Artif Cells Blood Substit Immobil Biotechnol Downloaded from informahealthcare.com by McMaster University on 02/16/15 For personal use only.
B I O W T . , ART. CELLS EL IMMOB. BIOTECH.,
20(2-4), 839-842 (1992)
DEVELOPMENT OF HIGHLY FLUID, CONCENTRATED AND STABLE FLUOROCARBON EMULSIONS FOR DIAGNOSIS AND THERAPY
J.G. Riess, J.L. Dalfors. G.K. Hanna. D.H. Klein. M.-P.Krafft. T.J. Pelura and E.G. Schutt Alllance Pharmaceutical Corp.,San Diego, Calgornia,USA
Abstract A challenging aim in developing injectable fluorocarbon emulsions is to combine good flow characteristics (especially at low shear rates) with the high fluorocaim concentration quired for high oxygen delivery or effective contrast in imaging, long shelf life, and biological acceptability. A good balance of these sometimes conflicting objectives has been achieved with 90% w/v concentrated emulsions of various fluorocarbons. including the radiopaque oxygen carrier peduorooctylbromide (PFOB. pemubron). The sterile emulsions have viscosities of about 20 cPs at a shear rate of 1 =I; the viscosity decreases rapidly with fluorocarbonconcentration.and at 60% w/v the viscosity is less than that of human blood. The emulsions are suitable for injection as prepared. and m stable unfrozen for Over a year. Introduction Several key improvements over the first-generationFluosol-typeemulsions were indispensablein order to give the FC-emulsion approach to blood substitutesits full potential. These include enhanced oxygencarrying capacity, and improved temperam and shelf stability to avoid the need for freezing and the consequent complex and unfriendly thawing and admixing procedure which results from this situation [I]. The same needs hold when the emulsions are destined to serve as contrast agents in diagnosis, maximum contrast should be pmvided under minimum volume. Significantlymore effective 100% whr concentrated fluorocarbonemulsions had been developed previously 12.31. which demonstrate efficacity both as contrast agents (431 and as oxygen carriers [2,3]. Viscosity. especially at low shear rates,incceases rapidly with concentration in this concentration range. and also depends strongly on the process and processing parameters used. Aq optimal balance has now been achieved between concentration,Viscosity and stability with the developnentof new 9096 w/v concentrated, fluid emulsions. Materials and Methods The 9oRo w/v concentrated fluorocarbonemulsions were stabilized with egg-yolk phospholipids. optimal stabilization was attained with 4%w/v of the surfactant. Other ingredients include an antioxidant, tocopherol, a heavy metal chelathg agent, EDTA. to protect the phospholipids from oxidation, a phosphate, or trishydroxpethyl aminomethane(THAhf). or amino acid buffer, and sodium chloride. Emulsification was performed under nitrogen by high-pressure mechanical homogenization using a Gaulin-type process. Sterilization was achieved at 121OC in a rotating autoclave. Viscosity measurements were made on a Bohlin CS Rheometer and a Bmokfield DV-Il Viscometer. Particle size distributionswere determined by photosedimentation (Horiba CAPA-700)and by sedimentationfield flow fractionation (FFFractionation, Inc.).
839 Copyright 0 1992 by Marcel Dekker. Inc.
Artif Cells Blood Substit Immobil Biotechnol Downloaded from informahealthcare.com by McMaster University on 02/16/15 For personal use only.
840
M E S S ET AL.
90% wlv
I I
-
0'
Y
- 60% wlv
0
1
20
10
20
40 56 Shearrate (sec-')
Fig. I :Viscosity of PFOBIEYP e d w n s of various concentrations as ofunction of shear rate.
2 3
150-
SI
J
,4
i
Q *
lm:I
rd
ir 50-
90% wlv PFOB 1
d
Fig. 2 : E@ct of bwwgenirarion pressure (PUG x 1ooO) on viscosity for similarly formulated 100% wlv and W% wh, conuntraled PFOB emulsions.
Table I : Chem'cal, Physical and Bwk38iCd Sfability of a 90% wlv PFOB Emulsion
2mhUm.T Median wrticlc Size.pm
0.25
0.34
0.60
rar
7.1
7.1
6.8
F~uFpttyAcids,mEqh Unemulsified PFOB. % LD,,,, mulrg PFOB
6.1
6.4
11.0
0.07
0.06
0.06
-45
- 45
-45
Artif Cells Blood Substit Immobil Biotechnol Downloaded from informahealthcare.com by McMaster University on 02/16/15 For personal use only.
DEVELOPHENT OF FLUOROCARBON EMULSIONS
841
Particle size (pm) Fig. 3 : Particle size distribution in a typical 909b wlv pnjluormctyl bromide emulsion stabilized with egg yolk phospholipids. nuaswed by photodcnn'tonutry. Thefirst bar at the left of the histogram corresponds w fluorocarbon-peeEYP vesicles [6].
When linear f l u o r o c m such as pefluorooctylbromide(PFOB, peflubron) or bis(F-butylkthene
a~ used. the calculated oxygencarryingcapacity of the 90%w/v concentrated emulsions is of 25 vol.% under 10096 O2or 15 vol.% at a clinically accepable F iQ of 0.6.
Results Figure 1 compares the viscosity of variously concentrated emulsions of comparable formulations as a function of shear rate. The fluidity of the 90% w/v concentrated emulsions is cu six times larger than for the ICE% emulsions at the reference shear rate of Is-'. For the 60% w/v emulsiorrs the viscosity is less than that of human blood. Earlier 100% w/v fluorocarbonemulsions were found to be rather sensitive to small variations in processing, sterilization and storage conditions. By contrast, the new 90% w/v formulation is remarkably insensitive to such variations, and can therefore be manufactured with a high degree of reproducibility. This is exemplified in Figure 2. which shows the effect of homogenization pressure on the emulsion's viscosity. Some chamcteristicsof the new emulsions and their variation over time at 5 and 30°C ~11:collected in Table 1. A typical particle size distributionhistogram is given in Figure 3. The 90%w/v emulsion is also significantly more stable under mechanical stness than the 100% w/v collcentraredone. The new emulsion also induces less plasma thromboxane production than either the more concentratedones or Fluosol.
References 1. J.G.Riess. Fluomarbon-based blood substitutes: what progress ? Intl. J. Artif. Org., 14,255 1991. 2. D.C. Long, D.M. Long. J.G.Riess. R. Follana. A. Burgan. R.F. Mattrey, in: Blood Substitutes (T.M.S. Chang, ed.) ; M m l Dekker, New York, 441.1989. 3. D.M.Long. D.C.Long. R.F. Mattrey. R.A. Long, A.R. Burgan, W.C. Herrick. D.. in: Blood Substitutes(T.M.S. Chang, ed.) ; Marcel Dekker. New York. 411,1989.
842
M E S S ET AL.
Artif Cells Blood Substit Immobil Biotechnol Downloaded from informahealthcare.com by McMaster University on 02/16/15 For personal use only.
4. RP. M m y . . Am. J. Radiol., 152, 247, 1989. 5. J.-N. Bruneton. M.N. Falewee. E. F w i s , P. Cambon. C. Philip, J.G.Riess, C. Balu-maestro, A. Rogopoulos. Radiology ,170, 179.1989. 6. M.P. Krafft, J.-P. Rolland. J.G. Riess, J. Phys. Chem., 95, xxx, 1991.
B I O W T . , ART. CELLS EL IMMOB. BIOTECH.,
20(2-4), 839-842 (1992)
DEVELOPMENT OF HIGHLY FLUID, CONCENTRATED AND STABLE FLUOROCARBON EMULSIONS FOR DIAGNOSIS AND THERAPY
J.G. Riess, J.L. Dalfors. G.K. Hanna. D.H. Klein. M.-P.Krafft. T.J. Pelura and E.G. Schutt Alllance Pharmaceutical Corp.,San Diego, Calgornia,USA
Abstract A challenging aim in developing injectable fluorocarbon emulsions is to combine good flow characteristics (especially at low shear rates) with the high fluorocaim concentration quired for high oxygen delivery or effective contrast in imaging, long shelf life, and biological acceptability. A good balance of these sometimes conflicting objectives has been achieved with 90% w/v concentrated emulsions of various fluorocarbons. including the radiopaque oxygen carrier peduorooctylbromide (PFOB. pemubron). The sterile emulsions have viscosities of about 20 cPs at a shear rate of 1 =I; the viscosity decreases rapidly with fluorocarbonconcentration.and at 60% w/v the viscosity is less than that of human blood. The emulsions are suitable for injection as prepared. and m stable unfrozen for Over a year. Introduction Several key improvements over the first-generationFluosol-typeemulsions were indispensablein order to give the FC-emulsion approach to blood substitutesits full potential. These include enhanced oxygencarrying capacity, and improved temperam and shelf stability to avoid the need for freezing and the consequent complex and unfriendly thawing and admixing procedure which results from this situation [I]. The same needs hold when the emulsions are destined to serve as contrast agents in diagnosis, maximum contrast should be pmvided under minimum volume. Significantlymore effective 100% whr concentrated fluorocarbonemulsions had been developed previously 12.31. which demonstrate efficacity both as contrast agents (431 and as oxygen carriers [2,3]. Viscosity. especially at low shear rates,incceases rapidly with concentration in this concentration range. and also depends strongly on the process and processing parameters used. Aq optimal balance has now been achieved between concentration,Viscosity and stability with the developnentof new 9096 w/v concentrated, fluid emulsions. Materials and Methods The 9oRo w/v concentrated fluorocarbonemulsions were stabilized with egg-yolk phospholipids. optimal stabilization was attained with 4%w/v of the surfactant. Other ingredients include an antioxidant, tocopherol, a heavy metal chelathg agent, EDTA. to protect the phospholipids from oxidation, a phosphate, or trishydroxpethyl aminomethane(THAhf). or amino acid buffer, and sodium chloride. Emulsification was performed under nitrogen by high-pressure mechanical homogenization using a Gaulin-type process. Sterilization was achieved at 121OC in a rotating autoclave. Viscosity measurements were made on a Bohlin CS Rheometer and a Bmokfield DV-Il Viscometer. Particle size distributionswere determined by photosedimentation (Horiba CAPA-700)and by sedimentationfield flow fractionation (FFFractionation, Inc.).
839 Copyright 0 1992 by Marcel Dekker. Inc.
Artif Cells Blood Substit Immobil Biotechnol Downloaded from informahealthcare.com by McMaster University on 02/16/15 For personal use only.
840
M E S S ET AL.
90% wlv
I I
-
0'
Y
- 60% wlv
0
1
20
10
20
40 56 Shearrate (sec-')
Fig. I :Viscosity of PFOBIEYP e d w n s of various concentrations as ofunction of shear rate.
2 3
150-
SI
J
,4
i
Q *
lm:I
rd
ir 50-
90% wlv PFOB 1
d
Fig. 2 : E@ct of bwwgenirarion pressure (PUG x 1ooO) on viscosity for similarly formulated 100% wlv and W% wh, conuntraled PFOB emulsions.
Table I : Chem'cal, Physical and Bwk38iCd Sfability of a 90% wlv PFOB Emulsion
2mhUm.T Median wrticlc Size.pm
0.25
0.34
0.60
rar
7.1
7.1
6.8
F~uFpttyAcids,mEqh Unemulsified PFOB. % LD,,,, mulrg PFOB
6.1
6.4
11.0
0.07
0.06
0.06
-45
- 45
-45
Artif Cells Blood Substit Immobil Biotechnol Downloaded from informahealthcare.com by McMaster University on 02/16/15 For personal use only.
DEVELOPHENT OF FLUOROCARBON EMULSIONS
841
Particle size (pm) Fig. 3 : Particle size distribution in a typical 909b wlv pnjluormctyl bromide emulsion stabilized with egg yolk phospholipids. nuaswed by photodcnn'tonutry. Thefirst bar at the left of the histogram corresponds w fluorocarbon-peeEYP vesicles [6].
When linear f l u o r o c m such as pefluorooctylbromide(PFOB, peflubron) or bis(F-butylkthene
a~ used. the calculated oxygencarryingcapacity of the 90%w/v concentrated emulsions is of 25 vol.% under 10096 O2or 15 vol.% at a clinically accepable F iQ of 0.6.
Results Figure 1 compares the viscosity of variously concentrated emulsions of comparable formulations as a function of shear rate. The fluidity of the 90% w/v concentrated emulsions is cu six times larger than for the ICE% emulsions at the reference shear rate of Is-'. For the 60% w/v emulsiorrs the viscosity is less than that of human blood. Earlier 100% w/v fluorocarbonemulsions were found to be rather sensitive to small variations in processing, sterilization and storage conditions. By contrast, the new 90% w/v formulation is remarkably insensitive to such variations, and can therefore be manufactured with a high degree of reproducibility. This is exemplified in Figure 2. which shows the effect of homogenization pressure on the emulsion's viscosity. Some chamcteristicsof the new emulsions and their variation over time at 5 and 30°C ~11:collected in Table 1. A typical particle size distributionhistogram is given in Figure 3. The 90%w/v emulsion is also significantly more stable under mechanical stness than the 100% w/v collcentraredone. The new emulsion also induces less plasma thromboxane production than either the more concentratedones or Fluosol.
References 1. J.G.Riess. Fluomarbon-based blood substitutes: what progress ? Intl. J. Artif. Org., 14,255 1991. 2. D.C. Long, D.M. Long. J.G.Riess. R. Follana. A. Burgan. R.F. Mattrey, in: Blood Substitutes (T.M.S. Chang, ed.) ; M m l Dekker, New York, 441.1989. 3. D.M.Long. D.C.Long. R.F. Mattrey. R.A. Long, A.R. Burgan, W.C. Herrick. D.. in: Blood Substitutes(T.M.S. Chang, ed.) ; Marcel Dekker. New York. 411,1989.
842
M E S S ET AL.
Artif Cells Blood Substit Immobil Biotechnol Downloaded from informahealthcare.com by McMaster University on 02/16/15 For personal use only.
4. RP. M m y . . Am. J. Radiol., 152, 247, 1989. 5. J.-N. Bruneton. M.N. Falewee. E. F w i s , P. Cambon. C. Philip, J.G.Riess, C. Balu-maestro, A. Rogopoulos. Radiology ,170, 179.1989. 6. M.P. Krafft, J.-P. Rolland. J.G. Riess, J. Phys. Chem., 95, xxx, 1991.
