Friday, September 2, 2016

Nanocarbon Materials for Photodynamic Therapy and Photothermal Therapy

Author(s):

Qian Li, Hong Ruan and Hongguang LiPages 58-64 (7)

Abstract:


Photodynamic therapy (PDT) and photothermal therapy (PTT) are two kinds of methodologies that can be applied to the treatment of cancer. They own some advantages over the existing strategies including chemo- and radiotherapy but at the same time, are also facing big challenges. During the past decades, great efforts have been devoted to overcome the bottlenecks and to push these two newly-emerging methodologies to practical applications. One of the big achievements is the utilization of nanocarbon materials in PDT and PTT. Nanocarbon materials include zero-dimensional fullerene, one-dimensional carbon nanotubes (CNTs), and two-dimensional graphene. Upon illumination, fullerene can generate reactive oxygen species (ROS) through both Type I and Type II photochemistry, which allows it a good candidate for PDT. CNTs and graphene generate significant amount of heat upon excitation with near-infrared light, which makes them suitable for PTT. In this review, recent developments of the application of nanocarbon materials in PDT and PTT are briefly summarized and discussed.

Keywords:

Carbon nanotubes, fullerene, graphene, photodynamic therapy, photothermal therapy, tumor.

Affiliation:

Laboratory of Clean Energy Chemistry and Materials, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, China.

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    The Oral and Intranasal Delivery of Propofol Using Chitosan Amphiphile Nanoparticles

    Author(s):

    Ijeoma F. Uchegbu, Marie-Christine Jones, Federica Corrente, Lisa Godfrey, Davide Laghezza, Maria Carafa, Per Holm and Andreas G. SchatzleinPages 65-74 (10)

    Abstract:


    The intravenous anaesthetic propofol acts on gamma amino butyric acid A (GABAA) receptors in the brain. Propofol is often used as a procedural sedative and is also effective (at sub-anaesthetic doses) against intractable migraine and non-migraine headaches. However intravenous propofol is associated with pain on injection and with peripherally mediated hypotension. Here we introduce N-palmitoyl-N-monomethyl-N,N-dimethyl-N,N,N-trimethyl-6-O-glycolchitosan (GCPQ) - propofol nanoparticles and demonstrate, for the first time, that propofol nanoparticles are centrally active via the oral and the intranasal routes. Utilising these routes would abolish the pain on injection and, with respect to the nasal route, reduce peripheral exposure. The nanoparticles are 40-500 nm in size and stable for 21 days at room temperature. Brain drug exposure with orally administered GCPQ-propofol nanoparticles (350 mg kg-1 propofol) was not significantly different from a comparable oral dose of Diprivan. However there was less inter-individual variability with the GCPQ formulation (brain concentration coefficient of variation at the 5 minute peak time point = 1.24 and 0.72 for the Diprivan and GCPQ nanoparticle formulations respectively). Furthermore there was increased inter-individual variability in the pharmacodynamic response to oral Diprivan when compared to oral GCPQ-propofol, as measured by the loss of righting reflex (LORR) time. The LORR time after oral doses of 250 mg kg-1 and 350 mg kg-1 propofol as Diprivan was 15.7±24.6 minutes and 47.2±35.70 minutes respectively while the LORR time after oral 250 mg kg-1 and 350 mg kg-1 GCPQpropofol was 0 minutes and 52.7±22.9 minutes respectively. These data have implications for the safety of oral Diprivan. Via the intranasal route, the LORR time with Diprivan (4mg kg-1 propofol) was not significantly different from that of intranasal saline, while the intranasal administration of GCPQ-propofol formulations (4 mg kg-1 and 8 mg kg-1 propofol) produced significantly higher LORR times than when saline was administered. In summary, these animal data demonstrate that GCPQ-propofol nanoparticles may provide an effective method of administering non-parenteral propofol for potential use in non-anaesthetic settings.

    Keywords:

    Anaesthetic, GCPQ, nanoparticles, nasal delivery, N-palmitoylation-N-monomethyl-N, N-dumethyl-N, N, Ntrimethyl- 6-O-glycolchitosan, oral propofol, propofol.

    Affiliation:

    UCL School of Pharmacy, Brunswick Square, London, UK.

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    Improved Oral Bioavailability of Cefuroxime Axetil Utilizing Nanosuspensions Developed by Media Milling Technique

    Author(s):

    Yomesh Patel, Aditi Poddar and Krutika K. SawantPages 75-86 (12)

    Abstract:


    Cefuroxime axetil is a Class IV drug as per the Biopharmaceutical Classification System. It is a prodrug of Cefuroxime which is practically insoluble in water with a log P of 3.8. The absolute bioavailability of cefuroxime axetil, determined after intravenous injection of 1 g of cefuroxime and oral administration of 1 g of cefuroxime axetil (uncoated tablet), is 32-35% (range 23-44%). The present investigation was aimed at preparation of nanosuspension of Cefuroxime axetil for improving its solubility and thereby its bioavailability. Cefuroxime axetil nanosuspensions were prepared by the media milling technique using zirconium oxide beads and characterized by particle size, saturation solubility, differential scanning calorimetry, scanning electron microscopy and transmission electron microscopy. The nanosuspensions were evaluated for in vivo diffusion studies, ex vivo intestinal permeability studies and in vivo bioavailability studies. The particle size of the drug was drastically reduced to 221.2±0.26 nm from 5 µm after nanosizing. Saturation solubility achieved was 2387±3.35 µg/ml which was 16 times more than the bulk drug. DSC thermograms confirmed the non interference of excipients on the drug particles. In vivo diffusion studies showed 94.17±5.689% drug release from nanosuspension as against 62.34±1.139% release from plain Cefuroxime axetil suspension in 24 hours. Similarly, for ex vivo studies, 57.52±1.159% was released from plain Cefuroxime Axetil suspension in comparison to 85.58±3.12% for nanosuspension in 24 hours. In vivo studies in rats demonstrated a two times increase in oral bioavailability from the nanosuspension in comparison to marketed formulation. Therefore, nanosuspension which exhibited improved solubility, dissolution and absorption could be a better option as a delivery system compared to the present oral suspension formulation.

    Keywords:

    Bioavailability, Cefuroxime axetil, media milling, nanosuspension, saturation solubility.

    Affiliation:

    TIFAC Centre of Relevance and Excellence, Centre of PG Studies and Research, Pharmacy Department, The Maharaja Sayajirao University of Baroda, Vadodara, Gujarat-390002, India.

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    Formulation Studies on Novel Self-Solidifying Self-Nanoemulsifying Drug Delivery Systems of Nebivolol Hydrochloride

    Author(s):

    Nilesh M. Khutle and Vijaya C.Pages 87-100 (14)

    Abstract:


    Nebivolol HCl (NBL) a third generation beta blocker poses lack of oral bioavailability (12%) owing to its low solubility and first pass biotransformation in liver. The present research was undertaken to prepare solid Selfnanoemulsifying drug delivery system (S-SNEDDS) of NBL which will present NBL at molecular level in nanoemulsion form throughout GIT. Increased solubility along with intestinal lymphatic transport of lipid rich nanoemulsified drug bypassing hepatic first pass may enhance bioavailability. Based on solubilization of the drug and spontaneity of selfemulsification, Peceol as an oily phase, Cremophore RH 40 and Gelucire 50/13 as surfactants and ethanol as cosurfactant/ co-solvent were selected as the excipients to produce NBL loaded S-SNEDDS. Total 9 formulations were made with different ratios of the excipients and the optimized formulation was selected on the basis of solidification of SNEDDS on refrigeration and maintenance of the solid state. Spherical shaped morphology of oil globules was confirmed by TEM analysis. On dilution S-SNEDDS showed nanoparticles of size 180-190nm with a Polydispersity index 0.4-0.8 and Zeta potential -5.17, -7.56mV. The DSC and X-ray diffraction patterns of the S-SNEDDS show the amorphous state of NBL in the lipid matrix. Developed S-SNEDDS showed pH-independent drug dissolution which in SIF was fourfold greater as compared to plain drug. The intestinal permeability by everted sac technique showed threefold increase in transportation of NBL from S-SNEDDS formulation compared to NBL solid suggesting that S-SNEDDS of NBL is an excellent and practical approach of enhancing the oral bioavailability through improved solubility.

    Keywords:

    Cremophore RH 40, gelucire 50/13, nebivolol hydrochloride, oral bioavailability, peceol, solid self-emulsifying drug delivery system.

    Affiliation:

    Department of Pharmaceutics, Ultra College of Pharmacy, Madurai-625020, Tamilnadu, India.

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    Stable Indomethacin Dispersions in Water from Drug, Ethanol, Cationic Lipid and Carboxymethyl-Cellulose

    Author(s):

    Eliete G. Lima, Luciano R. Gomes and Ana M. Carmona-RibeiroPages 126-135 (10)

    Abstract:


    Background: The problem of formulating hydrophobic drugs in aqueous solutions is addressed from the point of view of nanotechnology. Nanoparticles (NPs) can incorporate high drug-to-carrier molar ratios with optimal drug dispersion and colloidal stabilization in water solution, especially when a biocompatible and hydrophilic polymer acts as an outer stabilizing layer. The hydrophobic drug indomethacin (IN) and the cationic lipid dioctadecyldimethylammonium bromide (DODAB) are soluble in ethanol (ET) and this property is useful to formulate the drug.
    Objective: This work aims at optimal colloidal stability for aqueous IN dispersions employing IN/DODAB ethanolic solutions dispersed in water solutions of carboxy-methyl-cellulose (CMC).
    Method: Photographs, dynamic light scattering for sizing, zeta-potential and polydispersity analysis are determined as a function of time for one week and scanning electron microscopy (SEM) for dried dispersions.
    Results: Over a range of (CMC), NPs with good colloidal stability and absence of sedimentation were obtained both over a low or high (CMC) for (IN): (DODAB) around 1. Only around zero of zeta -potential there is precipitation with poor colloidal stabilization. The data point out a remarkable colloidal stability for IN/ET/DODAB/CMC NPs over a range of (CMC) (0.01-1 mg/mL). ET harmonizes lipid and drug imparting a good colloidal stability over the long run. The self-assembled NPs obtained in aqueous solution disassemble upon drying with appearance of fibers and aggregates reminiscent of NPs that occurred in water.
    Conclusion: The co-solubilization /nanoprecipitation process is a powerful strategy to disperse hydrophobic drugs as nanoparticles in water solution of biocompatible hydrophilic polymers.

    Keywords:

    Anti-inflammatory nonsteroidal drugs, dioctadecyldimethylammonium bromide, ethanol, carboxymethylcellulose, dynamic light scattering, colloidal stabilization, nanoparticles.

    Affiliation:

    Departmento de Bioquímica, Instituto de Química, Universidade de São Paulo, P.O. Box: 26077, 05513970, São Paulo, Brazil.

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