Beta-Blockers and Berberine: A Possible Dual Approach to Contrast Neuroblastoma Growth and Progression.

The use of nutraceuticals during cancer treatment is a long-lasting debate. Berberine (BBR) is an isoquinoline quaternary alkaloid extracted from a variety of medicinal plants. BBR has been shown to have therapeutic effects in different pathologies, particularly in cancer, where it affects pathways involved in tumor progression. In neuroblastoma, the most common extracranial childhood solid tumor, BBR, reduces tumor growth by regulating both stemness and differentiation features and by inducing apoptosis. At the same time, the inhibition of ß-adrenergic signaling leads to a reduction in growth and increase of differentiation of neuroblastoma. In this review, we summarize the possible beneficial effects of BBR in counteracting tumor growth and progression in various types of cancer and, in particular, in neuroblastoma. However, BBR administration, besides its numerous beneficial effects, presents a few side effects due to inhibition of MAO A enzyme in neuroblastoma cells. Therefore, herein, we proposed a novel therapeutic strategy to overcome side effects of BBR administration consisting of concomitant administration of BBR together with ß-blockers in neuroblastoma.

Discovery of ß-Adrenergic Receptors Blocker-Carbonic Anhydrase Inhibitor Hybrids for Multitargeted Antiglaucoma Therapy.

The combination of a ß-adrenergic receptors (AR) blocker and a carbonic anhydrase (CA, EC 4.2.1.1) inhibitor in eye drops formulations is one of the most clinically used treatment for glaucoma. A novel approach consisting of single-molecule, multitargeted compounds for the treatment of glaucoma is proposed here by designing compounds which concomitantly interact with the ß-adrenergic and CA targets. Most derivatives of the two series of benzenesulfonamides incorporating 2-hydroxypropylamine moieties reported here exhibited striking efficacy against the target hCA II and XII, whereas a subset of compounds also showed significant modulation of ß1- and ß2-ARs. X-ray crystallography studies provided rationale for the observed hCA inhibition. The best dual-agents decreased IOP more effectively than clinically used dorzolamide, timolol, and the combination of them in an animal model of glaucoma. The reported evidence supports the proof-of-concept of ß-ARs blocker-CAI hybrids for antiglaucoma therapy with an innovative mechanism of action.

Function-specific virtual screening for GPCR ligands using a combined scoring method.

The ability of scoring functions to correctly select and rank docking poses of small molecules in protein binding sites is highly target dependent, which presents a challenge for structure-based drug discovery. Here we describe a virtual screening method that combines an energy-based docking scoring function with a molecular interaction fingerprint (IFP) to identify new ligands based on G protein-coupled receptor (GPCR) crystal structures. The consensus scoring method is prospectively evaluated by: 1) the discovery of chemically novel, fragment-like, high affinity histamine H1 receptor (H1R) antagonists/inverse agonists, 2) the selective structure-based identification of ß2-adrenoceptor (ß2R) agonists, and 3) the experimental validation and comparison of the combined and individual scoring approaches. Systematic retrospective virtual screening simulations allowed the definition of scoring cut-offs for the identification of H1R and ß2R ligands and the selection of an optimal ß-adrenoceptor crystal structure for the discrimination between ß2R agonists and antagonists. The consensus approach resulted in the experimental validation of 53% of the ß2R and 73% of the H1R virtual screening hits with up to nanomolar affinities and potencies. The selective identification of ß2R agonists shows the possibilities of structure-based prediction of GPCR ligand function by integrating protein-ligand binding mode information.

Synthesis and ß-adrenergic blocking activity of oxime ether hybrids derived from a natural isochroman-4-one.

AIM: In a search for new cardiovascular drug candidates, a series of novel oxime ethers derived from a natural isochroman-4-one were synthesized. METHOD: Compounds 3 and 6, derived from the natural antihypertensive compound 7, 8-dihydroxy-3-methyl-isochroman-4-one (XJP), were designed and synthesized. Subsequently, a series of novel isochroman-4-one oxime ether hybrids were prepared by hybridizing various N-substituted isopropanolamine functionalities to isochroman-4-one oxime. Furthermore, ß1-adrenergic blocking activities of the synthesized compounds were assayed using the isolated rat left atria. RESULTS: Twenty target compounds were obtained, and the preliminary structure-activity relationships were deduced. The most promising compound Ic exhibited ß1-adrenoceptor blocking activity (inhibition: 52.2%) at 10(-7) mol·L(-1), which was superior to that of propranolol (inhibition: 49.7%). CONCLUSION: The results suggested that natural product XJP/isopropanolamine moiety hybrids may provide a promising approach for the discovery of novel cardiovascular drug candidates.

Activity of crude cold-water extract of the culinary-medicinal oyster mushroom, Pleurotus ostreatus (Jacq.:Fr.) P.Kumm. (higher Basidiomycetes), and timolol maleate on induced ocular hypertension.

Aqueous crude cold-water extract from the fruiting body of the culinary-medicinal oyster mushroom Pleurotus ostreatus was assessed for activity against increased intra-ocular pressure (IOP) in mice. A 0.1% dexamethasone instillation was used to raise the intra-ocular pressure in the animals above the 21-mmHg threshold limit. The extract has intrinsic anti-hypertensive properties that are dose dependent. A comparison analysis indicated that 150 mg/mL of the crude extract produced 57.69% reduction in the intra-ocular pressure, while doses of 100 mg/ mL and 200 mg/mL produced 44.78% and 70.03% IOP reduction, respectively, compared with timolol maleate with 57.69%. The results were significant at 0.05 confidence limit (p < 0.05) when compared to a placebo and therefore support its use for the treatment of increased intra-ocular pressure.

Release behaviour of propranolol HCl from hydrophilic matrix tablets containing psyllium powder in combination with hydrophilic polymers.

The objective of this study was to investigate the release behaviour of propranolol hydrochloride from psyllium matrices in the presence hydrophilic polymers. The dissolution test was carried out at pH 1.2 and pH 6.8. Binary mixtures of psyllium and hydroxypropyl methylcellulose (HPMC) used showed that an increase in the percentage of HPMC in the binary mixtures caused a significant decrease in the release rate of propranolol. Psyllium-alginate matrices produced lower drug release as compared to when the alginate was the matrix former alone. When sodium carboxy methyl cellulose (NaCMC) was incorporated into the psyllium, the results showed that matrices containing the ratio of psyllium-NaCMC in the 1:1 ratio are able to slow down the drug release significantly as compared to matrices made from only psyllium or NaCMC as retardant agent suggesting that there could be a synergistic effect between psyllium and NaCMC. The double-layered tablets showed that the psyllium and HPMC in the outer shell of an inner formulation of psyllium alone had the greatest effect of protecting the inner core and thus producing the lowest drug release (DE = 38%, MDT = 93 min). A significant decrease in the value of n in Q = kt(n) from 0.70 to 0.51 as the psyllium content was increased from 50 to 150 mg suggests that the presence of psyllium in HPMC matrices affected the release mechanism. Psyllium powder had the ability in the combination with other hydrophilic polymers to produce controlled release profiles. Care and consideration should as such be taken when formulating hydrophilic matrices in different combinations.

Brain mitochondrial drug delivery: influence of drug physicochemical properties.

PURPOSE: To determine the influence of drug physicochemical properties on brain mitochondrial delivery of 20 drugs at physiological pH. METHODS: The delivery of 8 cationic drugs (beta-blockers), 6 neutral drugs (corticosteroids), and 6 anionic drugs (non-steroidal anti-inflammatory drugs, NSAIDs) to isolated rat brain mitochondria was determined with and without membrane depolarization. Multiple linear regression was used to determine whether lipophilicity (Log D), charge, polarizability, polar surface area (PSA), and molecular weight influence mitochondrial delivery. RESULTS: The Log D for beta-blockers, corticosteroids, and NSAIDs was in the range of -1.41 to 1.37, 0.72 to 2.97, and -0.98 to 2, respectively. The % mitochondrial uptake increased exponentially with an increase in Log D for each class of drugs, with the uptake at a given lipophilicity obeying the rank order cationic>anionic>neutral. Valinomycin reduced membrane potential and the delivery of positively charged propranolol and betaxolol. The best equation for the combined data set was Log % Uptake = 0.333 Log D + 0.157 Charge - 0.887 Log PSA + 2.032 (R(2) = 0.738). CONCLUSIONS: Drug lipopohilicity, charge, and polar surface area and membrane potential influence mitochondrial drug delivery, with the uptake of positively charged, lipophilic molecules being the most efficient.

Investigational anabolic therapies for osteoporosis.

IMPORTANCE OF THE FIELD: Anabolic therapy, or stimulating the function of bone-forming osteoblasts, is the preferred pharmacological intervention for osteoporosis. AREAS COVERED IN THIS REVIEW: We reviewed bone anabolic agents currently under active investigation. The bone anabolic potential of IGF-I and parathyroid hormone-related protein is discussed in the light of animal data and human studies. We also discuss the use of antagonists of the calcium-sensing receptor (calcilytics) as orally administered small molecules capable of transiently elevating serum parathyroid hormone (PTH). Further, we reviewed novel anabolic agents targeting members of the wingless tail (Wnt) signaling family that regulate bone formation including DKK-1, sclerostin, Thp1, and glycogen synthase kinase 3beta. We have also followed up on the promise shown by beta-blockers in modulating the activity of sympathetic nervous system, thus affecting bone anabolism. We give critical consideration to neutralizing the activity of activin A, a negative regulator of bone mass by soluble activin receptor IIA, as a strategy to promote bone formation. WHAT THE READER WILL GAIN: Update on various strategies to promote osteoblast function currently under evaluation. TAKE HOME MESSAGE: In spite of favorable results in experimental models, none of these strategies has yet achieved the ultimate goal of providing an alternative to injectable PTH, the sole anabolic therapy in clinical use.

Compatibility of atenolol with excipients: LC-MS/TOF characterization of degradation/interaction products, and mechanisms of their formation.

A study was carried out to investigate compatibility of atenolol, a beta(1) blocker, with a variety of pharmaceutical excipients. The binary mixtures (1:1) of atenolol with the excipients were stored for 1 month at 40 degrees C/75% RH. The samples were directly observed for the physical changes, and also analyzed by a validated HPLC method to determine the chemical changes. The study revealed that atenolol was incompatible with ascorbic acid, citric acid and butylated hydroxyanisole. The degradation/interaction products formed in these mixtures were characterized by high resolution mass spectrometric and fragmentation analyses, using a LC-MS/TOF system. The identity of characterized structures was justified through mechanistic explanations.

Preparation and evaluation of self-nanoemulsifying tablets of carvedilol.

The purpose of this study was to combine the advantages of self-nanoemulsifying drug delivery systems and tablets as a conventional dosage form emphasizing the excipients' effect on the development of a new dosage form. Systems composed of HCO-40, Transcutol HP, and medium-chain triglyceride were prepared. Essential properties of the prepared systems regarding carvedilol solubility, a model drug, and self-emulsification time were determined. In order to optimize self-nanoemulsifying drug delivery systems (SNEDDS), formulation dispersion-drug precipitation test was performed in the absence and presence of cellulosic polymers. Furthermore, SNEDDS was loaded onto liquisolid powders. P-glycoprotein (P-gp) activity of the selected SNEDDS was tested using HCT-116 cells. Carvedilol showed acceptable solubility in the selected excipients. It also demonstrated improvement in the stability upon dilution with aqueous media in the presence of cellulosic polymers. Use of granulated silicon dioxide improved the physical properties of liquisolid powders containing SNEDDS. It improved the compressibility of the selected powders and the tested SNEDDS showed marked P-gp inhibition activity. Prepared self-nanoemulsifying tablet produced acceptable properties of immediate-release dosage forms and expected to increase the bioavailability of carvedilol.

Development of a reservoir-type transdermal enantioselective-controlled delivery system for racemic propranolol using a molecularly imprinted polymer composite membrane.

The aims of this study were to develop a transdermal patch for selective controlled delivery of the active S-enantiomer from racemic propranolol, and to evaluate its performance in vivo using Wistar rats. A molecularly imprinted polymer (MIP) thin-layer composited cellulose membrane with selectivity for S-propranolol was employed as the enantioselective-controlled release system. The effect of gel reservoir (poloxamer and chitosan) on enantioselective delivery was investigated. The chitosan gel allowed excellent selectivity for delivery of the S-propranolol enantiomer, whilst the more rheologically structured poloxamer gel formulation provided no selective release of S-propranolol. The chitosan gel exhibited high flux and had the ability to enantioselective deliver S-propranolol across excised rat skin. The results from confocal laser scanning microscopy study, carried out with the R- and S-propranolol enantiomers labeled with a 1-pyrenebutyric acid probe as fluorescent markers, suggested that the MIP composite membrane selectively regulated the release of the recognised S-enantiomer via a facilitated transport pathway through complex formation with the selective receptor sites, while the release of the R-enantiomer was via a non-selective route. The reservoir patch for enantiomer-controlled delivery of propranolol was therefore fabricated by incorporating the chitosan gel formulation containing racemic propranolol hydrochloride into the MIP composite membrane laminated backing. These patch devices were shown to exhibit the significant stereoselectivity uptake of propranolol when attached to the skin, using pharmacokinetic studies in rats. S-Propranolol enantiomer plasma concentration profiles for the transdermal patch in the in vivo study were comparable to data for the gel formulations that were applied directly to skin, and containing a single S-enantiomer of propranolol. The results demonstrate that the transdermal patch based on the MIP composite membrane-controlled release system may have potential in the enantioselective-controlled delivery of the S-isomer of racemic propranolol.

Variables influencing drug release from layered matrix system comprising hydroxypropyl methylcellulose.

The purpose of this study was to prepare and evaluate layered matrix tablets of propranolol HCl containing HPMC and phytowax as matrix component using direct compression technique. Layering with this polymeric matrix could prolong the release of drug and shift the release pattern approach to zero order as described from the least square curve fitting. Increasing the amount of coating layer could apparently prolong the drug release. The longer lag time of drug release from one planar apparently when the amount of coating layer was increased. HPMC concentration and compression force did not affect the drug release from this three-layer tablet. The drug release from this three-layer tablet was influenced by hydrodynamic force. An increase in stirring rate was a corresponding increasing in the release rate. From photoimage and SEM, gel mass of HPMC was increased with time during dissolution and covered the core surface, therefore dissolved drug molecules were allowed to diffuse out from the core through the polymer network of gel layer containing the porous structure. This suggested that HPMC and phytowax could be fabricated into the layered matrix tablet exhibiting sustained drug release.

Propranolol hydrochloride osmotic capsule with controlled onset of release.

Hard gelatin capsule was coated by a cellulose acetate as a semipermeable membrane with or without castor oil and filled with propranolol hydrochloride and sorbitol as an osmotic agent. After sealing the capsule with white bees wax plug, the onset of release and dissolution rate of the drug were studied. Water penetration into the capsule from the dissolution medium increases simultaneously the osmotic and hydrostatic pressures of its content. When the hydrostatic pressure is high enough to overweigh the gravity and frictional forces of the plug, the expulsion of the plug occurs and drug release starts. The effects of thicknesses of the membrane and plug as well as the concentrations of cellulose acetate and castor oil on the onset of drug release were presented by a polynomial model. We found that the effect of plug thickness on the onset of release is more important when the membrane is thicker. The results showed that the presence of caster oil in coating formulation (cellulose acetate 10% or 15%) increased the onset of release (t(o) values). The onset of release varied from 0.6 to 10.5 hr among which the onset times of 4.2, 4.8, 5.9, 5.5, 7.5, 5.0, 7.8 and 10.5 hr could be of use for either chronotherapeutic purposes in protection of patients against heart attacks and strokes during early morning hours or reducing daily frequency of dosage.

Development and in vitro evaluation of buccoadhesive carvedilol tablets.

Buccoadhesive tablets of carvedilol were prepared using HPMC K4M, HPMC K15M and Carbopol 934 as mucoadhesive polymers. Fifteen formulations were developed with varying concentrations of polymers. Formulations of the BC or BD series were composed of HPMC K4M or HPMC K15M in ratios of 1:1 to 1:5 whereas in the BE series Carbopol 934 was used (1:0.25 to 1:1.50). The formulations were tested for in vitro drug release, in vitro bioadhesion, moisture absorption and in vitro drug permeation through porcine buccal mucosa. Formulation BC3 showed maximum release of the drug (88.7 +/- 0.4%) with the Higuchi model release profile and permeated 21.5 +/- 2.9% of the drug (flux 8.35 +/- 0.291 microg h(-1)cm(-2)) permeation coefficient 1.34 +/- 0.05 cm h(-1)) through porcine buccal membrane. BC3 formulation showed 1.62 +/- 0.15 N of peak detachment force and 0.24 +/- 0.11 mJ of work of adhesion. FTIR results showed no evidence of interaction between the drug and polymers. XRD study revealed that the drug is in crystalline form in the polymer matrix. The results indicate that suitable bioadhesive buccal tablets with desired permeability could be prepared.

Phosphate concentrations in antiglaucoma medication.

BACKGROUND: Eye drops may contain phosphates as part of their buffer system. In the presence of epithelial keratopathy a high concentration of phosphate favours corneal calcification. To date European legislation does not require a quantitative declaration of the phosphates since buffers are regarded as additives. The knowledge of the phosphate concentration in medications helps to prevent corneal calcifications. Our study gives an overview on the amount of phosphate contained in antiglaucoma drops. METHODS: 21 samples of commercially available antiglaucoma drops were tested. The quantification of phosphate was performed using the molybdate method on a Modular P autoanalyzer. RESULTS: 10 of 21 (47 %) glaucoma drops had a phosphate concentration above physiological levels (> 1.45 mmol/L). A concentration higher than 100 mmol/L was found in four preparations that contained timolol. CONCLUSIONS: Many antiglaucoma drops contain unphysiological levels of phosphate, very high concentrations are found in some beta-blockers. These preparations have the potential to favour the formation of insoluble crystalline calcium phosphate deposits when used on a damaged corneal surface, and should therefore be avoided.

Development of mucoadhesive patches for buccal administration of carvedilol.

A buccal patch for systemic administration of carvedilol in the oral cavity has been developed using two different mucoadhesive polymers. The formulations were tested for in vitro drug permeation studies, buccal absorption test, in vitro release studies, moisture absorption studies and in vitro bioadhesion studies. The physicochemical interactions between carvedilol and polymers were investigated by Fourier transform infrared (FTIR) Spectroscopy. According to FTIR the drug did not show any evidence of an interaction with the polymers used and was present in an unchanged state. XRD studies reveal that the drug is in crystalline state in the polymer matrix. The results indicate that suitable bioadhesive buccal patches with desired permeability could be prepared. Bioavailability studies in healthy pigs reveal that carvedilol has got good buccal absorption. The bioavailability of carvedilol from buccal patches has increased 2.29 folds when compared to that of oral solution. The formulation AC5 (HPMC E 15) shows 84.85 + 0.089% release and 38.69 + 6.61% permeated through porcine buccal membrane in 4 hr. The basic pharmacokinetic parameters like the C(max), T(max) and AUC(total) were calculated and showed statistically significant difference (P<0.05) when given by buccal route compared to that of oral solution.

Potentiometric quasi-array employing calixarene derivatives for the high-throughput similarity/diversity screening of beta-adrenergic and beta-blocking chiral drugs by HPLC.

Performance of potentiometric quasi-array detection system consisted with the seven poly (vinyl chloride) (PVC) based liquid membrane electrodes in the cation-exchange HPLC using acetonitrile--40 mM phosphoric acid (15 : 85, v/v, pH* 2.35) for assessing of molecular similarity/diversity in a mini-library of beta-adrenergic and beta-blocking chiral drugs was presented. Macrocyclic compounds differing in stability of their conformers as well as in a size, steric hindrance and polarity of its internal cavities, comprising a series of five calix[6]arene derivatives completed with one modified calix[4]resorcinarene, were used as neutral ionophores to compose mentioned set of PVC-based electrodes. The output potentiometric responses were registered in the linear supernerstian range of calibration graph of each electrode, i.e. for a constant injected concentration 2.0 x 10(-4) M of investigated drugs, which is related to the amount frequently used at in vitro studies on pharmacological effects of these drugs. The impact of symmetry oriented supramolecular interactions on the responses of developed electrodes were characterised with proposed series of the highly significant quantitative structure-potentiometric response relationships (QSPRRs) combining both three-dimensional (3D) molecular descriptors of analysed drugs as well as lipophilicity and volume polarizability of calixarene-type ionophores. The principal components analysis (PCA) and unweighted hierarchical clustering analysis (HCA) were used as the pattern recognition techniques into collected potentiometric database for extraction of the useful information on the molecular and pharmacological similarity/diversity of analysed drugs, thus a high-throughput and consistent identification of therapeutically relevant agonists of beta2- and beta3-adrenoceptors and antagonists of beta1-adrenoceptor was especially achieved. This evidence supports also a hypothesis formulated by results of homology modelling on the subtle significance of an unrecognised supramolecular insertion processes of the chiral drug molecule into the flexible hydrophobic pocket(s) formed by seven helical transmembrane moving domains of beta-adrenoceptors on their final activation, sequestration, down-regulation or blockade.

Inhibition of (-)-propranolol hydrochloride by its enantiomer in white mice--a placebo-controlled randomized study.

BACKGROUND: A previous pilot study was performed to see if toxicity of (S)-(-)-propranolol hydrochloride may be inhibited by a potentized preparation of its enantiomer. The present study is based on the hypothesis that the toxic effects of an optical isomer, may be counteracted or reversed by the administration of a potentized preparation of one of its stereoisomers, and in particular the enantiomer. METHODS: 508 ICR conventional mice were used. 254 mice were administered (R)-(+)-propranolol HCl homeopathic potency prior to and during the experiment, and the other 254 were administered indistinguishable placebo. On the day of the experiment mice were anesthetized with intraperitoneal Rometar. Once sedated the mice were administered the LD50 dose of (-)-propranolol HCl intraperitoneally. RESULTS: The end point for statistical analysis was the difference in survival between the placebo and treatment mice. The odds ratio for survival of treatment mice relative to placebo mice was 1.52. The hypothesis of equal survival proportions gave a chi-square of 5.0429 (1 degree of freedom), which has a p-value of 0.0247. The analysis was then adjusted for mouse weight and intraperitoneal (-)-propranolol dosage using a logistic regression (LR) model. The LR treatment odds ratio was 1.51 and the LR treatment chi-square was 4.8112 (1 degree of freedom), which has a p-value of 0.0283. Consequently, we reject the null hypothesis of no treatment effect on survival. Eleven percent more treatment mice survived than placebo mice. CONCLUSION: We conclude that the toxicity of intraperitoneal (-)-propranolol HCl, may be counteracted by administration of a potency of its enantiomer, in ICR conventional mice which have survived preceding intraperitoneal Rometar injection, and pre-dosing with (+)-propranolol HCl homeopathic potency.

Influence of a new propranolol analogue on the rabbit myocardium in vitro.

Experiments with electrophysiology of the heart have been essential for the progress in diagnostics and pharmacotherapy of cardiovascular diseases. The aim of the study was to establish the influence of a new propranolol analogue on mechanical and bioelectrical activity of the rabbit heart in vitro. In the experiment, propranolol (1-isopropylamino-3-[1-naphthoxy]-2-propanol hydrochloride) and its newly synthesized analogue (1-[1,1-dimethyl-ethyl-amino]-3-[1-naphthoxy]-2-propanol hydrochloride) were used. Atrial trabecules were cut from right rabbit atrium. Each preparation consisted of cardiomyocytes and sino-atrial node cells. Preparations were stimulated with square pulses of direct current at a voltage of 20V, rate of 2 Hz and 1 ms duration. Propranolol and its analogue were applied at gradded concentration 10(-2) M, 10(-3) M, 10(-4) M, 10(-5) M, 10(-6) M and 10(-7) M. Mechanical (force of contraction, time of contraction and relaxation) and bioelectrical (amplitude and duration of action potentials) activities were examined. Bioelectrical activity of preparations was recorded using intracellular microelectrodes. LD(50) for new analogue was determined. Analogue diminished force of contraction and shortened time of contraction and relaxation of myocardium and decreased amplitude and duration of action potentials in sino-atrial node cells. It influenced mechanical and bioelectrical parameters to lesser degree than propranolol.