by Hank Rahe
All compounds developed with the intention of becoming a pharmaceutical product are potent by definition because they will have an effect upon the human being. The effect is beneficial for those who the compound is intended to treat but can cause significant damage to individuals for which the treatment is not intended.
The most significant exposure potential is the work place. The workplace can be the laboratory, site of manufacture, hospital or pharmacy. Each location requires proper protection of individuals to assure that the exposure limit for the compound is not exceeded. The protection device must eliminate the potent compound from entering the human body by the primary routes of exposure, breathing, ingestion and skin absorption. The exposure limit is the amount of a given compound that can be absorbed by an individual without causing an effect, often called the “no effect” level.
Traditional means of providing protection has been the use of PPE (personal protective equipment). PPE is design to provide a barrier that prevents the potent material from coming in contact with the primary routes of entry. Examples are gloves, protective clothing and masks, which either filter the air before it enters the body or prevents the compound from landing on exposed skin. These techniques protect only those with PPE and do nothing for individuals who may come in casual contact by being in the areas after the compound is present but before the area is decontaminated.
The PPE approach to containment worked well when the typical compound exposure limits were in milligrams because it took a significant amount of dust to cause casual contact to exceed the exposure limit. Many of today's compounds have exposure limits in the monogram levels creating an entirely different set of problems in the work place. Materials in these quantities may not be visible and significant quantities in terms of the exposure limits can be transported by contact with hands and feet. This fact combined with the OSHA requirement that engineered solutions be implemented where economically feasible is changing the approach to containment in many of the workplace environments.
Containment at the source or containing the activity involving the potent compound offers the ability to not only protect the individual working with the potent compound but also contains a defined area minimizing the potential for casual exposures. Experience has shown that this approach to containment not only offers higher assurance of personnel protection but also more efficient operations in the laboratory and clinical manufacturing operations. Faster turnaround of facilities has resulted because the cleaning of the individual unit operation can take place off line.
The preparation and delivery of the final drug substance either in the retail pharmacy or hospital setting is an area of increasing concern. The patient final dosage in all cases exceeds the “no effect” level for the compound. Exposure to multiple doses such as in the dispensing of tablets of a given compound or preparation of a number of injectable products without proper protection can result in exceeding the exposure limit. Casual contact by nurses delivering, administrating or checking products at the patient bedside can exceed the exposure limits for low exposure level products such as cytotoxics.
In the retail setting the counter where the pharmacist prepares the individual prescriptions is many times an open environment where customers can come in contact with airborne contamination. Many pharmacies use either counting trays or automatic counts to count out the tablets and capsules. These devices, if not properly cleaned between each product, can cross contaminate other prescriptions. This is not a problem except when the cross contamination is a highly potent compound. An example would be penicillin cross contaminating another product given to someone allergic to the antibiotic. The level of contamination need only to be in the monogram range for this to result in serious repercussions for the individual.
Hank Rahe is director of technology at Contain-Tech in Indianapolis. He is a member of the CleanRooms Editorial Advisory Board.