With the current outbreak and overspread of covid-19 viral infection, various processes like sterilization which used to be considered a “for granted”, “behind the curtain” process, have come to the limelight. People are highly concerned about consuming and utilizing sterilized goods and products. For ages, we have been using chemical agents to wash wounds and protect them against microbial infections. Such chemical agents sterilize the wound and kill any microbial contaminants which might be able to proliferate on the wound. These examples clearly express the importance of sterilization to protect the human body from foreign infections. They increase our curiosity to wonder about the role of sterilization peculiar to the field of pharmaceuticals.
Need for sterilization in Pharma
Pharma industries produce and use a variety of medical tools, diagnostic tools, and medicines that come in direct contact with patients, thus they prove to be potential carriers of microbial and viral contaminants. Many such tools and culture media are used in diagnostic laboratories. One can imagine the loss in terms of resources, hard work, and time that is incurred if a vital experiment for drug development goes wrong because of microbial contamination in the reagents and biochemical used. In laboratories, researchers tend to cultivate microbial colonies for their respective research areas, in such a situation use of a contaminated spreader would lead to the growth of contaminants on the plate, thus making the plate useless for further analysis. This surely demands for proper sterilization of media and tools at such facilities.
Antibiotics have proved to be a scientific accomplishment serving humans through histories of tough times like the world war. Many antibiotics like penicillin, ampicillin, etc. are produced inside cell systems and this production is carried out in large fermenters. In these fermenters, a bacterial culture is provided with the necessary nutrients and medium and it metabolizes those nutrients to produce antibiotics. Working with such intricate and complex systems, manufacturers use sterilized media and nutrients to prevent the fermenter from contaminants that might metabolize the nutrients to produce unwanted and unknown products. At such industrial sites, there is always a possibility for pathogenic spoilage in the media, but an equal tendency of contamination is shared by the fermenter setup and its tools. What if the impeller of the fermenter or the pH and O2 probes dipped deep down into the reaction mixture contain microbial contamination? Such contaminations are highly risky when medicines are being produced for human consumption, where the doses should be precisely up to the mark. Supporting this fact is the incident where Efficient Laboratories Inc. had to recall several batches of its Rompe Pecho cough syrup due to suspected microbial contamination, which resulted in vomiting and diarrhea illness amongst consumers and patients.
All these reasons sum up to imply that sterilization is an irrefutable process when it comes to dealing with pharmaceuticals and medical tools at health centers and laboratories.
Different methods for Sterilization
In pharmaceuticals, sterilization is carried out either by physical or chemical agents. Physically heating at high temperature is the most commonly used sterilization technique but it cannot be used to sterilize thermolabile materials like most of the drugs and biochemicals. So, to help deal with sterilization of thermolabile goods and solutions, chemical agents like Ethylene Oxide (EtO) are deployed to fulfill the job.
EtO works best in the gaseous form, it reacts with cell constituents like DNA, RNA, proteins, and undergoes a process called alkylation. Alkylation with EtO causes many amino acids to change their shape thus changing protein properties. Such altered proteins act like bullets that are shuttled in and out of the cell, thus breaching the cell wall which kills the cell. EtO can also alter DNA and RNA structures by reacting and alkylating various genetic residues inside the cell, which once altered are no longer able to express the vital proteins.
In pharma, EtO sterilization is used to treat dry materials like powders, medicinal pills, tools, and medical equipment. Since EtO gas does not possess high penetration power, treating aqueous solutions and bulky materials is still a challenge to solve.
Moving on from chemical agents, physical agents like irradiation and subjection to radiations is another powerful technique to sterilize materials. Radiations are highly energetic electromagnetic waves that can kill various microbial and viral contaminants. For example, Gamma radiations are high energy rays that penetrate through the cell wall. These rays collide with DNA and RNA molecules inside the cell, transfer the energy they carry with themselves to the chemical bonds of these molecules, and break them. Irradiation destroys the chemical bonds of essential biomolecules of the cell which ultimately leads to cell death.
Why preferences have shifted from EtO gas to Gamma sterilization
In comparison to EtO gas sterilization, Gamma radiations show excellent penetration power and can sterilize dry, liquid, and bulky loads. This gives Gamma irradiation a much more varied application area than EtO gas sterilization. Both these processes are extensively used at the industrial level but lately, Gamma irradiation has won much popular favor as compared to EtO gas sterilization.
We know that technologies often compete, so let us try to analyze the factors which led to the downfall of EtO. EtO sterilization was once considered to be the best mode of sterilization until one day a study concluded that EtO gas is a potential carcinogen and can act hazardous for industrial workers. Adding to the negatives, EtO is a highly flammable gas and its treatment is carried out in chambers that operate at high pressure. Such extreme working conditions are difficult to maintain and pose a high risk to the industrial plant. EtO gas sterilizers are very complex setups consisting of several steps which make this process a very slow one. All these factors stole the thunder from EtO gas Sterilization technique and made Gamma irradiation a preferred choice. Relatively, Gamma rays have very few side-effects, provided the treatment is being carried out in closed chambers. Moreover, Gamma rays can act in all kinds of temperature and pressure conditions without any posed risks.