Effects of Chemical Interaction

Because of the large number of different chemicals an individual may come in contact with at any given time (workplace, medications, diet, hobbies, etc.), it is necessary to consider how different chemicals may interact with each other. Interactions can occur through various mechanisms, such as alterations in absorption, protein binding, and the biotransformation and excretion of one or both of the interacting toxicants. In addition to these modes of interaction, the response of the organism to combinations of toxicants may be increased or decreased because of toxicologic responses at the site of action.

1. An additive effect occurs when the combined effect of two chemicals is equal to the sum of the effects of each agent given alone (example: 2 + 3 = 5). The effect most commonly observed when two chemicals are given together is an additive effect.

2. A synergistic effect occurs when the combined effects of two chemicals are much greater than the sum of the effects of each agent given alone (example: 2 + 2 = 20). For example, both carbon tetrachloride and ethanol are hepatotoxic compounds, but together they produce much more liver injury than the mathematical sum of their individual effects on liver at a given dose would suggest.

3. Potentiation occurs when one substance does not have a toxic effect on a certain organ or system but when added to another chemical makes that chemical much more toxic (example: 0 + 2 = 10). For example, Isopropanol is not hepatotoxic, but when it is administered in addition to carbon tetrachloride, the hepatotoxicity of carbon tetrachloride is much greater than is the case when it is given alone.

4. Antagonism occurs when two chemicals administered together interfere with each other's actions or one interferes with the action of the other (example: 4 + 6 = 8; 4 + (–4) = 0; 4 + 0 = 1).

There are four major types of antagonism: functional, chemical, dispositional, and receptor.

·                  Functional antagonism occurs when two chemicals counterbalance each other by producing opposite effects on the same physiologic function. For example, the marked fall in blood pressure during severe barbiturate intoxication can be antagonized effectively by the intravenous administration of a vasopressor agent such as norepinephrine or metaraminol.

·                  Chemical antagonism or inactivation is simply a chemical reaction between two compounds that produces a less toxic product. For example, chelators of metal ions decrease metal toxicity and antitoxins antagonize the action of various animal toxins.

·     Dispositional antagonism occurs when the absorption, biotransformation, distribution, or excretion of a chemical is altered so that the concentration and/or duration of the chemical at the target organ are diminished. Thus, the prevention of absorption of a toxicant by ipecac or charcoal, increased activity of metabolizing enzymes with enzyme inducers, and the increased excretion of a chemical caused by the administration of a diuretic are examples of dispositional antagonism.

·             Receptor antagonism occurs when two chemicals that bind to the same receptor produce less of an effect when given together than the addition of their separate effects (example: 4 + 6 = 8) or when one chemical antagonizes the effect of the second chemical (example: 0 + 4 = 1). Receptor antagonists often are termed blockers.

Aseptic Rooms

Aseptic rooms provide sterile, aseptic and isolator environments to the current standard focusing on key areas such as the control of microbiological contamination, differential room pressurization, terminal filtration, easily cleanable surfaces, controlled entry systems and airlocks, changing areas with integrated hygiene stations with the goal of minimizing contamination by pathogens. This is designed to integrate with containment and safety equipment.

Purpose

Aseptic technique is employed to maximize and maintain asepsis, the absence of pathogenic organisms, in the clinical setting. The goals of aseptic technique are to protect the patient from infection and to prevent the spread of pathogens. Often, practices that clean (remove dirt and other impurities), sanitize (reduce the number of microorganisms to safe levels), or disinfect (remove most microorganisms but not highly resistant ones) are not sufficient to prevent infection.

Importance of aseptic room in pharmaceuticals

Pharmaceuticals are substances which contain one or more pharmacologically, therapeutically , active substances, derived from chemical, mineral ,plant ,microbial or animal origin, which exhibit its therapeutic, pharmacological, chemical activity when applied or administered to human or animal. They are be used to treat human or animal diseases and disease conditions or symptoms.

Practice or methods adapted during and before the manufacturing of pharmaceuticals or drug substances to ensure that the pharmaceutical or drug substance manufactured meets highest purity quality standards, methods adapted are mostly pertaining to Personal hygiene , and environmental cleanliness, and are to eliminate microbial or particulate contamination or cross contamination.

Any novel, or upgraded methods or systems, operations, with respect to personal hygiene, machinery or tools, premises or environment and its control which assures better results with respect pharmaceutical good manufacturing practices. That means CGMP is never a constant or a stable process rather it is continuous phenomenon of improvement.

How aseptic room achieves

Clean rooms fall into two categories, unidirectional and non-unidirectional.

Unidirectional clean rooms normally have vertical airflow. Air flows downwards through HEPA filters located in the ceiling. The air is extracted through perforated flooring or grilles mounted on the walls at floor level. Airflow in a unidirectional clean room can also be horizontal.

Non unidirectional clean rooms have air flows from HEPA filters located in various positions and returned through opposite locations. Filters may be distributed at equal intervals throughout the room or grouped over critical areas. The distribution and returns in this instance mean that the air flow may be turbulent in nature.

The floors, walls and ceiling should be made of a smooth impervious material to ensure no particle shedding and easy cleaning. They should also be chemically resistant. All joins in the covering materials should be welded to ensure that there is no chance of seepage of cleaning fluids under the covering.

Doors should be easy to open and, where necessary, two doors linked together to form an air lock. This prevents a sudden rush of air when a door is opened. All doors should be controlled to prevent unwanted flow of air from one area to another by opening of doors simultaneously.

Benches should be made from one complete sheet of laminate because some liquids attack the adhesive at the joints and eventually cause lifting. Where possible made they should be made from stainless steel, which are impervious. They are usually wall-mounted to reduce dust collection and facilitate its detection and removal.

When storage space is required, cupboards are preferable to drawers because they are easier to clean. Cupboards should be dust proof and smooth inside. Rounded beading may be used to cover dust-retaining angles within storage spaces and between fixed benches and walls. Small units on castors make useful additions to the working surface.

Chairs must be adjustable and comfortable and covered with an impervious washable material.

Trolleys should be made from stainless steel and be easily cleanable.

Switches and sockets should be flush fitting and have plastic fingerplates.

There should be no

• Shelves, window ledges or door frames where dust might settle.
• Pipes or ductwork. (False ceilings should be fully sealed with lighting recessed).
• Sinks or drains.

Hand washing facilities should be available external to changing rooms. Taps should be elbow or foot operated so that cleaned hands are not used to turn the water off. Soap should be conveniently dispensed from a wall or bench dispenser. Electric hand dryers or high quality paper towels should be used to dry hands.

There should be a separate two-way transfer hatch system for the transfer of goods in and out of the clean room, to prevent contamination of environments.

There should be a support room from which materials can be passed into and out of the clean room through hatches.

There should be:

• smooth impervious surfaces
• no ledges for dust to gather
• surfaces which are easy to clean
• transfer systems/airlocks to prevent contamination
• no water sources

How aseptic room maintains

To maintain asepsis in the operating room include:

• All items in a sterile field must be sterile.
• Sterile packages or fields are opened or created as close as possible to time of actual use.
• Moist areas are not considered sterile.
• Contaminated items must be removed immediately from the sterile field.
• Gowns are considered sterile only in the front, from chest to waist and from the hands to slightly above the elbow.
• Tables are considered sterile only at or above the level of the table.
• Non-sterile items should not cross above a sterile field.
• There should be no talking, laughing, coughing, or sneezing across a sterile field.
• Personnel with colds should avoid working while ill or apply a double mask.
• Edges of sterile areas or fields (generally the outer inch) are not considered sterile.
• When in doubt about sterility, discard the potentially contaminated item and begin again.
• A safe space or margin of safety is maintained between sterile and nonsterile objects and areas.
• When pouring fluids, only the lip and inner cap of the pouring container is considered sterile; the pouring container should not touch the receiving container, and splashing should be avoided.
• Tears in barriers and expired sterilization dates are considered breaks in sterility.

Parental product require aseptic environment

Medications are given parenterally to the Patients who are not able to take medications by mouth, Need for rapid action of the medication as in emergency situations, Medication not available in a suitable dosage form to be given by mouth, Patients with difficulty absorbing medications. Parenteral product require aseptic environment during manufacturing, because-

• Parenteral administration bypasses the skin and gastrointestinal tract, the bodies natural barriers to infection.
• Giving a patient a contaminated product can cause serious adverse effects including death.
• Parenteral medications account for >40% of all medications administered in institutional practice.

How aseptic environment influence the quality of the product

Advanced aseptic processing strategies offer manufacturers the best solution for protecting the quality and safety of their products and for ensuring the highest contamination control standards possible for products that cannot be terminally sterilized--but it comes at a cost. Unlike terminal sterilization, aseptic processing lines don't involve a high-heat kill step for final products, which can mute food flavors and destroy pharmaceutical potency. But because they can't rely on that all-powerful, microbial-destroying heat treatment, manufacturers have to put in place strict controls, in-process control testing and validation steps throughout the manufacturing process to ensure, that no contaminants ever find their way into materials, components and final product.

These delicate products can be affected not only by temperature but also light, pH balance, sheer, and the velocity at which the product runs through a nozzle and hits the surface of a storage container.

An advanced aseptic process is one in which direct intervention with open product containers or exposed product contact surfaces by operators wearing conventional clean room garments is not required or permitted. Because, there is no opportunity to sterilize the product in its final container.