Isotechniques, or techniques of adjacent volumes, are a processing method for pharmaceutical preparations containing high-potency
active pharmaceutical ingredients (APIs) (e.g., cytostatics, hormones, and antibiotics) in absolute secure conditions to ensure
the safety of the operator and the quality of the finished product. Manufacturing using isotechniques takes place in isolators.
Isotechniques offer certain advantages for aseptic production of injectable, high-potency drugs. In the sanitized areas of
cleanrooms, the operator brings in contamination in a limited manner. A completely biodecontaminated environment exists inside
the isolator, where only the drug and material for manufacturing come in direct contact with the processing system. In such
operative circumstances, contamination by microbes is more limited than in cleanroom conditions because the absence of direct
human intervention allows for better cleaning and complete biodecontamination of the entire working environment. Complete
biodecontamination with vaporized hydrogen peroxide of the working area inside isolators allows for operation in a biodecontaminated
environment. Cleanrooms, however, are exclusively sanitized and operate under conditions of controlled contamination.
A biodecontaminated environment
The automatic cycle of biodecontamination guarantees the reproducibility of the process. Manual disinfection is a time-consuming
activity that may not be consistently performed and is dangerous because of the continuous exposure of operators to sanitizing
agents. Biodecontaminating agents such as vaporized hydrogen peroxide achieve sterilization by the dispersion of gas. The
gas can reach all surfaces exposed to its contact, even the hidden ones. Its products are oxygen and water, which are harmless.
Isotechniques also exceed the onerous barrier created by the modality of clothing and microbiological control. The US Food
and Drug Administration has expressed a favorable opinion for increasing the use of isotechniques for drug production in asepsis,
especially for the production of high-potency APIs.
Isolators for high-potency drugs
Some aspects to consider when using isolators while processing injectable, high-potency drugs are:
- Containment of contamination, particularly airborne contamination
- Individual protection of personnel
- Management of cross-contamination
- Aseptic processing and sterility of handled material and product
- Efficiency of biodecontamination cycles
- Efficiency of barriers and their integrity
- Management of the environmental impact as a result of the process (i.e., refluent, industrial waste, liquids, gas, and air).
A practical demonstration of the productions of liquids or lyophilized injectables in glass vials is shown in Figure 1. The
operating line is set up by several isolators partly connected in a row, where all manufacturing operations are done. These
operations are: weighing of raw materials, their volatilization in tanks, transfer of the solution to the dosage systems,
washing and depyrogenation of vials, filling of vials, capping (complete if liquid; partially, if liquids are to lyophilize),
eventual freeze-drying, sealing, external washing, and drying of filled and sealed vials.
Figure 1: Production flow for liquids in vials. (ALL FIGURES AND IMAGES ARE COURTESY OF THE AUTHOR.)
The process is made in a production line with isolators. The following are phases of the main production process:
- Phase I: Preparation of the distribution circuit (distributor, needles, and tubes)
- Phase II: Preparation of isolators (cleaning and biodecontamination)
- Phase III: Preparation of various materials (vials, stoppers, and seals)
- Phase IV: Preparation of the solution and its filtration.
Phase II is typically for a production process using isotechniques. Phase IV is strongly affected by the kind of API (i.e.,
high-potency) used in the solution preparation, and this aspect considerably changes the manipulation modalities of the API.