Levoz

Indications

• Bacterial infections
• Acute exacerbation of chronic obstructive pulmonary disease
• Community-acquired pneumonia
• Hospital-acquired pneumonia
• Urinary tract infections
• Complicated urinary tract infections
• Prostatitis
• Chronic pulmonary infections due to Pseudomonas aeruginosa
• Helicobacter pylori eradication (in combination with other drugs)

Dosage

Adults: 500 mg once daily for 5-14 days depending on the infection type and severity; for intravenous infusion, 500 mg to be given over at least 60 minutes.

Mechanism of action

Levofloxacin exerts its antimicrobial activity through the inhibition of two key bacterial enzymes: DNA gyrase and topoisomerase IV. DNA gyrase introduces negative supercoils into DNA during replication, while topoisomerase IV is essential for unlinking newly replicated chromosomes, allowing cell division. By inhibiting these enzymes, levofloxacin blocks DNA replication, resulting in cell death.

Pharmacodynamics

Levofloxacin is bactericidal and inhibits bacterial DNA replication. It has a longer duration of action than many other antibiotics, allowing for less frequent dosing. The drug may cause QTc-interval prolongation, necessitating caution in patients with risk factors for this condition. Levofloxacin shows in vitro activity against various bacterial pathogens, and while resistance can develop, it typically arises from mutations in target enzymes or drug efflux mechanisms.

Pharmacokinetics

Levofloxacin is well absorbed following oral administration, with peak plasma concentrations occurring within 1-2 hours. It has a volume of distribution of approximately 100 L and is approximately 30-40% protein bound. The drug is primarily excreted unchanged in the urine, with a half-life of about 6-8 hours, allowing for once or twice daily dosing.

Contra-indications

• Hypersensitivity to levofloxacin or other fluoroquinolones
• History of tendon disorders related to fluoroquinolone use
• Patients with a history of myasthenia gravis

Adverse effects

• Nausea
• Diarrhea
• Headache
• Dizziness
• QT interval prolongation
• Tendon rupture
• Clostridioides difficile-associated diarrhea
• Nephritis tubulointerstitial

Interactions

• Concurrent use with other drugs that prolong the QT interval
• Antacids, sucralfate, metal cations (e.g. magnesium, aluminum, calcium) can reduce absorption
• NSAIDs may increase the risk of CNS stimulation
• Warfarin may have increased anticoagulant effects

Precautions

• Use cautiously in patients with a history of seizures or CNS disorders
• Monitor for signs of tendon damage
• Consider risks in patients with electrolyte disturbances
• Use with caution in patients with renal impairment

Pregnancy

Manufacturer advises use only if potential benefit outweighs risk.

Breast-feeding

Manufacturer advises caution; levofloxacin may be excreted in breast milk.

Storage

Store at room temperature, away from moisture and heat. Protect from light.

Formulations

• 500 mg tablet for oral use
• Solution for intravenous infusion
• Nebuliser solution
• Eye drops

Indications

• Constipation
• Dietary fiber supplementation
• Irritable bowel syndrome
• Diverticular disease
• Weight management

Dosage

Children: Refer to appropriate guidelines for specific dosage; generally taken with adequate fluid intake.

Adults: Refer to appropriate guidelines for specific dosage; generally taken with adequate fluid intake.

Mechanism of action

Cellulose acts primarily as a bulk-forming laxative. It absorbs water in the intestines, which increases stool bulk and stimulates peristalsis, thus facilitating bowel movements. Additionally, cellulose is not digestible by human enzymes, leading to fermentation by gut bacteria, which may enhance gut health and alter gut microbiota composition.

Pharmacodynamics

Cellulose increases stool weight and frequency of bowel movements. It works by retaining water in the intestines, leading to softer stools and improved passage through the gastrointestinal tract. The bulking effect of cellulose can help alleviate constipation and promote overall digestive health. It may also play a role in cholesterol reduction and glycemic control through its effects on digestion and absorption of nutrients.

Pharmacokinetics

Cellulose is not absorbed into the bloodstream due to its indigestible nature. Instead, it passes through the gastrointestinal tract, where it adds bulk to the stool. Its fermentation by colonic bacteria produces short-chain fatty acids, which may have beneficial effects on colon health. The onset of action for cellulose as a laxative can vary but is generally within 24 to 72 hours after ingestion.

Adverse effects

• Bloating
• Flatulence
• Diarrhea
• Abdominal discomfort

Precautions

• Use with caution in patients with a history of gastrointestinal disorders.
• Monitor for potential allergic reactions in sensitive individuals.

Pregnancy

Cellulose is generally considered safe during pregnancy as it is a non-toxic, indigestible fiber.

Breast-feeding

Cellulose is also considered safe during breastfeeding; it is excreted in breast milk in negligible amounts.

Storage

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

Formulations

• Powder
• Capsules
• Tablets
• Granules

Indications

• Protection of drugs from degradation
• Taste masking
• Controlled release of active ingredients
• Improvement of patient compliance
• Targeted delivery of medications

Dosage

Children: Refer to specific product labeling for dosing information, as this varies widely based on formulation and indication.

Adults: Refer to specific product labeling for dosing information, as this varies widely based on formulation and indication.

Mechanism of action

The mechanism of action of coatings primarily involves the modification of drug release profiles. By altering the solubility and permeability of the drug through the coating material, the release rate can be controlled. For example, enteric coatings prevent drug dissolution in the acidic environment of the stomach, allowing the drug to be released in the more neutral pH of the intestine.

Pharmacodynamics

Pharmacodynamics of coated formulations can vary significantly based on the type of coating used. Immediate-release coatings dissolve quickly, leading to rapid absorption and onset of action. Controlled-release coatings are designed to dissolve slowly over time, providing a sustained release of the drug, which can lead to prolonged therapeutic effects and reduced dosing frequency. The choice of coating material and thickness influences the overall pharmacodynamic profile of the drug.

Pharmacokinetics

The pharmacokinetics of coated drugs are influenced by the coating material and the drug itself. Factors such as the rate of dissolution, absorption site, and first-pass metabolism play critical roles. Coatings can alter the bioavailability and distribution of the drug. For example, enteric coatings can enhance the absorption of drugs that are unstable in acidic conditions, potentially increasing their bioavailability when the drug reaches the intestine.

Pregnancy

Safety in pregnancy has not been established. Use only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

Caution is advised as it is not known whether it passes into breast milk.

Storage

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

Indications

• Wound healing
• Skin protection
• Drug delivery systems
• Anti-inflammatory treatments

Dosage

Children: Refer to specific product guidelines for paediatric dosage information, as it can vary based on the formulation and intended use.

Adults: Refer to specific product guidelines for dosage information, as it can vary based on the formulation and intended use.

Mechanism of action

Colloidal systems work by providing a surface for drug absorption and enhancing the bioavailability of the therapeutic agent. The small particle size of colloids allows for increased surface area, which can facilitate interactions with biological membranes and improve penetration. The stability of colloids also allows for a controlled release of the active components, prolonging their therapeutic effects.

Pharmacodynamics

The pharmacodynamic properties of colloidal formulations depend on the specific active ingredients and their interactions with biological systems. Generally, colloids can enhance the solubility and absorption of poorly water-soluble drugs. They may also provide a protective effect on tissues, reduce inflammation, and promote healing processes in the body. The efficacy of colloidal systems is influenced by factors such as particle size, concentration, and the nature of the dispersing medium.

Pharmacokinetics

The pharmacokinetics of colloidal systems can vary widely based on the formulation and the active ingredient used. Typically, colloids exhibit prolonged circulation times due to their size, and they may be taken up by cells through endocytosis. The release of the active ingredient is dependent on the stability of the colloidal system and environmental conditions such as pH and temperature. Elimination pathways can include renal excretion or degradation by phagocytic cells.

Pregnancy

There is limited data on the safety of colloidal solutions during pregnancy. They should only be used if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

Caution is advised when using colloidal solutions during breastfeeding. It is recommended to consult a healthcare professional before use.

Storage

Store in a cool, dry place away from direct sunlight. Ensure that the container is tightly closed to prevent contamination.

Indications

• Tablet formulation
• Capsule formulation
• Rapid release of active pharmaceutical ingredients

Dosage

Children: Refer to specific product guidelines for exact formulations. Typically used in concentrations of 1-5% in solid dosage forms.

Adults: Refer to specific product guidelines for exact formulations. Typically used in concentrations of 1-5% in solid dosage forms.

Mechanism of action

Crosscarmellose sodium works by swelling upon contact with water, leading to the rapid disintegration of the dosage form. This process increases the surface area of the active ingredient, promoting faster dissolution and absorption in the gastrointestinal tract. It does not possess any pharmacological activity of its own but acts as a functional excipient.

Pharmacodynamics

As a disintegrant, crosscarmellose sodium aids in the breakdown of solid dosage forms, allowing for quicker release and absorption of active ingredients. Its effectiveness is influenced by factors such as the formulation's composition, the presence of other excipients, and the conditions within the gastrointestinal environment.

Pharmacokinetics

Crosscarmellose sodium is not absorbed in the gastrointestinal tract and does not undergo metabolism. It functions primarily as a physical agent that enhances the disintegration of the dosage form. Its safety profile is well-established, and it is considered non-toxic and non-irritating.

Pregnancy

Crosscarmellose is considered safe for use during pregnancy as it is not systemically absorbed, but consult a healthcare provider for specific cases.

Breast-feeding

Crosscarmellose is not absorbed systemically and is generally considered safe during breastfeeding, but consult a healthcare provider for specific cases.

Storage

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

Formulations

• Tablets
• Capsules
• Powders

Dosage

Children: Refer to the BNF for Children for specific dosing recommendations.

Adults: Refer to the BNF for specific dosing recommendations.

Mechanism of action

The exact mechanism of action for Hemi is not explicitly detailed in the available resources, but compounds with similar structure may act by modulating neurotransmitter levels, inhibiting enzymes, or affecting cellular signaling pathways.

Pharmacodynamics

Hemi may exhibit pharmacodynamic properties that include modulation of neural activity or inhibition of specific biochemical pathways. Its effects could be dose-dependent and vary based on the therapeutic context.

Pharmacokinetics

The pharmacokinetic profile of Hemi, including absorption, distribution, metabolism, and excretion, is not well-documented in the provided resources. Generally, compounds in this class may undergo first-pass metabolism and have a variable half-life.

Dosage

Children: Refer to the specific formulation or active ingredient for dosing information.

Adults: Refer to the specific formulation or active ingredient for dosing information.

Mechanism of action

The mechanism of action of hemihydrate forms of drugs can vary widely depending on the specific compound. In many cases, the hemihydrate form enhances the solubility of the active ingredient, which facilitates its dissolution and absorption in the gastrointestinal tract.

Pharmacodynamics

Pharmacodynamics of hemihydrate compounds generally relates to the pharmacological effects that arise from the active drug once it is absorbed. The effects may vary based on the specific drug and its therapeutic target, but overall, the hemihydrate form aims to improve efficacy by ensuring adequate plasma concentrations are achieved more effectively than non-hydrated forms.

Pharmacokinetics

The pharmacokinetics of hemihydrate drugs typically demonstrate improved dissolution rates due to the presence of water, which can lead to increased absorption. This may result in quicker onset of action and modified half-lives. The specifics of absorption, distribution, metabolism, and excretion will depend on the active ingredient and its properties.

Pregnancy

Safety in pregnancy has not been established. 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 should be exercised when administered to a nursing mother.

Storage

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

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

• Nutritional support
• Source of carbohydrates
• Dietary fiber source
• Animal feed

Dosage

Children: As with adults, there are no specific dosing recommendations for maize for children. It can be introduced into the diet in age-appropriate forms and quantities, keeping in mind the overall dietary balance.

Adults: There are no specific dosing recommendations for maize as it is typically consumed as part of a balanced diet. It can be included in daily meals in various forms such as whole kernels, flour, or as part of dishes.

Mechanism of action

Maize primarily acts as a source of energy due to its high carbohydrate content. The complex carbohydrates in maize are broken down into glucose, which is then utilized by the body for energy production. It also contributes to dietary fiber intake, which can aid in digestive health and regulation of blood sugar levels.

Pharmacodynamics

The consumption of maize influences blood glucose and insulin levels due to its carbohydrate content. It has a relatively low glycemic index when consumed in whole form, which can help in managing blood sugar levels. The dietary fiber present in maize can also promote satiety and aid in weight management.

Pharmacokinetics

The digestion of maize begins in the mouth with salivary amylase breaking down starches into simpler sugars. In the stomach and small intestine, enzymes further break down these carbohydrates. The resultant glucose is absorbed into the bloodstream, where it is transported to cells for energy production. The absorption rate can vary based on the form of maize consumed (e.g., whole kernels versus processed forms).

Pregnancy

Maize is generally considered safe for consumption during pregnancy as it is a staple food and provides essential nutrients.

Breast-feeding

Maize is safe to consume while breastfeeding and can provide important nutrients to both the mother and the infant.

Storage

Store in a cool, dry place, away from moisture and pests. Properly sealed containers can help prolong shelf life.

Formulations

• Whole maize grains
• Maize flour (cornmeal)
• Maize starch
• Maize oil

Indications

• Used as an excipient in tablet formulations
• Used as a bulking agent in capsule formulations
• Used in food products as a thickener or stabilizer

Dosage

Children: Refer to specific product guidelines as dosage will depend on the formulation and the active ingredients.

Adults: Refer to specific product guidelines as dosage will depend on the formulation and the active ingredients.

Mechanism of action

Microcrystalline cellulose acts as a non-digestible filler that enhances the flow properties of powders during the manufacturing of tablets and capsules. It does not have a direct pharmacological action on the body but ensures that the active ingredients are effectively delivered to the patient.

Pharmacodynamics

As a non-active ingredient, microcrystalline cellulose does not exert pharmacodynamic effects typical of active pharmaceutical ingredients. Its primary role is to provide a stable and consistent matrix for the drug, facilitating the release of the active compound once ingested.

Pharmacokinetics

Microcrystalline cellulose is not absorbed in the gastrointestinal tract; it passes through the digestive system largely unchanged. It adds bulk to the stool, which may aid in promoting regular bowel movements. The substance is excreted in feces, where it contributes to dietary fiber intake.

Pregnancy

Data regarding the use of microcrystalline cellulose during pregnancy is limited. It is advisable to consult with healthcare professionals before use.

Breast-feeding

Microcrystalline cellulose is considered safe during breastfeeding, as it is not absorbed systemically.

Storage

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

Mechanism of action

The exact mechanism of action for Pink is not detailed in the provided information. However, compounds with similar structures often function as antagonists or inhibitors at certain receptors or enzymes, which modulates physiological processes.

Pharmacodynamics

Pharmacodynamics details for Pink are not specified. Typically, the pharmacodynamics of similar compounds involve interactions with neurotransmitter systems, influencing both central and peripheral nervous system functions. This can lead to varying therapeutic effects depending on the target receptors.

Pharmacokinetics

The pharmacokinetics of Pink, including absorption, distribution, metabolism, and excretion, are not explicitly stated. However, compounds of this nature generally exhibit moderate to high oral bioavailability, with metabolism primarily occurring in the liver, followed by renal excretion of metabolites.

Indications

• Used in agriculture to regulate plant growth
• Commonly applied to cereal crops to prevent lodging
• Enhances crop yield and stability

Mechanism of action

Chlormequat chloride acts at the nicotinic receptor site of the neuromuscular junction, functioning as a depolarizing agent. This action leads to initial muscular excitation which is then followed by muscle weakness. The acute toxicity of chlormequat chloride may result in respiratory arrest, and its effects can vary by species due to differing sensitivities to depolarizing neuromuscular blockers.

Pharmacodynamics

Chlormequat chloride inhibits gibberellin biosynthesis, a key hormone in plant growth regulation, which leads to reduced cell elongation and overall dwarfing of plants. This mechanism helps enhance crop stability and yield by minimizing the risk of lodging in cereals, thus promoting a more efficient harvest.

Pharmacokinetics

The pharmacokinetics of chlormequat chloride in plants involves absorption, translocation, and metabolism within plant tissues. It is rapidly absorbed and translocated throughout the plant, with a relatively short half-life, leading to effective growth regulation while minimizing residues in harvested products.

Pregnancy

No adequate and well-controlled studies in pregnant women have been conducted. Use only if clearly needed.

Breast-feeding

It is not known whether chlormequat chloride is excreted in human milk. Caution should be exercised when administering to a nursing mother.

Storage

Store in a cool, dry place. Keep container tightly closed.

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

• Silicosis
• Chronic obstructive pulmonary disease (COPD)
• Lung cancer associated with silica exposure

Dosage

Adults: Silica is not administered as a drug, but rather

Mechanism of action

Silica, particularly crystalline forms like quartz and cristobalite, can induce cytotoxicity and morphological transformation in cells. The cytotoxic effects are attributed to the presence of silanol groups and trace iron on the silica surface, which can generate reactive oxygen species. These interactions lead to cellular damage and transformation, suggesting multiple molecular mechanisms underlying silica's biological effects. The activity is sensitive to the silica's surface structure and composition, indicating that the biological response is a phenomenon originating from the silica's surface characteristics.

Pharmacodynamics

Silica's pharmacodynamic effects are largely related to its cytotoxic and transforming properties, particularly in lung tissue. The inhalation of crystalline silica can lead to the activation of inflammatory pathways, oxidative stress, and apoptosis in alveolar macrophages and epithelial cells. This can result in chronic inflammation, fibrosis, and ultimately, diseases such as silicosis and lung cancer. The degree of these effects varies based on the type of silica, its crystalline structure, and the presence of surface modifications.

Pharmacokinetics

The pharmacokinetics of silica is complex as it is not absorbed systemically when inhaled or ingested. Instead, inhaled silica particles can deposit in the alveolar region of the lungs, where they may persist for long periods. The body responds to silica exposure through inflammatory processes, and macrophages attempt to phagocytize silica particles. However, the persistence of these particles can lead to chronic lung conditions. Clearance mechanisms are inefficient, leading to prolonged retention in lung tissue.

Adverse effects

• Cytotoxicity
• Morphological transformation of cells
• Respiratory issues
• Silicosis
• Lung cancer

Precautions

• Use caution in occupational settings with silica dust exposure
• Regular monitoring of lung function in exposed individuals

Pregnancy

There is insufficient data on the effects of silica on pregnancy. It is advised to minimize exposure.

Breast-feeding

Limited data available; caution is advised due to potential respiratory effects.

Storage

Store in a cool, dry place, away from moisture and incompatible materials.

Formulations

• Crystalline silica
• Amorphous silica (diatomaceous earth)
• Silica gel

Mechanism of action

Levofloxacin, like other fluoroquinolone antibiotics, exerts its antimicrobial activity via the inhibition of two key bacterial enzymes: DNA gyrase and topoisomerase IV. Both targets are type II topoisomerases, but have unique functions within the bacterial cell. DNA gyrase is an enzyme found only in bacteria that introduces negative supercoils into DNA during replication - this helps to relieve torsional strain caused by the introduction of positive supercoils during replication, and these negative supercoils are essential for chromosome condensation and the promotion of transcription initiation. It is comprised of four subunits (two A subunits and two B subunits) of which the A subunits appear to be the target of fluoroquinolone antibiotics. Bacterial topoisomerase IV, in addition to contributing to the relaxation of positive supercoils, is essential at the terminal stages of DNA replication and functions to “unlink” newly replicated chromosomes to allow for the completion of cell division. Inhibition of these enzymes by levofloxacin likely occurs via complexation with the topoisomerase enzymes. The end result is a blockade of DNA replication, thus inhibiting cell division and resulting in cell death. Levofloxacin is the L-isomer of the racemate, ofloxacin, a quinolone antimicrobial agent. The antibacterial activity of ofloxacin resides primarily in the L-isomer. The mechanism of action of levofloxacin and other fluoroquinolone antimicrobials involves inhibition of bacterial topoisomerase IV and DNA gyrase (both of which are type II topoisomerases), enzymes required for DNA replication, transcription, repair and recombination. Fluoroquinolones prolong the QT interval by blocking voltage-gated potassium channels, especially the rapid component of the delayed rectifier potassium current I(Kr), expressed by HERG (the human ether-a-go-go-related gene). According to the available case reports and clinical studies, moxifloxacin carries the greatest risk of QT prolongation from all available quinolones in clinical practice and it should be used with caution in patients with predisposing factors for Torsades de pointes (TdP).

Pharmacodynamics

Levofloxacin is bactericidal and exerts its antimicrobial effects via inhibition of bacterial DNA replication. It has a relatively long duration of action in comparison with other antibiotics that allows for once or twice daily dosing. Levofloxacin is associated with QTc-interval prolongation and should be used with caution in patients with other risk factors for prolongation (e.g. hypokalemia, concomitant medications). Levofloxacin has demonstrated _in vitro_ activity against a number of aerobic gram-positive and gram-negative bacteria and may carry some activity against certain species of anaerobic bacteria and other pathogens such as _Chlamydia_ and _Legionella_. Resistance to levofloxacin may develop, and is generally due to mutations in DNA gyrase or topoisomerase IV, or via alterations to drug efflux. Cross-resistance may occur between levofloxacin and other fluoroquinolones, but is unlikely to develop between levofloxacin and other antibiotic classes (e.g. macrolides) due to significant differences in chemical structure and mechanism of action. As antimicrobial susceptibility patterns are geographically distinct, local antibiograms should be consulted to ensure adequate coverage of relevant pathogens prior to use.

Mechanism of action

Chlormequat chloride has been reported in the literature to act at the nicotinic receptor site of the neuromuscular junction. The test material may act as a depolarizing agent at this site, leading to muscular excitation followed by muscle weakness. Acute toxicity may lead to respiratory arrest. Acute toxicity of chlormequat chloride has also been reported to differ by species, which is likely due to sensitivity to depolarizing neuromuscular blockers.

Mechanism of action

...Some quartz and cristobalite dusts (crystalline) as well as the diatomaceous earths (amorphous), but not the pyrogenic amorphous silica, were cytotoxic and induced morphological transformation of SHE cells in a concentration-dependent manner. The ranking in cytotoxicity was different from that in transforming potency, suggesting two separate molecular mechanisms for the two effects. The cytotoxic and transforming potencies were different from one dust to another, even among the same structural silicas. The type of crystalline structure (quartz vs cristobalite) and the crystalline vs biogenic amorphous form did not correlate with cytotoxic or transforming potency of silica dusts. Comparison of cellular effects induced by original and surface modified samples revealed that several surface functionalities modulate cytotoxic and transforming potencies. The cytotoxic effects appeared to be related to the distribution and abundance of silanol groups and to the presence of trace amounts of iron on the silica surface. Silica particles with fractured surfaces and/or iron-active sites, able to generate reactive oxygen species, induced SHE cell transformation. The results show that the activity of silica at the cellular level is sensitive to the composition and structure of surface functionalities and confirm that the biological response to silica is a surface originated phenomenon. In vivo exposure of rat lungs to crystalline silica either by intratracheal instillation or by inhalation results in an increase in mRNA levels for inducible nitric oxide synthase (iNOS) in bronchoalveolar lavage cells (BALC), elevated nitric oxide (.NO) production by BALC, and an increase in .NO-dependent chemiluminescence (CL) from alveolar macrophages (AM). Induction of iNOS message occurs in both AM and polymorphonuclear leukocytes (PMN) harvested from silica-exposed lungs but is not significantly elevated in lavaged lung tissue. This review presents characteristics of simple and complicated coal workers' pneumoconiosis (CWP) as well as pathologic indices of acute and chronic silicosis by summarizing results of in vitro, animal, and human investigations. These results support four basic mechanisms in the etiology of CWP and silicosis: a) direct cytotoxicity of coal dust or silica, resulting in lung cell damage, release of lipases and proteases, and eventual lung scarring; b) activation of oxidant production by pulmonary phagocytes, which overwhelms the antioxidant defenses and leads to lipid peroxidation, protein nitrosation, cell injury, and lung scarring; c) activation of mediator release from alveolar macrophages and epithelial cells, which leads to recruitment of polymorphonuclear leukocytes and macrophages, resulting in the production of proinflammatory cytokines and reactive species and in further lung injury and scarring; d) secretion of growth factors from alveolar macrophages and epithelial cells, stimulating fibroblast proliferation and eventual scarring. Results of in vitro and animal studies provide a basis for proposing these mechanisms for the initiation and progression of pneumoconiosis. Data obtained from exposed workers lend support to these mechanisms. /The authors/ reported previously that freshly fractured silica (FFSi) induces activator protein-1 (AP-1) activation through extracellular signal-regulated protein kinases (ERKs) and p38 kinase pathways. In the present study, the biologic activities of FFSi and aged silica (ASi) were compared by measuring their effects on the AP-1 activation and phosphorylation of ERKs and p38 kinase. The roles of reactive oxygen species (ROS) in this silica-induced AP-1 activation were also investigated. FFSi-induced AP-1 activation was four times higher than that of ASi in JB6 cells. FFSi also caused greater phosphorylation of ERKs and p38 kinase than ASi. FFSi generated more ROS than ASi when incubated with the cells as measured by electron spin resonance (ESR). Studies using ROS-sensitive dyes and