Salimia Liniment

Indications

• Hepatic encephalopathy
• Urea cycle disorders
• Acid-base disturbances

Dosage

Children: Refer to the BNF for Children for specific pediatric dosing information.

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

Mechanism of action

Ammonia is crucial for renal excretion and metabolism, which aids in the regulation of acid-base balance by generating bicarbonate ions and promoting renal net acid excretion. Acute exposure to ammonia can activate NMDA receptor signaling pathways, while high concentrations resulting from urea cycle enzyme deficiencies can cause alterations in astrocyte morphology and increased neuroactive metabolites. This includes oxidative/nitrosative stress that impacts neuronal and astrocytic function, contributing to cerebral ammonia toxicity and related neuropsychiatric effects.

Pharmacodynamics

As a gas, ammonia acts as a natural respiratory stimulant. Its renal metabolism contributes to whole body acid-base balance, while its toxic effects at elevated levels can lead to significant neurophysiological changes, particularly in the context of liver dysfunction. Ammonia's role in stimulating oxidative stress responses in brain cells can lead to cellular damage and altered signaling pathways.

Pharmacokinetics

Ammonia is primarily metabolized in the liver, where it is converted to urea through the urea cycle, facilitating its excretion. The balance of ammonia production and clearance is critical for maintaining normal physiological functions. Following inhalation, ammonia is rapidly absorbed and can cause irritation in the respiratory tract. Renal function significantly influences ammonia levels in the body, with changes in kidney function affecting its excretion and thus systemic concentrations.

Pregnancy

Ammonia is generally considered unsafe during pregnancy due to potential risks to fetal development.

Breast-feeding

Ammonia may be present in breast milk; caution is advised.

Storage

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

Indications

• Topical pain relief
• Muscle aches
• Joint pain
• Inflammation

Dosage

Children: For children, the

Adults: For topical application, camphor is usually applied as needed to the affected area, following the instructions on the specific product used. Consult the product label or a healthcare professional for detailed dosing guidelines.

Mechanism of action

Camphor activates the transient receptor potential vanilloid 1 (TRPV1) and TRPV3 channels, which are involved in sensing pain and temperature. It requires higher concentrations to activate TRPV1 compared to capsaicin but notably desensitizes TRPV1 more rapidly and completely. This action is enhanced under inflamed conditions through phospholipase C-coupled receptor stimulation. The distinct activation pathways of camphor contribute to its analgesic effects, making it effective in reducing pain sensitivity.

Pharmacodynamics

The pharmacodynamic properties of camphor are primarily related to its interaction with TRPV1 and TRPV3 channels. By activating these receptors, camphor induces a sensation of warmth and can result in analgesia through sensory nerve excitation and subsequent desensitization. This mechanism is similar to that of other topical analgesics like capsaicin and menthol but is characterized by a faster desensitization of TRPV1. Additionally, camphor's effects may include local vasodilation and increased blood flow to the area of application, which can further alleviate pain and inflammation.

Pharmacokinetics

Camphor is absorbed through the skin when applied topically. Its pharmacokinetic profile involves distribution to various tissues, where it can exert local effects. The metabolism of camphor occurs primarily in the liver, and it is eliminated from the body mainly through urine. The onset of action is typically rapid due to its topical application, and the duration of effect may vary depending on the formulation and concentration used.

Adverse effects

• Skin irritation
• Allergic reactions
• Nausea
• Vomiting
• Dizziness

Precautions

• Use with caution in individuals with sensitive skin
• Avoid contact with eyes and mucous membranes
• Do not apply to broken or irritated skin
• Keep out of reach of children

Pregnancy

Camphor should be used with caution during pregnancy. It is advisable to consult a healthcare professional before use.

Breast-feeding

Camphor should be used with caution while breastfeeding. Consult a healthcare professional for advice.

Storage

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

Formulations

• Topical ointments
• Liniments
• Creams
• Gels

Indications

• Topical pain relief for conditions such as osteoarthritis and neuropathic pain
• Management of postherpetic neuralgia
• Supportive treatment for muscle and joint pain
• Stimulation of digestion and appetite

Dosage

Children: Dosage for pediatric patients should be determined by a healthcare provider, taking into consideration

Adults: Topical formulations generally recommend application to the affected area, with specific dosing instructions provided by the product label. For oral supplements, follow the manufacturer's guidelines or consult a healthcare professional.

Mechanism of action

Capsaicin, the main active component in Capsicum, exerts its effects by binding to the TRPV1 (transient receptor potential vanilloid 1) receptor, which is a cation channel involved in the transmission of pain and heat sensations. This binding leads to the depolarization of sensory neurons, resulting in the release of substance P, a neuropeptide associated with pain signaling. Continuous exposure to capsaicin results in the desensitization of these receptors, leading to decreased pain perception over time.

Pharmacodynamics

The analgesic properties of Capsicum are attributed to its ability to alter the perception of pain. Capsaicin induces a sensation of warmth and pain initially, which is followed by a prolonged analgesic effect due to the depletion of substance P from the nerve endings. Additionally, Capsicum may exhibit anti-inflammatory effects through the modulation of cytokine release and inhibition of inflammatory pathways, contributing to its therapeutic applications in pain management and inflammatory conditions.

Pharmacokinetics

Capsaicin is poorly absorbed when ingested orally, but it can be effectively absorbed through the skin when applied topically. After application, it is metabolized by the liver, and its metabolites are excreted primarily through the kidneys. The onset of action for topical preparations can vary, with effects often observed within hours. The duration of action may last from several hours to days, depending on the formulation and the area of application.

Adverse effects

• Burning sensation at the site of application
• Skin irritation or rash
• Gastrointestinal upset (if ingested)
• Allergic reactions

Precautions

• Avoid contact with eyes and mucous membranes
• Use caution in patients with sensitive skin
• Consult a healthcare professional before use in patients with underlying health conditions

Pregnancy

Capsicum is generally considered unsafe during pregnancy due to potential effects on the fetus. Pregnant women should consult a healthcare provider before use.

Breast-feeding

Capsicum should be used with caution during breastfeeding as it may affect milk production or flavor.

Storage

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

Formulations

• Topical ointments or creams
• Capsules
• Powdered form for oral use

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

Dosage

Children: Refer to specific drug formulation guidelines as methylated compounds encompass a wide range of pharmacological agents, each with its own dosing recommendations.

Adults: Refer to specific drug formulation guidelines as methylated compounds encompass a wide range of pharmacological agents, each with its own dosing recommendations.

Mechanism of action

Methylation can affect the pharmacokinetics of drugs by influencing their solubility, absorption, distribution, metabolism, and excretion. Methylated drugs may have enhanced or reduced activity compared to their unmethylated counterparts, depending on the target receptors and pathways involved. In the context of neurotransmitter metabolism, for example, methylation can lead to the production of active metabolites that exert their effects on the central nervous system.

Pharmacodynamics

The pharmacodynamics of methylated compounds can vary widely depending on the specific drug and its receptor interactions. Methylation can enhance lipophilicity, allowing for better penetration through biological membranes, which may increase the drug's potency or duration of action. Additionally, methylation can affect the binding affinity of a drug to its target, influencing the therapeutic outcome.

Pharmacokinetics

The pharmacokinetics of methylated compounds is influenced by their chemical structure, which affects their absorption, distribution, metabolism, and excretion. Methylated drugs may exhibit altered half-lives due to changes in metabolic pathways. For example, methylation can either activate or deactivate a drug, depending on the metabolic enzymes involved. The presence of methyl groups can also impact the drug's stability and solubility in biological fluids.

Pregnancy

The safety of methylated compounds during pregnancy varies depending on the specific compound and its pharmacological properties. It is essential to assess the benefits and risks before prescribing.

Breast-feeding

Methylated compounds may be excreted in breast milk; caution is advised when administering these medications to breastfeeding mothers.

Storage

Store in a cool, dry place away from light. Specific storage conditions can vary based on the specific methylated compound.

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

• Antimicrobial treatment
• Antioxidant therapy
• Flavoring agent in food
• Natural preservative
• Traditional medicine applications

Dosage

Children: Refer to specific product guidelines or consult a healthcare professional for appropriate dosing.

Adults: Refer to specific product guidelines or consult a healthcare professional for appropriate dosing.

Mechanism of action

The mechanism of action of oleoresin varies depending on its source and the specific compounds it contains. Generally, oleoresins exhibit antimicrobial activity, which may involve the disruption of microbial cell membranes or interference with metabolic processes. Additionally, some components may have anti-inflammatory and antioxidant effects, contributing to their therapeutic potential.

Pharmacodynamics

Oleoresins exhibit a range of pharmacodynamic effects, including antimicrobial, antioxidant, and anti-inflammatory activities. The specific effects will depend on the source of the oleoresin and its chemical composition. These properties are attributed to the various phytochemicals present, such as terpenes, phenolics, and other bioactive compounds, which can modulate biological pathways and influence physiological responses.

Pharmacokinetics

The pharmacokinetics of oleoresin are not well-defined due to the complexity of its composition. Generally, the absorption and metabolism of oleoresins can vary widely based on the individual compounds they contain. Lipophilic components may be absorbed through the gastrointestinal tract and metabolized in the liver, while other components may undergo different metabolic pathways. The elimination half-life is also variable, reflecting the diverse nature of its constituents.

Pregnancy

Safety in pregnancy has not been established, consult healthcare provider.

Breast-feeding

Consult healthcare provider before use during breastfeeding.

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

• Antiseptic use
• Solvent in pharmaceutical preparations
• Management of alcohol withdrawal syndrome
• Treatment of methanol poisoning (as an antidote)

Dosage

Children: Refer to specific medical guidelines or formularies for dosing information, as it varies widely based on the indication and formulation used.

Adults: Refer to specific medical guidelines or formularies for dosing information, as it varies widely based on the indication and formulation used.

Mechanism of action

Ethanol acts primarily by enhancing the effects of the neurotransmitter gamma-aminobutyric acid (GABA) at the GABA-A receptor, leading to increased inhibitory neurotransmission. It also inhibits the N-methyl-D-aspartate (NMDA) receptor, which contributes to its depressant effects. Additionally, ethanol affects the release of various neurotransmitters, including dopamine, which plays a role in the reward pathway and contributes to its addictive properties.

Pharmacodynamics

Ethanol's pharmacodynamic effects are dose-dependent. Low doses can produce mild euphoria, relaxation, and impaired motor coordination. As the dose increases, effects can progress to sedation, respiratory depression, and potentially coma or death in cases of severe intoxication. Chronic use can lead to tolerance and dependence, with withdrawal symptoms occurring upon cessation.

Pharmacokinetics

Ethanol is rapidly absorbed from the gastrointestinal tract, with peak blood concentrations occurring within 30 to 90 minutes after ingestion. It is distributed throughout body water, with a volume of distribution of approximately 0.5 to 0.7 L/kg. Ethanol is metabolized primarily by the liver through the action of alcohol dehydrogenase and aldehyde dehydrogenase, with a typical elimination rate of 10 to 20 mg/dL per hour. It is excreted in urine, breath, and sweat.

Adverse effects

• Nausea
• Vomiting
• Dizziness
• Headache
• Irritation of mucous membranes
• Depression of the central nervous system

Interactions

• Increased sedation with other CNS depressants
• Potential enhancement of effects of certain medications metabolized by the liver

Precautions

• Use with caution in patients with a history of substance abuse
• Monitor for signs of excessive sedation or respiratory depression
• Avoid use in patients with known hypersensitivity to alcohol or other ingredients

Pregnancy

Alcohol is generally advised against during pregnancy due to risks of fetal alcohol spectrum disorders and other complications.

Breast-feeding

Alcohol can pass into breast milk, and breastfeeding mothers should limit intake to avoid potential effects on the infant.

Storage

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

Formulations

• Spirit (ethanol-based liquid)
• Spirit of ammonia
• Spirit of camphor
• Spirit of turpentine

Indications

• Pain management
• Anxiety disorders
• Depression
• Attention-deficit hyperactivity disorder (ADHD)
• Substance use disorders
• Certain types of cancer

Dosage

Children: Refer to BNF for Children for specific paediatric dosing information as it varies widely among synthetic drugs.

Adults: Refer to specific product guidelines or BNF for dosing information as it varies widely among synthetic drugs.

Mechanism of action

Synthetic drugs can act through various mechanisms depending on their structure and intended use. They may function by inhibiting or activating specific receptors, modulating enzyme activity, or affecting neurotransmitter levels in the brain. For example, some synthetic opioids bind to the mu-opioid receptors in the central nervous system, producing analgesic effects.

Pharmacodynamics

The pharmacodynamics of synthetic drugs varies widely based on their chemical composition and target receptors. Generally, these drugs can produce a range of effects from sedation and analgesia to stimulation and increased energy. The potency and efficacy of synthetic drugs depend on their affinity for specific receptors and their ability to cross biological membranes.

Pharmacokinetics

Pharmacokinetics of synthetic drugs involves absorption, distribution, metabolism, and excretion (ADME). These drugs are typically well absorbed after administration, with bioavailability varying by route. They may be extensively metabolized in the liver, often resulting in active metabolites. Elimination half-lives can differ significantly, affecting dosing regimens and potential accumulation in the body.

Pregnancy

The safety of synthetic compounds during pregnancy varies widely. Always assess the specific compound and consult relevant guidelines.

Breast-feeding

The safety of synthetic compounds during breastfeeding depends on the specific compound. Consult relevant guidelines for each individual case.

Storage

Store in a cool, dry place, away from direct sunlight. Specific storage conditions may vary based on the individual compound.

Indications

• Local antiseptic
• Irritant for mucous membranes
• Traditional medicinal uses

Dosage

Children: Refer to established guidelines and clinical practice for specific dosages, as turpentine is not commonly used in modern medicine.

Adults: Refer to established guidelines and clinical practice for specific dosages, as turpentine is not commonly used in modern medicine.

Mechanism of action

Turpentine acts as a local irritant, leading to increased blood flow and inflammatory response in tissues. It may also exert some antimicrobial effects, although the exact pathways are not well defined. The main active components are terpenes, which can affect cellular membranes and interfere with microbial function.

Pharmacodynamics

Turpentine exhibits irritant properties, resulting in stimulation of sensory nerves and local inflammatory responses. It may also have some systemic effects when absorbed, which can lead to toxicity if ingested or inhaled in large amounts. The pharmacological effects are primarily due to its terpene content, which can impact various biological pathways.

Pharmacokinetics

Turpentine is rapidly absorbed through mucous membranes and skin. It is metabolized in the liver, where it undergoes oxidation and conjugation. The metabolites are primarily excreted via the urine. Due to its volatile nature, turpentine can also be inhaled, leading to rapid absorption into the bloodstream. The half-life of turpentine varies based on the method of exposure and individual metabolism.

Contra-indications

• Hypersensitivity to turpentine or any component of the formulation
• Pregnancy and lactation due to potential harmful effects

Adverse effects

• Skin irritation or dermatitis upon topical application
• Gastrointestinal disturbances such as nausea, vomiting, and diarrhea
• Respiratory irritation from inhalation
• Central nervous system effects including headache, dizziness, and confusion
• Kidney damage with prolonged exposure or high doses

Interactions

• May interact with other CNS depressants, increasing sedation
• Potentially enhances the effects of certain medications metabolized by the liver

Precautions

• Use with caution in individuals with pre-existing respiratory conditions
• Should not be ingested or applied to broken skin
• Avoid inhalation of vapors

Pregnancy

Not recommended. Potentially harmful effects on the fetus have been reported.

Breast-feeding

Not recommended. Potential for excretion in breast milk and harmful effects on the infant.

Storage

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

Formulations

• Topical ointments or liniments
• Inhalation solutions
• Oral preparations (not commonly recommended due to toxicity)

Mechanism of action

Renal excretion and metabolism of ammonia is critical in regulation of acid-base balance by generating bicarbonate ions and promoting renal net acid excretion, both under basal conditions and in response to acid-base disturbances. There is evidence that acute ammonia exposure activates NMDA receptor signalling pathways, and high concentrations of ammonia resulting from urea cycle enzyme deficiencies are associated with changes in astrocyte morphology due to glutamine accumulation, changes in the expression of key astrocyte proteins, and increased concentrations of neuroactive L-tryptophan metabolites. ... Ammonia plays a key role in the pathogenesis of hepatic encephalopathy, which manifests as a neuropsychiatric syndrome accompanying acute and chronic liver failure. One consequence of ammonia action on the brain is astrocyte swelling, which triggers the generation of oxidative/nitrosative stress at the level of NADPH oxidase, nitric oxide synthases and the mitochondria. A self-amplifying signaling loop between oxidative stress and astrocyte swelling has been proposed. Consequences of the ammonia-induced oxidative/nitrosative stress response are protein modifications through nitration of tyrosine residues and oxidation of astrocytic and neuronal RNA. Nitrosative stress also mobilizes zinc from intracellular stores with impact on gene expression. These alterations may at least in part mediate cerebral ammonia toxicity through disturbances of intracellular and intercellular signaling and of synaptic plasticity. Oxidative/nitrosative stress and a low-grade cerebral edema as key events in the pathogenesis of ammonia toxicity and hepatic encephalopathy may offer potential new strategies for treatment. Ammonia-induced oxidation of RNA and proteins may impair postsynaptic protein synthesis, which is critically involved in learning and memory consolidation. RNA oxidation offers a novel explanation for multiple disturbances of neurotransmitter systems and gene expression and the cognitive deficits observed in hepatic encephalopathy. SRP: Ammonia in an aqueous environment exists in equilibrium between ionized ammonium cation and the non-ionized ammonia. This equilibrium can be affected by buffers, pH, temperature, and salinity. Thus in many cases it is not possible to assign the associated toxicity to the ionized or non-ionized form of the ammonia-nitrogen. /Aqueous ammonia/ Mechanisms involved in hepatic encephalopathy (HE) still remain poorly understood. It is generally accepted that ammonia plays a major role in this disorder, and that astrocytes represent the principal target of ammonia neurotoxicity. In recent years, studies from several laboratories have uncovered a number of factors and pathways that appear to be critically involved in the pathogenesis of this disorder. Foremost is oxidative and nitrosative stress (ONS), which is largely initiated by an ammonia-induced increase in intracellular Ca(2+). Such increase in Ca(2+) activates a number of enzymes that promote the synthesis of reactive oxygen-nitrogen species, including constitutive nitric oxide synthase, NADPH oxidase and phospholipase A2. ONS subsequently induces the mitochondrial permeability transition, and activates mitogen-activated protein kinases and the transcription factor, nuclear factor-kappaB (NF-kappaB). These factors act to generate additional reactive oxygen-nitrogen species, to phosphorylate various proteins and transcription factors, and to cause mitochondrial dysfunction. This article reviews the role of these factors in the mechanism of HE and ammonia toxicity with a focus on astrocyte swelling and glutamate uptake, which are important consequences of ammonia neurotoxicity.... A new model for ammonia excretion in freshwater fish and its variable linkage to Na(+) uptake and acid excretion /is proposed/. In this model, /the Rhesus protein/ Rhag facilitates NH(3) flux out of the erythrocyte, Rhbg moves it across the basolateral membrane of the branchial i

Pharmacodynamics

As a gas, ammonia is a natural byproduct and respiratory stimulant. Its renal metabolism plays a role in whole body acid-base balance.

Mechanism of action

Camphor is a naturally occurring compound that is used as a major active ingredient of balms and liniments supplied as topical analgesics. ... Capsaicin and menthol, two other topically applied agents widely used for similar purposes, are known to excite and desensitize sensory nerves by acting on two members of transient receptor potential (TRP) channel superfamily: heat-sensitive TRP vanilloid subtype 1 (TRPV1) and cold-sensitive TRP channel M8, respectively. Camphor has recently been shown to activate TRPV3, and here /investigators/ show that camphor also activates heterologously expressed TRPV1, requiring higher concentrations than capsaicin. Activation was enhanced by phospholipase C-coupled receptor stimulation mimicking inflamed conditions. Similar camphor-activated TRPV1-like currents were observed in isolated rat DRG neurons and were strongly potentiated after activation of protein kinase C with phorbol-12-myristate-13-acetate. Camphor activation of rat TRPV1 was mediated by distinct channel regions from capsaicin, as indicated by camphor activation in the presence of the competitive inhibitor capsazepine and in a capsaicin-insensitive point mutant. Camphor did not activate the capsaicin-insensitive chicken TRPV1. TRPV1 desensitization is believed to contribute to the analgesic actions of capsaicin. /The authors/ found that, although camphor activates TRPV1 less effectively, camphor application desensitized TRPV1 more rapidly and completely than capsaicin. Conversely, TRPV3 current sensitized after repeated camphor applications, which is inconsistent with the analgesic role of camphor. /Investigators/ also found that camphor inhibited several other related TRP channels, including ankyrin-repeat TRP 1 (TRPA1). The camphor-induced desensitization of TRPV1 and block of TRPA1 may underlie the analgesic effects of camphor.