Low temperature vapor phase sterilization and storage of biologically active injectable materials

A method for sterilizing solid particulate materials intended to be mixed with a liquid carrier prior to the parenteral or hypodermic introduction into the body of humans and animals. The predetermined amount of particulate material is placed in a sealable container, an amount of ethyl alcohol sufficient to produce a vapor concentration in said container which is toxic to any microorganisms in the particulate material, is added to the container and the container is sealed. When ready for use, the contents of the container may be mixed with sterile water for introduction into the body of humans and animals. This method is particularly useful with materials which tend to decompose when stored as a solution or when exposed to the conditions of normal sterilization procedures and a preferred embodiment involves the sterilization of fine crystalline sodium ascorbate.

BACKGROUND OF THE INVENTION 
Conventional sterilization methods for injectable solutions or suspensions 
generally comprise the exposure of the preformed mixture to high 
temperatures or ionizing radiation sufficient to kill any microorganisms 
present. This approach cannot be used with materials that will be 
adversely affected by the sterilizing conditions. Another approach is the 
sterile membrane filtratration system in which the solution is passed 
through a sterile Millipore filter system. This technique can be 
cumbersome, involved and expensive. Both approaches, however, fail to come 
to grips with the problem associated with solutions which tend to 
decompose relatively rapidly thereby having an intolerably low shelf life. 
Such materials as sodium ascorbate, for example, are available in 50 ml 
vials containing 25% sodium ascorbate solution (12.5 grams sodium 
ascorbate) preserved with sodium sulfite and benzyl alcohol. When such 
materials are used, for example, in the treatment of humans and animals in 
the manner described by F. R. Klenner (J. International Acad. Prev. Med., 
vol. 1, No. 1, pages 49-65 (1974) and W. O. Belfield et al (J. 
International Acad. Prev. Med., vol. 2, No. 3, pages 10- 26 (1975), and E. 
Cameron et al, J. Internat. Res. Commun., vol. 1, No. 6, pages 38 (1973), 
the sulfite produced adverse side effects resembling those of beri-beri as 
a result of the reaction of the sulfite with the patient's vitamin 
B.sub.1. The manufacturer, upon request, has produced vials without the 
sulfite but the manufacturer believes the shelf life is so short that they 
do not distribute the product through normal channels. What is needed is 
an inexpensive means for sterilizing sensitive materials in the solid 
state so that they can be stored for long periods and mixed with sterile 
water immediately prior to use. This invention describes such an approach. 
It is accordingly an object of this invention to provide a simple 
economical method for sterilizing sensitive solid materials. 
It is another object of this invention to provide a sterile container of a 
sensitive solid material. 
A further object of this invention is to provide sterilization with a 
non-toxic, volatile sterilizing agent that does not have to be removed 
from the mixture before use, and in the quantities employed for 
sterilization it would be normally metabolized by the body without any 
unfavorable side effects on injection. 
These and other objects of this invention will be readily apparent from the 
following description. 
DESCRIPTION OF THE INVENTION 
According to this invention a stable sterile particulate solid material is 
prepared by a simple, non-toxic, inexpensive means in a convenient cheap 
disposable container. The container and contents has a long shelf life and 
is capable of being simply and rapidly used by the physician or nurse in 
the preparation of fresh injectable solutions immediately before injection 
into the patient. 
The following description will be directed to the preferred embodiment of 
sodium ascorbate, but it should be recognized that the invention can be 
used with combinations of sodium ascorbate with other materials or with 
any other pharmaceutical material (without the presence of sodium 
ascorbate), that is non-reactive with ethyl alcohol. 
Sodium ascorbate, for example, is rather unstable to heat both in the dry 
state and in solution, so that the temperatures required for heat 
sterilization causes destruction and loss of activity of the ascorbate. 
Sterilization by sterile membrane filtration through a completely sterile 
system such as that manufactured by the Millipore Corporation can be done, 
but is limited to solutions. This is an expensive and time consuming 
operation, especially if it is necessary to first get the sodium ascorbate 
into solution, membrane filter this solution and then freeze-dry the 
sterile solution under sterile conditions to obtain a sterile dry powder 
for permanent shelf life stability in the dry state in the sterile 
packaged product. 
Another method of sterilization, by high energy radiation, requires a 
tremendous investment in special equipment and there is no data available 
on the effect of such high energy radiation on an unstable material like 
sodium ascorbate as to loss in activity and the shelf life stability of 
radiated ascorbate. 
I have overcome all these objections to present customary sterilization 
procedures by the provision of a very simple, elegant and inexpensive, 
non-toxic procedure for the low-temperature, vapor phase sterilization, 
which produces a stable particulate material suitable for injection 
purposes, with no loss of activity. 
The principle of the method is to place a weighed charge of, for example, 
sodium ascorbate (fine crystals preferred) into a suitable sealable 
container (glass, plastic or other) and add a quantity of ethyl alcohol 
sufficient to produce a high enough concentration of alcoholic vapor to 
effectively kill and inactivate any viable microorganisms adhering to the 
sodium ascorbate during the shelf-life storage time of the package 
containing it. At the time the physician or nurse wants to prepare the 
solution for injection, they either remove or penetrate the seal with a 
sterile hypodermic syringe and add the required amount of sterile water 
for injection needed for the prepartion of the solution. The sodium 
ascorbate quickly dissolves and the solution is ready for injection into 
the patient or for further dilution for parenteral drip therapy. No 
attempt is made to remove the ethyl alcohol as the amount originally added 
is so small and harmless and will be normally metabolized after injection 
into the patient, with no deleterious side effects or toxicity. The 
patient is thus assured a perfectly fresh solution of the proper ascorbate 
strength as the time between preparation and administration is so short 
that no loss of ascorbate activity can take place. 
The amount of ethyl alcohol required in this treatment is very small and is 
easily calculated from the volume of the container and the fact that 100 
milligrams of ethyl alcohol alcohol (100%) will produce approximately 50 
milliliters of saturated vapor at room temperature. If a 6 ounce (170 ml) 
container is used, then about 360 milligrams of ethyl will be required to 
fill the container with ethyl alcohol vapor. Less quantities than that 
giving 100% saturation, like 50% saturation, will also be effective, but I 
prefer to use an amount giving about 150% saturation. Substantially larger 
amounts of ethyl alcohol beyond about 150% are unnecessary and only add to 
the costs. The amounts of ethyl alcohol needed are so small that they do 
not "wet" the powder, with visible liquid in the interstices of the 
particulate materials. Besides, keeping the ethyl alcohol levels minimal 
is desirable, to avoid unnecessary increases in the alcohol blood levels 
of the patients. The adult blood volume is about 4 liters so the ethyl 
alcohol added in the above example would produce an insignificant rise of 
about 0.01% in the alcohol blood level. 
The ethyl alcohol concentration in the alcohol liquid added to the dry 
particulate material is not critical, but should be preferably high to 
avoid adding excessive water to the mixture along with the alcohol. 100% 
or absolute alcohol may be employed, but the less expensive azeotropic 
concentration of about 95% ethyl alcohol is preferred. Lesser 
concentrations can be used but require more liquid to generate the 
required vapor volumes. 
The costs of the finished sterile product of this invention will be low, 
being not much more than the costs of the raw materials and package, as 
there are no involved expensive processing operations to produce 
sterility. This results in substantial savings to the patient in the cost 
of medical care. 
Other materials like soluble vitamins, minerals or other drugs that are 
required to be injected along with the ascorbate may be added to the 
sodium ascorbate in the package and the ethyl alcohol added to the mixture 
before the package is sealed. In this way the other additives for 
injection are sterilized at the same time as the sodium ascorbate. 
Sterile water "For Injection" is the preferred liquid for dissolving the 
treated sodium ascorbate of this invention. I have found that if this 
injectable grade of water is not available, particularly in veterinary 
medicine, boiled and cooled distilled water or even plain tap water may be 
used for dilution, without harmful effect on the patient.

The following are typical examples of the procedure of this patent: 
EXAMPLE 1 
Into a clean 6 ounce screw capped bottle wiegh 15 grams of sodium ascorbate 
fine crystals. Add 360 milligrams of ethyl alcohol (0.46 ml 95% ethyl 
alcohol), seal tightly and shake vigorously to distribute the alcohol and 
permit rapid vaporization throughout the sealed bottle. Allow to stand. 
EXAMPLE 2 
Weigh 30 grams of sodium ascorbate into a dry 1 liter plastic parenteral 
bag. add 600 milligrams of ethyl alcohol (0.8 ml of 90% ethyl alcohol) and 
mix thoroughly with the contained powder. Fold the bag and store flat (to 
limit the internal volume) until ready to use. Dilute with 1 liter of 
sterile water "For Injection", immediately before connecting to the 
patient. This will produce a fresh sterile isotonic parenteral solution of 
sodium ascorbate suitable for continuous intravenous drip therapy. 
EXAMPLE 3 
Weigh 20 grams of sodium ascorbate (fine crystals) into a 100 ml sealable 
vial and add 300 milligrams of ethyl alcohol (0.48 ml 70% ethyl alcohol). 
Shake thoroughly and seal with a closure that can be sterily penetrated by 
a hypodermic needle. Allow to stand. When ready for use, draw 100 ml of 
sterile water for injection into a sterile hypodermic syringe. Penetrate 
the cap with the hypodermic needle and add sufficient water to dissolve 
the sodium ascorbate by swirling, without removing the hypodermic from the 
vial. When dissolved the solution is sucked back into the hypodermic 
syringe, mixed and is ready for injection. 
EXAMPLE 4 
10 grams of sodium ascorbate (fine crystals) are weighed into a 100 ml 
sealable vial and 300 milligrams of ethyl alcohol is added (0.38 ml 
absolute alcohol) and the vial is sealed and shaken as in Example 3 and is 
handled similarly. 
While this invention has been disclosed with respect to specific 
embodiments, it is not limited thereto. Various modifications can be made 
without departing from the scope of the invention which is limited only by 
the following claims wherein: