Tizigesic 4

Indications

• Spasticity associated with multiple sclerosis
• Spasticity due to spinal cord injury or disease

Dosage

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

Adults: Initially 2 mg daily, increased in steps of 2 mg at intervals of 1 to 4 days, with a maximum of 36 mg per day in divided doses.

Mechanism of action

Tizanidine reduces spasticity by causing presynaptic inhibition of motor neurons through agonist actions at Alpha-2 adrenergic receptor sites. This central action decreases the release of excitatory amino acids like glutamate and aspartate, which are involved in muscle spasm. The primary effect occurs on spinal polysynaptic pathways, and it may also exhibit anti-nociceptive and anticonvulsant effects through its action on Alpha-2 receptors.

Pharmacodynamics

Tizanidine is effective in reducing muscle spasticity, characterized by increased muscle tone and involuntary contractions, which can significantly impair mobility and quality of life. By acting as an agonist at Alpha-2 adrenergic receptors, Tizanidine allows for the relief of muscle tightness and spasms, enabling individuals to engage more comfortably in daily activities. It does not exert direct effects on skeletal muscle fibers or the neuromuscular junction and shows minimal impact on monosynaptic spinal reflexes.

Pharmacokinetics

Tizanidine is rapidly absorbed after oral administration, with peak plasma concentrations typically occurring within 1 to 2 hours. It has a relatively short half-life, necessitating multiple daily doses for effective management of spasticity. The drug is extensively metabolized in the liver, primarily by the cytochrome P450 system, and caution is advised in patients with hepatic impairment due to the potential for altered drug levels. Renal impairment may also influence its pharmacokinetics.

Contra-indications

• Brain damage
• Coma
• Epilepsy
• Myasthenia gravis
• Pre-coma

Adverse effects

• Angioedema
• Anxiety
• Bradycardia
• Confusion
• Conjunctivitis
• Dizziness
• Drowsiness
• Dyspepsia
• Fever
• Flushing
• Headache
• Hepatic disorders
• Hypotension
• Insomnia
• Leukopenia
• Memory loss
• Nasal congestion
• Nausea
• Seizures
• Skin reactions
• Syncope
• Taste disturbance
• Metallic taste
• Vertigo
• Vision disorders
• Vomiting

Interactions

• Combined hormonal contraceptives: Severe (increases exposure)
• Mexiletine: Severe (increases exposure)
• Osilodrostat: Severe (increases exposure)
• Ciprofloxacin: Severe (increases exposure)
• Rucaparib: Severe (increases exposure)
• Fluvoxamine: Severe (increases exposure)
• Vemurafenib: Severe (increases exposure)
• Givosiran: Moderate (increases exposure)
• Axitinib: Unknown (increases exposure)
• Ritonavir: Unknown (decreases exposure)

Precautions

• Caution in hepatic impairment (risk of increased half-life)
• Caution in renal impairment
• Drowsiness may affect performance of skilled tasks (e.g., driving); effects may be enhanced by alcohol

Pregnancy

Avoid in the first trimester; thereafter, sufficient use only if potential benefit outweighs risk (no information available).

Breast-feeding

Avoid-no information available.

Storage

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

Formulations

• Tablets: 2 mg, 3 mg, 4 mg
• Oral suspension: 36 mg per day

Indications

• Caffeine sensitivity
• Fatigue management
• Attention deficit hyperactivity disorder (ADHD)
• Weight loss adjunct
• Respiratory stimulant in apnea of prematurity

Dosage

Children: Refer to specific drug guidelines or product information for dosing as it varies by indication and formulation.

Adults: Refer to specific drug guidelines or product information for dosing as it varies by indication and formulation.

Mechanism of action

The mechanism of action for anhydrous substances varies depending on the specific drug in its anhydrous form. Generally, the absence of water can alter the solubility and absorption of the drug, enhancing its bioavailability. For example, in the case of anhydrous caffeine, it acts as a central nervous system stimulant by antagonizing adenosine receptors and increasing the release of neurotransmitters like dopamine and norepinephrine.

Pharmacodynamics

Pharmacodynamics of anhydrous formulations depends on the specific active ingredient. In the case of stimulants such as caffeine, the pharmacodynamic effects include increased alertness, reduced perception of fatigue, and improved cognitive performance. The anhydrous form may allow for faster onset of action and increased potency compared to its hydrated counterpart.

Pharmacokinetics

Pharmacokinetics will vary by compound, but generally, anhydrous forms may exhibit altered absorption rates due to their increased solubility. The distribution, metabolism, and excretion profiles can also be influenced by the absence of water, potentially leading to quicker therapeutic effects or side effects. For instance, anhydrous caffeine is rapidly absorbed in the gastrointestinal tract, with peak plasma concentrations occurring within 30 to 60 minutes.

Pregnancy

The safety of anhydrous substances during pregnancy has not been thoroughly established. It is advisable to consult healthcare professionals before use.

Breast-feeding

It is recommended to exercise caution and seek professional advice before using anhydrous substances while breastfeeding.

Storage

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

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

• Hypovolemic shock
• Severe burns
• Postoperative fluid replacement
• Sepsis
• Trauma management

Dosage

Children: Refer to established guidelines for specific dosing, as it varies based on the type of colloidal solution used and the clinical condition being treated.

Adults: Refer to established guidelines for specific dosing, as it varies based on the type of colloidal solution used and the clinical condition being treated.

Mechanism of action

Colloidal solutions work by maintaining oncotic pressure in the blood, thus helping to retain fluid within the vascular system. This is primarily due to the large molecular weight of the colloidal particles, which cannot easily pass through capillary walls. The presence of colloids in the blood helps to draw water into the circulation, increasing blood volume and improving tissue perfusion.

Pharmacodynamics

The pharmacodynamics of colloidal solutions are centered on their ability to exert osmotic pressure, which helps maintain blood volume and pressure. This effect is particularly important in conditions such as hypovolemia and shock, where fluid replacement is necessary to restore hemodynamic stability. The efficacy of colloidal solutions can vary depending on the type of colloid used, as well as the underlying clinical condition being treated.

Pharmacokinetics

Colloidal solutions are typically administered intravenously and their pharmacokinetics can vary based on the specific formulation. Generally, colloids are distributed throughout the vascular compartment and have a longer duration of action compared to crystalloids, as they remain in circulation longer. The elimination of colloids is primarily through the reticuloendothelial system, where they are metabolized or eliminated by the liver and spleen. Factors such as particle size and composition can influence their distribution and clearance.

Adverse effects

• Allergic reactions
• Injection site reactions
• Nausea
• Vomiting
• Headache
• Fever

Precautions

• Use with caution in patients with known allergies to any component of the formulation
• Monitor for signs of hypersensitivity during administration
• Consider volume overload in patients with cardiac or renal impairment

Pregnancy

The safety of colloidal solutions during 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 colloidal solutions are excreted in human milk. Caution should be exercised when administering to breastfeeding mothers.

Storage

Store at room temperature, protect from light, and do not freeze. Keep out of reach of children.

Formulations

• Colloidal silver
• Colloidal gold
• Colloidal iron
• Other metal colloids

Indications

• Lactose intolerance
• As a filler or excipient in pharmaceutical formulations

Dosage

Children: Refer to the BNF for Children for specific dosing information based on age and clinical context.

Adults: Refer to the BNF for specific dosing information based on clinical context.

Mechanism of action

Lactose is metabolized in the intestine by the enzyme lactase into its constituent monosaccharides, glucose and galactose. In individuals with lactase deficiency, unabsorbed lactose passes into the colon, where it is fermented by bacteria, leading to gas production and osmotic effects that contribute to diarrhea.

Pharmacodynamics

The pharmacodynamics of lactose are primarily related to its effects on gastrointestinal function. In healthy individuals, lactose is effectively broken down into glucose and galactose, which are absorbed and utilized for energy. In individuals with lactose intolerance, the unabsorbed lactose can cause osmotic diarrhea and colonic fermentation, leading to discomfort and symptoms associated with lactose intolerance.

Pharmacokinetics

Lactose is not absorbed in the gastrointestinal tract until it is hydrolyzed into glucose and galactose by lactase. The absorption of glucose and galactose occurs in the small intestine. The half-life is not applicable as lactose is not typically administered as a medication but is rather ingested as a natural component of food. Its metabolism primarily occurs in the intestine.

Adverse effects

• Bloating
• Diarrhea
• Abdominal pain
• Flatulence

Precautions

• Use with caution in patients with lactose intolerance.
• Consider potential for gastrointestinal upset in sensitive individuals.

Pregnancy

Lactose is generally considered safe for use during pregnancy. However, consult a healthcare professional for individual advice.

Breast-feeding

Lactose is safe to use while breastfeeding, as it is a natural sugar present in breast milk.

Storage

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

Formulations

• Powder
• Granules
• Tablets
• Syrup

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.

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

Dosage

Children: Refer to established dietary guidelines for children, as specific dosing for stearic acid is not typically defined.

Adults: Refer to established dietary guidelines and clinical recommendations for fatty acid intake, as specific dosing for stearic acid is not typically defined.

Mechanism of action

Stearic acid is metabolized in the liver and can be converted to oleic acid through a process called desaturation. It does not significantly affect cholesterol levels compared to other saturated fatty acids, as it can be converted into monounsaturated fatty acids. Stearic acid may also modulate signaling pathways involved in inflammation and metabolism.

Pharmacodynamics

Stearic acid exhibits various physiological effects, including modulation of lipid metabolism. It has been shown to influence the composition of cell membranes and can affect the fluidity and function of membranes due to its saturated structure. Stearic acid may also play a role in the regulation of gene expression related to lipid metabolism and inflammation.

Pharmacokinetics

Stearic acid is absorbed from the gastrointestinal tract and is incorporated into chylomicrons for transport in the bloodstream. It is metabolized primarily in the liver, where it undergoes beta-oxidation to produce energy. The elimination half-life and specific metabolic pathways may vary based on dietary intake and individual metabolic differences.

Pregnancy

There are no established guidelines regarding the use of stearic acid during pregnancy. Consultation with a healthcare provider is recommended.

Breast-feeding

There is limited information available on the use of stearic acid during breastfeeding. Caution is advised.

Storage

Store in a cool, dry place away from direct sunlight. Keep container tightly closed.

Formulations

• Capsules
• Tablets
• Powder
• Topical ointments

Mechanism of action

Tizanidine reduces spasticity by causing presynaptic inhibition of motor neurons via agonist actions at Alpha-2 adrenergic receptor sites. This drug is centrally acting and leads to a reduction in the release of excitatory amino acids like glutamate and aspartate, which cause neuronal firing that leads to muscle spasm. The above reduction and excitatory neurotransmitter release results in presynaptic inhibition of motor neurons. The strongest effect of tizanidine has been shown to occur on spinal polysynaptic pathways. The anti-nociceptive and anticonvulsant activities of tizanidine may also be attributed to agonist action on Alpha-2 receptors. Tizanidine also binds with weaker affinity to the Alpha-1 receptors, explaining its slight and temporary effect on the cardiovascular system.

Pharmacodynamics

**A note on spasticity** Spasticity is an increase in muscle accompanied by uncontrolled, repetitive contractions of skeletal muscles which are involuntary. The patient suffering from muscle spasticity may have reduced mobility and high levels of pain, contributing to poor quality of life and problems performing activities of personal hygiene and care. **General effects** Tizanidine is a rapidly acting drug used for the relief of muscle spasticity when it is required for performing specific activities. It acts as an agonist at Alpha-2 adrenergic receptor sites and relieves symptoms of muscle spasticity, allowing the continuation of normal daily activities. In animal models, tizanidine has not been shown to exert direct effects on skeletal muscle fibers or the neuromuscular junction, and has shown no significant effect on monosynaptic spinal reflexes (consisting of the communication between only 1 sensory neuron and 1 motor neuron). The frequency of muscle spasm and clonus are shown to be decreased by tizanidine. Tizanidine shows a stronger action on polysynaptic reflexes, which involve several interneurons (relay neurons) communicating with motor neurons stimulating muscle movement. **Effects on blood pressure and heart rate** This drug decreases heart rate and blood pressure in humans. Despite this, rebound hypertension and tachycardia along with increased spasticity can occur when tizanidine is abruptly discontinued.

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