Radiopaque Liposomes: Effect of Formulation Conditions on Encapsulation Efficiency

Benita, Simon; Poly, P.A; Puisieux, F.; Delattre, Jacques

doi:10.1002/jps.2600731223

Cited by 47 publications

(12 citation statements)

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“…pressed as drug content and encapsulation capacity (5). The encapsulation parameter, which is defined as the encapsulation capacity (milliliters/millimoles), is a function of the liposome size and the number of lamellae per vesicle.…”

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confidence: 99%

Ofloxacin-Loaded Liposomes: In Vitro Activity and Drug Accumulation in Bacteria

Furneri¹,

Fresta

Puglisi

et al. 2000

Antimicrob Agents Chemother

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Different ofloxacin-loaded unilamellar vesicles were prepared by the extrusion technique, and their antimicrobial activities were determined in comparison to those of the free drug by means of MIC determinations with both American Type Culture Collection standards and wild-type bacterial strains (six strains of Enterococcus faecalis, seven strains of Escherichia coli, six strains of Staphylococcus aureus, and six strains of Pseudomonas aeruginosa). The accumulation of ofloxacin and liposome-ofloxacin was measured by determining the amount of the drug inside the bacteria as a function of time. Encapsulated fluoroquinolone yielded MICs which were at least twofold lower than those obtained with the free drug. In particular, liposomes made up of dimyristoylphosphatidylcholine-cholesterol-dipalmitoylphosphatidylserine and dimyristoylphosphatidylcholine-cholesterol-dihexadecylphosphate (4:3:4 molar ratio) provided the best improvement in antimicrobial activity against the various bacterial strains investigated. The liposome formulation produced higher intracellular fluoroquinolone concentrations than those achieved simultaneously with the free drug in both E. coli and P. aeruginosa.Since the discovery of the original DNA gyrase inhibitor nalidixic acid, numerous structural modifications have been carried out to the quinolone nucleus to increase antimicrobial activity and improve pharmacokinetic performance (12,22,29,46).The efficacy of fluoroquinolone antibiotics has led to their proposed use for the treatment and prophylaxis of different bacterial diseases: therapy for the respiratory tract, skin structure, and bone and gastrointestinal infections, as well as urinary tract infections (20,21,23,36,41). However, many studies were developed to improve the potency and spectrum, to achieve sustained blood levels, and to reduce as much as possible drug interactions with various metabolic pathways and physiological processes. Particularly, the use of antibiotic "carrier/delivery systems" would result in enhanced concentrations of the antimicrobial agent at the site of infection. In fact, delivery systems can contribute to (i) targeting of the drug to the infected tissues, (ii) increasing intracellular antibiotic concentrations, and (iii) reducing toxicity of potentially toxic drugs resulting from the targeting to the infectious organisms.Liposomes are possible carriers for controlled drug delivery and targeting by the intravenous route. As with most drug carriers, liposomes have been extensively used in an attempt to improve the selective delivery and the therapeutic index of antimicrobial agents (3, 47). Liposomes, artificial phospholipid membranes, are usually produced from naturally occurring, biodegradable, and nontoxic lipids, such as lecithin, cholesterol, and phosphatidylserine.The aim of the study described here was to investigate the antimicrobial activity against and accumulation in bacteria of ofloxacin-loaded liposomes (of different lipid compositions) in comparison to those of free drugs. Our preliminary experi...

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mentioning

confidence: 99%

Ofloxacin-Loaded Liposomes: In Vitro Activity and Drug Accumulation in Bacteria

Furneri¹,

Fresta

Puglisi

et al. 2000

Antimicrob Agents Chemother

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“…The reduction of mobility observed in the moths of group EC ( Figure 2B) can be associated either with the stress caused by primary dermal irritability of a few formulation components, mainly solvents and a few tensioactives, or with the presence of a greater amount of insecticide in its free form in this kind of formulation (Benita et al, 1984). In the present study, the behavior of thanatopsis was observed, so, the insect was considered dead when it did not move for a period of three minutes of observation after being stimulated.…”

Section: Resultsmentioning

confidence: 99%

“…It is used in the concentration of 48 g active ingredient per hectare (equivalent to 100 mL.ha -1 ). In the form of emulsifiable concentrate, the bioinsecticide was formulated through a mixture of active ingredients, emulsifiers and solvents (Knowles, 2008); in the form of suspension capsules, it was made through the interfacial polymerization method by coacervation in liquid phase (Benita et al, 1984); and deionized water was used for aspersion in the negative control group.…”

Section: Methodsmentioning

confidence: 99%

Efficacy evaluation of spinosad bioinsecticide capsules suspension for the control of Helicoverpa armigera

Souza¹,

Maranho²,

Cardoso³

2017

Afr. J. Biotechnol.

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Helicoverpa armigera caterpillar causes serious economic crop losses in Brazil, mainly in the corn, cotton and soybean farming. The aim of this study was to compare the efficiency of bioinsecticide Spinosad in the form of suspension capsules and emulsifiable concentrate in the dosage of 48 g i.a. ha -1 for control of H. armigera. The experiment was conducted in three different groups treated separately with emulsifiable concentrate (EC) with 48% of spinosad; suspension capsules (SC) with 48% of spinosad; and control group treatment with deionized water. Caterpillars were used in the early stage (1 and 2 days old larvae), and maintained under laboratory conditions (24 ± 1°C, 65 ± 5% RH and a 12:12 h light: dark photoperiod). The mortality was recorded and the affected behavior of treated larvae was checked every 30 min for a period of 8 h. The results show the efficacy of spinosad for control of H. armigera in the emulsifiable concentrate group treatment at 92.6 and 88.9%, and in the suspension capsule group treatment at 88.9 and 87.0%, respectively, in the first and second bioassay. It was concluded that the spinosad 48 g i.a. ha -1 is efficient in the control of H. armigera in micro encapsulated formulations, promoting less environmental damage by reducing the level of pesticides in the environment by the smaller concentration of the active ingredient through capsule suspension formulation and revealed economic viability and promotion of extended release of active ingredients.

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“…34 The entrapped aliquot was calculated with respect to the difference from the starting material. The encapsulated 30-mer ODN amount is expressed as encapsulation capacity (EC; µL/µmol lipid); this calculation has been reported elsewhere 35 and as a percentage of the starting material which was entrapped.…”

Section: Methodsmentioning

confidence: 99%

Liposomal Delivery of a 30-mer Antisense Oligodeoxynucleotide To Inhibit Proopiomelanocortin Expression†

Fresta¹,

Chillemi²,

Spampinato³

et al. 1998

Journal of Pharmaceutical Sciences

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An oligodeoxynucleic sequence of 30 bases (30-mer ODN), complementary to a region of beta-endorphin mRNA, was synthesized to have an antisense effect with regard to the expression of this oligopeptide. Following the solid-phase synthesis of the oligodeoxynucleotide, the 30-mer ODN was encapsulated within liposomes to provide a higher resistance against DNases and an improved entrance into cells. The most suitable liposome formulation as a 30-mer ODN carrier consisted of small unilamellar vesicles (50 nm) with an encapsulation capacity of 4.76 microL/micromol. The liposomal formulations containing dipalmitoyl-DL-alpha-phosphatidyl-L-serine presented fusogenic properties, which are of great importance for the delivery of antisense compounds. The antisense activity of 30-mer ODN-loaded liposomes was evaluated by the determination of beta-endorphin levels in AtT-20 cells. The free 30-mer ODN did not provide any lowering of the beta-endorphin production, whereas the liposomally entrapped compound elicited a concentration-dependent inhibition. The inhibition was determined by a sequence-specific binding of the 30-mer ODN with the target mRNA.

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Radiopaque Liposomes: Effect of Formulation Conditions on Encapsulation Efficiency

Cited by 47 publications

References 12 publications

Ofloxacin-Loaded Liposomes: In Vitro Activity and Drug Accumulation in Bacteria

Ofloxacin-Loaded Liposomes: In Vitro Activity and Drug Accumulation in Bacteria

Efficacy evaluation of spinosad bioinsecticide capsules suspension for the control of Helicoverpa armigera

Liposomal Delivery of a 30-mer Antisense Oligodeoxynucleotide To Inhibit Proopiomelanocortin Expression†

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