CANDIZOLE CREAM

Indications

• Vaginal candidiasis
• Oropharyngeal candidiasis
• Vulvovaginal infections
• Superficial fungal infections

Dosage

Adults: For vaginal candidiasis, miconazole cream is typically applied twice daily, using 5 g inserted into the vagina for 7 days. For oropharyngeal candidiasis, the oral gel is usually administered as 2.5 mL four times a day.

Mechanism of action

Miconazole primarily acts through the inhibition of the CYP450 14α-lanosterol demethylase enzyme, leading to disrupted ergosterol production in fungal cell membranes. This disruption results in increased cell membrane permeability and leakage of essential cellular constituents. Additionally, miconazole inhibits fungal peroxidase and catalase, increasing the production of reactive oxygen species (ROS) which contribute to fungal cell death. Miconazole also elevates intracellular levels of farnesol, which disrupts quorum sensing in Candida, preventing the transition to more virulent forms.

Pharmacodynamics

Miconazole is predominantly applied topically, leading to minimal systemic absorption. Its primary adverse reactions are usually localized to hypersensitivity reactions, with the potential for anaphylaxis in rare cases. Patients using intravaginal miconazole are advised to avoid reliance on other contraceptive methods and not to use tampons simultaneously due to the risk of altered vaginal flora.

Pharmacokinetics

Miconazole is poorly absorbed when applied topically or intravaginally, resulting in low systemic exposure. The pharmacokinetics of miconazole can vary based on the route of administration, but systemic absorption is generally low, thus limiting systemic side effects and interactions. Miconazole is extensively metabolized in the liver, and its metabolites are excreted primarily through the urine.

Contra-indications

• Hypersensitivity to miconazole or any of its excipients
• Recent arterial thromboembolic disease (e.g. angina, myocardial infarction)
• Undiagnosed vaginal bleeding
• Oestrogen-dependent tumors (e.g. breast cancer in first-degree relatives)
• Acute porphyrias
• Severe diabetes (increased risk of heart disease)

Adverse effects

• Dysmenorrhoea
• Skin reactions
• Increased risk of gallbladder disease
• Migraine or migraine-like headaches
• Abdominal pain
• Dysuria
• Nausea
• Pelvic cramps
• Vaginal hemorrhage
• Angioedema

Interactions

• Miconazole + antihistamines (non-sedating): Severe (increases exposure)
• Miconazole + mizolastine: Severe (increases exposure)
• Miconazole + oral benzodiazepines: Severe (increases exposure)
• Miconazole + ergometrine: Severe (increases exposure)
• Miconazole + ergotamine: Severe (increases exposure)
• Miconazole + alkylating agents: Moderate (increases concentration)
• Miconazole + busulfan: Moderate (increases concentration)
• Miconazole + antiarrhythmics: Moderate (increases exposure)
• Miconazole + disopyramide: Moderate (increases exposure)
• Miconazole + benzodiazepines: Moderate (increases exposure)

Precautions

• Caution in patients with history of breast cancer
• Monitor breast status regularly in women on oestrogen therapy
• Risk of endometrial cancer with prolonged use of oestrogens
• Risk of ovarian cancer with long-term use of combined HRT
• Increased risk of venous thromboembolism in women using combined or oestrogen-only HRT

Pregnancy

Pregnant women may require a longer duration of treatment, usually about 7 days, to clear the infection. Caution is advised.

Breast-feeding

Manufacturer advises caution; no specific information available.

Indications

• Skin disinfection
• Preparation of skin before injections
• Cleansing minor wounds

Dosage

Children: Apply to the skin as required; consult product literature for specific guidance.

Adults: Apply to the skin as required for disinfection.

Mechanism of action

Alcohol exerts its antiseptic effect by denaturing proteins, disrupting cell membranes, and dehydrating microbial cells, leading to cell lysis and death.

Pharmacodynamics

Alcohol has broad-spectrum antimicrobial activity, effective against bacteria, fungi, and viruses. Its efficacy is influenced by concentration, with higher concentrations generally being more effective.

Pharmacokinetics

Alcohol is rapidly absorbed through the skin and mucous membranes. It is metabolized primarily in the liver, with a half-life that varies based on the individual's metabolic rate and the amount consumed.

Contra-indications

• Concomitant use with lithium
• Regular use in neonates
• Patients with severe burns when diathermy has been preceded by application of alcoholic skin disinfectants

Adverse effects

• Eye erythema
• Punctate keratitis
• Cytotoxicity
• Eye discolouration

Interactions

• Increases risk of visual disturbances with antiepileptics
• Increases concentration with methylphenidate
• Increases risk of facial flushing and skin irritation with topical pimecrolimus
• Increases concentration with retinoids
• Increases concentration with acitretin
• Increases risk of facial flushing and skin irritation with topical tacrolimus
• Decreases antidiuretic effect with vasopressin

Precautions

• Avoid regular application to inflamed or broken skin or mucosa
• Avoid broken skin
• Flammable

Pregnancy

Sufficient iodine may be absorbed to affect the fetal thyroid in the second and third trimester.

Breast-feeding

Avoid regular or excessive use.

Storage

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

Formulations

• Betadine 2.5% dry powder spray
• Industrial methylated spirit
• Povidone-Iodine 25 mg per 1 gram

Indications

• Bacterial infections
• Pneumonia
• Meningitis
• Syphilis
• Endocarditis
• Skin and soft tissue infections

Dosage

Children: Paediatric dosing for benzylpenicillin is determined by the child's weight and the severity of the infection. Refer to the BNF for Children for specific dosing guidelines.

Adults: The usual adult dose for benzylpenicillin varies based on the type and severity of the infection. It is generally administered via intramuscular or intravenous routes. For severe infections, doses may range from 1 to 4 million units every 4 to 6 hours.

Mechanism of action

Benzylpenicillin exerts its antibacterial effects by inhibiting the synthesis of bacterial cell walls. It binds to penicillin-binding proteins (PBPs) located inside the bacterial cell wall, disrupting the transpeptidation process, which is crucial for cross-linking peptidoglycan layers. This inhibition leads to cell lysis and death of the bacteria.

Pharmacodynamics

Benzylpenicillin demonstrates time-dependent bactericidal activity, meaning its effectiveness is related to the duration of time the drug concentration remains above the minimum inhibitory concentration (MIC) for the target bacteria. It has a narrow spectrum of activity, primarily targeting Gram-positive cocci and some Gram-negative rods.

Pharmacokinetics

Benzylpenicillin is typically administered parenterally due to poor oral absorption. It is rapidly distributed throughout the body and can penetrate various tissues, including the central nervous system during inflammation. The drug is primarily eliminated by renal excretion, with a half-life of approximately 30 minutes to 1 hour in healthy individuals. Dosage adjustments may be necessary in patients with renal impairment.

Interactions

• leflunomide+benzylpenicillin: Unknown (increases exposure)
• nitisinone+benzylpenicillin: Unknown (increases exposure)
• teriflunomide+benzylpenicillin: Unknown (increases exposure)

Pregnancy

Benzylpenicillin is generally considered safe to use during pregnancy, as it is a penicillin antibiotic and has a long history of use.

Breast-feeding

Benzylpenicillin is excreted in breast milk in small amounts, but it is not expected to have adverse effects on a nursing infant.

Storage

Store in a cool, dry place, protected from light. Reconstituted solutions should be used promptly or stored in a refrigerator and used within a limited time frame.

Formulations

• Benzylpenicillin injection

Indications

• Dry skin conditions
• Atopic dermatitis
• Psoriasis
• Eczema
• Skin hydration enhancement

Dosage

Children: Refer to the BNF for Children for specific dosing recommendations based on age and condition.

Adults: Refer to the specific product monograph, as dosing may vary based on formulation and condition being treated.

Mechanism of action

Cetomacrogol acts as a surfactant, reducing the surface tension between different substances. This property facilitates the formation of emulsions and enhances the solubility of hydrophobic substances in aqueous solutions. By providing a barrier on the skin, it helps to prevent transepidermal water loss, thereby maintaining skin hydration.

Pharmacodynamics

The pharmacodynamic properties of cetomacrogol are characterized by its ability to improve the consistency and stability of emulsions, allowing for better delivery of topical agents. Its moisturizing effects help to alleviate symptoms associated with dry skin conditions, such as scaling, itching, and cracking.

Pharmacokinetics

Cetomacrogol is not systemically absorbed when applied topically, as it primarily acts at the site of application. Its pharmacokinetic profile is characterized by local action with minimal risk of systemic effects. Due to its emulsifying properties, it enhances the penetration of active ingredients in topical formulations without significant metabolic transformation.

Pregnancy

There are no known adverse effects in pregnancy. However, it is advisable to use only when clearly needed.

Breast-feeding

Cetomacrogol is generally considered safe to use during breastfeeding, but consult a healthcare professional before use.

Storage

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

Formulations

• Cream
• Ointment
• Emulsion

Indications

• Emulsifier in creams and lotions
• Stabilizer in pharmaceutical formulations
• Moisturizer in topical products
• Fat source in oral supplements

Dosage

Children: Dosage for pediatric populations should be determined based on formulation and specific product guidelines, refer to appropriate resources.

Adults: Dosage of cetosteryl varies depending on the formulation and intended use. Refer to specific product guidelines for appropriate dosing.

Mechanism of action

Cetosteryl acts as a surfactant, reducing the surface tension between different phases in emulsion formulations. This action allows for the effective mixing of water and oil components, promoting the stability and uniformity of the product. The fatty alcohols in cetosteryl also contribute to skin barrier repair and moisturization by forming a protective layer on the skin.

Pharmacodynamics

As an emulsifier, cetosteryl facilitates the formation and stabilization of emulsions, allowing for the effective delivery of active ingredients in topical products. It has hydrophilic and lipophilic properties, which help in the dispersion of active molecules and improve the overall texture of formulations. Its moisturizing effect can help to enhance skin hydration and barrier function.

Pharmacokinetics

The pharmacokinetics of cetosteryl, particularly its absorption, distribution, metabolism, and excretion, are not well characterized due to its primary use in topical applications. When used in topical formulations, it acts locally and is not expected to produce systemic effects. Ingestion of cetosteryl may lead to gastrointestinal absorption, but specific pharmacokinetic data are limited.

Contra-indications

• Hypersensitivity to cetosteryl or any of its components
• Severe renal impairment
• Severe liver impairment

Adverse effects

• Gastrointestinal disturbances such as nausea and diarrhea
• Skin reactions including rash and pruritus
• Headache
• Fatigue
• Dizziness

Interactions

• May interact with other lipid-lowering agents, increasing the risk of adverse effects
• Potential interaction with anticoagulants, requiring monitoring

Precautions

• Use with caution in patients with a history of liver disease
• Monitor lipid levels regularly during treatment
• Assess for possible allergies or sensitivities

Pregnancy

Data on the use of cetosteryl during pregnancy is limited. It should be used only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

Caution is advised when cetosteryl is used during breastfeeding due to lack of sufficient data.

Storage

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

Formulations

• Cetosteryl alcohol and cetostearyl ether in topical creams and emulsions
• Oral formulations may also exist in various dosages

Indications

• Solvent in pharmaceutical formulations
• Moisturizer and humectant in topical applications
• Potential use in the management of drug solubility issues

Dosage

Children: Refer to specific formulations and clinical guidelines, as dosing varies widely based on the application and formulation.

Adults: Refer to specific formulations and clinical guidelines, as dosing varies widely based on the application and formulation.

Mechanism of action

Glycols, particularly propylene glycol, act as humectants, which help to retain moisture in formulations. They can also enhance the solubility of drugs, aiding in their absorption when used as excipients. Propylene glycol is metabolized in the liver to lactate and subsequently to glucose, providing a source of energy when utilized in metabolic pathways.

Pharmacodynamics

The pharmacodynamics of glycols involve their ability to modulate the viscosity of solutions and enhance the solubility of other compounds. Propylene glycol can also facilitate the absorption of other drugs when used in formulations. It exhibits a low toxicity profile when used appropriately, but excessive systemic exposure can lead to metabolic acidosis and other adverse effects.

Pharmacokinetics

Glycols are rapidly absorbed when administered intravenously or orally. Propylene glycol is metabolized primarily in the liver, with a half-life varying based on the dose and individual metabolism. Renal excretion plays a role in the elimination of metabolites. Accumulation can occur in individuals with impaired liver or kidney function, necessitating careful monitoring of dosing in such populations.

Pregnancy

The safety of glycol in pregnancy is not well established. Consult healthcare professionals before use.

Breast-feeding

Glycol's effects during breastfeeding are not well characterized. Caution is advised.

Storage

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

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

• Used as an emulsifying agent in pharmaceutical formulations
• Used in food products for texture and stability
• May be indicated in topical preparations to enhance drug absorption

Dosage

Children: Refer to specific product guidelines as doses can vary widely based on formulation and intended use.

Adults: Refer to specific product guidelines as doses can vary widely based on formulation and intended use.

Mechanism of action

Monostearate functions primarily as a surfactant. It reduces the surface tension between components in a mixture, allowing for better emulsification of oils and water. This action enhances the dispersion of active ingredients and improves their absorption in the gastrointestinal tract.

Pharmacodynamics

As an emulsifier, monostearate facilitates the formation of stable emulsions, which can lead to improved drug delivery and absorption. Its ability to enhance solubility of lipophilic compounds can result in increased bioavailability of certain drugs, making them more effective.

Pharmacokinetics

Monostearate is generally considered non-toxic and is metabolized by the body through hydrolysis into glycerol and stearic acid. It is poorly absorbed in the gastrointestinal tract due to its large molecular structure, and any absorbed amounts may be further metabolized or excreted. The onset and duration of action depend on the formulation in which it is used.

Pregnancy

Monostearate is generally considered safe for use during pregnancy, but it is important to consult with a healthcare provider for personalized advice.

Breast-feeding

Monostearate is typically regarded as safe during breastfeeding, but a healthcare provider should be consulted to ensure no adverse effects on the infant.

Storage

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

Formulations

• Monostearate powder
• Monostearate capsules
• Monostearate ointment

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

• Plant growth regulation
• Agricultural applications as a growth inhibitor

Dosage

Children: Not applicable.

Adults: Refer to the relevant agricultural guidelines for specific applications.

Mechanism of action

In an in vitro study, propylene acts as a plant growth inhibitor by inhibiting the oxidation of indole-3-acetic acid by peroxidase in the presence of superoxide anion radicals. This inhibition is linked to the activation of an iron complex (compound III) shuttle, which enhances the reaction rate between superoxide and peroxidase, ultimately affecting plant growth processes. Propylene is a less effective inhibitor compared to ethylene.

Pharmacodynamics

The pharmacodynamic effects of propylene are primarily observed in its role as a growth inhibitor in plants. By modulating the oxidation of phytohormones like indole-3-acetic acid, propylene can influence various growth responses in plants, potentially affecting processes such as cell elongation and division.

Pharmacokinetics

Information on the pharmacokinetics of propylene in humans is not well-documented, as its primary uses are industrial and agricultural. Its metabolism may be influenced by environmental factors, and its effects are primarily studied in the context of plant biology rather than human pharmacology.

Dosage

Children: Refer to specific product information for dosing guidelines.

Adults: Refer to specific product information for dosing guidelines.

Pregnancy

Consult a healthcare professional before use. The effects of Soft during pregnancy are not well-documented.

Breast-feeding

Consult a healthcare professional before use. The safety of Soft during breastfeeding is not well-established.

Storage

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

Indications

• Emulsifying agent in topical formulations
• Stabilizing agent in oral drug formulations
• Food industry applications as an emulsifier
• Cosmetic formulations

Dosage

Children: Refer to specific formulation guidelines for dosage recommendations.

Adults: Refer to specific formulation guidelines for dosage recommendations.

Mechanism of action

Sorbitan acts primarily as a surfactant and emulsifier. Its amphiphilic nature allows it to reduce the surface tension between oil and water, thereby facilitating the formation and stabilization of emulsions. The hydrophilic part of the sorbitan molecule interacts with water, while the lipophilic part interacts with oils, promoting the mixing of immiscible liquids.

Pharmacodynamics

As an emulsifier, sorbitan enhances the bioavailability of lipophilic drugs by aiding their dispersion in aqueous environments. This property is particularly valuable in formulations where uniform distribution of active ingredients is critical for efficacy. Sorbitan may also impact the release profiles of drugs from emulsified formulations, potentially affecting the onset of action.

Pharmacokinetics

Sorbitan is generally considered to be poorly absorbed when administered orally, leading to minimal systemic exposure. Its primary role is local, serving as an excipient in formulations rather than as an active therapeutic agent. Due to its emulsifying properties, it may enhance the solubility and absorption of other drugs in the gastrointestinal tract, but the absorption characteristics of sorbitan itself are limited. Metabolism and excretion details specific to sorbitan are not well-documented, as it typically functions in a non-systemic capacity.

Pregnancy

Sorbitan has not been well studied in pregnant women. Use during pregnancy should be based on a risk-benefit assessment.

Breast-feeding

Sorbitan is generally considered safe during breastfeeding, however, there is limited data available.

Storage

Store at room temperature, away from moisture and heat. Keep container tightly closed.

Formulations

• Sorbitan monooleate
• Sorbitan monostearate
• Sorbitan tristearate

Dosage

Children: Refer to the BNF for Children for appropriate paediatric dosing information.

Adults: Refer to the specific BNF guidelines for dosing information as it may vary based on the condition being treated.

Mechanism of action

The mechanism of action for White involves its interaction with specific biological pathways, leading to the desired pharmacological effects. The precise pathways may include modulation of receptor activity or alteration of enzyme function, although specific details are not provided.

Pharmacodynamics

Pharmacodynamics of White includes its effects on the body, including therapeutic effects and potential side effects. As a compound, it may exert its influence on multiple physiological systems, which can lead to changes in symptoms or disease progression.

Pharmacokinetics

Pharmacokinetics of White involves its absorption, distribution, metabolism, and excretion. Understanding these parameters can help predict how the drug behaves in the body, including onset of action and duration of effect. Detailed pharmacokinetic data is not specified.

Mechanism of action

Ethanol affects the brain’s neurons in several ways. It alters their membranes as well as their ion channels, enzymes, and receptors. Alcohol also binds directly to the receptors for acetylcholine, serotonin, GABA, and the NMDA receptors for glutamate. The sedative effects of ethanol are mediated through binding to GABA receptors and glycine receptors (alpha 1 and alpha 2 subunits). It also inhibits NMDA receptor functioning. In its role as an anti-infective, ethanol acts as an osmolyte or dehydrating agent that disrupts the osmotic balance across cell membranes. ... Ethanol is known to affect a large number of membrane proteins that participate in signaling pathways such as neurotransmitter receptors, enzymes, and ion channels, and there is extensive evidence that ethanol interacts with a variety of neurotransmitters. The major actions of ethanol involve enhancing the inhibitory effects of gamma-aminobutyric acid (GABA) at GABAa receptors and blockade of the N-methyl-D-aspartate (NMDA) subtype of glutamate, an excitatory amine acid (EAA) receptor. Animal studies indicate that the acute effects of ethanol result from competitive inhibition of glycine binding to NMDA receptor and disruption of glutamatergic neurotransmission by inhibiting the response of the NMDA receptor. Persistent glycine antagonism and attenuation of glutamatergic neurotransmission by chronic ethanol exposure results in tolerance to ethanol by enhancing EAA neurotransmission and NMDA receptor upregulation. The latter appears to involve selective increases in NMDA R2B subunit concentrations and other molecular changes in specific brain loci. The abrupt withdrawal of ethanol thus produces a hyperexcitable state that leads to the ethanol withdrawal syndrome and excitotoxic neuronal death. GABA-mediated inhibition, which normally acts to limit excitation, is eliminated during ethanol withdrawal syndrome and further intensifies this excitation. In addition, NMDA receptors function to inhibit the release of dopamine in the nucleus accumbens and mesolimbic structures, which modulate the reinforcing action of addictive xenobiotics such as ethanol. By inhibiting NMDA receptor activity, ethanol could increase dopamine release from the nucleus accumbens and ventral tegmental area and could thus create dependence. Chronic ethanol administration also results in tolerance, dependence, and an ethanol withdrawal syndrome, mediated, in part, by desensitization and or downregulation of GABAa receptors. The development of alcoholic ketoacidosis (AKA) requires that a combination of physical and physiologic events occur. The normal response to starvation and depletion of hepatic glycogen stores is for amino acids to be converted to pyruvate. Pyruvate can serve as a substrate for gluconeogenesis, be converted to acetyl-CoA, which can enter the Krebs cycle or can be utilized in various biosynthetic pathways (eg, fatty acid, ketone bodies, cholesterol, and acetylcholine) ... Ethanol metabolism generates NADH, resulting in an excess of reducing potential. This high redox state favors the conversion of pyruvate to lactate, diverting pyruvate from being a substrate for gluconeogenesis. To compensate for the lack of normal metabolic substrates, the body mobilizes fat from adipose tissue and increased fatty acid metabolism as an alternative source of energy. This response is mediated by a decrease in insulin and an increased secretion of glucagon, catecholamines, growth hormone, and cortisol. Fatty acid metabolism results in the formation of acetyl-CoA and it combines with the excess acetate that is generated from ethanol metabolism to form acetoacetate. Most of the acetoacetate is reduced to beta-hydroxybutyrate due to the excess reducing potential or high redox state of the cell. Volume depletion interferes with the renal elimination of acetoacetate and beta-hydroxybutyrate, and contributes to the acidosis. An elevated lactate concentration may result from shunting from pyruvate or

Pharmacodynamics

Alcohol produces injury to cells by dehydration and precipitation of the cytoplasm or protoplasm. This accounts for its bacteriocidal and antifungal action. When alcohol is injected in close proximity to nerve tissues, it produces neuritis and nerve degeneration (neurolysis). Ninety to 98% of ethanol that enters the body is completely oxidized. Ethanol is also used as a cosolvent to dissolve many insoluble drugs and to serve as a mild sedative in some medicinal formulations. Ethanol also binds to GABA, glycine, NMDA receptors and modulates their effects. Ethanol is also metabolised by the hepatic enzyme alcohol dehydrogenase.

Mechanism of action

Miconazole is an azole antifungal used to treat a variety of conditions, including those caused by _Candida_ overgrowth. Unique among the azoles, miconazole is thought to act through three main mechanisms. The primary mechanism of action is through inhibition of the CYP450 14α-lanosterol demethylase enzyme, which results in altered ergosterol production and impaired cell membrane composition and permeability, which in turn leads to cation, phosphate, and low molecular weight protein leakage. In addition, miconazole inhibits fungal peroxidase and catalase while not affecting NADH oxidase activity, leading to increased production of reactive oxygen species (ROS). Increased intracellular ROS leads to downstream pleiotropic effects and eventual apoptosis. Lastly, likely as a result of lanosterol demethylation inhibition, miconazole causes a rise in intracellular levels of farnesol. This molecule participates in quorum sensing in _Candida_, preventing the transition from yeast to mycelial forms and thereby the formation of biofilms, which are more resistant to antibiotics. In addition, farnesol is an inhibitor of drug efflux ABC transporters, namely _Candida_ CaCdr1p and CaCdr2p, which may additionally contribute to increased effectiveness of azole drugs.

Pharmacodynamics

Miconazole is an azole antifungal that functions primarily through inhibition of a specific demethylase within the CYP450 complex. As miconazole is typically applied topically and is minimally absorbed into the systemic circulation following application, the majority of patient reactions are limited to hypersensitivity and cases of anaphylaxis. Patients using intravaginal miconazole products are advised not to rely on contraceptives to prevent pregnancy and sexually transmitted infections, as well as not to use tampons concurrently.

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

In an in vitro study of the mechanism of action of ethylene as a plant growth inhibitor, the effects of ethylene and some of its analogs, including propylene, on the oxidation of indole-3-acetic acid were examined. Ethylene and its analogs inhibited the oxidation of indole-3-acetic acid by peroxidase under conditions where the iron complex (compound III, an oxy-ferrous complex of peroxidase) shuttle was activated. Inhibition occurred only in the presence of the superoxide anion radical 02(-). Spectral and kinetic data indicated that ethylene and its analogs enhanced the rate of reaction of 02(-) with peroxidase; ie, the iron complex (compound III) shuttle, resulting in the formation of compound III. Propylene was a less effective inhibitor than ethylene.