Perobar 5%

Dosage

Children: Refer to established clinical guidelines or resources for appropriate dosing information.

Adults: Refer to established clinical guidelines or resources for appropriate dosing information.

Pregnancy

Information on the use of Beatle during pregnancy is limited. It is advisable to consult healthcare professionals before use.

Breast-feeding

Data on the excretion of Beatle in human milk is not well-studied. Caution is recommended when administering to breastfeeding women.

Storage

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

Indications

• Acne vulgaris
• Comedonal acne
• Inflammatory acne

Dosage

Children: Refer to the BNF for Children for specific dosing recommendations, as pediatric dosing may vary based on age and severity of condition.

Adults: Apply a thin layer to the affected area once or twice daily, gradually increasing frequency as tolerated. Start with once daily application and may increase to twice daily after a week if skin irritation is manageable.

Mechanism of action

The peroxide bond of benzoyl peroxide is cleaved to form two benzoyloxy radicals. These radicals nonspecifically interact with bacterial proteins, disrupting their function and survival. This leads to a reduction in keratin and sebum accumulation around hair follicles. Additionally, benzoyl peroxide enhances the turnover rate of epithelial cells, facilitating skin peeling and helping to break down comedones.

Pharmacodynamics

Benzoyl peroxide acts as a topical agent that generates free radicals to effectively break down comedones and promote epithelial cell turnover. Its action is short-lived, as the active free radical metabolites quickly react to form inactive compounds. The therapeutic index is wide, with rare occurrences of overdose, although skin irritation, dryness, and increased susceptibility to sunburn are common side effects.

Pharmacokinetics

Benzoyl peroxide is applied topically, leading to localized effects with minimal systemic absorption. Its rapid conversion into inactive metabolites limits its duration of action. The compound is metabolized in the skin, and its peak effects are typically observed shortly after application. Due to its formulation and route of administration, the pharmacokinetic profile is characterized by a localized action with reduced risk of systemic side effects.

Adverse effects

• Skin irritation
• Dryness
• Sunburn
• Peeling of skin

Precautions

• Avoid contact with eyes and mucous membranes
• Use with caution in patients with sensitive skin

Pregnancy

Benzoyl peroxide is generally considered safe for use during pregnancy, but it is advisable to consult a healthcare professional before use.

Breast-feeding

Benzoyl peroxide is excreted in breast milk in small amounts. Consult a healthcare professional before use while breastfeeding.

Storage

Store in a cool, dry place away from direct sunlight.

Formulations

• Topical gel
• Topical cream
• Topical lotion

Indications

• Monitoring respiratory function
• Assessment of metabolic status
• Management of respiratory acidosis
• Management of respiratory alkalosis

Dosage

Children: Dosing for interventions related to carbon dioxide levels in pediatric patients should be guided by clinical protocols and the BNF for Children.

Adults: Dosing for interventions related to carbon dioxide levels is typically based on clinical assessment and individual patient needs. Refer to clinical guidelines for specific scenarios.

Mechanism of action

Carbon dioxide acts primarily as a signaling molecule in the body, influencing respiratory drive and blood pH. It is produced during cellular respiration and is a critical component of the bicarbonate buffering system, which helps maintain acid-base homeostasis. Elevated levels of CO2 in the blood stimulate ventilation in the lungs, increasing the rate of gas exchange and facilitating the removal of excess CO2.

Pharmacodynamics

The pharmacodynamic effects of dioxides, particularly carbon dioxide, are closely related to its concentration in the blood. As CO2 levels increase, it leads to respiratory acidosis, which can stimulate the respiratory centers in the brain to increase ventilation. Conversely, low levels of CO2 can cause respiratory alkalosis, potentially leading to decreased respiratory drive. CO2 also plays a role in vasodilation and can affect blood flow and pressure through its influence on smooth muscle tone.

Pharmacokinetics

Carbon dioxide is produced endogenously during metabolic processes and is transported in the bloodstream primarily in three forms: dissolved in plasma, as bicarbonate ions (HCO3-), and bound to hemoglobin. The half-life of CO2 in the bloodstream is very short due to its rapid exchange with alveolar gas in the lungs. The elimination of CO2 occurs through exhalation, making it a dynamic component of respiratory physiology.

Pregnancy

Data on the effects of dioxide during pregnancy are limited. Caution is advised due to potential risks associated with exposure.

Breast-feeding

Limited data are available regarding the excretion of dioxide in human milk. Caution is recommended.

Storage

Store in a cool, dry place, away from direct sunlight and moisture.

Indications

• Dehydration
• Electrolyte imbalance
• Supportive care in various medical conditions

Dosage

Children: Hydration needs in children depend on age, weight, and activity. Refer to specific pediatric guidelines for detailed recommendations on fluid intake.

Adults: Hydration needs vary by individual; general guidance suggests approximately 2-3 liters of water per day for adults, adjusted for activity level, climate, and health status.

Mechanism of action

Hydrous does not have a specific mechanism of action like traditional drugs, as it is a solvent and medium for biochemical reactions. It facilitates various biological processes by dissolving solutes and enabling chemical reactions necessary for life, including metabolic reactions and cellular function.

Pharmacodynamics

As a fundamental component of living organisms, hydrous plays a critical role in maintaining homeostasis. It aids in the absorption and transport of nutrients, regulates body temperature through perspiration, and participates in metabolic reactions. Its presence is crucial for enzyme activity and cellular respiration.

Pharmacokinetics

Hydrous does not undergo metabolism in the traditional sense. Its absorption occurs through the gastrointestinal tract when ingested, and it is distributed throughout the body via the circulatory system. Water is excreted primarily through urine, sweat, and respiration, maintaining a balance through renal function and homeostatic mechanisms.

Pregnancy

Hydrous is not recommended during pregnancy unless clearly needed. Consult a healthcare provider for specific recommendations.

Breast-feeding

Hydrous should be used with caution during breastfeeding. Consult a healthcare provider for specific recommendations.

Storage

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

Indications

• Vision correction
• Phototherapy for skin conditions (e.g., psoriasis, eczema)
• Treatment of seasonal affective disorder (SAD)
• Circadian rhythm disorders
• Wound healing

Dosage

Children: Light therapy for paediatric patients should be approached with caution and always under professional guidance. Specific dosages will depend on the individual treatment protocol and condition being addressed.

Adults: Dosage of light therapy varies based on the condition being treated and should be tailored to individual needs, typically ranging from 15 minutes to 2 hours of exposure per day depending on the specific treatment protocol.

Mechanism of action

Light affects biological systems primarily through phototransduction, which involves the conversion of light into electrical signals within photoreceptor cells in the retina. This process initiates a cascade of biochemical reactions that ultimately lead to visual perception. In addition, specific wavelengths of light can interact with various biological molecules, triggering cellular responses such as the production of vitamin D through skin exposure to UVB radiation.

Pharmacodynamics

The pharmacodynamic effects of light are highly dependent on its wavelength and intensity. Short-wavelength blue light (around 480 nm) is known to influence circadian rhythms by affecting melatonin secretion. In therapeutic settings, light can modulate biological responses, such as promoting wound healing, reducing inflammation, and alleviating symptoms of seasonal affective disorder (SAD) through bright light therapy.

Pharmacokinetics

Light does not undergo traditional pharmacokinetic processes such as absorption, distribution, metabolism, or excretion. Instead, its effects are immediate and localized, depending on the intensity and duration of exposure. The penetration depth of light varies with wavelength; for example, UV light can penetrate the skin and affect deeper tissues, while visible light primarily affects the surface layers.

Pregnancy

There is limited data on the effects of light exposure during pregnancy. However, excessive exposure to bright light can be harmful to both the mother and the developing fetus.

Breast-feeding

Light exposure is generally considered safe while breastfeeding, but excessive exposure should be avoided to prevent potential harm to the infant.

Storage

Light should be properly controlled and managed in environments where it is used, ensuring that exposure levels are safe and effective.

Indications

• Insecticide for agricultural use
• Research tool in toxicology

Dosage

Children: Refer to the BNF for Children for specific dosing and administration guidelines.

Adults: Refer to the BNF for specific dosing and administration guidelines.

Mechanism of action

Methyl parathion acts primarily by inhibiting the enzyme acetylcholinesterase, which is essential for the breakdown of the neurotransmitter acetylcholine. Its active metabolite, methyl paraoxon, is a potent inhibitor of both acetylcholinesterase and butyrylcholinesterase. The inhibition of these enzymes results in the accumulation of acetylcholine at synapses, leading to overstimulation of cholinergic receptors and resultant toxic effects.

Pharmacodynamics

The pharmacodynamics of methyl parathion involve its action as a noncompetitive inhibitor of acetylcholinesterase, causing prolonged effects of acetylcholine due to its inability to be hydrolyzed. The resultant cholinergic toxicity can lead to symptoms such as muscle twitching, respiratory distress, and potentially fatal outcomes if not treated promptly. The extent of inhibition is dose-dependent, with significant toxicity occurring after substantial enzyme inhibition.

Pharmacokinetics

Methyl parathion is absorbed through the gastrointestinal tract and can also be absorbed through the skin and respiratory tract. It is metabolized in the liver to form methyl paraoxon, which is responsible for the majority of its toxic effects. The distribution of methyl parathion in body tissues is influenced by its lipophilicity, and it is primarily excreted as metabolites in the urine. The elimination half-life and specific pharmacokinetic parameters can vary based on individual metabolism and exposure levels.

Pregnancy

There are no adequate and well-controlled studies in pregnant women. Use only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

It is not known whether this drug is excreted in human milk. Caution is advised when administering to nursing women.

Storage

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

Formulations

• Liquid formulation

Indications

• Food preservation
• Antioxidant in pharmaceuticals
• Treatment of certain conditions related to sulfite sensitivity

Dosage

Children: Refer to BNF for Children for appropriate paediatric dosing guidelines.

Adults: Refer to specific formulations and clinical guidelines for appropriate dosing, as it varies based on the condition being treated.

Mechanism of action

Metabisulfite acts primarily as a reducing agent, which means it can donate electrons to other compounds, thereby preventing their oxidation. This property is utilized in food preservation and in various chemical reactions. The compound participates in metabolic pathways such as the thiosulfate oxidation and sulfur oxidation pathways, suggesting its role in sulfur metabolism within certain organisms.

Pharmacodynamics

Metabisulfite's pharmacodynamics involve its role as an antioxidant and a preservative. By preventing the oxidation of sensitive compounds, it helps maintain the stability and efficacy of pharmaceuticals and food products. However, it can also induce allergic reactions in sensitive individuals, particularly in those with asthma.

Pharmacokinetics

Metabisulfite is rapidly absorbed when ingested and is metabolized in the body to sulfate, which is then excreted via the kidneys. Its half-life and specific pharmacokinetic parameters can vary based on the route of administration and individual patient factors.

Indications

• Energy source
• Dietary staple
• Culinary ingredient

Dosage

Children: Noodles do not have a specific dosage for children as they are a food item. Portion sizes should be appropriate for the child's age, appetite, and dietary requirements.

Adults: Noodles do not have a specific dosage as they are a food item. Portion sizes may vary based on individual dietary needs and preferences.

Mechanism of action

Noodles do not have a pharmacological mechanism of action, as they are a food product rather than a drug. However, they provide a source of carbohydrates, which the body breaks down into glucose, supplying energy for cellular functions.

Pharmacodynamics

As a food source, noodles primarily act to provide energy through carbohydrates. The breakdown of starches in noodles leads to the release of glucose into the bloodstream, which is utilized by the body for energy. The glycemic index of noodles can vary depending on the type of flour used and the cooking method, affecting how quickly glucose is absorbed.

Pharmacokinetics

Noodles do not have pharmacokinetic properties in the same way drugs do. However, the digestion and absorption of carbohydrates from noodles occur in the gastrointestinal tract, where enzymes such as amylase break down starches into simpler sugars. Absorption mainly takes place in the small intestine, and the rate of digestion can be influenced by factors such as the composition of the noodle and the presence of other foods.

Pregnancy

Noodles are generally safe to consume during pregnancy, provided they are made from safe ingredients and cooked properly.

Breast-feeding

Noodles can be consumed while breastfeeding, as they do not pose significant risks to breastfeeding infants.

Storage

Store in a cool, dry place, away from direct sunlight and moisture.

Formulations

• wheat noodles
• rice noodles
• egg noodles
• glass noodles

Indications

• Constipation
• Dry skin
• Skin irritation

Dosage

Children: Refer to specific guidelines and prescribing information for paediatric dosing.

Adults: Refer to specific guidelines and prescribing information for adult dosing.

Mechanism of action

Paraffin acts as a lubricating agent in the gastrointestinal tract. It coats the stool and the intestinal walls, which helps to ease the passage of feces by reducing friction. This action promotes bowel movements and alleviates constipation. When used topically, it forms a barrier on the skin, which helps to retain moisture and protect against irritants.

Pharmacodynamics

Paraffin has a low viscosity and surface tension, which allows it to spread easily over surfaces. Its lubricating properties facilitate the movement of stool through the intestines, while its emollient properties help in maintaining skin hydration and barrier function. The onset of action for oral administration typically occurs within 6 to 8 hours, making it effective in treating occasional constipation.

Pharmacokinetics

Paraffin is not absorbed systemically when ingested; it remains in the gastrointestinal tract and is excreted unchanged in the feces. After oral administration, it acts locally in the intestines without significant systemic effects. When used topically, it remains on the skin surface and does not penetrate deeply, providing a protective layer without altering systemic pharmacokinetics.

Adverse effects

• Abdominal cramps
• Diarrhea
• Nausea
• Vomiting
• Lipid pneumonia (when aspirated)
• Electrolyte imbalances

Precautions

• Use with caution in patients with gastrointestinal obstruction
• Avoid in patients with a history of aspiration
• Monitor for signs of dehydration with prolonged use

Pregnancy

Use only if clearly needed. Consult a healthcare provider for advice.

Breast-feeding

Paraffin can be excreted in breast milk, use with caution.

Storage

Store at room temperature away from moisture and heat.

Formulations

• Liquid paraffin
• Soft paraffin (for topical use)

Indications

• Personal fragrance enhancement
• Mood enhancement
• Social interaction
• Cosmetic use

Dosage

Children: Perfume is not typically recommended for use in children due to the potential for skin irritation and allergic reactions. Refer to guidelines for specific products.

Adults: Perfume is applied as desired, typically in small amounts to pulse points such as the wrists, neck, or behind the ears.

Mechanism of action

The mechanism of action of perfume involves the interaction of volatile aromatic compounds with olfactory receptors in the nasal cavity. These receptors send signals to the brain, which interprets the scent, triggering emotional and physiological responses. Perfumes can influence mood, evoke memories, and enhance social interactions by engaging the limbic system, which is involved in emotion and memory.

Pharmacodynamics

Perfume does not have pharmacodynamic effects in the traditional sense as medicinal drugs do. However, certain components may have mild effects on mood and emotional well-being by stimulating the olfactory system. Essential oils present in some perfumes may also have mild antidepressant or relaxing properties, although these effects are not clinically significant.

Pharmacokinetics

Perfume is primarily applied topically to the skin or clothing, where it evaporates and releases fragrance into the air. The compounds in perfume can be absorbed through the skin, but systemic absorption is generally low. The duration and intensity of fragrance depend on the volatility of the components used and their concentration. The scent usually lasts from a few hours to a day, depending on the formulation and individual skin chemistry.

Adverse effects

• Skin irritation
• Allergic reactions
• Headaches
• Respiratory issues
• Nausea

Precautions

• Use with caution in individuals with sensitive skin or allergies
• Avoid direct contact with eyes
• Use in well-ventilated areas to prevent respiratory irritation

Pregnancy

Generally regarded as safe in pregnancy, but some fragrances may cause allergic reactions or sensitivities.

Breast-feeding

Generally considered safe, but individual fragrances should be assessed for potential allergens.

Storage

Store in a cool, dry place away from direct sunlight and heat sources.

Formulations

• Eau de parfum
• Eau de toilette
• Cologne
• Perfume oil
• Body spray

Indications

• Topical antiseptic for minor cuts and abrasions
• Wound cleansing
• Deodorizing agent

Dosage

Children: For paediatric use, hydrogen peroxide can be applied topically as a 3% solution. Consult the BNF for Children for detailed dosing guidance.

Adults: Hydrogen peroxide is typically applied topically as a 3% solution. It can be used to cleanse the affected area one to three times daily. For specific dosing, refer to the BNF.

Mechanism of action

The production of free hydroxyl radicals in the Fenton reaction is thought to be the basis of the biocidal actions of hydrogen peroxide. Free radicals lead to oxidative damage to proteins and membrane lipids in vivo. The release of nascent oxygen upon contact with catalase-containing tissues exerts antibacterial action, while effervescence mechanically loosens tissue debris and pus. Hydrogen peroxide is particularly effective on wounds, denuded areas, and mucous membranes.

Pharmacodynamics

Hydrogen peroxide exhibits antimicrobial properties against a wide range of microorganisms, including resistant forms such as bacterial spores and protozoal cysts. It acts as an oxidative biocide, generating free radicals that induce damage to DNA, proteins, and membrane lipids via oxidation. Its mechanical action of effervescence assists in the removal of tissue debris, which is a crucial aspect of its effectiveness in wound management.

Pharmacokinetics

Hydrogen peroxide's pharmacokinetics are not extensively detailed in the literature, but it is known to have poor tissue and wound penetration. The presence of reactive organic materials, such as pus and blood, diminishes its efficacy. The mechanical action of effervescence is significant in enhancing its antibacterial effects, particularly in contaminated wounds.

Adverse effects

• Skin irritation
• Burning sensation
• Allergic reactions

Precautions

• Avoid contact with eyes and mucous membranes
• Use with caution in patients with a history of hypersensitivity
• Do not apply to deep or puncture wounds

Pregnancy

Hydrogen peroxide should be used in pregnancy only if the potential benefit justifies the potential risk to the fetus. Consult a healthcare provider before use.

Breast-feeding

Caution is advised when using hydrogen peroxide while breastfeeding. Consult a healthcare provider for guidance.

Storage

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

Formulations

• Topical solution
• Ointment

Dosage

Children: Refer to specific drug formulations and product labels as purified substances can vary widely in their use and dosing.

Adults: Refer to specific drug formulations and product labels as purified substances can vary widely in their use and dosing.

Mechanism of action

The mechanism of action for purified compounds varies widely depending on the specific substance. Generally, purified drugs exert their effects by interacting with specific biological targets, such as receptors, enzymes, or ion channels, leading to a desired therapeutic effect. This interaction can involve binding to receptors to activate or inhibit signaling pathways, modulating enzymatic activity, or altering physiological processes.

Pharmacodynamics

Pharmacodynamics describes the effects of a drug on the body and the relationship between drug concentration and effect. For purified drugs, this can involve dose-response relationships and the time course of their action. The purified form often enhances potency and reduces variability in response among patients, which can lead to more predictable therapeutic outcomes. The overall effect is determined by the drug's affinity for its target, the efficacy of the drug-receptor interaction, and the downstream signaling pathways activated as a result of this interaction.

Pharmacokinetics

Pharmacokinetics involves the absorption, distribution, metabolism, and excretion (ADME) of a drug. For purified substances, absorption can be more efficient due to the absence of impurities that may affect solubility or stability. Distribution may also be enhanced, leading to higher bioavailability. Metabolism can be influenced by the structure of the purified compound, as it may be metabolized more readily by liver enzymes. Excretion typically occurs through the kidneys or liver, depending on the molecular characteristics of the purified drug.

Pregnancy

Consult with a healthcare professional, as the safety of purified forms of medications during pregnancy may vary depending on the specific substance.

Breast-feeding

Consult with a healthcare professional, as the safety of purified forms of medications during breastfeeding may vary depending on the specific substance.

Storage

Store in a cool, dry place, away from light and moisture, and keep out of reach of children.

Indications

• General hand hygiene
• Personal cleanliness
• Infection control and prevention
• Preparation for surgical procedures

Dosage

Children: For children, wet hands, apply a small amount of soap, lather while singing a song for at least 20 seconds, and rinse thoroughly with water. Adjust the quantity based on the child's age and hand size.

Adults: For hand hygiene, wet hands, apply a sufficient amount of soap, lather for at least 20 seconds, and rinse thoroughly with water.

Mechanism of action

Soap operates primarily through the mechanism of emulsification. The amphiphilic structure of soap molecules allows them to interact with both water and oil. The hydrophobic tails of soap molecules attach to grease and dirt, while the hydrophilic heads remain in the aqueous environment, allowing the dirt to be washed away with water.

Pharmacodynamics

Soap does not have pharmacodynamic effects in the conventional sense as it is not absorbed into the body for systemic action. Instead, its effectiveness is based on its ability to disrupt the lipid membranes of microorganisms, leading to cell lysis and removal of pathogens from the skin surface during washing.

Pharmacokinetics

Soap is not absorbed systemically; therefore, pharmacokinetic parameters such as absorption, distribution, metabolism, and excretion do not apply. Its action is localized to the skin and surfaces where it is applied, facilitating the physical removal of contaminants through rinsing with water.

Pregnancy

Soap is generally considered safe for use during pregnancy. It is important to choose gentle, non-irritating formulations to avoid skin sensitivity.

Breast-feeding

Soap is safe for use while breastfeeding. Care should be taken to use mild products that do not irritate the skin, especially around the breast area.

Storage

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

Formulations

• Bar soap
• Liquid soap
• Foam soap
• Antibacterial soap
• Moisturizing soap

Indications

• Orthopedic implants
• Dental implants
• Prosthetic devices
• Surgical instruments

Mechanism of action

Titanium does not have a specific mechanism of action as it is not a drug in the traditional sense. Instead, its biocompatibility allows it to integrate with biological tissues without eliciting significant immune responses, making it suitable for use in implants and prosthetic devices. The presence of titanium ions can influence biological processes, including cell proliferation and differentiation.

Pharmacodynamics

Titanium itself does not exhibit pharmacodynamics as it is not administered as a drug. Its interactions within biological systems are primarily mechanical and structural, providing support and stability in orthopedic and dental applications. The biocompatibility of titanium allows for favorable tissue integration and reduced rejection rates compared to other materials.

Pharmacokinetics

As titanium is not a pharmacological agent, traditional pharmacokinetic parameters such as absorption, distribution, metabolism, and excretion do not apply. Titanium is typically utilized in solid forms, such as implants, where it remains localized and does not undergo metabolism or systemic circulation.

Pregnancy

There is limited data on the use of titanium during pregnancy. Consult a healthcare professional before use.

Breast-feeding

There is limited data on the excretion of titanium in breast milk. Consult a healthcare professional before use.

Storage

Store in a cool, dry place away from direct sunlight.

Mechanism of action

Acne vulgaris is caused by inflammation in the pilosebaceous gland. Acne is generally caused by increased excretion of sebum from pilosebaceous glands, endocrine factors such as androgenic hormones, keratin developing around follicles, bacterial growth, and inflammation. These factors contribute to the formation of comedones (whiteheads and blackheads). The peroxide bond of benzoyl peroxide is cleaved to form 2 benzoyloxy radicals. These radicals interact nonspecifically with bacterial proteins, interfering with their function, and survival of the bacteria. Over time, free radical interactions with bacterial proteins lead to decreased keratin and sebum around follicles. Benzoyl peroxide can also increase the turnover rate of epithelial cells, leading to skin peeling, and breaking down comedones.

Pharmacodynamics

Benzoyl peroxide is a topical treatment for acne that generates free radicals to break down comedones and increase the rate of epithelial cell turnover. It has a short duration of action as its active free radical metabolites quickly react to form inactive metabolites. The therapeutic index is wide, as overdoses are rare, however patients may still experience skin peeling. Patients should be counselled regarding increased risks of skin irritation, dryness, and sunburn.

Mechanism of action

Acute poisoning ... is related to ... inhibiting action on enzyme acetylcholinesterase. Toxic manifestations generally occur only after more than 50% of plasma cholinesterase is inhibited. ... Methyl parathion ... depend on oxidative activation by replacement of thiono-sulfur with oxygen for ... toxicity. Methyl parathion has only a slight inhibitory action on acetylcholinesterase and butyrylcholinesterase, but its active metabolite, methyl paraoxon, is a potent inhibitor of both these enzymes. A study was conducted examining the inhibition of (Ca2+ and Mg2+)-ATPase by parathion (56382) and methyl parathion. Enzyme activity was assessed spectrophotometrically in pig erythrocyte membranes containing calcium2+ (Ca2+) and magnesium2+ and in solubilized membrane preparations incubated with the test agents. The enzyme response to ATP was biphasic. Equations expressing the kinetics of the substrate curves described two classes of the ATP binding active site, one with high affinity and low maximum rate and one with low affinity and high maximum rate. High affinity active sites were stimulated by low ATP concentrations (20 uM), whereas low affinity active sites were stimulated by high ATP levels (2 mM). Parathion and methylparathion dose dependently inhibited enzyme activity; parathion had a greater inhibitory effect than methylparathion. Lineweaver-Burke and Dixon plots indicated noncompetitive inhibition. Parathion and methylparathion induced enzyme inhibition occurred over a range of free calcium ion concentrations (0.5 to 5 mM); the inhibition was significantly greater at lower Ca2+ concentrations (1 to 100 uM) than at higher concentrations. The authors conclude that parathion and methylparathion inhibit ATPase activity by binding to a site on the enzyme rather than through an interaction with associated lipids. For more Mechanism of Action (Complete) data for METHYL PARATHION (6 total), please visit the HSDB record page.

Mechanism of action

The production of free hydroxyl radicals in the Fenton reaction is thought to be the basis of biocidal actions of hydrogen peroxide. Free radicals eventually lead to oxidative damage proteins and membrane lipids _in vivo_. The oxidizing radical as the ferryl radical induces DNA oxidation. Hydrogen peroxide topical solution is a weak antibacterial agent, a wound cleanser, and a deodorant. The pharmacologic activity of the drug depends on the release of nascent oxygen which has a powerful oxidizing effect that destroys some microorganisms and chemically alters many organic substances. When hydrogen peroxide topical solution comes in contact with tissues that contain the enzyme catalase, the solution releases oxygen which exerts antibacterial action; the mechanical effect of effervescence loosens tissue debris and pus. The release of nascent oxygen and effervescence is more rapid on wounds, denuded areas, and mucous membranes than on unbroken skin. The presence of reactive organic material such as pus and blood diminishes the efficiency of hydrogen peroxide. The antibacterial activity of hydrogen peroxide is relatively weak and slow and the drug exhibits poor tissue and wound penetration. Hydrogen peroxide's mechanical effect of effervescence and resultant removal of tissue debris is probably a more effective means of reducing the bacterial content of wounds, denuded areas, and mucous membranes than actual antibacterial activity. The drug also appears to have a styptic effect when applied topically to minor wounds. Concentrated solutions of hydrogen peroxide have a bleaching effect on hair and may injure tissue. Increases in the levels of reactive oxygen species (ROS) are correlated with a decrease in calcineurin (CN) activity under oxidative or neuropathological conditions. However, the molecular mechanism underlying this ROS-mediated CN inactivation remains unclear. Here, we describe a mechanism for the inactivation of CN by hydrogen peroxide. The treatment of mouse primary cortical neuron cells with Abeta(1-42) peptide and hydrogen peroxide triggered the proteolytic cleavage of CN and decreased its enzymatic activity. In addition, hydrogen peroxide was found to cleave CN in different types of cells. Calcium influx was not involved in CN inactivation during hydrogen peroxide-mediated cleavage, but CN cleavage was partially blocked by chloroquine, indicating that an unidentified lysosomal protease is probably involved in its hydrogen peroxide-mediated cleavage. Treatment with hydrogen peroxide triggered CN cleavage at a specific sequence within its catalytic domain, and the cleaved form of CN had no enzymatic ability to dephosphorylate nuclear factor in activated T cells. Thus, our findings suggest a molecular mechanism by which hydrogen peroxide inactivates CN by proteolysis in ROS-related diseases. Matrix metalloproteinase-2 (MMP-2) is well known to proteolyse both extracellular and intracellular proteins. Reactive oxygen species activate MMP-2 at both transcriptional and post-translational levels, thus MMP-2 activation is considered an early event in oxidative stress injury. Although hydrogen peroxide is widely used to trigger oxidative stress-induced cell death, the type of cell death (apoptosis vs. necrosis) in cardiomyocytes is still controversial depending on the concentration used and the exposure time. We ... investigated the mode of cell death in neonatal rat cardiomyocytes induced by different concentrations (50-500 uM) of hydrogen peroxide at various time intervals after exposure and determined whether MMP-2 is implicated in hydrogen peroxide-induced cardiomyocyte death. Treating cardiomyocytes with hydrogen peroxide led to elevated MMP-2 level/activity with maximal effects seen at 200 uM. Hydrogen peroxide caused necrotic cell death by disrupting the plasmalemma as evidenced by the release of lactate dehydrogenase in a concentration- and time-dependent manner as well as the necrotic cleavage of PARP-1. The absence o

Pharmacodynamics

Hydrogen peroxide exhibits antimicrobial properties against most forms of microorganisms, including dormant forms with known high resistance profiles, such as bacterial spores and protozoal cysts. It acts as an oxidative biocide to generate free radical species to induce DNA, protein and membrane lipid damage via oxidation.