Abstract:
The present invention is directed to a sterile pharmaceutical composition comprising a propofol containing oil-in-water emulsion formulation having as an antimicrobial agent, a member selected from the group consisting of benzyl alcohol and sodium ethylene diamine tetraacetate; benzethonium chloride; and benzyl alcohol and sodium benzoate.

Description:
RELATED APPLICATIONS 
     The above-identified application is a continuation-in-part of U.S. application Ser. No. 09/178,347, filed Oct. 23, 1998. 
    
    
     FIELD OF THE INVENTION 
     The present Invention relates to pharmaceutical compositions containing 2,6-diisopropylphenol. 
     BACKGROUND OF THE INVENTION 
     Propofol (2,6-diisopropylphenol) is an injectable anesthetic which has hypnotic properties and can be used to induce and maintain general anesthesia and sedation. Injectable anesthetics such as propofol are administered directly into the bloodstream. This results in a rapid onset of anesthesia influenced almost entirely by the rate at which the anesthetic agent crosses the blood-brain barrier. Therefore, the anesthetic agent must have sufficient lipid solubility to be able to cross this barrier and depress the relevant mechanisms of the brain. Propofol is poorly water soluble and therefore is generally formulated as an emulsion. However, propofol containing emulsions have been shown to support microbial growth. Therefore it is desirable to formulate propofol emulsions in a manner in which microbial growth is prevented. Disodium EDTA (ethylenediamine tetraacetate) has been shown to delay, but not prevent, the onset of microbial growth in propofol emulsions. See U.S. Pat. No. 5,714,520. 
     Accordingly it is an object of the present invention to provide a propofol containing pharmaceutical composition that provides antimicrobial benefits above that found in existing compositions and/or prevents the onset of microbial growth in such compositions. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a sterile pharmaceutical composition comprising a propofol containing oil-in-water emulsion formulation having as an antimicrobial agent, a member selected from the group consisting of benzyl alcohol; benzyl alcohol and disodium ethylenediamine tetraacetate; benzethonium chloride; and benzyl alcohol and sodium benzoate. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The term &#34;antimicrobial&#34; means an agent which delays onset or retards rate of growth to less than 1 logarithmic increase over a 24 hour period as compared to an unpreserved formulation. 
     The composition of the present invention comprises an oil-in-water emulsion in which the 2,6-diisopropylphenol, either alone or dissolved in a water immiscible solvent, for example a vegetable oil, is emulsified with water by means of surfactant. 
     Typically the solvent is an oil such as soybean oil, safflower oil, cottonseed oil, corn oil, sunflower oil, arachis oil, castor oil, or olive oil. Preferably the oil is soybean oil. Alternatively the solvent can be an ester of a medium or long chain fatty acid, for example a mono-,di-, or triglyceride; or a compound such as ethyl oleate, isopropyl myristate, isopropyl palmitate, a glycerol ester or a polyoxyl hydrogenated castor oil. Other suitable solvents may be marine oils, for example cod liver or other fish derived oils, or fractionated oils, such as fractionated coconut oil or modified soybean oil. The composition of present invention may also comprise a mixture of two or more of the above water immiscible solvents. 
     The 2,6-diisopropylphenol, either alone or dissolved in the water immiscible solvent, is emulsified in an aqueous medium with the aid of a surfactant. Suitable surfactants include synthetic non-ionic surfactants, for example ethoxylated ethers and ethoxylated esters, polypropylene polyethylene block copolymers, and phosphatides, as for example egg and soy phosphatides. Preferably, the surfactant is egg phosphatide. 
     Preferred compositions of the present invention comprise from 0.1 to 5.0% by weight, preferably 1 to 2% by weight, and most preferably 1% by weight of 2,6-diisopropylphenol; from to 1 to 30% by weight, preferably 10 to 20% by weight of a water immiscible solvent; and from about 0.2 to 2.0% by weight, preferably 1.2% by weight of a surfactant. The compositions of the present invention can also contain pH adjusting agents such as sodium hydroxide or hydrochloric acid so they can be formulated at a physiologically neutral pH. 
     The compositions of the present invention may also be made isotonic by the incorporation of a suitable additive such as glycerol. 
     The balance of the composition is made up with water. 
     The antimicrobial systems utilized in the compositions of the present invention are selected from the group consisting of benzyl alcohol; benzyl alcohol and disodium ethylenediamine tetraacetate; benzethonium chloride; and benzyl alcohol and sodium benzoate. The concentration of the antimicrobial agents in the final composition will vary depending on the particular agent or agents selected. For instance in a preferred composition of the invention the amount of benzyl alcohol is in the range of about 0.0175% to 0.9% (w/v), more preferably about 0.07% to about 0.45%, most preferred in the range of 0.15%. In an alternate preferred composition of the invention, the amount of benzyl alcohol is about 0.07% to about 0.9%, optionally including an amount of disodium EDTA of about 0.005%. Yet another embodiment provides a composition including an amount of benzethonium chloride of about 0.01% to about 0.1%. Optionally, the composition of the present invention includes 0.07% sodium benzoate. The most preferred compositions of the present invention include benzyl alcohol and sodium benzoate. The compositions of the present invention may be prepared by conventional processes as for example that disclosed in U.S. Pat. No. 5,714,520. 
     A particularly preferred composition of the present invention is as set forth below. 
     
                       TABLE 1______________________________________(weight percent)          Broad      Preferred                            Particularly Preferred  Component Range Range Amount______________________________________2,6-       0.1-5.0    1.0-2.0  1.0  diisopropylphenol  Soybean Oil  1.0-30.0 10.0-30.0 10.0  Egg Phosphatide 0.2-2.0 0.7-2.0 1.2  Benzyl alcohol 0.0175-0.9   0.07-0.45 0.15  Sodium benzoate   0-0.07 0.07 0.07  Glycerol 2.0-3.0 2.35-2.75 2.25  Sodium Hydroxide q.s. q.s. q.s.  Water for Injection to 100 to 100 to 100______________________________________ 
    
     The compositions of the present invention may be used as is conventional in the art, e.g., for the induction of anesthesia prior to maintenance with a conventional inhalation anesthetic; as a sole anesthetic agent for short duration, by repeated administration, or by continuous infusion. The compositions of the invention may be used as a sole anesthetic agent of longer duration. 
    
    
     The invention is illustrated by the following representative examples: 
     EXAMPLE 1 
     The compositions of the present invention may be formulated following procedures well known to those skilled in the art. Specific reference is made to U.S. Pat. No. 5,714,520 which is hereby incorporated by reference. 
     EXAMPLE 2 
     Propofol oil-in-water emulsions containing 0.45% benzyl alcohol/0.005% disoduim EDTA, 0.035% benzyl alcohol/0.005% disodium EDTA, 0.45% benzyl alcohol/0.07% sodium benzoate, and 0.035%benzyl alcohol/0.07% sodium benzoate were tested by the USP 23 preservative effectiveness test as described in United States Pharmacopoeia 23-NF 18, 1995 Ed., Chapter 51, which is incorporated herein by reference. Briefly, this involves inoculating the test solution with 10 5  to 10 6  test organisms per milliliter and then determining the number of surviving organisms after 7, 14, 21, and 28 days incubation at 20-25° C. using standard microbiological methods. Day 0 data is not required by USP 23 but was included in this study. A filtration and buffer wash method was used to remove the inactivating agents for purposes of recovering the microorganisms, but other equivalent methods can also be validated for use. The USP test organisms include the bacteria Staphylococcus aureus, Escherichia coli, and Pseudomonoas aeruginosa, a yeast (Candida albicans), and a mold (Aspergillus niger). In order to meet the criteria of the USP 23 preservative effectiveness test, the bacteria must demonstrate a 90% (1 logarithmic) reduction at Day 7 and a 99.9% reduction (3 logarithmic) reduction at Day 14 from the initial inoculum level. The initial inoculum level can either be calculated knowing the stock culture concentration or by using a buffer control instead of the test solution. The results, using formulations which are 10% fat emulsions, are given below in Tables 2 through 5 where the number reported in the number of organisms pre milliliter. ND means not detected, i.e., below the levels of detection by the assay. Although same formulations did not meet the criteria of the USP test, in most cases they met the definition of &#34;antimicrobial&#34;. 
     
                       TABLE 2______________________________________(0.45% Benzyl Alcohol/0.005% Disodium EDTA)  Organism                        P.  Time A. niger C. albicans E. Coli aeruginosa S. aureus______________________________________Inoculum   390,000 440,000   750,000                           460,000 610,000  per ml  product  0 Hr. 300,000 360,000 380,000 310,000 380,000  Day 7 210,000 340,000 680 3,000 47,000  Day 14 210,000 350,000 190 200 7,200  Day 21 3,400 270,000 40 60 4,300  Day 28 130 105,000 10 10 1,020______________________________________ 
    
     
                       TABLE 3______________________________________(0.035% Benzyl Alcohol/0.005% Disodium EDTA)  Organism                        P.  Time A. niger C. albicans E. coli aeruginosa S. aureus______________________________________Inoculum   390,000 440,000   750,000                           460,000 610,000  per ml  product  0 Hr. 300,000 310,000 360,000 310,000 430,000  Day 7 300,000 330,000 40 105,000 36,000  Day 14 210,000 310,000 &lt;10 68,000 3,500ND  Day 21 120,000 320,000 &lt;10 67,000 740ND  Day 28 29,000 110,000 &gt;10 38,000 170ND______________________________________ 
    
     
                       TABLE 4______________________________________(0.45 Benzyl Alcohol/0.07 Sodium Benzoate)  Organism                        P.  Time A. niger C. albicans E. coli aeruginosa S. aureus______________________________________Inoculum   390,000 440,000   750,000                           460,000 610,000  per ml  product  0 Hr. 290,000 340,000 380,000 440,000 390,000  Day 7 260,000 390,000 86,000 101,000 30,000  Day 14 29,000 350,000 62,000 14,900 1,350  Day 21 22,000 203,000 80,000 2,800 100  Day 28 290 87,000 76,000 150 10______________________________________ 
    
     
                       TABLE 5______________________________________(0.035 Benzyl Alcohol/0.07% Sodium Benzoate)  Organism                        P.  Time A. niger C. albicans E. coli aeruginosa S. aureus______________________________________Inoculum  390,000 440,000   750,000                           460,000 610,000  per ml  product  0 Hr. 370,000 450,000 420,000 550,000 520,000  Day 7 250,000 530,000 8,800,000 3,500,000 310,000  Day 14 130,000 410,000 7,100,000 3,400,000 92,000  Day 21 41,000 440,000 5,800,000 30,000 49,000  Day 28 13,000 300,000 2,180,000 7,000 22,100______________________________________ 
    
     EXAMPLE 3 
     The antimicrobial properties of various propofol formulations were determined by a spiked hold time study. Briefly, a propofol formulation is inoculated to achieve approximately 100 organisms per 10 mL sample. The organisms used include Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, Candida albicans, Bacillus subtilis, Aspergillus niger, and Clostridium sporogenes. The inoculated samples are held for various times and then filtered in duplicate. The filters are washed with buffer and then placed on appropriate agar growth media. 
     The antimicrobial agents should reduce the growth rate such that there is less than a 1 logarithm increase within a 24 hour period. 
     C. albicans presented the most resistance to the preservative system. The C. albicans results from the spiked hold time study are shown in Table 6 for various propofol formulations. E. coli, P. aeruginosa, and B. subtilis also demonstrated some resistance to the antimicrobial agents (data not shown). The remaining test organisms increased less than 2-fold over the 7 day test period. The results are shown in organisms per mL of test solution. A value of &gt;300 indicates too numerous to count; these data points may still meet the acceptance criteria of less than 1 logarithmic increase. In the Tables, BA=Benzyl Alcohol, NB=Sodium Benzoate. The percent of benzyl alcohol is indicated in w/v for each formulation. The percent Sodium benzoate, when present, is 0.07% (w/v). 
     
                       TABLE 6______________________________________Formulation 0 hours 24 hours  48 hours                                 7 days______________________________________0.45  BA/NB     37       35     28      56  0.15 BA only 59 102 &gt;300 &gt;300  0.15 BA/NB 59  45 &gt;300 &gt;300  0.13 BA/NB 66  57 &gt;300 &gt;300  0.10 BA/NB 53  59 &gt;300 &gt;300  0.07 BA/NB 34 120 &gt;300 &gt;300  0.035 BA/NB 33 125 &gt;300 &gt;300  0.0175 BA/NB 38 185 &gt;300 &gt;300______________________________________ 
    
     EXAMPLE 4 
     Propofol oil-in-water emulsions containing 0.45% benzyl alcohol/0.07% sodium benzoate, 0.035%benzyl alcohol/0.07% sodium benzoate, 0.035% benzyl alcohol/0.005% disodium EDTA, and 0.045% benzyl alcohol/0.005% disodium EDTA were tested by the USP 23 preservative effectiveness test as described in Example 2. The results, using formulations which are 1% fat emulsions, are given below in Tables 7 through 10 where the number reported in the number of organisms per milliliter. Lowering the percent oil, increased the effectiveness of the preservative(s) compound in Example 2. 
     
                       TABLE 7______________________________________(0.45% Benzyl Alcohol/0.07% Sodium Benzoate)  Organism                        P.  Time A. niger C. albicans E. coli aeruginosa S. aureus______________________________________Inoculum   390,000 440,000   750,000                           460,000 610,000  per ml  product  0 Hr. 470,000 1,000 &lt;10  1,200 &lt;100ND  Day 7 33,000 &lt;100 &lt;10 &lt;10 &lt;100  Day 14 &lt;10 &lt;100 &lt;10 &lt;10 &lt;100   ND ND ND ND ND  Day 21 &lt;10 &lt;100 &lt;10 &lt;10 &lt;100   ND ND ND ND ND  Day 28 &lt;10 &lt;100 &gt;10 &lt;10 &lt;100   ND ND ND ND ND______________________________________ 
    
     
                       TABLE 8______________________________________(0.035% Benzyl Alcohol/0.07% Sodium Benzoate)  Organism                        P.  Time A. niger C. albicans E. coli aeruginosa S. aureus______________________________________Inoculum   390,000 440,000   750,000                           460,000 610,000  per ml  product  0 Hr 420,000 1,050 &lt;10 5,500 20ND  Day 7 200,000 &lt;10 &lt;10 5,200 &lt;10    ND ND  ND  Day 14 14,000 &lt;10 &lt;10 3,700 &lt;10    ND ND  ND  Day 21 14,000 &lt;10 &lt;10 4,100 &lt;10    ND ND  ND  Day 28 17,000 &lt;10 &gt;10 5,000 &lt;10    ND ND  ND______________________________________ 
    
     
                       TABLE 9______________________________________(0.035% Benzyl Alcohol/0.005% Disodium EDTA)  Organism                        P.  Time A. niger C. albicans E. coli aeruginosa S. aureus______________________________________Inoculum   390,000 440,000   750,000                           460,000 610,000  per ml  product  0 Hr. 460,000 112,000 &lt;10 680 100ND  Day 7 290,000 &lt;10 &lt;10 &lt;10 &lt;100    ND ND ND ND  Day 14 4,100 &lt;10 &lt;10 &lt;10 &lt;100    ND ND ND ND  Day 21 2,900 &lt;10 &lt;10 &lt;10 &lt;100    ND ND ND ND  Day 28 2,700 &lt;10 &gt;10 &lt;10 &lt;100    ND ND ND ND______________________________________ 
    
     
                       TABLE 10______________________________________(0.45% Benzyl Alcohol/0.005% Disodium EDTA)  Organism                        P.  Time A. niger C. albicans E. coli aeruginosa S. aureus______________________________________Inoculum   390,000 440,000   750,000                           460,000 610,000  per ml  product  0 Hr. 320,000 300 &lt;10 &lt;10 &lt;10ND ND ND  Day 7 260 &lt;10 &lt;10 &lt;10 &lt;10    ND ND ND ND  Day 14 &lt;10 &lt;10 &lt;10 &lt;10 &lt;10   ND ND ND ND ND  Day 21 &lt;10 &lt;10 &lt;10 &lt;10 &lt;10   ND ND ND ND ND  Day 28 &lt;10 &lt;10 &lt;10 &lt;10 &lt;10   ND ND ND ND ND______________________________________ 
    
     EXAMPLE 5 
     Propofol oil-in-water emulsions containing 0.45%/benzyl alcohol/0.005% disodium EDTA and 0.45% benzyl alcohol/0.07% sodium benzoate were tested by the USP 23 preservative effectiveness test as described in Example 2. The results, using formulations which are 1% fat emulsions of a medium chain triglyceride oil, are given below in Tables 11 and 12 where the number reported is the number of organisms per milliliter. 
     
                       TABLE 11______________________________________(0.45% Benzyl Alcohol/0.005% Disodium EDTA)  Organism                        P.  Time A. niger C. albicans E. coli aeruginosa S. aureus______________________________________Inoculum   390,000 440,000   750,000                           460,000 610,000  per ml  product  0 Hr. 490,000 180 &lt;10 &lt;10 &lt;10ND ND ND  Day 7 28,000 &lt;10 &lt;10 &lt;10 &lt;10    ND ND ND ND  Day 14 &lt;10 &lt;10 &lt;10 &lt;10 &lt;10   ND ND ND ND ND  Day 21 &lt;10 &lt;10 &lt;10 &lt;10 &lt;10   ND ND ND ND ND  Day 28 &lt;10 &lt;10 &lt;10 &lt;10 &lt;10   ND ND ND ND ND______________________________________ 
    
     
                       TABLE 12______________________________________(0.45% Benzyl Alcohol/0.07% Sodium Benzoate)  Organism                        P.  Time A. niger C. albicans E. coli aeruginosa S. aureus______________________________________Inoculum   390,000 440,000   750,000                           460,000 610,000  per ml  product  0 Hr. 420,000 260 &lt;10 1,780 &lt;10ND  ND  Day 7 20,000 &lt;10 &lt;10 &lt;10 &lt;10    ND ND ND ND  Day 14 &lt;10 &lt;10 &lt;10 &lt;10 &lt;10   ND ND ND ND ND  Day 21 &lt;10 &lt;10 &lt;10 &lt;10 &lt;10   ND ND ND ND ND  Day 28 &lt;10 &lt;10 &lt;10 &lt;10 &lt;10   ND ND ND ND ND______________________________________