Preclinical Evaluation of a Novel Once-a-Day Brimonidine Ophthalmic Nanosuspension.

Purpose: This article aims to describe a preclinical proof of concept for a novel once-a-day (OD) brimonidine ophthalmic nanosuspension. Methods: The preclinical proof of concept was established using New Zealand white rabbits as animal models. Dose-finding, multiple-dose efficacy, ocular pharmacokinetic, and hemodynamic studies were performed in normotensive rabbits. Steroid-induced ocular hypertension model in rabbits was used to study efficacy in glaucomatous pathophysiology. The test (0.35% OD suspension) and reference (0.15% three times a day [TID] solution) were compared. Results: The intraocular pressure (IOP) reduction was sustained for 0.35% and 0.5% strengths but not for other lower strengths tested or reference strengths. A 0.35% OD suspension reduced IOP >2 mmHg after 24 h of dosing, which was not seen with the reference. After multiple dosing, 0.35% OD suspension reduced IOP by 4-6 mmHg after 24 h, which was comparable to the 0.15% TID reference solution. An ocular pharmacokinetic study showed that the brimonidine was rapidly absorbed and distributed throughout the eye after topical administration. Concentration was higher in tissues with high α2 receptors, such as cornea-conjunctiva, iris/ciliary body, and choroid/retina. The steady-state concentrations in these organs were also significant after 24 h of the last dose. There was an indication of increased plasma levels, so a hemodynamic study was performed to assess any adverse effects. All hemodynamic parameters were normal and no new unusual safety findings were observed. Conclusions: The study demonstrated that the novel brimonidine 0.35% ophthalmic nanosuspension is both safe and effective when administered OD and is comparable to the marketed reference formulation administered TID.

Plasma and cerebrospinal fluid pharmacokinetics of vodobatinib, a neuroprotective c-Abl tyrosine kinase inhibitor for the treatment of Parkinson's disease.

BACKGROUND: Preclinical evidence suggests that c-Abl is critical in the pathogenesis of Parkinson's Disease (PD). Vodobatinib (K0706) is a potent, specific Abl kinase inhibitor currently being developed for the treatment of PD. In previously reported studies, nilotinib, a multikinase c-Abl inhibitor, did not show clinical activity as evidenced by no improvement of symptoms or the rate of decline after one to six months of treatment at the maximum permissible dose, presumably because of insufficient CNS penetration. Here we report clinical PK and safety data for vodobatinib. OBJECTIVES: To determine safety, plasma PK, and CSF penetration of vodobatinib in healthy volunteers and PD subjects following oral administration, and compare CSF levels to in vitro concentrations required for c-Abl inhibition relative to data reported for nilotinib. METHODS: Inhibition of c-Abl kinase activity and c-Abl binding affinity were first assessed in vitro. Healthy human volunteers and PD patients received various oral doses of vodobatinib once-daily for seven and fourteen days respectively, to assess safety, and plasma and CSF PK. RESULTS: In in vitro assays, vodobatinib was more potent (kinase IC50 = 0.9 nM) than nilotinib (kinase IC50 = 15-45 nM). Administration of vodobatinib 48, 192 and 384 mg to healthy subjects for 7 days yielded mean Cmax, CSF values of 1.8, 11.6, and 12.2 nM respectively, with the two highest doses exceeding the IC50 over the entire dosing interval. Cavg, CSF values were 6-8 times greater than the IC50. Comparable CSF levels were observed in PD patients. All doses were well tolerated in both cohorts. CONCLUSION: Based on achieved CSF concentrations, the potential for c-Abl inhibition in the brain is substantially higher with vodobatinib than with nilotinib. The CSF PK profile of vodobatinib is suitable for determining if c-Abl inhibition will be neuroprotective in PD patients.

Syringic Acid Ameliorates Cardiac, Hepatic, Renal and Neuronal Damage Induced by Chronic Hyperglycaemia in Wistar Rats: A Behavioural, Biochemical and Histological Analysis.

This study investigated the effects of syringic acid (SA) on renal, cardiac, hepatic, and neuronal diabetic complications in streptozotocin-induced neonatal (nSTZ) diabetic rats. STZ (110 mg/kg i.p) was injected into Wistar rat neonates as a split dose (second and third postnatal day). Diabetes mellitus was diagnosed in adults by measuring fasting blood glucose levels, urine volume, and food and water intake. The treatment of SA (25 mg/kg, 50 mg/kg p.o) was given from the 8th to 18th postnatal week. To assess the development of diabetic complications and the effect of therapy, biochemical indicators in serum and behavioural parameters were recorded at specific intervals during the study period. SA (25 mg/kg, 50 mg/kg p.o) treatment reduced hyperglycaemia, polydipsia, polyphagia, polyuria, relative organ weight, cardiac hypertrophic indices, inflammatory markers, cell injury markers, glycated haemoglobin, histopathological score, and oxidative stress, and increased Na/K ATPase activity. These findings suggest that SA might significantly alleviate diabetic complications and/or renal, neuronal, cardiac, and hepatic damage in nSTZ diabetic rats.

Development and characterization of liposomal formulation of bortezomib.

Bortezomib is a proteasome inhibitor used for the treatment of multiple myeloma. The poor pharmacokinetic profile and off-target adverse effects provide a strong incentive to develop drug delivery systems for bortezomib. In the past, liposomal encapsulation has been proven to improve the therapeutic index of a variety of anti-neoplastic therapeutics. Here, we developed and characterized liposomal bortezomib formulations in order to find the most optimal loading conditions. Polyols were used to entrap bortezomib inside the liposomes as boronate ester via a remote loading strategy. Effect of various polyols, incubation duration, temperature, and total lipid concentration on loading efficiency was examined. Moreover, the effect of drug/lipid ratio on the release kinetics was studied. Loading efficiency was maximal when using meglumine plus mannitol as entrapping agents. Loading at room temperature was better than at 60 °C and loading efficiency was increased with increasing total lipid concentrations. There was a positive correlation between drug/lipid ratio and released amount of bortezomib. In vitro release kinetics in HBS and human plasma showed time dependent release. In HBS, at 4 °C, only 20% of the drug was released in three weeks, whereas at 37 °C 85% of the drug was released in 24 h. In human plasma, 5% of the drug retained after 24 h indicating faster release. Taken together, the most favorable liposomal formulation of bortezomib should be further exploited to study in vitro and in vivo efficacy performance.

Liposomal dexamethasone inhibits tumor growth in an advanced human-mouse hybrid model of multiple myeloma.

Glucocorticoids are the cornerstone in the clinic for treatment of hematological malignancies, including multiple myeloma. Nevertheless, poor pharmacokinetic properties of glucocorticoids require high and frequent dosing with the off-target adverse effects defining the maximum dose. Recently, nanomedicine formulations of glucocorticoids have been developed that improve the pharmacokinetic profile, limit adverse effects and improve solid tumor accumulation. Multiple myeloma is a hematological malignancy characterized by uncontrolled growth of plasma cells. These tumors initiate increased angiogenesis and microvessel density in the bone marrow, which might be exploited using nanomedicines, such as liposomes. Nano-sized particles can accumulate as a result of the increased vascular leakiness at the bone marrow tumor lesions. Pre-clinical screening of novel anti-myeloma therapeutics in vivo requires a suitable animal model that represents key features of the disease. In this study, we show that fluorescently labeled long circulating liposomes were found in plasma up to 24 h after injection in an advanced human-mouse hybrid model of multiple myeloma. Besides the organs involved in clearance, liposomes were also found to accumulate in tumor bearing human-bone scaffolds. The therapeutic efficacy of liposomal dexamethasone phosphate was evaluated in this model showing strong tumor growth inhibition while free drug being ineffective at an equivalent dose (4 mg/kg) regimen. The liposomal formulation slightly reduced total body weight of myeloma-bearing mice during the course of treatment, which appeared reversible when treatment was stopped. Liposomal dexamethasone could be further developed as monotherapy or could fit in with existing therapy regimens to improve therapeutic outcomes for multiple myeloma.

Nanomedicines for the treatment of hematological malignancies.

Hematological malignancies (HM) are a collection of malignant transformations originating from cells in the primary or secondary lymphoid organs. Leukemia, lymphoma, and multiple myeloma comprise the three major types of HM. Current treatment consists of bone marrow transplantation, radiotherapy, immunotherapy and chemotherapy. Although, many chemotherapeutic drugs are clinically available for the treatment of HM, the use of these agents is limited due to dose-related toxicity and lack of specificity to tumor tissue. Moreover, the poor pharmacokinetic profile of most of the chemotherapeutics requires high dosage and frequent administration to maintain therapeutic levels at the target site, both increasing adverse effects. This underlines an urgent need for a suitable drug delivery system to improve efficacy, safety, and pharmacokinetic properties of conventional therapeutics. Nanomedicines have proven to enhance these properties for anticancer therapeutics. The most extensively studied nanomedicine systems are lipid-based nanoparticles and polymeric nanoparticles. Typically, nanomedicines are small sub-micron sized particles in the size range of 20-200 nm. The biocompatible and biodegradable nature of nanomedicines makes them attractive vehicles to improve drug delivery. Their small size allows them to extravasate and accumulate at malignant sites passively by means of the enhanced permeability and retention (EPR) effect, resulting from rapid angiogenesis and inflammation. Moreover, the specificity to the target tissue can be further enhanced by surface modification of nanoparticles. This review describes currently available therapies as well as limitations and potential advantages of nanomedicine formulations for treatment of various types of HM. Additionally, recent investigational and approved nanomedicine formulations and their limited applications in HM are discussed.

Induction of glucose intolerance by acute administration of rimonabant.

BACKGROUND/AIMS: Rimonabant is a cannabinoid CB1 receptor antagonist. Other CB1 antagonists have biphasic effects on blood glucose levels following acute administration. We therefore tested the effects of rimonabant on glucose tolerance following acute administration. METHODS: We tested the effects of oral and intracerebroventricular administration of rimonabant on blood glucose and gastrointestinal transit in mice following oral and intravenous glucose challenge. RESULTS: We found a dose-dependent increase in blood glucose from oral doses of rimonabant of 3 mg/kg and above. WIN55,212-2 (3 mg/kg), a cannabinoid receptor agonist, did not influence blood glucose in the presence or absence of rimonabant. Rimonabant did not induce release of glucose from isolated rat hepatocytes or modify serum insulin concentration in mice. Intracerebroventricular administration of rimonabant caused increases in blood glucose and gastrointestinal transit, suggesting a central nervous system site of action. Increases in blood glucose by rimonabant were partially blocked by the dopamine receptor antagonist haloperidol and significantly blocked by the 5-hydroxytryptophan(5-HT) depleting agent p-CPA and the 5-HT 3 receptor antagonist ondansetron. CONCLUSIONS: Rimonabant causes dose-dependent increase in glucose profile upon glucose challenge partially mediated by the central nervous system control of gastrointestinal carbohydrate absorption through pathways that are modulated by both 5-HT and dopamine.

Allergic rhinitis: an update on disease, present treatments and future prospects.

Allergic rhinitis (AR) is an inflammation of nasal mucosa mediated by IgE-associated processes occurring independently, or concurrently with asthma. AR is characterized by sensitization-formation and expression of antigen specific IgE, followed by inflammation in two phases. The early phase response involves cross linking of IgE molecules leading to degranulation of mast cells and release of preformed mediators such as histamine and tryptase, or newly synthesized mediators such as prostaglandins and leukotrienes. The late phase response is predominated by the presence of eosinophils, lymphocytes, cytokines, and adhesion molecules. Newer insights reveal that the whole phenomenon of immunological inflammation is intricately knit with neural pathways, which strongly influence the process. Furthermore, AR can impact psychological health and vice versa. Classical pharmacotherapy of AR includes use of oral or topical antihistamines, oral antileukotrienes, topical corticosteroids, mast cell stabilizers, decongestants, and an anticholinergic agent. Among immunomodulatory treatments, immunotherapy is gaining widespread use, while antibody treatment is restricted mainly to resistant cases. Several small molecules with improved safety profile, or targeting novel mechanisms are in the clinical research. Newer antihistamines and corticosteroids with improved safety profile and antagonists of the prostaglandin D(2) (CRTH2) receptors are likely to be available for clinical use in the near future. Lack of properly validated animal models and complexities associated with clinical evaluation are some of the challenges facing the researchers in AR. Comprehensive understanding of immunological and neurological processes in AR would facilitate the future quest for more effective and safer management of this disease.

Characterization of anti-inflammatory properties and evidence for no sedation liability for the novel antihistamine SUN-1334H.

BACKGROUND: The anti-inflammatory potential of antihistamines has significant clinical utility. Long-term pharmacotherapy of so-called 'safe' antihistamines may be hampered by side effects in the central nervous system. In the present study, the new potential antihistamine SUN-1334H was compared with different antihistamines for anti-inflammatory effects, sedation potential and interaction with alcohol. METHOD: Nasal and skin allergy were induced in guinea pig and mice by ovalbumin sensitization and challenge. Neurogenic nasal inflammation was induced by capsaicin. Sedation potential and interaction with alcohol were assessed by i.v. and intracerebroventricular pentobarbital-induced sedation and alcohol-induced ataxia models. RESULTS: Ovalbumin sensitization and challenge caused rhinitis pathology including inflammatory cell infiltration, IL-4, and protein leakage in the nasal lavage fluid (NLF) and presence of inflammatory cells in nasal epithelium. A 5-day treatment of antihistamines reduced these markers of inflammation. SUN-1334H, cetirizine and hydroxyzine caused comparable inhibition of NLF leukocytes, IL-4 and total protein concentrations. Fexofenadine and desloratadine showed moderate inhibition of NLF leukocytes and had no significant effect on IL-4 concentration. While fexofenadine had no effect on total protein concentration, the effect of desloratadine was comparable with the other antihistamines. In neurogenic nasal inflammation induced by capsaicin, SUN-1334H and fexofenadine caused better inhibition at lower and middle dose levels than the other antihistamines. In skin allergy models, SUN-1334H showed potent reduction of passive and active cutaneous anaphylactic reactions. In central nervous system side effects models, SUN-1334H, desloratadine and fexofenadine were devoid of any significant effects. CONCLUSIONS: The results are suggestive of a high anti-inflammatory to sedation index of SUN-1334H among leading antihistamines.

Validation of guinea pig model of allergic rhinitis by oral and topical drugs.

Ovalbumin-induced guinea pig model of rhinitis was assessed for its utility in the studies of rhinitis. Systemic sensitization and challenge with ovalbumin-induced rhinitis symptoms and an increase in anti-OVA-IgE and IgG titers, positive skin reactions and nasal lavage IL-4 concentration. Histopathology of nasal mucosa showed infiltration of eosinophils and other inflammatory cells consistent with the symptoms. Topical sensitization of ovalbumin yielded inconsistent symptoms of rhinitis. In systemic sensitization model, repeated challenge of ovalbumin caused similar response for at least 3 consecutive challenges. The symptoms were affected by relative humidity in the air and dosing volume of topical drugs. Sneezing and lacrimation were reduced by acute oral administration of the H1 receptor antagonists and steroids or the prophylactic oral administration of cysteinyl leukotriene (CysLT1) receptor antagonist montelukast or acute topical antihistamines, mast cell stabilizer sodium cromoglycate and anticholinergic agent ipratropium bromide, but not by a topical steroid. Nose rubbing was reduced significantly by some oral and topical antihistamines. Oral steroids offered excellent protection against all symptoms. Dexamethasone and montelukast also inhibited nasal lavage IL-4 concentration and inflammatory cell infiltration. Treatment with topical steroid fluticasone for 2 weeks had no effect on sneezing or rubbing. However, it caused complete inhibition of congestion. The cyclooxygenase inhibitor indomethacin had no effect on symptoms of rhinitis. The adrenergic alpha receptor agonist-decongestant oxymetazoline caused reduction in congestion. These results suggest that differential responsiveness to symptoms of rhinitis by a new agent can be very well profiled in the model in congruence with the mediation pathways and mechanism of action of drugs. The model provides complete symptomatic characterization of rhinitis and is a good tool for its study.

Preclinical efficacy and safety pharmacology of SUN-1334H, a potent orally active antihistamine agent.

OBJECTIVE: These studies aimed to outline the in vitro and in vivo histamine H(1) receptor antagonistic activity and safety pharmacology of SUN-1334H, a new potent antihistamine agent under clinical development. METHODS: In vitro antihistamine activity and selectivity of SUN-1334H was evaluated in a panel of receptor and enzyme assays and functional assays using isolated tissues. In vivo antihistamine and antiallergy efficacy were assessed following oral administration of SUN-1334H in histamine-induced bronchoconstriction in guinea pigs, skin wheal in beagle dogs and ovalbumin-induced rhinitis (sneezing, vascular permeability and intranasal pressure) in guinea pigs. Cardiovascular safety was assessed by CHO-K1/human ether-à-go-go related gene (hERG) K(+) current assay, dog telemetry and guinea-pig ECG. CNS safety was assessed by functional observational battery in rats and pentobarbital-induced sedation and pentylenetetrazol-induced convulsions in mice. The effect on intestinal motility was assessed in rats. RESULTS: In vitro receptor binding assays showed that SUN-1334H had high histamine H(1) receptor binding affinity with an inhibition constant value of 9.7 nmol/L and either no or insignificant affinity with a panel of receptors and enzymes. In functional assays, SUN-1334H caused potent inhibition of histamine-induced contractions of isolated guinea-pig ileum with an IC(50) (half the maximal inhibitory concentration) of 0.198 micromol/L. In contrast, SUN-1334H had no significant effect on isolated tissue contractions induced by cholinergic, H(2)-histaminergic, serotonergic, adrenergic receptor agonists or BaCl(2). In studies of animal models of histamine-mediated disorders, SUN-1334H potently inhibited histamine-induced bronchospasm over 24 hours following oral administration and completely suppressed histamine-induced skin wheal in beagle dogs and ovalbumin-induced rhinitis in guinea pigs. In CHO-K1/hERG cells, SUN-1334H did not modulate hERG K(+)-currents at concentrations as high as 100 micromol/L. Cardiovascular and CNS function and intestinal motility were not altered at doses several-fold greater than those required for efficacy, indicating a good safety profile of the drug. CONCLUSIONS: SUN-1334H is a potent, orally active, highly selective H(1) receptor antagonist with a long duration of action in its preclinical profile. It has potential for the treatment of disorders involving histamine as a mediator.

Timed pentylenetetrazol infusion test: a comparative analysis with s.c.PTZ and MES models of anticonvulsant screening in mice.

The intravenous pentylenetetrazol (i.v.PTZ) seizure test provides threshold dose for induction of seizures in individual animals. In the present study, the i.v. and s.c.PTZ seizure models in mice were compared for seizure pattern, intra- and interanimal variability. Anticonvulsant activities of several antiepileptic drugs (AEDs) at non-ataxic dose levels were evaluated in the PTZ and maximal electroshock (MES) seizure tests. In the i.v.PTZ test, at 0.5 ml/min rate of administration, the mean threshold PTZ doses for induction of clonus and tonic extensor were 44.17 and 99.59 mg/kg, respectively. The intra- and interanimal variabilities in the seizure response were low in the i.v.PTZ as compared to the s.c.PTZ model. Phenobarbital sodium, ethosuximide, sodium valproate, diazepam, tiagabine, oxcarbazepine and zonisamide enhanced threshold or onset latency for clonus in the i.v. and s.c.PTZ tests, respectively. Levetiracetam and pregabalin were active in the i.v.PTZ test, but had no effect in the s.c.PTZ test. Ability of AEDs to protect from tonic extensor was compared in the MES and i.v.PTZ tests. For this effect, phenobarbital sodium, phenytoin, carbamazepine, sodium valproate, gabapentin, oxcarbazepine, zonisamide and pregabalin were effective in the i.v.PTZ and MES tests. Ethosuximide, diazepam and levetiracetam were effective in the i.v.PTZ test, but not the MES test. On the contrary, lamotrigine and topiramate were active in the MES, but not the i.v.PTZ test. These results indicate that it is advantageous to use i.v.PTZ test as an acute seizure model for screening of antiepileptic drugs. This model can identify molecules with varied mechanism of action and broad clinical utility in the treatment of epilepsy.