PEXARITE 500

Indications

• Cerebral edema
• Elevated intracranial pressure
• Acute kidney injury
• Oliguria
• Glaucoma
• Renal function diagnostic aid

Dosage

Adults: For cerebral edema, administer 0

Mechanism of action

Mannitol elevates blood plasma osmolality, resulting in enhanced flow of water from tissues, including the brain and cerebrospinal fluid, into interstitial fluid and plasma. This action reduces cerebral edema and intracranial pressure. As a diuretic, it increases the osmolality of glomerular filtrate, leading to increased urinary excretion of water and preventing sodium and chloride reabsorption in the renal tubules. Mannitol also facilitates the urinary excretion of toxic substances and can help in assessing renal function by measuring glomerular filtration rate (GFR).

Pharmacodynamics

Mannitol is classified as an osmotic diuretic. It is chemically similar to other sugar alcohols but has a unique ability to promote diuresis by remaining unabsorbed in the renal tubules. Its use is indicated for conditions associated with increased body fluids, such as cerebral edema and glaucoma. Mannitol may be combined with other diuretics to enhance diuretic efficacy. Inhaled formulations are used in cystic fibrosis, though they may cause bronchospasm and hemoptysis.

Pharmacokinetics

Mannitol is freely filtered by the glomeruli with less than 10% tubular reabsorption, which allows for its urinary excretion rate to serve as a measurement of GFR. It does not undergo significant metabolism and is eliminated primarily through the kidneys. The onset of action occurs within 30 to 60 minutes after intravenous administration, with effects lasting for several hours. Administration may require monitoring of renal function and fluid balance.

Contra-indications

• Anuria
• Severe dehydration
• Severe renal impairment
• Intracranial bleeding

Adverse effects

• Asthenia
• Gastrointestinal disturbances
• Dry mouth
• Confusion
• Visual impairment
• Hypotension
• Electrolyte imbalances
• Pulmonary edema
• Hemoptysis (with inhalation use)
• Bronchospasm (with inhalation use)

Interactions

• Potassium-sparing diuretics may increase the risk of hyperkalemia
• Other diuretics may have additive effects
• Caution with nephrotoxic agents

Precautions

• Caution in patients with diabetes mellitus
• Caution in the elderly
• Caution in patients with gout
• Caution in patients with hepatic impairment
• Monitor renal function and electrolytes regularly
• May cause blue fluorescence of urine

Pregnancy

Manufacturer advises avoid due to potential toxicity in animal studies.

Breast-feeding

Manufacturer advises avoid due to lack of information available.

Storage

Store in a cool, dry place, away from light. Do not freeze.

Formulations

• Solution for injection
• Inhalation powder
• Oral solution

Indications

• Malignant pleural mesothelioma (in combination with cisplatin)
• Locally advanced or metastatic non-small cell lung cancer (NSCLC) other than predominantly squamous cell histology (first-line therapy in combination with cisplatin)
• Second-line treatment of locally advanced or metastatic NSCLC (monotherapy)

Mechanism of action

Pemetrexed inhibits several folate-dependent enzymes, including thymidylate synthase (TS), dihydrofolate reductase (DHFR), and glycinamide ribonucleotide formyltransferase (GARFT). These enzymes are crucial for the de novo biosynthesis of thymidine and purine nucleotides. Upon entering the cell, pemetrexed is converted into polyglutamate forms by folylpolyglutamate synthetase, which are retained within the cell and act as potent inhibitors of TS and GARFT, prolonging the drug's action in tumor cells.

Pharmacodynamics

In vitro studies indicate that pemetrexed effectively inhibits the growth of mesothelioma cell lines, demonstrating synergistic effects when used in combination with cisplatin. The drug's pharmacodynamic effects correlate with systemic exposure, particularly the depth of the absolute neutrophil counts (ANC) nadir, which is influenced by the concurrent administration of folic acid and vitamin B12. Notably, there is no cumulative effect of pemetrexed on ANC nadir across multiple treatment cycles.

Pharmacokinetics

Pemetrexed is administered as a solution for infusion and is absorbed into cells via reduced folate carriers and membrane folate binding proteins. Once inside the cells, it undergoes polyglutamation, which enhances its retention and activity. The pharmacokinetic profile indicates that the drug has an extended intracellular half-life due to its polyglutamate forms, resulting in prolonged effects in malignant tissues. Its clearance and distribution are influenced by factors such as renal function and the use of folate supplementation.

Adverse effects

• Appetite decreased
• Fatigue
• Nausea
• Vomiting
• Diarrhea
• Anemia
• Neutropenia
• Thrombocytopenia
• Rash
• Stomatitis

Interactions

• Aspirin: Moderate (increases exposure)
• NSAIDs: Moderate (increases exposure)
• Pyrimethamine: Unknown (increases risk of adverse effects)
• Live vaccines: Unknown (increases risk of generalized infection, possibly life-threatening)

Precautions

• Prophylactic folic acid supplementation required
• History of diabetes
• History of cardiovascular disease

Pregnancy

Pemetrexed is not recommended during pregnancy due to potential harm to the fetus.

Breast-feeding

It is not known whether pemetrexed is excreted in human milk; caution is advised.

Storage

Store in the original container, protected from light. Once reconstituted, use immediately.

Formulations

• Pemetrexed 100 mg powder for concentrate for solution for infusion
• Pemetrexed 500 mg powder for concentrate for solution for infusion
• Pemetrexed 850 mg/34 ml concentrate for solution for infusion
• Pemetrexed 1 g/40 ml concentrate for solution for infusion

Indications

• Electrolyte replacement
• Volume expansion in hypovolemic patients
• Management of hyponatremia
• Support in intravenous fluid therapy

Dosage

Children: Refer to the BNF for Children for appropriate dosing in paediatric patients, as dosages may vary based on the formulation and clinical condition.

Adults: Refer to specific product information or clinical guidelines for dosage recommendations, as disodium is often part of combination products.

Mechanism of action

Disodium compounds often function by providing sodium ions that are essential for various physiological processes. Sodium ions play a critical role in maintaining osmotic balance, nerve impulse transmission, and muscle contraction. In the context of intravenous solutions, disodium helps to restore electrolyte balance in patients.

Pharmacodynamics

The pharmacodynamics of disodium is primarily related to its role in electrolyte balance and fluid homeostasis. Sodium ions are vital for the function of excitable tissues, including neurons and muscle cells. Changes in sodium levels can affect blood pressure, hydration status, and overall cellular function.

Pharmacokinetics

The pharmacokinetics of disodium compounds depend on their specific formulation and route of administration. When administered intravenously, disodium is rapidly distributed in the extracellular fluid, where it helps to maintain osmotic pressure. Sodium is primarily excreted by the kidneys, and its levels can be influenced by fluid intake, dietary sodium, and renal function.

Pregnancy

Use with caution. Consult a healthcare provider for specific guidance.

Breast-feeding

Use with caution. Consult a healthcare provider for specific guidance.

Storage

Store at room temperature, away from moisture and direct sunlight.

Dosage

Children: Refer to specific product guidelines for dosage recommendations.

Adults: Refer to specific product guidelines for dosage recommendations.

Mechanism of action

The mechanism of action of hemipentahydrate varies depending on the specific compound it is associated with. Generally, compounds in a hemipentahydrate form are designed to dissolve in bodily fluids, allowing for the active ingredients to be released and exert their pharmacological effects. This can involve interactions with specific receptors or enzymes, leading to therapeutic outcomes.

Pharmacodynamics

Pharmacodynamics of hemipentahydrate compounds is reliant on the active drug's properties. Typically, these compounds may exhibit effects such as anti-inflammatory, analgesic, or antimicrobial actions, depending on the specific drug. The pharmacological effect is often dose-dependent, requiring careful consideration of the concentration of the active ingredient released from the hemipentahydrate form.

Pharmacokinetics

The pharmacokinetics of hemipentahydrate compounds include absorption, distribution, metabolism, and excretion (ADME). The hydration state can influence the solubility and, consequently, the absorption profile of the drug. Once absorbed, the distribution throughout the body will depend on the drug’s lipophilicity and protein binding capacity. Metabolism usually occurs in the liver, where the active compound may be converted into metabolites, and excretion typically happens via the kidneys.

Pregnancy

Safety in pregnancy has not been established. Consult healthcare provider before use.

Breast-feeding

Safety during breastfeeding has not been established. Consult healthcare provider before use.

Storage

Store in a cool, dry place away from light. Keep out of reach of children.

Indications

• Anxiety disorders
• Depression
• Neurological conditions

Dosage

Children: Refer to specific clinical guidelines or consult a healthcare provider for appropriate pediatric dosing.

Adults: Refer to specific clinical guidelines or consult a healthcare provider for appropriate dosing.

Mechanism of action

The precise mechanism of action for hemipentahydrobromide is not well-documented. However, compounds of this class often act on neurotransmitter receptors or ion channels, influencing synaptic transmission and neuronal excitability. This can lead to therapeutic effects in conditions like anxiety or depression, though further specific information is necessary for conclusive understanding.

Pharmacodynamics

Hemipentahydrobromide may exhibit dose-dependent effects on the central nervous system, potentially enhancing inhibitory neurotransmission through modulation of GABAergic pathways or antagonizing excitatory neurotransmitters. Its pharmacodynamic profile would depend on its affinity for various receptors and its effects on neuronal signaling pathways.

Pharmacokinetics

The pharmacokinetic properties of hemipentahydrobromide, such as absorption, distribution, metabolism, and excretion, are not well-established. Typically, drugs in this category may demonstrate variable absorption rates depending on formulation, while distribution may be influenced by lipophilicity. Metabolism could involve hepatic pathways, and elimination may be renal or through bile, requiring clinical monitoring for individual patient response.

Pregnancy

The safety of hemipentahydrobromide in pregnancy has not been established. Use with caution and only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

It is not known whether hemipentahydrobromide is excreted in human milk. Caution is advised when administering to nursing mothers.

Storage

Store at room temperature, away from light and moisture. Keep out of reach of children.

Indications

• Adjustment of pH in pharmaceutical formulations
• Facilitation of drug absorption
• Used in sterile preparations

Dosage

Children: Refer to specific product guidelines for dosing information, as hydrochloric acid is typically used in a controlled setting based on formulation requirements.

Adults: Refer to specific product guidelines for dosing information, as hydrochloric acid is typically used in a controlled setting based on formulation requirements.

Mechanism of action

Hydrochloric acid dissociates in aqueous solution to release hydrogen ions (H+), leading to a decrease in pH. This acidic environment promotes the activation of pepsinogen to pepsin, an enzyme essential for protein digestion. Additionally, the acidity aids in the absorption of certain minerals and drugs that require an acidic environment for optimal bioavailability.

Pharmacodynamics

The primary pharmacodynamic action of hydrochloric acid is the maintenance of gastric acidity, which is essential for normal digestive processes. The acidic environment helps in denaturing proteins, activating digestive enzymes, and providing a barrier against pathogenic microorganisms. Its effects can influence the absorption and efficacy of various medications, particularly those that are pH-dependent.

Pharmacokinetics

Hydrochloric acid does not undergo significant systemic absorption when used in its normal contexts, as it acts locally within the gastrointestinal tract. The amount of hydrochloric acid produced by the stomach varies with food intake and physiological needs. It is secreted by parietal cells in the gastric mucosa, and its secretion is regulated by neural, hormonal, and local factors. The half-life of hydrochloric acid is not applicable as it is continuously produced and neutralized within the gastrointestinal tract.

Contra-indications

• Hypersensitivity to hydrochloric acid or any of its components
• Severe renal impairment
• Active gastrointestinal bleeding

Adverse effects

• Abdominal pain
• Diarrhea
• Nausea
• Vomiting
• Esophageal irritation
• Gastric mucosal irritation
• Electrolyte imbalances

Interactions

• May interact with alkaline substances, potentially neutralizing hydrochloric acid
• Caution with antacids as they may affect the efficacy of hydrochloric acid

Precautions

• Use with caution in patients with a history of gastritis or gastric ulcers
• Monitor electrolytes in prolonged use
• Use cautiously in patients with respiratory conditions due to potential aspiration risks

Pregnancy

Hydrochloric acid is classified as a category C drug. Use during pregnancy only if clearly needed and the potential benefits justify the risks to the fetus.

Breast-feeding

There is limited data on the excretion of hydrochloric acid in human milk. Use with caution during breastfeeding.

Storage

Store in a cool, dry place away from direct sunlight and heat. Ensure the container is tightly closed.

Formulations

• Oral solutions
• Injectable forms
• Tablets

Dosage

Children: Refer to specific guidelines for pediatric dosing; consult the BNF for Children for accurate dosage information.

Adults: Refer to specific guidelines for use; dosage may vary based on the context of use.

Mechanism of action

Hydroxide ions act primarily as bases, neutralizing acids to form water and salts. They participate in various biochemical pathways, including selenium metabolism and the degradation of reactive oxygen species. Hydroxide can influence enzyme activity and stability by altering the pH of the environment, thereby affecting metabolic reactions.

Pharmacodynamics

Hydroxide ions can impact biological processes by changing the local pH, which influences enzyme activity, ion transport, and the solubility of other compounds. Their ability to neutralize acids can help regulate physiological pH, contributing to homeostasis in living organisms.

Pharmacokinetics

As an inorganic ion, hydroxide does not undergo traditional pharmacokinetic processes like absorption, distribution, metabolism, or excretion. Instead, it is rapidly equilibrated in biological fluids and participates in acid-base reactions, having immediate effects on the local environment.

Pregnancy

There is limited information regarding the use of hydroxide during pregnancy. Consult a healthcare professional for advice.

Breast-feeding

Limited data is available on the excretion of hydroxide in breast milk. Consult a healthcare professional before use.

Storage

Store in a cool, dry place away from direct sunlight. Keep out of reach of children.

Indications

• Cryotherapy for the destruction of abnormal tissue
• Treatment of warts, moles, and other skin lesions
• Nitrogen narcosis in diving

Dosage

Children: Refer to the BNF for Children for appropriate dosing recommendations in paediatric patients.

Adults: For cryotherapy, the dosage and duration depend on the specific condition being treated and should be determined by the healthcare provider. Refer to specific guidelines for each condition.

Mechanism of action

In cryotherapy, the mechanism of action involves three stages: heat transfer, cell injury, and inflammation. The boiling point of liquid nitrogen is -196°C, which initiates heat transfer, leading to cell injury during the thawing process. The inflammation stage follows, characterized by edema and erythema, resulting from cellular death and contributing to local cell destruction. Additionally, nitrogen can cause direct toxic effects on brain functions, leading to nitrogen narcosis, which impairs cognitive abilities and motor functions due to its impact on nerve conduction.

Pharmacodynamics

Nitrogen's pharmacodynamics relate to its behavior in cryotherapy and asphyxiation. In cryotherapy, it induces tissue destruction through rapid cooling, leading to apoptosis of abnormal cells. In high-pressure environments, nitrogen narcosis affects the central nervous system, producing symptoms similar to alcohol intoxication, ultimately decreasing reasoning, decision-making abilities, and manual dexterity.

Pharmacokinetics

Nitrogen does not undergo metabolism in the traditional sense, as it is an inert gas at physiological conditions. Its pharmacokinetics involve physical principles of gas exchange and partial pressures. In the case of nitrogen narcosis, the effects are influenced by the partial pressure of nitrogen in the bloodstream, which increases with depth during diving. Nitrogen is primarily eliminated from the body through respiration.

Adverse effects

• Narcotic effect at high pressures
• Stupor or euphoria
• Decreased motor function and manual dexterity
• Asphyxiation due to oxygen displacement

Precautions

• Careful monitoring in environments with high nitrogen pressures
• Avoidance of rapid ascents in diving to prevent nitrogen narcosis
• Use in controlled settings to prevent asphyxiation risks

Pregnancy

Nitrogen is generally considered safe in terms of direct effects during pregnancy; however, the safety of exposure in high-pressure environments should be assessed.

Breast-feeding

Nitrogen is not known to affect breastfeeding; however, caution is recommended in environments where nitrogen levels may displace oxygen.

Storage

Store in a cool, dry place away from heat sources; liquid nitrogen should be handled with care due to extreme cold.

Formulations

• Liquid nitrogen
• Nitrogen gas (compressed)

Mechanism of action

Mannitol is an osmotic diuretic that is metabolically inert in humans and occurs naturally, as a sugar or sugar alcohol, in fruits and vegetables. Mannitol elevates blood plasma osmolality, resulting in enhanced flow of water from tissues, including the brain and cerebrospinal fluid, into interstitial fluid and plasma. As a result, cerebral edema, elevated intracranial pressure, and cerebrospinal fluid volume and pressure may be reduced. As a diurectic mannitol induces diuresis because it is not reabsorbed in the renal tubule, thereby increasing the osmolality of the glomerular filtrate, facilitating excretion of water, and inhibiting the renal tubular reabsorption of sodium, chloride, and other solutes. Mannitol promotes the urinary excretion of toxic materials and protects against nephrotoxicity by preventing the concentration of toxic substances in the tubular fluid. As an Antiglaucoma agent mannitol levates blood plasma osmolarity, resulting in enhanced flow of water from the eye into plasma and a consequent reduction in intraocular pressure. As a renal function diagnostic aid mannitol is freely filtered by the glomeruli with less than 10% tubular reabsorption. Therefore, its urinary excretion rate may serve as a measurement of glomerular filtration rate (GFR). The exact mechanism of action of inhaled mannitol in the symptomatic maintenance treatment of cystic fibrosis remains unclear. It is hypothesized that mannitol produces an osmotic gradient across the airway epithelium that draws fluid into the extracellular space and alters the properties of the airway surface mucus layer, allowing easier mucociliary clearance. MANNITOL IS.../USED/ IN PROPHYLAXIS OF ACUTE RENAL FAILURE. IT IS USED FOR THIS PURPOSE IN CONDITIONS AS DIVERSE AS CARDIOVASCULAR OPERATIONS, SEVERE TRAUMATIC INJURY, OPERATIONS IN THE PRESENCE OF SEVERE JAUNDICE, AND MGMNT OF HEMOLYTIC TRANSFUSION REACTIONS. IN EACH OF THESE CONDITIONS, A PRECIPITOUS FALL IN THE FLOW OF URINE MAY BE ANTICIPATED EITHER AS THE RESULT OF AN ACUTELY REDUCED FILTRATION RATE OR FROM ACUTE CHANGES IN TUBULAR PERMEABILITY. THE LATTER MAY BE CONSEQUENCE OF THE PRESENCE OF NOXIOUS AGENT WITHIN THE TUBULAR FLUID IN EXCESSIVELY HIGH CONCN, IN SOME INSTANCES SUFFICIENT TO RESULT IN ACTUAL PRECIPITATION. IN THESE SITUATIONS, MANNITOL EXERTS OSMOTIC EFFECT WITHIN THE TUBULAR FLUID, INHIBITS WATER REABSORPTION, & MAINTAINS THE RATE OF URINE FLOW. ...CONCN OF TOXIC AGENT WITHIN TUBULAR FLUID DOES NOT REACH EXCESSIVELY HIGH LEVELS THAT OTHERWISE WOULD HAVE BEEN ACHIEVED BY MORE COMPLETE REABSORPTION OF WATER. ...EVEN THOUGH /GLOMERULAR/ FILTRATION RATE IS REDUCED, MANNITOL IS STILL FILTERED @ GLOMERULUS. THE TUBULAR IMPERMEABILITY TO MANNITOL IS NOT ALTERED BY ACUTE RENAL ISCHEMIA OF SHORT DURATION. HENCE, THE MANNITOL THAT IS FILTERED IS ALSO EXCRETED IN THE VOIDED URINE. UNREABSORBED SOLUTE LIMITS BACK DIFFUSION OF WATER. ...URINE VOL CAN BE MAINTAINED EVEN IN PRESENCE OF DECR GLOMERULAR FILTRATION.

Pharmacodynamics

Chemically, mannitol is an alcohol and a sugar, or a polyol; it is similar to xylitol or sorbitol. However, mannitol has a tendency to lose a hydrogen ion in aqueous solutions, which causes the solution to become acidic. For this reason, it is not uncommon to add a substance to adjust its pH, such as sodium bicarbonate. Mannitol is commonly used to increase urine production (diuretic). It is also used to treat or prevent medical conditions that are caused by an increase in body fluids/water (e.g., cerebral edema, glaucoma, kidney failure). Mannitol is frequently given along with other diuretics (e.g., furosemide, chlorothiazide) and/or IV fluid replacement. Inhaled mannitol has the possibility to cause bronchospasm and hemoptysis; the occurrence of either should lead to discontinuation of inhaled mannitol.

Mechanism of action

Pemetrexed is an antifolate containing the pyrrolopyrimidine-based nucleus that exerts its antineoplastic activity by disrupting folate-dependent metabolic processes essential for cell replication. In vitro studies have shown that pemetrexed inhibits thymidylate synthase (TS), dihydrofolate reductase (DHFR), and glycinamide ribonucleotide formyltransferase (GARFT), all folate-dependent enzymes involved in the de novo biosynthesis of thymidine and purine nucleotides. Pemetrexed is transported into cells by both the reduced folate carrier and membrane folate binding protein transport systems. Once in the cell, pemetrexed is converted to polyglutamate forms by the enzyme folylpolyglutamate synthetase. The polyglutamate forms are retained in cells and are inhibitors of TS and GARFT. Polyglutamation is a time- and concentration-dependent process that occurs in tumor cells and, to a lesser extent, in normal tissues. Polyglutamated metabolites have an increased intracellular half-life resulting in prolonged drug action in malignant cells. Pemetrexed is an antifolate containing the pyrrolopyrimidine-based nucleus that exerts its antineoplastic activity by disrupting folate-dependent metabolic processes essential for cell replication. In vitro studies have shown that pemetrexed inhibits thymidylate synthase (TS), dihydrofolate reductase (DHFR), and glycinamide ribonucleotide formyltransferase (GARFT), all folate-dependent enzymes involved in the de novo biosynthesis of thymidine and purine nucleotides. Pemetrexed is transported into cells by both the reduced folate carrier and membrane folate binding protein transport systems. Once in the cell, pemetrexed is converted to polyglutamate forms by the enzyme folyl polyglutamate synthase. The polyglutamate forms are retained in cells and are inhibitors of TS and GARFT. Polyglutamation is a time- and concentration-dependent process that occurs in tumor cells and, to a lesser extent, in normal tissues. Polyglutamated metabolites have an increased intracellular half-life resulting in prolonged drug action in malignant cells. ... Activity of the /pemetrexed/ may be partially preserved under conditions in which cells are highly resistant to other thymidylate synthase inhibitors, possibly because of premetrexed's secondary inhibitory effects on purine synthesis. ... Pemetrexed activity is modulated by natural folates within cells that compete for polyglutamation at the level of folylpolyglutamate synthetase. Cells resistant to methotrexate because of impaired transport via the reduced folate carrier may retain partial sensitivity to pemetrexed. This is due to concurrent diminished transport of physiologic reduced folates and contraction of the cellular folate pool, thereby relaxing the usual level of suppression of pemetrexed polyglutamation. The risk of pemetrexed toxicity is increased when cellular folates are suboptimal.

Pharmacodynamics

Pemetrexed inhibited the in vitro growth of mesothelioma cell lines (MSTO-211H, NCI-H2052) and showed synergistic effects when combined with cisplatin. Based on population pharmacodynamic analyses, the depth of the absolute neutrophil counts (ANC) nadir correlates with systemic exposure to pemetrexed and supplementation with folic acid and vitamin B12. There is no cumulative effect of pemetrexed exposure on ANC nadir over multiple treatment cycles.

Mechanism of action

In cryotherapy, mechanism of action could be classified into three stages: 1. heat transfer, 2. cell injury and 3. inflammation. Boiling point of liquid nitrogen is -196°C, which is the responsible for creating the initial stage which is heat transfer. The second stage is cell injury which is induced during thawing conditions of the cells. The last step in the cryotherapy is the inflammation stage which is characterized by edema and erythema. Inflammation occurs as a result of cellular death and it helps in local cell destruction. ... Nitrogen also has a direct toxic action of its own, affecting brain functions and inducing a stupor or euphoria. Nitrogen narcosis ("rapture of the deep" or "the martini effect") results from a direct toxic effect of high nitrogen pressure on nerve conduction and produces effects similar to alcohol intoxication. Complex reasoning, decision-making ability, motor function, and manual dexerity decrease. Individuals vary in this response widely, but it typically can be noticed among divers at depths exceeding 100 ft (30 m). For example, certain individuals experience no effect at depths of < or = 130 ft, whereas others feel some effect at around 80 ft. Nonetheless, the narcotic effect increases with increasing depth so that each additional 50 ft incrementally produces the effect of "another martini". A simple asphyxiant, nitrogen's main toxicty arises from its ability to displace O2 and generate an atmosphere that does not support the chemical reactions needed for maintenance of life. The displacement of O2 can be complete or incomplete, leading to varying degrees of hypoxia. Nitrogen is an inert substance and does not exert a direct toxicological effect. Nitrogen acts by the physiological effect of simple asphyxia on the target species within a Controlled Atmosphere Treatment (CAT) bubble. The biocide action of nitrogen is due to its displacement of oxygen from an atmospheric oxygen level of 20.8% to levels < 0.2% v/v in the CAT bubble. The level of oxygen is the critical factor. Victims exposed to atmospheres deficient in oxygen, i.e. < 19%, will begin to display signs and symptoms of oxygen-deficient exposure of air due to an increase in nitrogen.