DK155867B - EMULSION PREPARATION OF PERFLUORED COMPOUNDS FOR USE AS SYNTHETIC BLOOD - Google Patents

Description

DK 155867 B

The present invention relates to an emulsion preparation of perfluorinated compounds for use as synthetic blood.

The need for synthetic blood is well known. Blood becomes 5 more expensive and more expensive, it is perishable, it must fit the recipient's blood type, and the transfusion itself can cause liver inflammation if strict procedures are not adhered to. In addition, blood donations appear to be somewhat seasonal, and they often do not coincide with the usually random need for blood.

A synthetic blood must have several different properties. First of all, and quite obviously, it must have a high oxygen and carbon dioxide solubility, since its essential function is to transport oxygen and carbon dioxide. A synthetic blood must also be non-toxic and in this context it is desirable that no residual of the synthetic blood be left in vital organs when replaced with natural blood.

Another necessary feature of blood substitutes is that they must meet certain vapor pressure requirements. The blood substitutes leave the body through exhalation and evaporation through the skin. Preferably, blood replacement leaves the body at about the same rate as that at which new, natural blood is formed by the body. If the substitute vapor pressure is too low, it stays in the body for too long, while, if too high, it evaporates throughout the body surface and causes problems related to diving sickness.

Blood substitutes should also be able to form extremely stable emulsions, this ability being even more significant in perfusion materials. Blood substitutes are usually immiscible with blood and, if used alone, can cause embolism. This problem is solved by using the blood substitute in aqueous emulsion and it is clear that the emulsion must not be broken during use or storage. In the case of 35 perfusion materials, this requirement is even more stringent as the oxygenators used to convert oxygen to per

DK 155867 B

the fusion material, creates very high shear stresses and will break all emulsions except the most stable ones. Another reason why aqueous emulsions are used is that salts are added to the water to maintain the salt balance of the body.

The Green Cross Corporation, Osaka, Japan, has published a document dated September 11, 1974 regarding emulsions of perfluorinated compounds as oxygen and carbon dioxide carriers. Some of the compounds described in the present invention are also mentioned by Clark et al. in Microvascular Research, Volume 8/3 1974, also presented at the Oxygen Transport to Tissue Symposium, Atlantic City, N. J., April 11, 1974. The blood substitute and perfusion material chosen so far has been perfluorodecaline. It has 15 more desirable properties, but the compounds described in the present invention appear to be superior in several respects to perfluorodecaline.

The present invention relates to an emulsion composition for use as synthetic blood and containing a non-aromatizable perfluorinated compound in water, wherein the amount of water is greater than 40% by volume, and said emulsion contains a non-toxic emulsifier which is characterized in that it perfluorinated compound is lower alkyl adamantane, except for dimethyladamantane, preferably 1-methyladamantane, the amount of which in the emulsion is 10-30% by volume and having a particle size of approx.

0, 001-10 µιη, preferably 50% by weight of the particles having a size of 0.05-0.3 µm and furthermore, if desired, the emulsion preparation has a content of 10-100 cm3 of oxygen (25 ° C, 30%). 760 mm Hg) per 100 cm 3 of the perfluorinated compound.

Said perfluorinated lower alkyl adamantanes have an extremely high oxygen solubility, leave a very small residue in the body, form extremely stable emulsions and have a very satisfactory vapor pressure for the present application.

The lower alkyladamantanes are e.g. methyladamantane,

DK 155867 B

3 ethyladamantane, ethylmethyladamantane, ethyldimethyladamantan and triethyladamantan.

The lower alkyl adamantanes are used as mentioned in perfluorinated form. As used herein, the term perfluorinated comprises 5 compounds of which at least 95% by weight is completely fluorinated (i.e., perfluorinated in the strict sense), preferably at least 98% and most preferably 100%. In all cases less than 100%, the remaining amount will naturally be highly fluorinated.

Fluorination is carried out by known methods. The alkyl adamantane can e.g. is slowly passed over a layer of COF3 containing 2-3 times the stoichiometric amount of fluorine at 250-275 ° C to give a partial fluorination. The procedure is then repeated at 300-350 ° C to give a complete fluorination of the whole except for a few 15 percent impurities which are both saturated, partially fluorinated compounds and olefinic carbon fluorides. The former compounds boil at least 10 ° C higher than the desired perfluoro compound and are removed by distillation. The latter compounds boil at practically the same temperature, and are therefore extracted with an amine such as diethylamine (DEA). Remaining amine is removed with concentrated sulfuric acid. The residual acid is removed with 1% sodium hydrogen carbonate solution, which is then extracted with acetone. Finally, the remaining acetone is distilled off.

Usually, the emulsion composition contains 1-5 volume percent of an emulsifier. The selection of an emulsifier is not critical, but the emulsifier should be non-toxic and form a stable emulsion. The preferred emulsifier is egg yolk phospholide, as it is well known that this is harmless to the body. Also suitable for perfusion purposes are polyoxyethylenes and polyoxypropylenes which are commercially available as "Pluronics". The "Pluronic® F-68" has a molecular weight of 8,350 and forms a very stable emulsion.

The emulsion can be prepared by conventional emulsifiers which produce high shear stresses such as a Manton-Gaulin homogenizer. Partikelstør-

DK 155867 B

As mentioned, the journey in the emulsion is 0.001-10 μια, often 0.01-10 μια and usually 0.05-0.5 μια, and preferably 50% by weight of the particles have diameters of 0.05-0.3 μια. As is well known, the particle size can be set by the shear stress applied. The actual particle size of the emulsion is not as critical as its stability, which is further discussed below.

As stated above, retention of the material in the body is important. In the following, perfluorinated (PF) methyladamantane (MA) is compared with PF tributylamine (TBA), decalin (D) and methyldecaline (MD). These compounds are the best blood substitutes and perfusion materials to date. Emulsions containing 10% of the material to be tested, surfactant and water are prepared and tested in the manner described in Science, Volume 181, August 1973, page 681. The various emulsions are injected into mice. The mice are killed at different intervals thereafter, the liver is analyzed and the percentage ratio between the initial amount of injected PF material and the 20 amount still in the liver is determined. The results obtained are listed below.

Percentage of dose in the liver after the indicated number of weeks_ 25

Compound 2 6 12 20 PFD 2 2 2 2 30 PFMD 30 19 2 2 PFTBA 38 30 30 30 PFMA the body) is as good or better than PFD.

The relative stability of a PFMA emulsion is excellent, being stable for an unspecified period of 40 (e.g., over 6 months) at 4-7 ° C, while the PFD emulsion in

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5 breaks during a few days at room temperature and a few weeks at 4-7 ° C. PFTBA is also excellent. See, e.g. Journal of Microvascular Research, August, 1974. In addition to the emulsion stability, an emulsion made from PFMA exhibits an optical density of 0.65, which means that the particle size of the material is much smaller and is therefore much easier to emulsify than PFTBA which gives a value of 2.2.

It has also been found that the perfluorinated compounds of this invention have a very low toxicity. LD50 of the compounds of this invention after infusion compared to other compounds are as follows: LD50 (mg / kg)

Emulsion 1 hour 3 days 7 days 10.9% PFD 190 160 159 5% PFMA> 200> 200> 200 20 10% PFTBA> 200 120 120

As stated above, the present perfluorinated compounds have a high oxygen and carbon dioxide solubility. Eg. the perfluorinated compounds can usually contain approx. 40-60 cm3 of oxygen per 100 cc of carbon fluoride, and the carbon dioxide solubility is about twice that. Normal blood will absorb approx. 20 cc of oxygen per 100 cc of blood and has a carbon dioxide solubility twice that of oxygen solubility. The compositions of the invention will normally contain 30-60 cm 3 of oxygen per day. 100 cc of the perfluorinated material, but as mentioned, ratios as low as 10 cc 100 cc and as high as 100 cc per

100 cm3. All of the above solubilities are at 25 ° C 35 and 760 mm Hg.

In the following examples, it will be understood, as noted above, that the perfluorinated compounds of the present invention comprise compounds which are fully fluorinated for at least 95% by weight, preferably at least 98% and especially 100% fluorinated.

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6, i.e. perfluorinated. The compounds less than 100% fluorinated are still highly fluorinated.

Example 1 5 To 10 cm 3 of perfluoromethyladamantane are added 5 g of egg yolk phospholipid emulsifier. Distilled water is then added to the mixture to a total volume of 50 cm 3. The solution is filtered through a 10 µm millipore filter and the solution cooled to ca. 0-5 ° C with an ice bath, 10 is treated in an ultrasonic apparatus. During this treatment, the optical density of samples of 5 cm3 is measured at regular intervals until a constant optical density is obtained, which means that the smallest possible particle size in the emulsion is reached. Then the ultrasonic treatment is stopped and a stable aqueous emulsion with 20% by volume perfluoromethyladamantane is obtained.

Example 2

To 5 cc of perfluoromethyladamantane is added 25 g of 20 egg yolk phospholipid emulsifier. Then distilled water is added to the mixture to a total volume of 500 cm 3. The solution is filtered through a 10 µm millipore filter and the solution homogenized in a Manton-Gaulin homogenizer equipped with a cooler. During homogenization 25, the optical density of 5 cm 3 emulsion samples is measured at regular intervals until a constant optical density is obtained, which means that the smallest possible particle size in the emulsion is reached. The homogenization is then stopped and a stable aqueous emulsion is obtained with 10% by volume of perfluoromethyladamantane.

Example 3

To 100 cc of perfluoroethyl methyladamantane is added 50 g of Pluronic F68 emulsifier. Then distilled water is added to the mixture to a total volume of 500 cm 3. The solution is filtered through a 10 Mm millipore filter, and

DK 155867 B

The solution is homogenized in a Manton-Gaulin homogenizer equipped with a cooler. During homogenization, the optical density of 5 cm3 emulsion samples is measured at regular intervals until a constant optical density is reached.

Then the homogenization is stopped and a stable aqueous emulsion is obtained with 20% by volume perfluoroethylmethyl adamantane.

Example 4 By proceeding as described in Example 3 but starting from perfluorotriethyladamantane, a stable aqueous emulsion is obtained with 20% by volume of perfluorotriethyladamantane.

Example 5 By proceeding as described in Example 1 but using perfluorotrimethyladamantane, a stable aqueous emulsion is obtained with 10% by volume of perfluorotrimethyladamantane.

Example 6 By proceeding as described in Example 2 but using perfluoroethyl dimethyladamantane and "Pluronic F68" as the emulsifier, a stable aqueous emulsion is obtained with 10 volume percent perfluoroethyl dimethyladamantane.

Example 7

Proceeding as described in Example 1 but using perfluoroethyladamantane, a stable aqueous emulsion is obtained with 10% by volume perfluoroethyladamantane.

Claims (1)

An emulsion composition for use as a synthetic blood containing a non-aromatizable perfluorinated compound in water, wherein the amount of water is greater than 40 volume percent and said emulsion contains a non-toxic emulsifier characterized in that the perfluorinated compound is lower -alkyl-adamantane, other than dimethyl-adamantane, preferably 1-methyl-adamantane, the amount of which in the emulsion is 10-30% by volume and having a particle size of about 10%. 0.001-10 μιη, preferably 50% by weight of the particles having a size of 0.05-0.3 μη, and the emulsion preparation additionally having a content of 10-100 cm 3 oxygen (25 ° C, 760 mm Hg) if desired. 100 cm 3 of the perfluorinated compound.