Perfluorodecalin Emulsion Research Articles

Design, synthesis and emulsifying properties of new perfluoroalkylated phosphatidylcholines

The achievement of fluorocarbon-based injectable O 2 delivery systems and the full exploitation of their potential has established the need for new fluorophilic surfactants and co-surfactants for improving and manipulating the emulsions' characteristics in order to adjust them to specific therapeutic applications. New perfluoroalkylated phospholipids (F-alkylGPCs) have been developped which are structural analog of phosphatidylcholine present in the natural phospholipids used in injectable emulsions. Their synthesis is based on the phosphorylation of rac-1,2-di-(F-alkylacyl)-3-glycerol with 2-bromoethyldichlorophosphate, followed by reaction with an amine. ▪ When taken as the sole surfactant, the new F-alkylGPCs allow the preparation of perfluorodecalin (FDC) emulsions. The efficiency of the emulsifier improves when the perfiuoroalkylated tail length or the Fn/Cm ratio are increased. The most efficient surfactant, compound 2, in spite of its being monodisperse, is as efficient as egg yolk phospholipids (EYP), a mixture of natural phospholipids. The co-surfactant properties of the F-alkylGPCs with EYP are related to the surfactant's total chain length. Compound 4 demonstrated a strong synergistic stabilizing effect with EYP while 3 did not improve the emulsions' characteristics and 2 lead to large particle size emulsions. These results will be rationalized in terms of interactions of the surfactant's perfluoroalkylated tail with the fluorocarbon phase and with the fatty acid chains of the EYP.

Detrimental effect of excess lecithin on the stability of fluorocarbon/lecithin emulsions

The formation and stability of concentrated lecithin-stabilized emulsions of perfluorodecalin (100% and 70% w/v, i.e. 51.5% and 36.1% v/v) have been studied for lecithin/fluorocarbon ratios ranging from 2 to 11. The stability was found to go through a maximum for a lecithin/fluorocarbon ratio of 4-6%

A stable perfluorochemical blood substitute

A stable emulsion of perfluorodecalin, made up of 34 percent (vol/vol) perfluorodecalin dispersed by sonication in isotonic Tyrode's buffer (pH 7.4) containing egg yolk lecithin, has been developed. The viscosity of the emulsion is the same as that of human blood, and the particle size is 0.2 microns in diameter. On storage at 5 degrees C, there was no change in viscosity for up to 60 weeks. At 21 degrees C, viscosity increased after 20 weeks of storage; this increase was considerably diminished by the presence of tocopherol in the emulsion. The accumulation of malondialdehyde indicated that there was continuous slow oxidation of the lecithin on storage of the emulsion at either 5 or 21 degrees C; this oxidation was markedly reduced by the presence of tocopherol.

Perfluorodimorpholinoalkanes as stabilizing additives in perfluorocarbon-emulsions

The interfacial behaviour of perfluorodecalin in contact with water was investigated in relation to added perfluorodimorpholinoalkane. An equation was found for calculating the interfacial tension curves. A new theory on the stabilizing effect of perfluorodimorpholinoalkanes in emulsions of perfluorodecalin was developed taking into account the interfacial tension and stability curves. Perfluorodimorpholinoalkanes might be called ‘Interfacial Active Compounds’ (IFACs) because of their behaviour at the water/perfluorodecalin interface.

Amine(polyfluoroalkoxyacyl)imide surfactants [1

Twenty-one examples ( 10a–d, 11a–1 and 12a–e) of a new class of surfactants, the amine(polyfluoroalkoxyacyl)imides, were prepared by the reaction of esters containing polyfluoroalkoxy groups with tertiary alkylaminimides and hydroxyalkylaminimides. Included are five examples of difunctional aminacylimides that contain the hydrophilic portion of the molecule in the middle. These new surfactants are among the most potent known in their ability to form aqueous solutions with very low surface tensions and can be used to prepare stable emulsions of perfluorodecalin in water. Two new esters (ethyl perfluorooctyloxyacetate, 7, and ethyl 1 H,1 H- perfluorooctyloxyacetate, 9) used as intermediates to the surfactants were prepared by the alkylation of perfluoro- and 1 H,1 H-perfluorooctanol salts with ethyl bromoacetate. Other esters used in the preparation of the surfactants were derived from oligomers of hexafluoropropene oxide.

Effects of emulsified perfluorochemicals on liver aryl esterase in rats

1. The effects of intravenous (i.v.) injection of various perfluorochemical (PFC) emulsions have been studied separately in male and female rats. 2. Injection of 10 ml/kg body weight of either Fluosol-DA 20% (F-DA) or a novel perfluorodecalin emulsion containing a C-16 oil additive in male rats increased liver weight up to 7 days later; no corresponding change occured in response to injection of Oxypherol (FC-43). 3. Liver weight was also increased in female rats at 72 hr after injection of the novel emulsion but this was less pronounced than in males; liver weight in female rats was unchanged in response to injection of either F-DA or FC-43. 4. Mean liver aryl esterase activity in male rats was increased 2- to 3-fold ( P < 0.05) at 7 days a injection of the novel emulsion. No significant alterations in aryl esterase activity occurred in respons to injection of either F-DA or FC-43, although in both cases there was a trend towards increased activity 5. Liver aryl esterase activity in female rats was significantly ( P < 0.05) decreased at 72 hr foll FC-43 injection with similar, but much less pronounced, changes occurring in response to injection of F-DA and the novel emulsion. 6. These results show that injection of a single low dose of emulsified PFCs into rats can alter hepatic microsomal aryl esterase activity but the response is highly variable, depending on composition of emulsion injected and sex of recipient.

Effects of Perfluorodecalin and Perfluorooctylbromide Emulsions on Peak Contractile Force and ATP Levels in the Guinea PIG Left Atrium

The isolated, electrically-driven, guinea pig left atrium was used to study the ability of two perfluorocarbon emulsions to prevent anaerobic hypofunction in the myocardium. A 20% perfluorodecalin (PFD) emulsion maintained peak tension at 80% of aerated levels for more than 20 minutes. Emulsions of perfluorooctylbromide (PFOB) ranging from 25 to 100% produced a similar result, except that the 25% emulsion could not maintain contractions for the entire time period. Peak tension of atria bathed in K-H solution decreased to less than 50% over the same time period. Both 20% PFD and 100% PFOB maintained myocardial ATP levels at pre-hypoxic levels for at least twenty minutes after aeration was terminated. Unaerated atria, bathed in Krebs-Henseleit solution only, exhibited a significant decline in tissue ATP levels at this time. It appears that perfluorocarbon emulsions may delay oxygen desaturation and thereby protect cardiac tissue from ATP depletion and impaired cardiac function associated with hypoxia. This tissue preparation was found to be very useful for determining the efficacy of potential oxygen carriers.

Thermal stability of fluorocarbon emulsions that transport oxygen

Pluronic F-68 (Poloxamer 188) is a non-ionic block co-polymer which has been used to emulsify perfluorocarbons (PFCs) for use as oxygen transport fluids. The surfactant has been shown to be an effective stabiliser of perfluorodecalin emulsions. Autoclaving is the most practical method of sterilising parenteral formulations, but PF-68 stabilized perfluorodecalin emulsions break down rapidly on autoclaving which prevents this technique being used. Presented here are results which suggest that the observed breakdown of the emulsions on autoclaving is related to the cloud point of the surfactant. This is further underlined by the effect of additives which elevate or depress the surfactant cloud point and change the stability of the corresponding emulsions. We have used such additives to prepare PF-68 stabilized perfluorodecalin emulsions which are stable to sterilization by autoclaving.

Affinity chromatography on triazine dyes immobilized on novel perfluorocarbon supports

A bis-substituted conjugate of the dichlorotriazinyl dye C.I. Reactive Blue 4 (Procion Blue MX-R) with 1H,1H-pentadecafluorooctylamine was synthesised and characterised. This novel conjugate showed strong surface activity on aqueous-fluorocarbon interfaces and was used to prepare dyed liquid and solid perfluorocarbon supports for affinity chromatography. Rabbit muscle lactate dehydrogenase was purified up to 8.4-fold from a crude extract by chromatography on the surface active dye adsorbed on perfluorodecalin emulsion droplets and on a powdered microparticulate fluoropolymer. The performance of these novel affinity supports was shown to be comparable to adsorbents prepared by using the same triazine dye immobilised on agarose gels. Two further surface active dichlorotriazinyl dye conjugates were immobilised on liquid and solid perfluorocarbon supports and tested using protein purification protocols to illustrate the applicability of this novel technique.

Phase i/ii study of fluosol®-DA and 100% oxygen as an adjuvant to radiation in the treatment of advanced squamous cell tumors of the head and neck

Fluosol®-DA 20% (Fluoso®) is an emulsion of perfluorodecalin and perfluorotripropylamine, which has the ability to carry oxygen and has been shown to enhance the ability of radiation to control tumors in animal studies. Since November 1984, patients with unresectable squamous cell carcinomas of the head and neck have been enrolled in a study to evaluate the safety and potential efficacy of this adjuvant therapy. Forty-six patients were entered of which 37 completed radiation and are evaluable. Patients were infused weekly with Fluosol® and then breathed 100% oxygen for a minimum of 30 minutes prior to and during radiation. Eleven patients received 5 infusions of 8 mL/Kg, four patients 6 infusions of 8 mL/Kg, five patients 5 infusions of 9 mL/Kg, seven patients 7 infusions of 7 mL/Kg and eight patients 8 infusions of 7 mL/Kg. Nine patients had Stage III disease, 20 patients Stage IV disease and 8 patients had failed previous therapy with chemotherapy and/or surgery. The radiation doses delivered ranged from 6600 cGy to 7500 cGy. The overall complete response rate for this group was 76%. All 9 Stage III patients were complete responders, 13 of 20 Stage IV responded and 6 of 8 with previous therapy were complete responders. The survival rate at 1 year was 67% for absolute and 78% as determinant. Of those patients achieving a complete response, 75% continued free of disease 1 year after therapy. Out of 254 total test doses, 11 patients experienced a reaction to the test dose of Fluosol®. Of 235 total infusions 6 patients experienced a reaction during the Fluosol® infusion with 7 patients experiencing post infusion reactions. These were readily controlled with diphenhydramine or acetominophen. Elevated liver enzymes were observed in some patients with a mean time to normalization of 102 days for alkaline phosphatase, 39 days for SGOT, and 46 days for SGPT.

Effects of emulsified perfluorochemicals on liver cytochromes P-450 in rats

1. The effects of intravenous (i.v.) injection of various perfluorochemical (PFC) emulsions or different fractions of the non-ionic poloxamer surfactant, Pluronic F-68, have been studied separately in male and female rats. 2. Injection of 10 ml/kg body wt of either Fluosol-DA 20% (F-DA) or a novel perfluorodecalin emulsion containing a C-16 oil additive in male rats increased liver weight up to 7 days later; no corresponding effect occurred in response to injection of Oxypherol (FC-43). 3. Liver weight was also increased in female rats at 72 hr after injection of the novel emulsion but this was less pronounced than in males; liver weight in female rats was unchanged in response to injection of either F-DA or FC-43. 4. Mean liver microsomal cytochromes P-450 concentrations in male rats were increased 2–3 fold at 72 hr after injection of either F-DA or the novel emulsion with a less pronounced increase also seen at 7 days in animals receiving the novel emulsion. No significant alterations in cytochrome concentration occurred in response to injection of FC-43 or either commercial grade or purified pluronic solution. 5. Liver cytochromes P-450 concentrations in female rats were unaffected by any of the experimental treatments. 6. These results show that injection of a single low dose of emulsified PFCs into male rats can increase hepatic microsomal cytochromes P-450 concentration but the response is highly variable, depending on composition of emulsion injected.

Alteration by perfluorodecalin of hepatic metabolism and excretion of phenobarbital

The bile duct was cannulated in rats that had been infused intravenously with an emulsion of perfluorodecalin at intervals from 2 to 34 weeks earlier. After injection of [ 14C]phenobarbital, urine and bile were collected during the next 24 hr and were analyzed for phenobarbital and its metabolites. There was a decrease in the biliary excretion of phenobarbital and its metabolites for several weeks after infusion of perfluorodecalin, but conjugation of the metabolites was not decreased. The reduced excretion returned to normal after about 20 weeks.

Novel compositions of emulsified perfluorochemicals for biological uses.

Physico-chemical characteristics of novel perfluorodecalin emulsions stabilized against Ostwald ripening by the addition of polycyclic, perfluorinated oil additives are described. The effects of varying both oil additive and emulsifier concentrations have been examined. Stabilizing effects of additives were found to be related to molecular weight and hence, boiling point and vapour pressure.

Perfluorochemicals as US contrast agents for tumor imaging and hepatosplenography: preliminary clinical results.

In animals, perfluorochemicals (PFCs) are effective ultrasound (US) contrast agents that produce hepatic, splenic, and tumor enhancement. The use of Fluosol-DA 20%, an emulsion of perfluorodecalin and perfluorotripropylamine, was studied in nine non-critically ill patients with cancer who had liver lesions. US studies without Fluosol were compared with studies obtained 24, 48, and 72 hours after Fluosol infusion. Vital signs and extensive laboratory analyses are performed before and after Fluosol infusion. Liver metastases from colonic, pancreatic, and gastric carcinoma exhibited rim or diffuse enhancement after a Fluosol dose of 1.6 g/kg or greater. Fluosol produced echogenic enhancement of the liver and spleen relative to kidney at a dose of 2.4 g/kg, allowing the detection of nonenhancing lesions. In addition, Fluosol at a dose of 1.6 g/kg or greater allowed detection of lesions not seen before contrast medium was administered in three of the seven patients studied. There was a mild increase in the level of serum glutamic oxaloacetic transaminase in two patients, one given 2.4 and the other 3.2 g/kg of Fluosol. Mild and transient allergic reactions without change in vital signs were experienced by two patients.

Efficacy of perfluorodecalin as an oxygen carrier for mouse and rat testes perfused in vitro.

Perfluorodecalin is a superior artificial oxygen carrier because of its high oxygen dissolving capacity, low toxicity, and short retention times within tissues. However, the instability of perfluorodecalin emulsions has hindered its application in blood substitutes. The present study addressed two questions. First, is perfluorodecalin deleterious to the endocrine function of testes? This question was examined by comparing testosterone secretion by testes perfused in vitro with medium incorporating either perfluorodecalin or erythrocytes as oxygen carriers. Second, can stable emulsions of perfluorodecalin be attained with the new surfactant Butronic U-1? This question was approached by determining the stability of perfluorodecalin emulsions containing either Butronic U-1 or Pluronic F-68, a proven ineffective surfactant. The experimental results support the efficacy of perfluorodecalin emulsions as oxygen carriers for mouse and rat testes perfused in vitro. Perfluorodecalin emulsions formed with Butronic U-1 were stable during the 4-hr perfusions but not during long-term storage.

Effects of emulsified perfluorochemicals on growth and ultrastructure of microbial cells in culture

The effects of emulsified perfluorochemicals (PFCs) and some of their constituents on growth and ultrastructure of microbial cells in culture have been studied. Growth rate ofE. coli was inhibited by stem emulsion from the proprietary formulation, Fluosol-DA 20%, and also by a combination of the Pluronic F-68 surfactant and yolk phospholipid emulsion stabilizer. Yeast growth was also inhibited by Fluosol stem emulsion and by pluronic alone. Electron microscopical examination of thin sections of yeast cells following culture in perfluorodecalin emulsion revealed cytoplasmic vacuolation and other ultrastructural perturbations resembling those reported previously in mammalian cells cultured with emulsified PFCs; no comparable structural changes inE. coli were observed.

The influence of oxygenation on the 19F spin-lattice relaxation rates of fluosol-DA (artificial blood)

The spin-lattice relaxation rates (1/T1) were measured at 94.1 MHz for six peaks in the 19F NMR spectrum of the perfluorochemical blood substitute fluosol-DA, which contains a mixed emulsion of perfluorodecalin and perfluorotripropylamine. Each of these rates increased linearly with the percentage of oxygen dissolved in the emulsion. Relative values of the linear increase for different peaks established that, for perfluorotripropylamine in the mixed emulsion, the oxygen-fluorocarbon interaction is loosely but preferentially oriented in a manner similar to that previously established for other pure fluorocarbons. The uncertainty in the oxygen level estimated from T1 measurements is somewhat less than 5% O2 and it is thus established that quantitative noninvasive oxygenation measurements can be made to sufficient precision by this approach, using fluosol-DA and 19F spin-lattice relaxation.

Effect of perfluorodecalin on the microsomal mono-oxygenase system in perfused rat livers.

1. An emulsion of perfluorodecalin was used as a substitute for erythrocytes in a synthetic medium in the perfusion of isolated rat livers. 2. The efficiency of this oxygen carrier in maintaining liver viability and function was compared with an erythrocyte-containing medium. 3. Activities of the microsomal mono-oxygenase system, secretion of bile and concn. of transaminases, potassium, glucose, urea, pO2 and pCO2 in the medium, and ATP and glycogen in the tissue, did not differ in the two experimental conditions.

Emulsions of perfluorinated compounds for use in quality control of blood gas analyses.

We prepared emulsions of perfluorinated compounds and examined their utility as liquid matrixes for tonometry in quality control of blood pH and gas analyses. Emulsions of perfluorotributylamine and perfluorodecalin, prepared by sonication, consisted largely of particles not exceeding 0.2 micrometer in diameter. Unlike most aqueous solutions these materials were not easily contaminated by room air and can be reliably used for tonometry liquids. Results for pCO2 and pO2 agreed well with calculated values. Average day-to-day coefficients of variation for emulsions of perfluorotributylamine were 2.9% for pH (within the range 7.11-7.60), 4.4% for pCO2 (2.88-9.17 kPa), and 1.6% for pO2 (7.76-40.67 kPa).

Changes in oxygen supply levels in rats after exchange blood transfusion with perfluorodecalin emulsion

Changes in oxygen supply levels in rats after exchange blood transfusion with perfluorodecalin emulsion