A
within the body. A typical 3-D projection image of a rat with head and neck xenograft located on the nape of the neck acquired 24 hours after intravenous injection of neutral liposomes labeled with technetium-99m mTc is shown in Figure 1C. Using image-processing software, transaxial, sagittal, and coronal views of the 3-D volume can be displayed. Figure 2 shows the different image views for the same rat as Figure 1C. SPECT imaging has been used to monitor the distribution of Caelyx radiolabeled...
Effect Of Drugrelease Rate On Therapeutic Effect
Until now, there have been very few studies on the implications of drug-release rates for the therapeutic effects of lipid-based formulations. The drug-delivery community is now beginning to try to design experiments that will shed light on this important concept. It is useful to consider the two extremes. If the drug is released rapidly from the formulation see Section on Rapid-Release Formulations of Lipid-Based Drugs , then the therapeutic effect will be approximately equivalent to that of...
Info Lqx
Figure 1 One compartment model for intravenous administration of free drug. A The drug rapidly equilibrates between plasma central compartment and tissues tissue compartment and is eliminated from the plasma B and the tissues C with log-linear pharmacokinetics. The rate of elimination is the elimination rate constant K, which equals the slope of the line. Figure 2 Log-linear pharmacokinetics PK for the central compartment for sterically stabilized liposomal sustained release drugs is not due,...
Diaphragmatic Targeting with AvidinBiotinLiposome System
It was serendipitously discovered that when 99mTc-biotin-liposomes containing blue dye were injected into the peritoneal cavity and avidin was simultaneously injected into the pleural cavity surrounding the lungs, the liposomes aggregated strongly in the diaphragm as well as in the mediastinal nodes. This accumulation in the diaphragm occurred when the avidin draining from the pleural space into the diaphragmatic lymphatics encountered the biotin-liposomes draining from the peritoneal space...
References Jxf
1. Moghimi SM, Rajabi-Siahboomi AR. Advanced colloid-based systems for efficient delivery of drugs and diagnostic agents to the lymphatic tissues. Prog Biophys Mol Biol 1996 65 221. 2. Velinova M, et al. Morphological observations on the fate of liposomes in the regional lymph nodes after footpad injection in rats. Biochim Biophys Acta 1996 1299 207. 3. Oussoren C, et al. Lymphatic uptake and biodistribution of liposomes after subcutaneous injection. II. Influence of liposomal size, lipid...
Liposome Production and Characterization 19
SSL were generated upon solubilization in chloroform of cholesterol, DSPC, and distearyl phosphatidyl ethanolamine DSPE -PEG2000. The molar ratio used was 1 0.65 phospholipids to cholesterol. The lipids were then dried down in a rotatory evaporator. Upon rehydration and mechanical dispersion into a solution of Mart-1 peptides in phosphate buffered saline PBS , multilamellar liposomes were formed. SSL batches were then submitted to five cycles of freeze-thaw. Sizing down of SSL to 100 nm small...
QUANTITATION OF LYMPHNODE DELIVERY Methods of Reporting LymphNode Delivery
The research literature reporting liposome uptake in lymph nodes can be very confusing. This is due to the tendency of many investigators to only report the percent uptake in the lymph node as a percent of the injected dose per gram of tissue. Although reporting uptake as percent of the injected dose per gram makes sense from a drug delivery standpoint, it does not easily allow the reader to determine what percent of the total administered dose accumulates in the lymph node. For instance, in...
Functions of Lung Surfactant System
Initially, surfactant was thought to be a key player only in the biophysical behavior of the lung. It is known that during the cycle of inspiration and expiration, fast and repeated alteration of alveolar surface size and, correspondingly, the area of surfactant cover occur. The surface tension of water which covers glicocalex of alveolar cells is 72mN m. Surfactant adsorption on alveolar surface decreases the surface tension to 23mN m, which facilitates the work of breath and provides...
Intrapleural Administration of Liposomes for Cancer Therapy
The pleural space is the region between the mesothelium of the parietal pleura, which surrounds and covers the inner surface of the thoracic cage, mediastinum, and diaphragm and the visceral pleura, which covers the entire surface of the lung. Openings between mesothelial cells in the diaphragm and in the dorso-caudal part of the thorax-called stomata are the exit points for pleural liquid, protein, and cells that are removed from the pleural space 53.54 . The stomata communicates directly with...
Bioavailability Of Liposomal Drugs
Drugs entrapped in liposomal sustained release systems are not bioavailable, are protected from degradation and metabolism, and have no biological activity until the drug is released from the carrier. An understanding of the rate and extent of bioavailability of liposomal drugs at their site of action is important for the optimal design of liposomal carriers. However, it is the total drug levels in tissues of interest such as tumors that are normally reported, and total drug consists of both...
Surfactant Preparations of Natural Origin
The preparations of natural origin can be divided into two subgroups modified natural surfactants Surfacten, Survanta, Curosurf, and Surfactant-HL-10 and nonmodified natural surfactants Alveofact, Infasurf, bovine lipid extract surfactant BLES , Surfactant-BL, Surfactant-HL, and human surfactant from amniotic fluid . They are obtained from bovine and porcine lungs or from human amniotic fluid and contain surfactant-associated proteins and all classes of PL. Modified Natural Surfactant...
Info Xmu
PEG-liposomes, 5 j,mol PL kg PEG-liposomes, 5 j,mol PL kg PEG-liposomes, 0.0001-0.01 mol PL kg PEG-liposomes, 0.05-25 nmol PL kg NonPEG-liposomes, large cationic liposomes, large anionic liposomes, 25 nmol PL kg Small PEG-liposomes, small nonPEG-liposomes, small cationic liposomes, small anionic liposomes, 0.1 j,mol PL kg PEG-liposomes, 0.1 j,mol PL kg PEG-liposomes, 70 j,mol TL kg PEG-liposomes with ODN, 70 imol TL kg NonPEG-liposomes, exchangeable PEG-liposomes, with ODN, 70 j,mol TL kg...
Info Yst
Note Patients were classified into four groups according to the concurrent presence or absence of HSR and C reactivity, as follows true positive tp HSR , C , false positive fp HSR , C , true negative tn HSR , C , and false negative fn HSR , C . In addition, laboratory reactors were stratified to three categories on the basis of 10 minutes SC5b-9 values, as specified in column 1. The 0.98 and 1.96 mg mL cut-off values represent two and four times the upper limit of normal SC5b-9 levels 0.49 mg...
Other Factors that Affect Emulsion Stability
There are several other factors that, if not controlled rigorously, can affect emulsion stability. These were investigated in detail with the emulsion used for clinical trials in prostate cancer patients, i.e., 1 mL of 100mM phospholipid Figure 6 Effect of total liposomal phospholipid concentration on the stability of liposomal oil-in-water emulsions. Liposomes containing various amounts of phospholipids were emulsified with 40 light mineral oil. The amount of separation was measured as a...
Info Dgx
Figure 3 Diphtheria toxoid tryptophan quenching by acrylamide in function of pH. The fluorescence spectra were performed in the absence F0 or in the presence F of different acrylamide concentrations and in different pHs as indicated. Horses have been used in immunization protocols for large-scale production of antisera against Dtxd and other toxins. Horses used to produce hyperimmune sera against Dtxd are injected with injections of 200 Lfs floc-culation units, 1Lf 2.5 mg of Dtxd of protein,...
Membrane Characteristics Of Dividing Endothelial Cells
The molecular structures responsible for enhanced binding and uptake of CL complexes by tumor endothelial cells are not known, but electrostatic interactions are thought to be a paramount driving force. Therefore, negatively charged molecules and structures overexpressed during the process of angiogenesis are presumably the target and are responsible for the accumulation of the cationic carriers Fig. 2 . It is known that tumor endothelial cells divide much more rapidly compared to quiescent...
References Qvt
1. Siemann DW, Bibby MC, Dark GG, et al. Differentiation and definition of vascular-targeted therapies. Clin Cancer Res 2005 11 416. 2. Tozer GM, Kanthou C, Baguley BC. Disrupting tumour blood vessels. Nat Rev Cancer 2005 5 423. 3. Inai T, Mancuso M, Hashizume H, et al. Inhibition of vascular endothelial growth factor VEGF signaling in cancer causes loss of endothelial fenestrations, regression of tumor vessels, and appearance of basement membrane ghosts. Am J Pathol 2004 165 35. 4. Willett CG,...
Intraoperative Therapy for Positive Tumor Margins and Treatment of Lymph Nodes
One possible use of therapeutic liposomes is to target residual tumor in the intraoperative situation. In many cases, the surgeon is unable to remove all of the cancer during surgery so that the margins of the resected tumor are positive. This generally means that there is cancer remaining at the operative site that severely compromises patient survival. This positive margin can frequently be determined during the operation. Therapeutic liposomes that target residual tumor could be injected in...
Effect Of Liposome Size Dosing Schedule And Dose Intensity
Quite a lot of work has been done in the past on the effect of liposome size on the plasma PK of liposomes reviewed in Ref. 2 . We have recently extended these studies to examine the effect of size on uptake of liposomal DXR into various tissues, including tumor tissue 29 . Liposomes and other macromo-lecular structures accumulate in solid tumors via the enhanced permeability and retention effect 30 . The vasculature of solid tumors is reported to have increased permeability to macromolecules...
Studying the Fate of Liposomes Liposomal Markers
To investigate the in vivo fate of liposomes, numerous liposomal markers are available. Radiolabels, either encapsulated water-soluble compounds or bilayer-incorporated lipid labels, provide a sensitive and powerful tool to determine liposome biodistribution. Most lipids can be purchased in one or more radiolabeled forms. The choice of the radiolabeled compound primarily depends on the nature of the experiment, e.g., long-term or short-term experiments, determination of binding and uptake, or...
Liposome Pharmacokinetics after Intratumoral Administration
Studies of liposome intratumoral pharmacokinetics have been stimulated by attempts to use liposomes as gene carriers. Clinical trials using cationic liposomes carrying E1A gene were performed to treat squamous cell carcinoma using an intratumoral injection technique 73,74 . Pharmacokinetic studies have indicated that the size and surface charge of liposomes have a significant effect on their in vivo intratumoral distribution 75,76 . Increasing the liposome diameter and adding a positive surface...
Preparation of Mannosylated Clodronate Liposomes for CNS Research
For some studies in the CNS, e.g., for research on the role of macrophages in experimental allergic encephalomyelitis, a rodent model for multiple sclerosis, clodronate liposomes should be mannosylated 28,29 . 1.85mg mL -aminophenyl a-d-mannopyranoside syn. manno-side solution in methanol 100 mg mL phosphatidylcholine egg lectin solution in chloroform, filtered through 0.2-mm pore filter 10 mg mL cholesterol solution in chloroform, filtered through 0.2-mm pore filter 0.7 M clodronate solution...
References Axd
1. Alving CR. Liposomes as carriers of antigens and adjuvants. J Immunol Meth 1991 140 1-13. 2. Alving CR, Koulchin V, Glenn GM, Rao M. Liposomes as carriers of peptide antigens induction of antibodies and cytotoxic T lymphocytes to conjugated and unconjugated peptides. Immunol Rev 1995 145 5-31. 3. Allison AG, Gregoriadis G. Liposomes as immunological adjuvants. Nature 1974 252 252. 4. Uemura K, Nicolotti RA, Six HR, Kinsky SC. Antibody formation in response to liposomal model membranes...
References Cpl
1. Orr RM, O'Neill CF. Patent review Therapeutic applications for antisense oligonucleotides. Curr Opin Mol Ther 2000 2 325-331. 2. Orr RM, Dorr FA. Clinical studies of antisense oligonucleotides for cancer therapy. Methods Mol Med 2005 106 85-111. 3. Akhtar S, Hughes MD, Khan A, et al. The delivery of antisense therapeutics. Adv Drug Deliv Rev 2000 44 3-21. 4. Crooke ST. Antisense strategies. Curr Mol Med 2004 4 465-487. 5. Shi F, Hoekstra D. Effective intracellular delivery of...
Info Yfo
International Standard Book Number-10 0-8493-9725-1 Hardcover International Standard Book Number-13 978-0-8493-9725-7 Hardcover This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. A wide variety of references are listed. Reasonable efforts have been made to publish reliable data and information, but the author and the publisher cannot assume responsibility for the validity of all materials...
Liposomes for Anticancer LymphNode Drug Delivery
The investigation of liposomes as a carrier for lymph node drug delivery was first performed by Segal et al. in 1975 49 . Following the intratesticular injection of liposomes encapsulating the anticancer drug actinomycin D, high concentrations of the drug were found in the local lymph nodes. Subsequently, Hirnle et al. turned to liposomes as an improved carrier for intralymphatically delivered drugs compared with bleomycin emulsions 50 . A study in rabbits used liposome-encapsulated bleomycin...
Visualization of Liposome Accumulation in the Ischemic Tissue and Increase in
The hypothesis that the selective accumulation of ATP-L in the ischemic tissue and direct ATP delivery to ischemic cells are responsible for myocardial protection was confirmed by fluorescence microscopy of heart cryosections after the perfusion with liposomes labeled with rhodamine Rh -phosphati-dylethanol-amine PE and loaded with fluoroscein-isothiocyanate FITC -dextran. Figure 3A shows an extensive association of fluorescently labeled liposomes Fig. 3A, 3 and intraliposomal load Fig.3A, 2...
Info Std
Abbreviations DMPC, DMPG, wide-bore glass funnel. Chloroform is added to the funnel, rinsing any residual lipids into the flask. DMPC and cholesterol are readily soluble at the concentrations used. Chloroform is added just below the neck and the flask is shaken to facilitate the dissolution of the lipids. Chloroform is then added up to the calibration line. DMPG is just soluble in 100 chloroform at the 20 mM concentration used. The flask can be warmed in a 37 C water bath, to facilitate...
Frtargeted Liposomes
FR-targeted liposomes were first reported by Lee and Low in the early 1990s 28,46 . Their studies showed that folate tethered liposomes have high affinity to FR cells and are efficiently internalized by receptor-mediated endocytosis. A lengthy spacer was found to be necessary between folic acid and its lipid anchor to enable FR binding, presumably to overcome steric hindrance encountered by the liposome when approaching the cellular surface. FR-targeted liposomes containing a long linker e.g.,...
Introduction Rpu
A number of liposomal and lipid-based products have reached the market, with a full pipeline of similar products in clinical trials or preclinical development 1 . In spite of this, there is not a good understanding of how the physical properties of the various drug formulations affect the pharmacokinetics PK and biopharmaceutics BP of their associated drugs relative to free conventional drugs. The terminology used in this field has evolved over time, which has caused some confusion, e.g., in...
AvidinBiotinLiposome System for Intraperitoneal and LymphNode Drug Delivery
Few of the above previously described studies with intraperitoneally administered liposomes have focused on the fact that intraperitoneally administered liposomes clear from the peritoneum by passing through the lymphatic vessels that provide an opportunity to deliver therapeutic agents to these lymph nodes. The liposomes pass through and are partially trapped in lesser or greater degrees by the lymph nodes that drain from the peritoneum. These lymph nodes frequently contain cancer metastasis...
Composition of Lung Surfactant
The composition of the surfactant may vary with such factors as species, age, lung compartment, disease states, diet, method of isolation, and so on 37 . Surfactant isolated from lung BAL of healthy mammals consists of about 90 lipids and 10 proteins. Ten percent to twenty percent of the lipids are neutral and the remaining 80 to 90 is PL. About 80 of PL is phosphatidylcholine PC , about 50 to 60 of PC is DPPC, and about 10 of PL is PG. There are also small quantities of...
THERAPEUTIC INDEX ENHANCEMENT Oncology
The key to success of any new oncology drug is, of course, useful efficacy with manageable side effects. For a drug-delivery system such as a liposome, what is added is improvement in principle in either or both of these aspects, so as to effect an improved product. In the cases of liposomal reformulation of generic drugs, i.e., those liposomal formulations which are attempts to improve an established anticancer drug, the fundamental question of efficacy is at least reasonably clearly defined...
DELIVERY OF THERAPEUTIC OLIGONUCLEOTIDES IN pHSENSITIVE LIPOSOMES
The first use of pH-sensitive liposomes to mediate intracellular delivery of antisense oligonucleotides was reported by Ropert et al. 56,61 . The oligonucleotide was against the env gene mRNA of Friend retrovirus. A significant inhibition of viral replication was observed when the antisense oligonucleo-tides were delivered in liposomes composed of DOPE OA Chol, compared to that observed with non-pH-sensitive liposomes. Selvam et al. 62 reported the sequence-specific suppression of HIV-1...
Dopc
Molecular Weight 786.14 Molecular Formula C H NOsP Molecular Weight 786.14 Molecular Formula C H NOsP Molecular Weight 853.93 Molecular Formula C47H5,NO. Molecular Weight 853.93 Molecular Formula C47H5,NO. Molecular Weight 365.37 22.99 388.36 Molecular Formula C20H17N2O5Na Molecular Weight 365.37 22.99 388.36 Molecular Formula C20H17N2O5Na Figure 3 Important molecules for the formation of EndoTAG formulations. DOTAP cationic, high fluidity , DOPC zwitterionic, high fluidity , and cholesterol...
MOLECULAR SETUP OF EndoTAG
EndoTAGR is the technology platform of cationic nanoparticles for neovascular targeting, being developed at MediGene AG. The formulations are administered as IV infusion of the aqueous colloidal dispersion. All products that are realized on this basis comprise a cationic nano-particulate carrier and an active agent. For the cationic carrier, various types of colloidal particles comprising liposomes, micelles, emulsion droplets polymer particles, or any other type of nanoparticle can be chosen....
One Compartment Model for Free Drugs
In a one compartment model for free drugs, after intravenous IV administration, free conventional drug equilibrates rapidly between the plasma and Table 2 Properties of Liposome-Entrapped Drug vs. Released Drug Biologically inactive until it is released Protected from degradation and metabolism Has the same PK BD as the liposomes themselves, if the release rate is slow usual routes for the free drug Has the same PK BD as free drug given by the same route, and at the same site of administration...
Preparation Of Liposomes
A liposome formulation, termed as the Walter Reed Army Institute of Research WRAIR liposomes, was developed in our laboratory. This formulation has been used in human clinical trials and contains dimyristoyl phosphatidylcholine, dimyristoyl phosphatidylglycerol, and cholesterol Avanti Polar Lipids, Alabaster, Alabama, U.S.A. in molar ratios of 1.8 0.2 1.5, and 1.6mg mL of lipid A and an encapsulated protein antigen 28,29 . This formulation of liposomes has also been shown to be an effective...
Liposomes Targeted to Liver Sinusoidal Endothelial Cells
When human serum albumin HSA derivatized with cz's-aconitic anhydride Aco-HSA was covalently coupled to liposomes, it mediated efficient in vivo uptake of these liposomes by scavenger receptors present on liver ECs 70 . Within 30 minutes of injection of these targeted liposomes, the liver accounted for more than 80 of the uptake from the blood. Liver ECs contributed for about two-thirds of this liver uptake, and more than 80 of the EC population participated in the uptake of the Aco-HSA...
MANUFACTURE OF LIPOSOMES Glassware
The glassware used in the manufacture of liposomes should be thoroughly cleaned and free of residual detergents. Phosphate-based detergents should be avoided. Disposable glass pipets also should be avoided, because the blue graduations are soluble in chloroform and will contaminate the liposomes. The preparation of liposomes utilizes rotary evaporation and lyophilization, which concentrates contaminants leading to impure and potentially leaky liposome formulations. There are several cleaning...
Preparation of Chloroform and Lipid Stocks
Liposomes are made by first mixing the lipids dissolved in chloroform. Chloroform is highly unstable, undergoing free radical degradation and is consequently sensitive to light, heat, and oxygen. It is essential that the chloroform be highly purified, stabilized by the addition of ethanol at 0.75 or higher concentrations, and used within 90 days of manufacture. Either chloroform is purchased that meets these criteria directly from Honeywell Burdick amp Jackson Muskegon, Michigan, U.S.A. or...
pHSENSITIVE LIPOSOMES
The concept of pH-sensitive liposomes emerged from the observation that certain enveloped viruses infect cells following acidification of the endosomal lumen to infect cells, and from the knowledge that some pathological tissues tumors, inflamed, and infected tissue have a more acidic environment compared to normal tissues. Although pH-sensitive liposomes are stable at physiological pH, they destabilize under acidic conditions, leading to the release of their aqueous contents 30-32 . In...
Subcutaneous Administration
Subcutaneously injected clodronate liposomes are able to deplete macrophages in the draining lymph nodes of mice and rats. Such liposomes, when e.g., injected in the footpad of mice, led to the depletion of subcapsular sinus lining macrophages and medulla macrophages in the draining popliteal lymph nodes 15 . Macrophages in the paracortical fields and those in the follicles were not affected, emphasizing the existence of a barrier formed by reticular fibers and or densely packed lymphocytes in...
Intratracheal and Intranasal Administration
Alveolar macrophages form a first line of defense against microorganisms entering the lung via the airways. In contrast to the interstitial macrophages that are separated from the alveolar space by an epithelial barrier, alveolar macrophages which are located in the alveolar space have direct access to liposomes administered via the airways, for instance by intratracheal instillation, intranasal administration or by the application of aerosolized liposomes. The direct access of clodronate...
Liposomal Amphotericin BAmBisomeToxicity Aspects
Amphotericin B remains the drug of choice for the treatment of life-threatening, systemic fungal infections. Nevertheless, the use of amphotericin B in the mixed micelle surfactant deoxycholate formulation d-AmB has been limited by severe toxic side effects, including dose-limiting nephrotox-icity. Several relatively new formulations have received regulatory approval amphotericin B colloidal dispersion ABCD 22 , amphotericin B lipid complex ABLC Abelcet 23 , and liposomal amphotericin B...
AvidinBiotin Liposomes Method For Intrapleural and Mediastinal LymphNode Drug
Our group has investigated the avidin biotin-liposome system as a method to prolong drug delivery and increase liposomal drug retention in the pleural cavity and the mediastinal nodes that receive drainage from this cavity using a rat model 4,41 . The avidin biotin-liposome system can greatly prolong the retention of liposomes in the pleural space and also greatly increase liposome trapping in the mediastinal nodes 4 . Mediastinal nodes are important therapeutic targets. Mediastinal nodes are...
Figure 8 The Molecular Properties Of Camptothecin
Figure 8 The molecular properties of camptothecin CPT are determined by the pH-dependent equilibrium between the lactone and the carboxylate form. The lac-tone is poorly soluble in water and it is stable only at low pH. At physiological pH and higher, the carboxylate predominates. In EndoTAG -2, CPT is used in the lipid-bound form, a new type of CPT drug with favorable molecular and pharmacological characteristics. Abbreviations CPT, camptothecin CL, cationic lipid. form and on finding means...
References Dty
1. Allen TM, Cullis PR. Drug delivery systems entering the mainstream. Science 2004 303 1818-1822. 2. Allen TM, Stuart D. Liposome pharmacokinetics classical, sterically stabilized, cationic liposomes and immunoliposomes. In Janoff AS, ed. Liposomes Rational Design. New York Marcel Dekker, Inc., 1998 63-97. 3. Shargel L, Yu ABC. Applied biopharmaceutics and pharmacokinetics. 4th ed. McGraw Hill, 1999 768. 4. Gabizon A, Shiota R, Papahadjopoulos D. Pharmacokinetics and tissue distribution of...
Structure Of Lymph Node
Recently, liposomes have received much attention as lymph-node drug-delivery agents. This interest in the development of new methods of lymph-node drug-delivery stems from the increasing awareness of the importance of lymph nodes in cancer prognosis, their importance for vaccine immune stimulation and the realization that the lymph nodes harbor human immunodeficiency virus HIV as well as other infectious disease 1-4 . New methods of delivering drugs and antigens to lymph nodes are currently...
Index
coating in, 88 in rats, 82 ACK lysis buffer, 216 Acute lung injury ALI , 317 and acute respiratory distress syndrome ALI ARDS , 329 pathophysiology of, 329 reasons for failure, 331 surfactant application, 329-330 surfactant therapy efficiency of, 331 Acute respiratory distress syndrome ARDS , 317, 321-323 air-blood barrier permeability in, 322 lung surfactant in, 322 surfactant administration in, 323 Adenosine triphosphate ATP as bioenergic substrate, 96 in cardiomyocytes, 95 dephosphorylation,...