Dicetyl Phosphate Research Articles

ENHANCEMENT OF FOLLICULAR DELIVERY OF FINASTERIDE IN NIOSOMALAND PRONIOSOMAL GEL FORM FOR TREATING ANDROGENETIC ALOPECIA

Finasteride has not been explored extensively for the treatment of androgenic alopecia. The present workwas aimed to enhance the follicular delivery of finasteride topically by niosomal and proniosomal carriersystems for treating androgenetic alopecia. Finasteride niosomes were prepared by thin film hydrationmethod and proniosomes were prepared by coacervation phase separation method. The niosomesprepared with cholesterol-Span 20 (1:1) and proniosmes prepared with cholesterol-Span 20 (1:1) showedbetter mean vesicle size, drug content, in vitro release profile and skin permeability. The effect of chargeinducer, dicetyl phosphate (DCP) on skin permeability of niosomes and proniosomes was studied and itwas found to be less in this study. Stability studies were preformed and the formulation was found to bestable for 60 days. Clinical trials by phototrichogram method was performed for proniosomal formulationwith cholesterol-Span 20 (1:1) and DCP on twenty healthy male volunteers and it was found to increasethe anagen hair count of test group by 42.85 % when compared with the control group (6.6%), indicatingthe proniosomal gel formulation achieved the objective of enhancing the drug concentration in androgenicreceptors of hair shaft and thus it can be used safely for treating androgenic alopecia.

Effect of Process Factors on the Properties of Doxycycline Nanovesicles

Purpose: To develop and evaluation ascorbyl palmitate niosomes in order to achieve a transdermal and/or systemic nanocarier of doxycycline.Methods: Vesicles were formed from ascorbyl palmitate in combination with cholesterol and a negatively charged lipid, dicetyl phosphate. Niosomes were prepared by film hydration method followed by sonication in which aqueous doxycycline solution (in phosphate buffered saline) was encapsulated in the aqueous regions of the vesicles. The vesicles were evaluated for entrapment and in vitro release as well as for their thermal properties and shape by ultraviolet spectroscopy (UV), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM), respectively.  The effect of process conditions - sonication time, pH, hydration temperature and centrifuge speed - on niosome properties was investigated.Results: DSC of pure lipids, vesicles dispersion and mixture of lipids confirmed the formation of niosomes. Other results show that > 90 % of drug was entrapped in the vesicles and the vesicles were spherical in shape. Drug release from the vesicles was slow (< 60 % after 8 h). Nanovesicle size was significantly (p < 0.05) affected by sonication time and hydration pH. Although hydration temperature of 100 °C promoted the production of smaller vesicles, this temperature would likely cause drug degradation.Conclusion: The use of ascorbyl palmitate along with cholesterol and a charge inducer (dicetyl phosphate) yielded vesicles that satisfactorily encapsulated doxycycline solution. The resulting system can be applied for the formulation of doxycycline niosomes.Keywords: Doxycicline, Vesicles, Drug delivery, Ascorbyl palmitate, Niosomes.

Effect of formulation compositions on niosomal preparations

This study was aimed to investigate the effects of molar ratio of cholesterol to Span 60 and stabilizers (Solutol HS 15 or dicetyl phosphate (DCP)) on the entrapment of methylene blue, a model hydrophilic drug. The niosomes were prepared by the film hydration method and characterized for drug entrapment efficiency (EE), vesicle size, zeta potential and thermal properties of niosomal membrane. It was found that niosomal vesicles possessed median diameter ranging from 0.35 to 1.85 μm. The niosomes that were formulated with lower molar ratios of cholesterol to Span 60 of 0.33 and 0.50 produced significantly higher EE with both stabilizers when compared to cholesterol to Span 60 molar ratios of 1.0 and above (p < 0.05). The EE of niosomes stabilized with DCP was significantly higher (p < 0.05) than those prepared with Solutol HS 15 except at a molar ratio of cholesterol to Span 60 of 0.33. In conclusion, with low molar ratios of cholesterol to Span 60, more drugs could be entrapped within the niosomes regardless of the type of stabilizers. Furthermore, EE and median diameter of niosomes containing DCP were higher than those stabilized with Solutol HS 15.

Proliposome powders for enhanced intestinal absorption and bioavailability of raloxifene hydrochloride: effect of surface charge

The primary goal of the present study was to investigate the combined prospective of proliposomes and surface charge for the improved oral delivery of raloxifene hydrochloride (RXH). Keeping this objective, the present systematic study was focused to formulate proliposomes by varying the ratio of hydrogenated soyphosphatidylcholine and cholesterol. Furthermore, to assess the role of surface charge on improved absorption of RXH, anionic and cationic vesicles were prepared using dicetyl phosphate and stearylamine, respectively. The formulations were characterized for size, zeta potential and entrapment efficiency. The improved dissolution characteristics assessed from dissolution efficiency, mean dissolution rate were higher for proliposome formulations. The solid state characterization studies indicate the transformation of native crystalline form of the drug to amorphous and/or molecular state. The higher effective permeability coefficient and fraction absorbed in humans extrapolated from in situ single-pass intestinal absorption study data in rats provide an insight on the potential of proliposomes and cationic surface charge for augment in absorption across gastro intestinal barrier. To draw the conclusions, in vivo pharmacokinetic study carried out in rats indicate a threefold enhancement in the rate and extent of absorption of RXH from cationic proliposome formulation which unfurl the potential of proliposomes and role of cationic charge for improved oral delivery of RXH.

Development and Targeting Efficiency of Irinotecan Engineered Proniosomes

Purpose: This study is aimed at achieving improvement in the efficacy, reduced toxicity and enhancement of therapeutic index of irinotecan.Methods: Proniosomes of irinotecan hydrochloride trihydrate were prepared by slurry method using different surfactants, cholesterol and dicetyl phosphate. The formulations were then characterized with respect to shape, surface morphology, entrapment efficiency, in vitro drug release, in vivo drug targeting and stability.Results: The proniosomes were smooth in texture indicating, thin and uniform coating over maltodextrin powder. The highest entrapment efficiency was found for formulation F2 (74.9 &plusmn; 2.7 %). The highest cumulative drug release in 24 h was achieved with formulation F3 (98.2 %) In vivo results for the proniosomes reveal that the drug was preferentially targeted to liver followed by lung and spleen. Stability studies indicate that 4 &ordm;C was the most suitable condition for the storage of formulation F2.Conclusion: Proniosomes offer a suitable alternative colloidal carrier approach to achieving drug targeting. Proniosomes containing irinotecan are retained at targeted sites and are capable of releasing drug for an extended period of time.Keywords: Irinotecan, proniosomes, Drug targeting, In vivo tissue distribution, Stability studies.

Preparation of vesicle drug carrier from palm oil- and palm kernel oil-based glycosides

A new mixture of alkyl glycosides derived from palm oil (PO) or palm kernel oil (PKO) was synthesised. This mixture contains glycosylated disaccharide of either maltose or lactose with aliphatic chain that varies according to the PO or PKO fatty acids composition. The synthesis method produced no polymerised sugar unlike the production of the commercial glycosides (APG). The mixture only contains various glycosides differing by the alkyl chain and stereoisomers. Three anomeric mixtures can be produced depending on the reaction time and catalyst: α-dominant mixture, β-dominant mixture and equal mixture. The PO and PKO derived glycosides were able to form a stable vesicle with a small amount of dicetyl phosphate (DCP) and showed high vitamin E encapsulation efficiency. Low packing density of the membrane bilayer enabled more vitamin E to participate in the membrane formation. The anomeric mixtures of the maltosides provide no difference in membrane packing behaviour as it was governed by the hydrophilic region. Significant difference in membrane packing density was observed for lactosides anomeric mixtures because the packing behaviour was influenced by the hydrophobic region. Inclusion of cholesterol led to decrease in vitamin E encapsulation as well as reducing the stability of the vesicle system. The vesicular formulations of the glycosides were stable for 3 months when stored at refrigeration temperature.

Anionic liposome template synthesis of raspberry-like hollow silica particle under ambient conditions with basic catalyst

Hollow silica particle was obtained with a vesicle template synthesis in water under ambient conditions in the presence of ammonia. Biomimetic vesicles, liposomes were used, which consisted of a zwitterionic phospholipid, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC), and a tiny amount of charged amphiphiles, hexadecylamine (HDA) or dicetylphosphate (DCP). Aggregation of silica occurred for DPPC or cationic DPPC/HDA liposome, whereas well-dispersed hollow silica particle could be obtained for anionic DPPC/DCP liposome. The hollow particle synthesized with the anionic liposome had single-layered and raspberry-like structures. Electrostatic repulsion between anionic vesicles maintained stable dispersion of the as-synthesized particles during the reaction. Formation of the raspberry-like morphology is explained by silica particle precipitation selectively induced around the liposomes under basic conditions due to affinity of silica precursors for the liposomes. Synthesis of well-dispersed hollow silica particle with a raspberry-like morphology is the first report in vesicle template syntheses.

Bioavailability enhancement of zaleplon via proliposomes: Role of surface charge

The present systematic study focused to investigate the combined advantage of proliposomes and surface charge for improved oral delivery of zaleplon. The zaleplon loaded proliposomes were prepared using hydrogenated soyphosphatidylcholine (HSPC) and cholesterol (CHOL) in varying ratios, and the optimized formulation was tailored with dicetyl phosphate and stearylamine to obtain negative and positive charged vesicles, respectively. The formulations were characterized for micromeritics, size, zeta potential, and entrapment efficiency. Further, in vitro release and dissolution study carried out provide an insight on the stability and enhanced dissolution of zaleplon from proliposome formulations. The solid state characterization (SEM, DSC, and PXRD) studies unravel the transformation of zaleplon to amorphous or molecular state from the native crystalline form. To depict the conclusions, in situ single-pass perfusion and bioavailability studies were carried out in rats. The significant increase in effective permeability coefficient (Peff) and rate and extent of absorption from cationic vesicles indicate the importance of surface charge for effective uptake across the gastrointestinal tract. Overall a two- to fivefold enhancement in bioavailability in comparison with control confers the potential of proliposomes as suitable carriers for improved oral delivery of zaleplon.

Niosomes as a potential drug delivery system for increasing the efficacy and safety of nystatin

Nonionic surfactant (NIS) vesicles (niosomes) formed from self-assembly of hydrated synthetic NIS monomers are capable of entrapping a variety of drugs and have been evaluated as an alternative to liposomes. Nystatin (NYS) is a polyene antifungal drug that has been used in the treatment of cutaneous, vaginal and oral fungal infections since the 1950s. The aim of this work is to encapsulate NYS in niosomes to obtain a safe and effective formula administered parenterally for neutropenic patients. NYS niosomes were prepared by the thin-film hydration method using Span 60 or Span 40 and cholesterol (CHOL). Stearylamine and dicetyl phosphate were added as the positive and negative charge-inducing agents (CIA), respectively. Two molar ratios were used, namely NIS/CHOL/CIA (1:1:0.1 and 2:1:0.25). Neutral and positively charged niosomes gave the highest encapsulation efficiencies. NYS niosomes were characterized using transmission electron microscopy, differential scanning calorimetry and dynamic light scattering. The release of neutral and negatively charged NYS niosomes was estimated, and it showed a slow sustained release profile. A 25-kGy γ-irradiation dose was sufficient to sterilize the investigated vesicles. NYS niosomes exerted less nephrotoxicity and hepatotoxicity in vivo, showed higher level of drug in vital organs and revealed pronounced efficacy in elimination of the fungal burden in experimental animals infected with Candida albicans compared with those treated with free NYS. Niosomal encapsulation thus provided means for parenteral administration of NYS, reducing its toxicity and making it a more active antifungal agent.

Niosomal Delivery of Isoniazid - Development and Characterization

Purpose: To develop a niosomal formulation for the delivery of isoniazid to achieve effective treatment of tuberculosis.Methods: Niosomes were prepared by reverse phase evaporation method and given a charge with a charge-inducing agent, dicetyl phosphate. Drug entrapment efficiency in the niosomes was determined spectrophotometrically. The niosomes were further characterized for their particle size, polydispersity index (PI) and zeta potential as well as by scanning electron microscopy and stability studies. Furthermore, in vitro drug release and cellular uptake studies on the niosomes by macrophage J744 A were undertaken.Results: Suitable isoniazid niosomes were obtained. The niosomes demonstrated a potential to remain in the treated site for prolonged periods and were also capable of maintaining steady drug concentrations for up to 30 h. Cellular uptake of the drug-loaded niosomes by macrophage cells was as high as 61.8 %, a level that is capable of achieving effective treatment of tuberculosis.Conclusion: The isoniazid niosomes developed are capable of reducing drug dose and toxicity as well as dosing frequency which should bring about improved patient compliance. More importantly, macrophage targeting should be feasible at sites where tuberculosis bacteria are harbored.

Design and Evaluation of Controlled-Release Niosomes and Discomes for Naltrexone Hydrochloride Ocular Delivery

This study aimed at preparing and evaluating Span 60-based niosomes for ocular delivery of naltrexone hydrochloride (NTX). Selected charged lipids [dicetyl phosphate (DCP) and stearyl amine (STA)] and surfactants [poly-24-oxyethylene cholesteryl ether (C24) and sodium cholate (CH)] were investigated as bilayer membrane additives and prepared using four different methods. A 5-fold increase in NTX entrapment efficiency (EE%) was achieved with 2%-5% mol/mol additives. Differential scanning calorimetry thermograms revealed that the additives completely abolished gel/liquid transition suggesting that the bilayer membranes could accommodate the additives. The volume diameters D (4, 3) of the prepared niosomes were significantly [p < 0.05, analysis of variance (ANOVA)] dependent on the additive used. D (4,3) values of F-C24 and F-CH were 22.41 ± 1.40 and 5.37 ± 1.40 μ m, respectively. F-S60, F-DCP, and F-CH shapes were typical spherical, whereas F-C24 was oval giant niosomes (discomes). In vitro drug release parameters showed that the prepared niosomes significantly (p < 0.01, ANOVA) controlled NTX release rate and extent. Ex vivo transcorneal permeation studies conducted using excised cow corneas showed that niosomes were capable of controlling NTX permeation and enhance its corneal permeability. The prepared niosomal formulations were found practically nonirritant when applied onto the surface of a 10-day-old hen's chorioallantoic membrane.

An interfacial tension model of the interaction of water-soluble polymers with phospholipid composite monolayers.

The axi-symmetric drop-shape analysis-pendant drop technique has been used to measure interfacial tension at the chlorobenzene-water interface in the presence of adsorbed films of dimyristoylphosphatidylcholine (DMPC), dipalmitoylphosphatidylcholine (DPPC), DMPC-cholesterol, DPPC-cholesterol, DMPC-cholesterol-dicetyl phosphate (DCP) and DPPC-cholesterol-DCP. A surface-pressure function, pi * = pi lipid-polymer -pi lipid (where pi lipid is the surface pressure of the mono-layer without polymer and pi lipid-polymer is the surface pressure of the lipid mono-layer and adsorbed polymer at equilibrium at the chlorobenzene-water interface) was used to characterize the interaction of eight water-soluble polymers with the lipid films. The equation, delta pi * = pi II*-pi I* (where the subscripts II and I denote the higher and lower lipid composites, respectively) was used to determine the differential effect of cholesterol and DCP on mono-layer characteristics in the presence of 1% w/v polymer. Cholesterol or polymer individually condensed DMPC films and expanded DPPC films. However, composite films of DMPC-cholesterol-DCP and carboxymethylchitin (CM-chitin), poly(acrylic acid) (PAA) or poly(vinyl alcohol) (PVA) were more expanded than DMPC films whereas composite films of DPPC were neither more condensed nor expanded than DPPC films. A polymer impact ratio, P* = pi lipid-polymer/pi lpolymer was calculated and the polymers were ranked in order of their impact on the lipid film. PVA and polysaccharides gave low and high P* values, respectively, corresponding to high and low levels of film interaction, whereas PAA and hydrophobized polysaccharides gave intermediate values, indicating their affinity for and penetration of interfacial films with little disruption of the mono-layer. The results show that measurement of interfacial pressures at the chlorobenzene-water interface might be advantageous for evaluating the action of polymers on biological membranes.

A gamma scintigraphic evaluation of the precorneal residence of liposomal formulations in the rabbit.

Multilamellar liposomes were prepared from dipalmitoyl phosphatidylcholine or egg lecithin in combination with cholesterol and either dicetyl phosphate or stearylamine. The size and charge of the colloidal preparations were characterized before labelling with [111In]8-hydroxyquinoline. Freshly labelled liposomes were instilled into the eyes of unanaesthetized NZW rabbits and their disposition and drainage followed using gamma scintigraphy. A positive surface charge was found to affect significantly liposomal drainage rate, whereas an increase in size restricted drainage from the inner canthal region. Drainage of the suspending medium was directly compared with liposomes by labelling the medium with [99mTc] sodium pertechnetate and following the simultaneous change in removal of 99mTc and 111In from the precorneal area. Slower drainage rates were obtained for the suspending medium compared with solutions of the isotopes suggesting that the liposomes restricted solution drainage.

The effect of non-ionic surfactant vesicle (niosome) entrapment on the absorption and distribution of methotrexate in mice.

Non-ionic surfactant vesicles (niosomes) prepared from a non-ionic surfactant, cholesterol and dicetyl phosphate and containing methotrexate (MTX) have been administered to mice. Given intravenously the niosomes prolong the levels of MTX in the blood, large amounts of the drug being taken up by the liver. There was also an increased uptake of MTX into the brain, perhaps due to an effect of the niosome components on the permeability of the blood brain barrier. Absorption of the drug from the gastrointestinal tract following oral ingestion, appeared to be increased at some doses; most of the entrapped MTX was taken up by the liver, but uptake of MTX into the brain was also increased. The metabolic profile of the drug is altered by the niosomes which appear to prevent the rapid formation of 7-hydroxy methotrexate.

Encapsulation, stability and in-vitro release characteristics of liposomal formulations of colchicine.

The severe toxicity and low therapeutic index of colchicine limit its therapeutic use. Encapsulation in liposomes might reduce these toxic effects. The objective of this study was to determine the factors influencing encapsulation of colchicine in liposomes and to optimize the encapsulation parameters. Colchicine was encapsulated in multilamellar liposomes and large unilamellar liposomes prepared using various phospholipids. The effects of method of preparation, type of vesicle, charge, and concentration of cholesterol on encapsulation of colchicine in liposomes were investigated. Also, stability of colchicine under stress conditions and at various temperatures, and in-vitro release characteristics were determined. A significant difference in encapsulation of colchicine in multilamellar liposomes was observed when prepared by two different methods. Induction of charge on the liposome surface increased encapsulation of colchicine in multilamellar liposomes, but did not affect large unilamellar liposomes. The liposome preparations could withstand simulated transport conditions and frequent changes in temperature. Particle size and concentration of colchicine did not change significantly during storage at various temperatures for six months. In order to retain encapsulated colchicine in liposomes, storage at or below room temperature was found to be suitable. In-vitro release of colchicine from large unilamellar liposomes was biphasic and was influenced by two rate-limiting barriers, the dialysis membrane and the liposome bi-layers. For optimum encapsulation and stability of colchicine liposomes were prepared from a mixture of 1,2-distearoyl-sn-glycero-3-phosphocholine, cholesterol and either stearylamine or dicetyl phosphate.

Niosomal encapsulation of the antitubercular drug, pyrazinamide

It is estimated that more than one-third of the world population is infected with Mycobacterium tuberculosis. Pyrazinamide (PZA) plays a unique role in shortening therapy because it kills a population of semilatent tubercle bacilli residing in an acidic environment. Niosomes are vesicles made up of non-ionic surfactant and exhibit behavior similar to liposomes in vivo. Preparation of PZA niosomes took place using different molar ratios of Span 60 and Span 85, with cholesterol (CH) i.e. Span: CH (1:1) and (4:2). Dicetyl phosphate and stearyl amine were used in preparation of negative and positively charged niosomes, respectively. Free PZA was separated by cooling centrifugation and estimated spectrophotometrically at 268.4 nm. Niosomes were characterized by electron microscopy and differential scanning calorimetry. The highest percentage PZA entrapped was obtained using Span 60 and the molar ratio (4:2:1) negatively charged niosomes. This was followed by the neutral PZA neutral (4:2) Span 60 niosomes. Biological evaluation of selected PZA niosomal formulations took place on guinea pigs infected with M. tuberculosis. The present work is an attempt to target maximum concentration of PZA to the affected site (lungs) and to exclude undesirable side effects and decrease toxicity. Macrophage targeting and overcoming drug resistance is our final goal.

Niosomal Entrapment of Hydroxypropyl‐β‐cylodextrin‐Methotrexate Complex as a Drug Delivery Device

An inclusion complex of methotrexate with hydroxypropyl-β-cylodextrin (HPβCyD) was prepared with a view to increase entrapment efficiency and thereby improve the anticancer activity and stability of the drug. The complex and the plain drug were entrapped in the niosomes using cholesterol, Span 60 and dicetyl phosphate. The niosomal entrapment efficiency was higher (89%) in the case of the drug-complex than with the plain drug (67%). When administered to tumour-bearing BALB/c mice at a dose of 5 mg kg−1, the complex entrapped in the niosomes produced a higher percentage increase in life span. Better stability on storage was also observed with the niosome-entrapped complex. Thus complexation of methotrexate with HPβCyD increases the efficiency of entrapment in nonionic surfactant vesicles and the entrapped complex is stable and has improved anticancer activity.

Formulation and evaluation of niosomes.

Span 20-based niosome was prepared by lipid film hydration technique and loaded with Newcastle disease vaccine. Three batches with Span 20, cholesterol and dicetyl phosphate in micro molar ratios of 10:10:1; 15:15:1 and 20:20:1 were prepared and evaluated for encapsulation efficiency using haemagglutination test. The morphology of the vesicles was studied by means of transmission electron microscopy. Particle size, zeta potential and polydispersity index were determined by photon correlation spectroscopy using a nanosizer. Adjuvanticity was assessed using haemagglutination inhibition test. The vesicles of Span 20-based niosomes were distinct, near spherical large unilamellar vesicles. The vesicles were of varied sizes (<1000 nm) with the entrapped Newcastle disease vaccine in the core of the vaccine. The zeta potential had a peak at -50 mV. The polydispersity index was 0.68. Haemagglutination inhibition test showed a 71% increment in immune response over that of the marketed La Sota® vaccine which had a 60% increment in immune response. The niosomal vaccine did not alter but rather enhanced the immunogenicity of the Newcastle disease vaccine.

Development and Evaluation of Chitosan-Coated Liposomes for Oral DNA Vaccine: The Improvement of Peyer’s Patch Targeting Using a Polyplex-Loaded Liposomes

The aim of this study was to develop chitosan-coated and polyplex-loaded liposomes (PLLs) containing DNA vaccine for Peyer's patch targeting. Plain liposomes carrying plasmid pRc/CMV-HBs were prepared by the reverse-phase evaporation method. Chitosan coating was carried out by incubation of the liposomal suspensions with chitosan solution. Main lipid components of liposomes were phosphatidylcholine/cholesterol. Sodium deoxycholate and dicetyl phosphate were used as negative charge inducers. The zeta potentials of plain liposomes were strongly affected by the pH of the medium. Coating with chitosan variably increased the surface charges of the liposomes. To increase the zeta potential and stability of the liposome, chitosan was also used as a DNA condensing agent to form a polyplex. The PLLs were coated with chitosan solution. In vivo study of PLLs was carried out in comparison with chitosan-coated liposomes using plasmid encoding green fluorescence protein as a reporter. A single dose of plasmid equal to 100 μg was intragastrically inoculated into BALB/c mice. The expression of green fluorescence protein (GFP) was detected after 24 h using a confocal laser scanning microscope. The signal of GFP was obtained from positively charged chitosan-coated liposomes but found only at the upper part of duodenum. With chitosan-coated PLL540, the signal of GFP was found throughout the intestine. Chitosan-coated PLL demonstrated a higher potential to deliver the DNA to the distal intestine than the chitosan-coated liposomes due to the increase in permanent positive surface charges and the decreased enzymatic degradation.

Liposomes for enhanced cytotoxic activity of bleomycin

AbstractThe purpose of this study was to investigate the effect of liposome composition, which affects the nature of vesicular membrane on the cytotoxic efficacy of bleomycin. Formulation A comprised phosphatidylcholine (PC), cholesterol (CH), and dicetylphosphate (DCP). Formulation B employed PC, CH with dioleoylphosphatidylethanolamine (DOPE) as the fusogenic component. Formulation C consisted of rigid liposomes comprising dipalmitoylphosphatidylcholine (DPPC), CH, and DCP. Preparation D contained dioleoylphosphatidylcholine (DOPC), CH, and DCP. Formulation E employed the same components of B, with PC being replaced with Pegylated PC. The cytotoxic efficacy was monitored using the Daudi cell line obtained from Burkitt's lymphoma. Formulations A and B significantly increased the cell death via necrosis compared with drug solution. Formulation D produced marginal increase in the efficacy of bleomycin with the rigid vesicles being similar to the control. Pegylated liposomes (E) were as effective as A and B, but the cytotoxic effect was via apoptosis. In conclusion, the efficacy of liposomes depended on the composition with fusogenic, flexible, or Pegylated vesicles being superior. Drug Dev Res 72: 265–273, 2011. © 2010 Wiley‐Liss, Inc.