RUFENAC GEL

Indications

• Pain and inflammation in musculoskeletal disorders
• Rheumatic disease
• Osteoarthritis of the knee
• Postoperative pain
• Control of anterior segment inflammation following ophthalmic surgery

Dosage

Children: For paediatric dosing, please refer to the BNF for Children as specific dosages are not provided in this text.

Adults: For topical application, apply 3–4 times a day to the affected area. For injection, 75 mg may be administered intravenously, then 75 mg after 4–6 hours if required, up to a maximum of 150 mg per day for no more than 2 days.

Mechanism of action

Diclofenac sodium primarily acts as a selective inhibitor of cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2). By blocking these enzymes, diclofenac decreases the production of prostaglandins, which are mediators of inflammation and pain. This mechanism leads to reduced inflammatory responses and alleviation of pain.

Pharmacodynamics

The pharmacological effects of diclofenac include anti-inflammatory, analgesic, and antipyretic properties. The onset of action is typically within a few hours following administration, with peak effects seen within 1 to 2 hours. The duration of analgesia can vary depending on the formulation and dosage used.

Pharmacokinetics

Diclofenac is rapidly absorbed after oral administration, with peak plasma concentrations occurring within 1 to 2 hours. It is extensively metabolized in the liver to active metabolites and has a half-life of approximately 1 to 2 hours. The drug is primarily excreted in the urine, with both unchanged drug and metabolites being eliminated. Food can affect the absorption, so it is often recommended to take it on an empty stomach.

Contra-indications

• History of hypersensitivity to diclofenac or other NSAIDs
• Active gastrointestinal ulceration
• History of recurrent gastrointestinal bleeding
• History of cerebrovascular bleeding
• Severe renal impairment
• Severe hepatic impairment
• Dehydration
• Hypovolaemia
• History of asthma precipitated by NSAIDs
• History of gastro-intestinal perforation related to previous NSAID therapy
• History of confirmed or suspected hemorrhagic diathesis

Adverse effects

• Gastrointestinal discomfort
• Nausea
• Vomiting
• Diarrhea
• Constipation
• Headache
• Dizziness
• Rash
• Tinnitus
• Elevated liver enzymes
• Renal impairment
• Fluid retention
• Increased blood pressure

Interactions

• Increased risk of gastrointestinal bleeding when used with other NSAIDs or anticoagulants
• Caution with diuretics due to potential for renal impairment
• May enhance the effects of anticoagulants like warfarin
• Caution with antihypertensive medications due to potential for reduced efficacy

Precautions

• Use with caution in patients with a history of cardiovascular disease
• Monitor renal function in patients with pre-existing renal impairment
• Long-term use may affect female fertility, reversible upon discontinuation
• Use with caution during pregnancy, especially in the third trimester

Pregnancy

Avoid unless the potential benefit outweighs the risk. Avoid during the third trimester due to risks of fetal ductus arteriosus closure and pulmonary hypertension of the newborn.

Breast-feeding

Use with caution; amount in milk is generally too small to be harmful.

Storage

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

Formulations

• Diclofenac sodium 1% gel
• Diclofenac sodium 75 mg injection
• Diclofenac sodium eye drops 0.1% (Voltarol Ophtha)

Indications

• Pain and inflammation in musculoskeletal disorders
• Rheumatic diseases
• Acute gout
• Postoperative pain

Dosage

Children: For children aged 9–13 years (body weight 35 kg and above), up to 2 mg/kg daily in 3 divided doses; maximum 100 mg per day. For children aged 14–17 years, 75–100 mg daily in 2–3 divided doses.

Adults: 75–150 mg daily in 2–3 divided doses.

Mechanism of action

Diclofenac potassium works primarily by inhibiting the cyclooxygenase (COX) enzymes, specifically COX-1 and COX-2. This inhibition decreases the synthesis of prostaglandins, which are mediators involved in inflammation, pain, and fever. This action results in reduced inflammation and pain sensation in affected tissues.

Pharmacodynamics

The analgesic effects of diclofenac potassium are evident within a few hours after administration. It shows a dose-dependent response in reducing pain and inflammation, making it effective for managing acute pain and inflammatory conditions. The drug can also have a beneficial effect on reducing fever.

Pharmacokinetics

Diclofenac potassium is rapidly absorbed from the gastrointestinal tract, with peak plasma concentrations typically occurring within 1-2 hours after oral administration. It has a half-life of approximately 1-2 hours, but its anti-inflammatory effects can last longer due to its active metabolites. The drug is extensively metabolized in the liver, and its metabolites are excreted primarily in the urine.

Contra-indications

• Active gastrointestinal bleeding
• Active gastrointestinal ulceration
• History of recurrent gastrointestinal haemorrhage
• Cerebrovascular disorders
• History of hypersensitivity to aspirin or any other NSAID
• Severe cardiac impairment
• Severe hepatic impairment
• Severe renal impairment
• History of allergic disorders

Adverse effects

• Diarrhoea
• Gastrointestinal disturbances
• Headache
• Insomnia
• Malaise
• Acute gout pain
• Palpitations
• Skin reactions
• Vertigo
• Angioedema
• Decreased appetite
• Dyspepsia
• Hypertension
• Nephritis
• Neutropenia
• Photosensitivity
• Severe cutaneous adverse reactions
• Syncope
• Tachycardia
• Thrombocytopenia
• Tinnitus
• Blurred vision

Interactions

• Increased risk of gastrointestinal bleeding with other NSAIDs
• Caution with anticoagulants due to potential increased bleeding risk
• Caution with antihypertensives as NSAIDs may reduce their efficacy
• Caution with diuretics due to potential renal impairment

Precautions

• Caution in patients with dehydration
• Caution in elderly patients due to increased risk of serious side effects
• Caution in patients with a history of cardiovascular disease
• Use with caution in patients with renal impairment
• Monitor for signs of gastrointestinal bleeding

Pregnancy

Avoid unless the potential benefit outweighs the risk. Avoid during the third trimester due to risk of fetal ductus arteriosus closure and possible persistent pulmonary hypertension in the newborn.

Breast-feeding

Use with caution during breastfeeding; no specific information available.

Storage

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

Formulations

• Oral tablets
• Oral suspension

Indications

• Rheumatoid arthritis
• Osteoarthritis
• Ankylosing spondylitis
• Acute pain
• Dysmenorrhea
• Postoperative pain
• Inflammatory conditions

Dosage

Children: For children, the dosage must be determined based on weight and the specific indication. It is essential to refer

Adults: The usual oral dose for adults is 50 mg taken two to three times daily, with a maximum daily dose of 150 mg. In specific cases, doses may vary based on the condition being treated and the patient's response.

Mechanism of action

Diclofenac inhibits cyclooxygenase-1 and -2 (COX-1 and COX-2), enzymes responsible for the conversion of arachidonic acid to prostaglandins. This inhibition reduces the levels of prostaglandins G2, leading to decreased inflammation, pain, and fever. Prostaglandin E2 (PGE2), a primary mediator of nociception, is suppressed, which lowers pain sensitivity and peripheral sensitization via G-protein coupled receptors.

Pharmacodynamics

Diclofenac reduces inflammation and nociceptive pain while also exhibiting antipyretic effects. Its action can increase the risk of gastrointestinal ulceration due to the inhibition of protective mucus secretion in the stomach, which is a common side effect of NSAIDs.

Pharmacokinetics

Diclofenac is rapidly absorbed after oral administration, with peak plasma concentrations occurring within 1 to 2 hours. It has a high volume of distribution and is extensively metabolized in the liver, primarily by cytochrome P450 enzymes. The elimination half-life is approximately 1 to 2 hours, with metabolites excreted in urine. Its pharmacokinetics can be influenced by factors such as age, liver function, and concurrent medications.

Contra-indications

• Untreated local infection

Adverse effects

• Gastrointestinal ulceration
• Nausea
• Vomiting
• Diarrhea
• Abdominal pain
• Headache
• Dizziness
• Rash

Interactions

• Ciclosporin: Unknown (increases concentration)
• Iron chelators: Unknown (increases exposure)
• Deferiprone: Unknown (increases exposure)

Precautions

• Use with caution in patients with a history of gastrointestinal disease
• Monitor renal function in long-term use
• Consider cardiovascular risks in patients with pre-existing conditions

Pregnancy

Manufacturer advises to avoid unless essential.

Breast-feeding

Manufacturer advises to avoid unless essential.

Storage

Store below 25°C. Protect from light and moisture.

Formulations

• Diclofenac 50 mg oral tablet
• Diclofenac 100 mg extended-release oral tablet
• Diclofenac 75 mg injection
• Diclofenac 1% gel

Indications

• Nitrogen supplementation in clinical nutrition
• Management of metabolic alkalosis
• Treatment of certain types of kidney disorders

Dosage

Children: Specific pediatric dosing information is not detailed in the BNF. Refer to the BNF for Children for appropriate dosing based on age and condition.

Adults: Dosage varies based on clinical indication and should be guided by specific treatment protocols. Refer to clinical guidelines for detailed dosing information.

Mechanism of action

Ammonium ions participate in various metabolic pathways, including the biosynthesis of amino acids and nucleotides. It serves as a nitrogen source for organisms, facilitating the synthesis of essential biomolecules. The presence of ammonium can influence pH levels and osmotic balance within cells, thereby affecting cellular functions and enzyme activities.

Pharmacodynamics

Ammonium affects cellular metabolism by acting as a nitrogen donor in the synthesis of organic compounds. Its role in the nitrogen cycle and as a substrate in biochemical pathways allows for the maintenance of cellular functions, including energy production and cellular growth. Alterations in ammonium levels can influence various physiological processes, including neurotransmitter synthesis and energy metabolism.

Pharmacokinetics

Ammonium is readily absorbed and distributed in biological systems. It can be produced endogenously through amino acid metabolism or obtained from dietary sources. The excretion of ammonium primarily occurs through the kidneys, where it is converted to urea for elimination. Ammonium levels are regulated by various mechanisms, including the action of renal tubular cells that either secrete or reabsorb ammonium based on the body's needs.

Indications

• Cough associated with respiratory tract infections
• Acid-base disorders
• Edema management

Dosage

Children: Refer to the BNF for Children for appropriate paediatric dosing guidelines based on age and condition.

Adults: Refer to the BNF for specific adult dosing guidelines as they depend on the indication and clinical context.

Mechanism of action

Ammonium chloride increases acidity by raising hydrogen ion concentrations. It dissociates into ammonium and chloride ions; the ammonium is converted to urea in the liver, releasing hydrogen ions that lower pH. The chloride ions displace bicarbonate in extracellular fluid, leading to acidosis and increased renal excretion of electrolytes and water, resulting in fluid mobilization.

Pharmacodynamics

Ammonium chloride acts as a systemic acidifier, facilitating the excretion of chloride and sodium, while also increasing the acidity of body fluids. The conversion of ammonium to urea in the liver with the release of hydrogen ions contributes to a decrease in blood pH, affecting acid-base balance in the body.

Pharmacokinetics

Ammonium chloride is absorbed from the gastrointestinal tract and metabolized in the liver, where it is converted to urea. The dissociated ions impact renal function, leading to increased excretion of sodium, potassium, and water. The elimination half-life and specific metabolism details are not explicitly defined.

Adverse effects

• Nausea
• Vomiting
• Abdominal pain
• Diarrhea
• Dizziness
• Headache

Interactions

• Antacids may reduce the effectiveness of ammonium chloride
• Potassium-sparing diuretics may increase the risk of hyperkalemia

Precautions

• Use with caution in patients with renal impairment
• Monitor electrolyte levels during prolonged therapy
• Consider potential for acidosis in patients with liver disease

Pregnancy

Ammonium chloride should only be used during pregnancy if the potential benefit justifies the potential risk to the fetus. Consult a healthcare provider for individualized advice.

Breast-feeding

Ammonium chloride is excreted in breast milk. Use caution and consult a healthcare provider if breastfeeding.

Storage

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

Formulations

• Oral solution
• Powder for oral solution

Dosage

Children: Refer to BNF for Children for appropriate dosing guidelines, as specific therapeutic doses are not applicable for butane.

Adults: Refer to BNF for appropriate dosing guidelines, as specific therapeutic doses are not applicable for butane.

Mechanism of action

Butane acts primarily as a central nervous system depressant when inhaled, leading to hypoxia and potential cardiac complications. The inhalation of butane can result in a range of toxic effects, including asphyxia due to displacement of oxygen and direct toxic effects on cardiac tissues, which can lead to arrhythmias and myocardial damage.

Pharmacodynamics

The pharmacodynamic properties of butane involve its effects on the central nervous system, where it enhances inhibitory neurotransmission. This can lead to sedation and a decreased level of consciousness. Additionally, butane can cause cardiovascular effects, including changes in heart rhythm and potential myocardial ischemia due to oxygen deprivation.

Pharmacokinetics

Butane is rapidly absorbed through the lungs upon inhalation. Its distribution throughout the body is quick due to its lipophilic characteristics, allowing it to cross cell membranes efficiently. Metabolism of butane occurs primarily in the liver, although specific metabolic pathways are not extensively characterized. The elimination half-life is variable and dependent on the duration and intensity of exposure.

Contra-indications

• Hypersensitivity to butane or any of its components
• Severe respiratory insufficiency
• Acute or chronic pulmonary disease

Adverse effects

• Asphyxia
• Cardiac arrhythmias
• CNS depression
• Dizziness
• Headache
• Nausea
• Vomiting
• Confusion
• Loss of consciousness

Interactions

• May potentiate the effects of other CNS depressants
• Use with caution in patients receiving medications that affect cardiac rhythm

Precautions

• Use in well-ventilated areas to reduce inhalation risk
• Monitor patients for signs of respiratory distress
• Avoid use in individuals with a history of substance abuse

Pregnancy

There are no adequate and well-controlled studies in pregnant women. Use only if clearly needed and the potential benefits justify the potential risks.

Breast-feeding

It is not known whether butane is excreted in human milk. Caution should be exercised when administered to a nursing woman.

Storage

Store in a cool, well-ventilated area away from heat and flames. Keep container tightly closed.

Formulations

• Aerosol propellant
• Lighter refills

Indications

• Topical analgesic for muscle and joint pain
• Cough suppressant in cough drops and lozenges
• Relief of minor throat irritation
• Cooling agent in various cosmetic and personal care products

Dosage

Children: Refer to BNF for Children for specific dosing guidelines, as doses may vary based on age and formulation.

Adults: For topical use, apply a thin layer to the affected area not more than 3 to 4 times daily. For cough drops, follow the product-specific instructions as per the formulation.

Mechanism of action

Menthol acts as an agonist for the transient receptor potential subtype M8 (TRPM8), a non-selective cation channel that is activated by cold temperatures. This activation leads to calcium influx in mast cells, inducing the release of histamine, which can trigger allergic responses such as urticaria, asthma, and rhinitis. Menthol's ability to induce histamine release via TRPM8 suggests potential therapeutic applications for TRPM8 antagonists in managing cold- and menthol-induced allergies.

Pharmacodynamics

Menthol produces a cooling effect by stimulating sensory neurons that convey cold sensations. It interacts with TRPM8 channels, leading to the activation of intracellular signaling pathways that can result in vasodilation and increased blood flow to the area of application. This cooling sensation can provide symptomatic relief in conditions characterized by pain or irritation.

Pharmacokinetics

Menthol is absorbed through the skin and mucous membranes, with systemic effects depending on the route of administration. Its bioavailability can vary, and it is metabolized primarily in the liver. The elimination half-life and excretion pathways have not been extensively characterized, but menthol is generally considered to have a rapid onset of action with effects lasting for a few hours.

Adverse effects

• Allergic reactions
• Urticaria
• Asthma
• Rhinitis
• Skin irritation

Precautions

• Use with caution in patients with known allergies to menthol or related compounds
• May exacerbate asthma in sensitive individuals

Pregnancy

There are no well-controlled studies of menthol in pregnant women. Menthol should be used during pregnancy only if clearly needed.

Breast-feeding

Menthol is excreted in breast milk. Caution should be exercised when administering to nursing mothers.

Storage

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

Formulations

• Topical ointment
• Cream
• Liquid

Indications

• Allergic conditions
• Autoimmune diseases
• Asthma and chronic obstructive pulmonary disease (COPD)
• Certain cancers (e.g., leukemia, lymphoma)
• Skin conditions (e.g., dermatitis)
• Inflammatory bowel disease
• Multiple sclerosis exacerbations
• Severe infections requiring immunosuppression

Dosage

Children: Refer to BNF for Children for specific dosing; doses vary significantly based on the child's age, weight, and condition being treated.

Adults: Refer to BNF for specific dosing; typically, initial doses range from 4 to 48 mg depending on the severity of the condition.

Mechanism of action

Methylprednisolone exerts its effects by binding to glucocorticoid receptors, leading to the modulation of gene expression. This interaction influences the transcription of anti-inflammatory proteins while suppressing the expression of pro-inflammatory genes, ultimately resulting in reduced inflammation and immune response.

Pharmacodynamics

The pharmacodynamic effects of methylprednisolone are characterized by its ability to decrease inflammation, suppress the immune response, and affect carbohydrate metabolism. Therapeutic doses lead to various systemic effects, including modification of leukocyte distribution and inhibition of cytokine production.

Pharmacokinetics

Methylprednisolone is well absorbed after oral administration, with a bioavailability of approximately 50%. It has a volume of distribution that reflects extensive tissue binding. The drug is metabolized primarily in the liver through conjugation and reduction, and its metabolites are excreted in urine. The half-life varies based on the route of administration but is generally around 18 to 36 hours.

Adverse effects

• Increased blood pressure
• Hyperglycemia
• Weight gain
• Mood changes
• Insomnia
• Gastrointestinal disturbances
• Increased susceptibility to infections

Interactions

• methylphenidate+apraclonidine: Severe (decreases effects)
• methylthioninium chloride+bupropion: Severe (increases risk of severe hypertension)
• methylphenidate+linezolid: Severe (increases risk of elevated blood pressure)
• rasagiline+methylphenidate: Severe (increases risk of a hypertensive crisis)
• mao-inhibitors+methylphenidate: Severe (increases risk of a hypertensive crisis)
• dronedarone+methylprednisolone: Moderate (increases exposure)
• miconazole+methylprednisolone: Moderate (increases concentration)
• antifungals, azoles+methylprednisolone: Moderate (increases exposure)
• crizotinib+methylprednisolone: Moderate (increases exposure)

Precautions

• Use with caution in patients with hypertension
• Monitor blood glucose levels in diabetic patients
• Consider potential for infection risk due to immunosuppression
• Evaluate for psychiatric effects in susceptible individuals

Pregnancy

Corticosteroids may be used during pregnancy if the potential benefit justifies the risk to the fetus. Careful monitoring is advised.

Breast-feeding

Corticosteroids are excreted in breast milk; caution is advised. Monitor the infant for potential effects.

Storage

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

Formulations

• Tablets
• Injectable solutions
• Topical preparations

Mechanism of action

Methylsulphate functions as a methylating agent, transferring a methyl group to nucleophiles. This process involves the formation of a sulfonium ion, which is highly reactive and can readily react with nucleophilic sites on various substrates, leading to methylation reactions.

Pharmacodynamics

The pharmacodynamics of methylsulphate is primarily related to its role as a methylating agent in biochemical reactions. It can alter the structure and function of biological molecules, potentially affecting cellular processes and signaling pathways. However, detailed pharmacodynamic studies specific to therapeutic use are limited.

Pharmacokinetics

There is limited information on the pharmacokinetics of methylsulphate, given its typical use as a reagent in laboratory settings rather than a clinical drug. When used in chemical reactions, its reactivity and transformation into other compounds would dictate its pharmacokinetic profile, which could vary significantly based on the specific context of use.

Pregnancy

There is limited data on the use of methylsulphate in pregnancy. Consult relevant guidelines.

Breast-feeding

Data on the excretion of methylsulphate in human milk is not available. Caution is advised.

Storage

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

Indications

• Pain relief
• Fever reduction
• Inflammatory conditions such as arthritis
• Prevention of cardiovascular events in certain populations

Dosage

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

Adults: Refer to the BNF for specific dosing guidelines.

Mechanism of action

Salicylate works by inhibiting the enzyme cyclooxygenase (COX), which is involved in the synthesis of prostaglandins. Prostaglandins are lipid compounds that mediate inflammation, pain, and fever. By decreasing the production of these compounds, salicylate effectively reduces inflammation and provides analgesic and antipyretic effects.

Pharmacodynamics

The pharmacodynamic effects of salicylate include analgesia, antipyresis, and anti-inflammatory action. It reduces the sensitivity of pain receptors and inhibits the generation of pain signals. The antipyretic effect is achieved through action on the hypothalamus, leading to peripheral vasodilation and sweating, thereby reducing body temperature. The drug also modulates the immune response, contributing to its anti-inflammatory properties.

Pharmacokinetics

Salicylate is rapidly absorbed from the gastrointestinal tract following oral administration. Peak plasma concentrations are typically reached within 1 to 2 hours. It is extensively metabolized in the liver, primarily through conjugation, and its metabolites are excreted in the urine. The elimination half-life of salicylate varies depending on the dose and the presence of other medications, averaging around 2 to 3 hours at low doses, but can be prolonged at higher doses due to saturation of metabolic pathways.

Contra-indications

• Hypersensitivity to salicylates
• Active peptic ulcer disease
• Severe hepatic impairment
• Severe renal impairment
• Bleeding disorders
• Children with viral infections (due to risk of Reye's syndrome)

Adverse effects

• Gastrointestinal irritation
• Nausea
• Vomiting
• Tinnitus
• Hearing loss
• Allergic reactions
• Rash
• Asthma exacerbation
• Gastric ulceration

Interactions

• Anticoagulants (increased bleeding risk)
• Methotrexate (increased toxicity)
• NSAIDs (increased gastrointestinal side effects)
• Diuretics (reduced efficacy)
• Alcohol (increased risk of gastrointestinal bleeding)

Precautions

• Use with caution in patients with a history of gastrointestinal disease
• Monitor renal function in long-term use
• Caution in patients with asthma or allergies
• Consider alternative therapy in children with viral infections

Pregnancy

Use with caution during pregnancy, particularly in the third trimester, as it may affect fetal development.

Breast-feeding

Salicylate is excreted in breast milk; caution is advised when administering to breastfeeding mothers.

Storage

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

Formulations

• Tablets
• Oral suspension
• Topical preparations
• Suppositories

Indications

• Fluid and electrolyte replenishment
• Management of hyponatremia
• Induction of abortion in specific medical circumstances

Dosage

Children: Refer to the BNF for Children for appropriate dosing information for pediatric patients.

Adults: Refer to the BNF for specific dosing guidelines based on clinical context and condition being treated.

Mechanism of action

Sodium and chloride, as major electrolytes in the extracellular fluid, work together to control extracellular volume and blood pressure. Disturbances in sodium concentrations are linked to disorders of water balance. Intra-amniotic instillation of hypertonic sodium chloride may induce uterine contractions, leading to abortion, potentially mediated by prostaglandins released from damaged decidual cells.

Pharmacodynamics

Sodium, the principal cation in extracellular fluid, is critical for regulating water distribution, fluid balance, and osmotic pressure in body fluids. It works in conjunction with chloride and bicarbonate to maintain acid-base equilibrium. Chloride, as the major extracellular anion, mirrors sodium metabolism, and alterations in acid-base balance are reflected in chloride concentrations.

Pharmacokinetics

Sodium and chloride ions are absorbed from the gastrointestinal tract and distributed throughout the body fluids. Their concentration in extracellular fluid is tightly regulated by mechanisms involving renal excretion and hormonal control, primarily through aldosterone. Changes in dietary intake can also influence sodium levels significantly.

Pregnancy

Intra-amniotic instillation of hypertonic sodium chloride is associated with abortion and fetal death. Caution is advised during pregnancy.

Breast-feeding

Sodium is considered safe during breastfeeding as it is an essential electrolyte.

Storage

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

Formulations

• 20% sodium chloride injection

Mechanism of action

Diclofenac inhibits cyclooxygenase-1 and -2, the enzymes responsible for production of prostaglandin (PG) G₂ which is the precursor to other PGs. These molecules have broad activity in pain and inflammation and the inhibition of their production is the common mechanism linking each effect of diclofenac. PGE₂ is the primary PG involved in modulation of nociception. It mediates peripheral sensitization through a variety of effects. PGE₂ activates the G_q-coupled EP₁ receptor leading to increased activity of the inositol trisphosphate/phospholipase C pathway. Activation of this pathway releases intracellular stores of calcium which directly reduces action potential threshold and activates protein kinase C (PKC) which contributes to several indirect mechanisms. PGE₂ also activates the EP₄ receptor, coupled to G_s, which activates the adenylyl cyclase/protein kinase A (AC/PKA) signaling pathway. PKA and PKC both contribute to the potentiation of transient receptor potential cation channel subfamily V member 1 (TRPV1) potentiation, which increases sensitivity to heat stimuli. They also activate tetrodotoxin-resistant sodium channels and inhibit inward potassium currents. PKA further contributes to the activation of the P2X3 purine receptor and sensitization of T-type calcium channels. The activation and sensitization of depolarizing ion channels and inhibition of inward potassium currents serve to reduce the intensity of stimulus necessary to generate action potentials in nociceptive sensory afferents. PGE₂ act via EP₃ to increase sensitivity to bradykinin and via EP₂ to further increase heat sensitivity. Central sensitization occurs in the dorsal horn of the spinal cord and is mediated by the EP₂ receptor which couples to G_s. Pre-synaptically, this receptor increases the release of pro-nociceptive neurotransmitters glutamate, CGRP, and substance P. Post-synaptically it increases the activity of AMPA and NMDA receptors and produces inhibition of inhibitory glycinergic neurons. Together these lead to a reduced threshold of activating, allowing low intensity stimuli to generate pain signals. PGI₂ is known to play a role via its G_s-coupled IP receptor although the magnitude of its contribution varies. It has been proposed to be of greater importance in painful inflammatory conditions such as arthritis. By limiting sensitization, both peripheral and central, via these pathways NSAIDs can effectively reduce inflammatory pain. PGI₂ and PGE₂ contribute to acute inflammation via their IP and EP₂ receptors. Similarly to β adrenergic receptors these are G_s-coupled and mediate vasodilation through the AC/PKA pathway. PGE₂ also contributes by increasing leukocyte adhesion to the endothelium and attracts the cells to the site of injury. PGD₂ plays a role in the activation of endothelial cell release of cytokines through its DP₁ receptor. PGI₂ and PGE₂ modulate T-helper cell activation and differentiation through IP, EP₂, and EP₄ receptors which is believed to be an important activity in the pathology of arthritic conditions. By limiting the production of these PGs at the site of injury, NSAIDs can reduce inflammation. PGE₂ can cross the blood-brain barrier and act on excitatory G_q EP₃ receptors on thermoregulatory neurons in the hypothalamus. This activation triggers an increase in heat-generation and a reduction in heat-loss to produce a fever. NSAIDs prevent the generation of PGE₂ thereby reducing the activity of these neurons. Diclofenac has pharmacologic actions similar to those of other prototypical NSAIAs. The drug exhibits anti-inflammatory, analgesic, and antipyretic activity. The exact mechanisms have not been c

Pharmacodynamics

Diclofenac reduces inflammation and by extension reduces nociceptive pain and combats fever. It also increases the risk of developing a gastrointestinal ulcer by inhibiting the production of protective mucus in the stomach.

Mechanism of action

Ammonium chloride increases acidity by increasing the amount of hydrogen ion concentrations. Ammonium chloride can be used as an expectorant due to its irritative action on the bronchial mucosa. This effect causes the production of respiratory tract fluid which in order facilitates the effective cough. The acid-forming properties of ammonium chloride result from dissociation of the salt to an ammonium cation and a chloride anion. In patients with normal hepatic function, the ammonium cation is converted to urea by the liver and a hydrogen cation is released which reacts with a bicarbonate ion to form water and carbon dioxide. The chloride anion combines with fixed bases in the extracellular fluid, thereby reducing the alkaline reserve of the body. The net result is the displacement of bicarbonate ions by chloride anions. The displacement of bicarbonate by chloride alters the bicarbonate:carbonic acid ratio if the body and acidosis results. The increased chloride concentration in the extracellular fluid produces an increased load to the renal tubules and appreciable amounts of chloride anions escape reabsorption. These anions are excreted along with cations and water. Sodium is the principal cation excreted; however, potassium excretion may also be increased to some degree. By increasing the excretion of both extracellular electrolytes and water, ammonium chloride causes a net loss of extracellular fluid and promotes the mobilization of edema fluid.

Pharmacodynamics

Systemic acidifier. In liver ammonium chloride is converted into urea with the liberation of hydrogen ions ( which lowers the pH) and chloride.

Mechanism of action

...Not infrequently intentional butane inhalation results in high morbidity and mortality. A fatal outcome of butane abuse can be caused by asphyxia, cardiac arrhythmia or trauma. The reported number of cases in which death was the consequence of pure butane inhalation is limited, and in most cases a mixture of propellants was involved. This report covers two cases of sudden death due to the sniffing of a cigarette lighter refill containing butane. Autopsy was followed by toxicological, pathohistological and immunohistochemical analysis. Butane gas was confirmed in samples of blood, urine, brain and lungs... Histology showed almost identical changes in the lungs and heart in both cases. The morphology of heart damage on standard H/E stains was of special interest because it displayed all the characteristics of chronic and acute myocardial hypoxia found in the absence of atherosclerotic heart disease. In order to confirm early cardiac death caused by asphyxia due to butane inhalation a panel of immunohistochemical agents was used...

Mechanism of action

Exposure to low temperatures often causes allergic responses or urticaria. Similarly, menthol, a common food additive is also known to cause urticaria, asthma, and rhinitis. However, despite the obvious clinical implications, the molecular mechanisms responsible for inducing allergic responses to low temperatures and menthol have not been determined. Because a non-selective cation channel, transient receptor potential subtype M8 (TRPM8) is activated by cold and menthol, we hypothesized that this channel mediates cold- and menthol-induced histamine release in mast cells. Here, we report that TRPM8 is expressed in the basophilic leukemia mast cell line, RBL-2H3, and that exposure to menthol or low temperatures induced Ca(2+) influx in RBL-2H3 cells, which was reversed by a TRPM8 blocker. Furthermore, menthol, a TRPM8 agonist, induced the dose-dependent release of histamine from RBL-2H3 cells. When TRPM8 transcripts were reduced by siRNA (small interfering RNA), menthol- and cold-induced Ca(2+) influx and histamine release were significantly reduced. In addition, subcutaneous injection of menthol evoked scratching, a typical histamine-induced response which was reversed by a TRPM8 blocker. Thus, our findings indicate that TRPM8 mediates the menthol- and cold-induced allergic responses of mast cells, and suggest that TRPM8 antagonists be viewed as potential treatments for cold- and menthol-induced allergies. /DL-Menthol/ Menthol's characteristic cooling sensation is due, in part, to the activation of sensory neurons generally termed transient receptor potential (TRP) channels, in particular transient receptor potential melastatin family member 8 (TRPM8) and transient receptor potential subfamily A, member 1 (TRPA1). Menthol acts upon TRPM8 receptors by rapidly increasing intracellular calcium and mobilizing calcium flux through the channels to induce cold response signals at the application site. Aside from its cold-inducing sensation capabilities, menthol exhibits cytotoxic effects in cancer cells, induces reduction in malignant cell growth, and engages in synergistic excitation of GABA receptors and sodium ion channels resulting in analgesia. /DL-Menthol/ In recent years, the transient receptor potential melastatin member 8 (TRPM8) channel has emerged as a promising prognostic marker and putative therapeutic target in prostate cancer. We have found that forced overexpression of TRPM8 in PC-3 cells can inhibit the cell proliferation and motility probably through the TRPM8 activation. In this study, we aimed to investigate whether activating the TRPM8 channel by its selective agonist menthol can inhibit the proliferation and motility of androgen-independent prostate cancer (AIPC) with remarkable expression of TRPM8. Menthol is a naturally occurring compound, which has been widely used in cosmetics and pharmaceutical products, and also as flavoring in food. DU145 cells are androgen-independent but have a remarkable expression of TRPM8. The demonstration of the existence of TRPM8 and the absence of TRPA1 in DU145 cells provided the foundation for the following experiments, because both TRPM8 and TRPA1 are molecular targets of menthol. The outcome of MTT assay indicated that menthol inhibited the cell growth (p < 0.01). Cell cycle distribution and scratch assay analysis revealed that menthol induced cell cycle arrest at the G(0)/G(1) phase (p < 0.01). Furthermore, menthol inhibited the migration of DU145 cells by downregulating the focal-adhesion kinase. So it suggests that the activation of the existing TRPM8 channels may serve as a potential and pragmatic treatment for those AIPC with remarkable expression of TRPM8, and menthol is a useful compound for future development as an anticancer agent. /DL-Menthol/

Mechanism of action

Sodium and chloride - major electrolytes of the fluid compartment outside of cells (i.e., extracellular) - work together to control extracellular volume and blood pressure. Disturbances in sodium concentrations in the extracellular fluid are associated with disorders of water balance. Intra-amniotic instillation of 20% sodium chloride injection induces abortion and fetal death. Although the mechanism has not been conclusively determined, some studies indicate that the drug's abortifacient activity may be mediated by prostaglandins released from decidual cells damaged by hypertonic solutions of sodium chloride. Hypertonic sodium chloride-induced uterine contractions are usually sufficient to cause evacuation of both the fetus and placenta; however, abortion may be incomplete in 25-40% of patients. /20% injection/

Pharmacodynamics

Sodium, the major cation of the extracellular fluid, functions primarily in the control of water distribution, fluid balance, and osmotic pressure of body fluids. Sodium is also associated with chloride and bicarbonate in the regulation of the acid-base equilibrium of body fluid. Chloride, the major extracellular anion, closely follows the metabolism of sodium, and changes in the acid-base balance of the body are reflected by changes in the chloride concentration.