Bowie Dick test for Vacuum Sterilizers.

Bowie Dick test has been widely used in pharmaceutical industries for the vacuum sterilizers. This test was developed by J. H. Bowie and J. Dick. This test is perform to verify heat penetration inside the chamber. As we know that pressure and vacuum pluses are there in steam sterilizers. The purpose of pressure and vacuum pulse is to effectively remove air from the chamber because air is a bad conductor of heat and if air pockets are present inside the chamber then it would be very difficult to sterilize the load. Heat penetration can be checked by oberving class 2 chemical indicator sheet which is used for this test. If colour change of the indicator sheet is uniform then it means air has effectively removed from the chamber and no air pockets left inside the chamber during sterilization. But if colour change is not uniform then it means these pulses are not effective to remove all air and air pockets from the chamber. In the past time, bowie dick test was performed by using layer of towels having an indicator sheet inbetween the towels. These towels were placed over the drain point which would be considered as cold spot of the autoclave. But now a days this towel concept has been replaced by the bowie dick pack. Different companies provide different bowie dick test kit but the purpose of all these kits it to check heat penetration inside the load. As per HTM 2010 guideline, it is also called standard test pack. Total weight of the pack should be 7.0±0.7 kg and height of the pack should be 25 cm or 250 mm. This test has to be perfomed on daily basis as per HTM 2010 guideline.The basic principle of this test is that when we run the bowie dick cycle air is removed from the chamber and all air trapped inside the bowie dick pack which we place over the drain point of the autoclave. If air removal is effective than heat penetration will be proper and there will be unifrom colour change of the indicator sheet. And if air removal is not effective then colour change will not be uniform. There are different type of bowie dick test packs available in the market. For example one of them is a set of paper sheets in a pack and middle of these sheets there would be a chemical indicator sheet. To use this type of bowie dick pack just place the pack as such over the drain point, no need to maintain the weight and height of the pack. Another one is having a S.S holder which can hold a bunch of sheet and in the middle, indicator sheet would be there and that pack has to be placed over the drain point. This one provide the required pressure on the pack (weight) and required height is maintained by the SS holder.

Why 70% Isopropyl alcohol is used as disinfectant in pharmaceutical industries?

Iso-propyl alcohol (IPA) is widely used as a disinfectant in pharmaceutical companies . IPA is very effective on gram positive as well as gram negative bacteria. Most of the hand disinfectants available in the market contains IPA as an active component just because of its effectiveness. IPA is very effective and kill microbial cell with in a few seconds. But one limitation of IPA is that it is not effective against bacterial and fungal spores. Disinfectant efficacy depends upon two factors. First is concentration of disinfectant solution and second is contact time. Disinfectant validation activity also depends upon these two factors. In pharmaceuticals that's why validation activity must be performed to validate its effective concentration and contact time. Different guidelines and pharmacopoeias recommend 70% IPA solution because at this particular concentration, IPA is very effective. But why 70% IPA is effective and recommended by pharmacopoeias and guidelines why not 100 %? The reason is behind the mode of action of 70% IPA. Bacterial cells have proteins in their cell wall and when this protein comes in contact with the 70% IPA during disinfectant application, coagulation of proteins takes places in which denaturation of proteins occurred and after that IPA penetrate in the interior of the cell which cause lysis or death of the cell. Protein coagulation also happens in case of 100% IPA but with very fast rate and because of this very fast protein coagulation process denatured protein forms protective layer out side of the cell. When this happens, 100% can not penetrate inside the cell and not able to kill the microbe. Microorganisms become dormant in that conditions. In case of 70% IPA protein coagulation takes place with a slow rate and due to this 70% IPA get enough time to penetrate in the cell and kill the microorganism. Another factor is contact time, 70% IPA takes longer time to evaporate from any surface hence get enough contact time and in this mean time it show its efficacy but in case of 100% IPA, evaporation will be very fast, contact time will be less and it will not be so effective against microbes. That's why 70% IPA solution is used as disinfectant in pharmaceuticals industries.