ghrelin secretion in fasted and cisplatin-treated rats. Hypothalamic ghrelin secretion changes after vagotomy or administration of cisplatin. Cisplatin + rikkunshito, a serotonin 2C receptor antagonist or serotonin 3 receptor antagonist, was investigated. The effects of intracerebroventricular (icv) administration of ghrelin or the serotonin 2C receptor antagonist SB242084 on food intake were also evaluated in cisplatin-treated rats. Hypothalamic ghrelin secretion significantly increased in 24-h-fasted rats compared to freely fed rats and was markedly reduced 24 and 48 h after cisplatin treatment in cisplatin-treated rats compared to saline-treated rats, although their plasma ghrelin levels were comparable. In cisplatin-treated rats, icv ghrelin administration reversed the decrease in food intake, vagotomy partially restored hypothalamic ghrelin secretion, and hypothalamic serotonin 2C receptor mRNA expression increased significantly. Administration of rikkunshito (an endogenous ghrelin enhancer) or a serotonin 2C receptor antagonist reversed the decrease in hypothalamic ghrelin secretion and food intake 24 h after cisplatin treatment. Cisplatin-induced anorexia is mediated through reduced hypothalamic ghrelin secretion. Cerebral serotonin 2C receptor activation partially induces decrease in hypothalamic ghrelin secretion, and rikkunshito suppresses cisplatin-induced anorexia by enhancing this secretion.

Roflumilast for the treatment of chronic obstructive pulmonary disease.

Chronic obstructive pulmonary disease (COPD) is a progressive disease of the airways that is triggered primarily by smoking. It manifests clinically with dyspnea, cough and sputum production, all of which become aggravated with disease progression. The only intervention that can halt the decline in lung function in COPD is smoking cessation--other interventions and therapeutic treatments can only slow down the progression of the disease. Pharmacologic treatment of stable COPD consists primarily of bronchodilators, which are used for relieving symptoms and reducing lung function decline, and corticosteroids, which are used for minimizing the associated inflammation. Methylxanthines are non-selective phosphodiesterase (PDE) inhibitors with bronchodilatory and anti-inflammatory effects; however, their use in COPD and other respiratory conditions is limited by their narrow therapeutic index and poor safety profile. Cilomilast and roflumilast are selective PDE4 inhibitors that are currently in pre-registration and phase III clinical trials, respectively, for the treatment of COPD (cilomilast and roflumilast) and asthma (roflumilast).

CYP3A induction by N-hydroxyformamide tumor necrosis factor-alpha converting enzyme/matrix metalloproteinase inhibitors use of a pregname X receptor activation assay and primary hepatocyte culture for assessing induction potential in humans.

A series of N-hydroxyformamide tumor necrosis factor-alpha converting enzyme (TACE)/matrix metalloprotease (MMP) inhibitors were evaluated for their potential to induce human cytochrome P450 3A (CYP3A). Two in vitro assays were used: 1) a cell-based reporter gene assay for activation of the pregnane X receptor (PXR), and 2) a primary "sandwich" culture of human hepatocytes. Approximately 50 TACE/MMP inhibitors were evaluated in the human PXR assay. A range of PXR activation was observed, 0 to 150% of the activation of the known human CYP3A inducer rifampicin. Three TACE/MMP inhibitors were evaluated in rat and human hepatocytes. Significantly higher PXR activation/CYP3A induction was observed in PXR/hepatocyte models, respectively, for (2R,3S) 3-(formyl-hydroxyamino)-2-(2-methyl-1-propyl)-4-methylpentanoic acid [(1S,2S)-2-methyl-1-(2-pyridylcarbamoyl)-1-butyl]amide (GW3333) compared with (2R,3S)-6,6,6-trifluoro-3-[formyl(hydroxy)amino]-2-isobutyl-N-[(1S,2R)-2-methoxy-1-[(1,3-thiazol-2-ylamino)carbonyl]propyl]hexanamide (GW6495) and (2R)-N-[(1S)-2,2-dimethyl-1-[(methylamino)carbonyl]-propyl]-2-[(1S)-1-[formyl(hydroxy)amino]ethyl]-5-phenylpentanamide (GI4023). The CYP3A induction level achieved with GW3333 at a concentration of approximately 10 microM in human hepatocytes was comparable to that achieved with rifampicin at a concentration of 10 microM. The extent of rodent CYP3A induction caused by GW3333 was confirmed in vivo after daily oral administration for 14 days to rats. In conclusion, GW3333 is a potential inducer of CYP3A expression in vivo in humans, but other N-hydroxyformamides are less likely to induce CYP3A.

Analgesic activity following combined oral administration of flupirtine maleate and peripherally acting analgesics in mice and rats.

Concomitant administration of flupirtine maleate at a single low dose (15 mg/kg, mice; 35 mg/kg, rats) with a wide range of doses of each of the peripherally acting analgesics enhanced the antinociceptive activity of paracetamol, acetylsalicyclic acid and ibuprofen in the acetic acid writhing test, acetylsalicylic acid in the hot plate test and paracetamol, acetylsalicyclic acid and ibuprofen in the Randall-Selitto test. The concomitant administration of a single low dose of the peripherally acting analgesics (at about 1/2 ED50) with a wide range of doses of flupirtine maleate resulted in enhancement of flupirtine maleate analgesic activity by paracetamol (in the hot plate and Randall-Selitto tests), acetylsalicyclic acid (in the acetic acid writhing test), ibuprofen (in the Randall-Selitto test) and indomethacin (in the acetic acid and Randall-Selitto tests). Thus flupirtine maleate enhanced the analgesic activity of paracetamol, acetylsalicyclic acid and ibuprofen in mice and rats. Each of the peripherally acting analgesics enhanced the analgesic activity of flupirtine maleate in one or more of the analgesic tests used.

Flupirtine: the first Italian experience.

This paper reports the results of five single-dose short-term, controlled clinical trials conducted in Italy with the structurally new analgesic flupirtine. A total of 200 patients were enrolled in the trials. One hundred and two patients received flupirtine, 61 were treated with reference drugs (suprofen and paracetamol) and 37 were on placebo. Analgesic efficacy was evaluated in post-episiotomy pain (2 studies and 70 patients), post-traumatic pain (2 studies and 100 patients) and in 30 post-operative patients. Flupirtine was given as a single dose of 100 mg (one capsule) or as a single day's treatment (100 mg t.i.d.). For suprofen and paracetamol, oral doses of 200 mg and 500 mg respectively were used. A semi-quantitative four- or five-point scale or a linear analogue scale was used to determine the degree of pain. In post-episiotomy pain, the time required to achieve a reduction of 50% of the initial pain was also used. In post-operative pain, flupirtine induced a 69% reduction in the pain score 6 hours after administration, compared with 26% in the placebo group. In post-episiotomy pain and pain due to sport injury, flupirtine showed greater efficacy as judged by the number of patients reporting good and acceptable pain relief, and a faster onset of pain relief than suprofen (episiotomy) or paracetamol plus massage (sport injury). The adverse reaction, nausea, was complained of once only during treatment with flupirtine.

Chronic congestive heart failure. Where have we been? Where are we heading?

Chronic congestive heart failure is a frequently occurring disease associated with an impaired quality of life and significant mortality rate. Progress has been made in dissecting the pathophysiologic changes of congestive failure and in using vasodilators, newer positive inotropic agents, and other treatment modalities. Despite these advances, the overall mortality rate from congestive heart failure has not decreased. Further, many unanswered questions remain: How and why does a myocardial cell die? How should quality of life be measured? When should vasodilators and positive inotropic agents be given? What role do receptors play in pathogenesis and therapy? Can sudden death in heart failure be prevented? These and other questions will provide the stimulus for further studies in congestive heart failure.

[Pymadine, a new type of non-depolarizing muscle-relaxant antagonist]. / Pymadine, un nou tip de antagonist al miorelaxantelor nedepolarizante.

The paper presents the author's experience in post-anesthetic decurarization with a new antagonist of competitive curare. Presented for the first time in 1970, 4-amino-pyridine was found o tbe a substance with a different mode of action than that of reversible inhibitors of cholinesterase, without parasympaticomimetic effects, and without untoward effects on the cardio-circulatory function. It also has a central analeptic effect. This is why the authors consider the new drug as a powerful means for reversing the competitive neuromuscular blockage.

4-Aminopyridine potentiates neostigmine and pyridostigmine in man.

To elucidate the interaction of 4-aminopyridine with neostigmine and pyridostigmine, the authors studied 57 anesthetized surgical patients using a technique of constant infusion of pancuronium to quantitate antagonist activity. 4-Aminopyridine, 0.15 or 0.35 mg/kg, produced no antagonism, while 0.5 mg/kg produced a mean 24 +/- 6 per cent (peak) antagonism. The dose that produced 50 per cent antagonism (ED50) of neostigmine alone was 22 micrograms/kg; with 0.35 mg/kg 4-aminopyridine, it was 7 micrograms/kg. The ED50 of pyridostigmine alone was 110 micrograms/kg; with 0.35 mg/kg 4-aminopyridine, it was 27 micrograms/kg. 4-Aminopyridine prolonged the onset times of both neostigmine and pyridostigmine, but prolonged the duration of action of neostigmine only. At a given level of antagonism of pancuronium, adding 4-aminopyridine 0.35 mg/kg, to neostigmine and to pyridostigmine decreased the amounts of atropine needed to prevent a change in heart rate by 68 and 70 per cent, respectively. The authors conclude that 4-aminopyridine potentiates antagonism of a pancuronium-induced neuromuscular blockade by neostigmine or pyridostigmine. Also, less atropine is needed to prevent cardiac muscarinic stimulation when 4-aminopyridine is used with either neostigmine or pyridostigmine.