Sinegra 100

Indications

• Erectile dysfunction
• Pulmonary arterial hypertension

Dosage

Children: Not licensed for use in children; therefore, specific dosing is not provided.

Adults: For erectile dysfunction, the initial dose is 50 mg taken approximately 1 hour before sexual activity, with adjustments possible based on efficacy and tolerability (maximum of 100 mg). For pulmonary arterial hypertension, the recommended dose is 20 mg three times a day.

Mechanism of action

Sildenafil works by selectively inhibiting phosphodiesterase type 5 (PDE5), an enzyme that degrades cyclic guanosine monophosphate (cGMP) in the corpus cavernosum of the penis. During sexual stimulation, nitric oxide (NO) is released, which activates guanylate cyclase, leading to increased cGMP levels. This results in smooth muscle relaxation and increased blood flow, facilitating an erection. In pulmonary vasculature, sildenafil enhances cGMP levels, promoting vasodilation.

Pharmacodynamics

Sildenafil exhibits high selectivity for PDE5, being approximately 10-times more potent than for PDE6, which is involved in retinal function, and significantly more selective over other phosphodiesterases. This selectivity minimizes adverse effects related to vision. Clinical studies demonstrate that sildenafil improves erectile function significantly in response to sexual stimulation, with effects generally observed within 60 minutes post-administration, lasting for several hours.

Pharmacokinetics

Sildenafil is rapidly absorbed, with peak plasma concentrations occurring within 30 to 120 minutes after oral administration. Its bioavailability is approximately 40%, and it is extensively metabolized in the liver, primarily by CYP3A4 and CYP2C9 enzymes. The elimination half-life is about 4 hours, and it is excreted mainly in the urine as metabolites. Renal impairment may affect its clearance, necessitating dose adjustments in patients with significant renal dysfunction.

Contra-indications

• Hereditary degenerative retinal disorders
• History of non-arteritic anterior ischaemic optic neuropathy
• Recent history of myocardial infarction
• Recent history of stroke
• Systolic blood pressure below 90 mmHg
• Active peptic ulceration
• Anatomical deformation of the penis
• Severe cardiovascular disease
• Severe hepatic impairment
• Predisposition to priapism

Adverse effects

• Headaches
• Nasal complaints
• Asthenia
• Dizziness
• Drowsiness
• Dyspnoea
• Gastrointestinal discomfort
• Muscle complaints
• Nausea
• Palpitations
• Vision blurred
• Vomiting
• Angina pectoris
• Chest pain
• Diarrhoea
• Dry mouth
• Emotional disorder
• Genital pruritus
• Gout
• Haematuria
• Hypertension
• Increased risk of infection
• Influenza-like illness
• Insomnia
• Peripheral oedema
• Rash
• Seasonal allergy
• Tachycardia
• Urinary frequency
• Increased weight

Interactions

• Moderate interactions with antifungals (azoles) that increase exposure
• Moderate interactions with crizotinib, imatinib, letermovir, nilotinib that increase exposure
• Unknown interactions with cobicistat, idelalisib, ribociclib that may increase exposure
• Caution advised with concurrent use of moderate or potent inhibitors of CYP3A4

Precautions

• Careful monitoring in elderly patients and those with severe heart failure
• Caution in patients with anatomical deformation of the penis
• Consideration for active peptic ulceration and bleeding disorders
• Use of effective contraception required during administration
• Pregnancy tests advised for women of childbearing potential
• Caution in patients with cardiovascular disease

Pregnancy

Avoid; teratogenic in animal studies.

Breast-feeding

Manufacturer advises

Indications

• Methemoglobinemia
• Urinary tract infections
• Surgical marking
• Treatment of certain types of cyanide poisoning

Dosage

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

Adults: Refer to the relevant clinical guidelines or the BNF for specific dosing recommendations.

Mechanism of action

Methylene blue acts as a reducing agent, converting methemoglobin back to its functional form, hemoglobin. This is primarily achieved through its action as an electron donor, facilitating the reduction of ferric iron (Fe3+) in hemoglobin to ferrous iron (Fe2+), thereby restoring its oxygen-carrying capacity. It also exhibits antimicrobial properties through its ability to generate reactive oxygen species when exposed to light, which can inhibit bacterial growth.

Pharmacodynamics

The pharmacodynamics of methylene blue involve its role in enhancing oxygen delivery in patients suffering from methemoglobinemia. By converting methemoglobin back to hemoglobin, it effectively increases the amount of hemoglobin available for oxygen transport. The drug also shows effects on the vascular system, where it can induce vasodilation and influence blood pressure.

Pharmacokinetics

Methylene blue is rapidly absorbed after intravenous administration, with peak plasma concentrations occurring within 1 to 3 hours. It is extensively distributed in body tissues and fluids, including the liver, kidneys, and lungs. The drug undergoes hepatic metabolism, primarily through the cytochrome P450 system, and is excreted mainly through urine. The half-life ranges from 5 to 24 hours, depending on the dosage and individual patient factors.

Pregnancy

Consult healthcare provider before use, as safety in pregnancy is not established.

Breast-feeding

Consult healthcare provider before use, as safety during breastfeeding is not established.

Storage

Store in a cool, dry place away from 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

• Used as a disintegrant in tablet formulations
• Enhances the bioavailability of active pharmaceutical ingredients

Dosage

Children: Refer to the specific formulation guidelines, as dosage will vary based on the active ingredient and formulation type.

Adults: Refer to the specific formulation guidelines, as dosage will vary based on the active ingredient and formulation type.

Mechanism of action

Croscarmellose sodium works by swelling and absorbing water when it comes into contact with gastrointestinal fluids. This swelling leads to the rapid disintegration of the tablet or capsule matrix, facilitating the release and absorption of the active pharmaceutical ingredients.

Pharmacodynamics

Croscarmellose sodium is classified as a superdisintegrant. Its ability to rapidly disintegrate solid dosage forms can significantly enhance the dissolution rate of the active ingredient, which is crucial for achieving therapeutic effects in a timely manner.

Pharmacokinetics

Croscarmellose sodium is not absorbed in the gastrointestinal tract and does not exert pharmacological effects in the body. It is considered non-toxic and is excreted unchanged. Its main role is as an excipient, influencing the formulation's characteristics rather than the pharmacokinetics of the active ingredients.

Precautions

• Use with caution in patients with known hypersensitivity to croscarmellose or its components.

Pregnancy

Safety in pregnancy has not been established. Use only if clearly needed.

Breast-feeding

Caution is advised when using during breastfeeding, as safety has not been established.

Storage

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

Formulations

• Powder
• Granules

Indications

• Oxidative stress-related conditions
• Inflammatory conditions
• Potential anti-aging applications
• Vascular health enhancement

Dosage

Children: Refer to specific product formulations and guidelines, as dosing can vary based on the concentration of hydrogen in the product used.

Adults: Refer to specific product formulations and guidelines, as dosing can vary based on the concentration of hydrogen in the product used.

Mechanism of action

Molecular hydrogen acts primarily as an antioxidant and anti-inflammatory agent. It is believed to exert its beneficial effects through the activation of the Nrf2 pathway, which enhances the expression of antioxidant enzymes and protects cells from oxidative stress. Hydrogen-rich environments have been shown to mitigate the harmful effects of various toxins on human umbilical vein endothelial cells, thereby promoting vascular health and longevity.

Pharmacodynamics

Hydrogen's pharmacodynamic properties are linked to its role as a potent antioxidant, which reduces reactive oxygen species (ROS) and modulates inflammation. It has been documented to counteract cellular senescence in endothelial cells, thereby maintaining vascular integrity and promoting overall health. The long-lasting effects of hydrogen exposure can be observed even after its concentration in the medium has decreased, suggesting a sustained activation of protective cellular pathways.

Pharmacokinetics

Hydrogen is a gaseous molecule that diffuses rapidly across biological membranes. Its absorption and distribution in the body are influenced by the method of administration, with hydrogen-rich water being a common delivery form. Once in the bloodstream, hydrogen is quickly utilized by tissues, and its concentration diminishes rapidly, with a half-life that can vary based on conditions. The elimination of hydrogen primarily occurs via exhalation, making it a non-toxic molecule with a favorable safety profile.

Pregnancy

Hydrogen is generally considered safe during pregnancy, but it is advisable to consult a healthcare provider for specific recommendations.

Breast-feeding

Hydrogen is considered safe during breastfeeding, but as with any substance, it is recommended to discuss with a healthcare provider.

Storage

Hydrogen should be stored in a cool, dry place away from direct sunlight and heat sources, in appropriate gas cylinders designed for compressed gases.

Formulations

• Hydrogen gas (H2)
• Hydrogen-rich water

Mechanism of action

Hydrogenphosphate acts as a substrate for various enzymatic reactions where phosphate groups are transferred or incorporated into organic molecules. It is involved in metabolic pathways such as nicotine biosynthesis and NAD/NADH cycling, facilitating biochemical reactions that are vital for cellular function.

Pharmacodynamics

Hydrogenphosphate is crucial for maintaining cellular homeostasis. It regulates acid-base balance and is involved in energy metabolism. The phosphate groups it provides are integral to the structure and function of ATP, which is the primary energy currency of the cell. Additionally, hydrogenphosphate influences signal transduction pathways through phosphorylation and dephosphorylation processes.

Pharmacokinetics

Hydrogenphosphate is readily absorbed in the gastrointestinal tract and distributed throughout the body. Its elimination primarily occurs through renal excretion, where it is filtered and reabsorbed by the kidneys. The balance of hydrogenphosphate levels is tightly regulated by various physiological mechanisms to ensure proper metabolic function.

Pregnancy

There is limited information regarding the safety of hydrogenphosphate in pregnancy. Consult relevant guidelines and consider potential risks versus benefits.

Breast-feeding

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

Storage

Store in a cool, dry place away from direct sunlight. Ensure containers are tightly closed.

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

• Tablet coating
• Granule coating
• Improvement of drug stability
• Taste masking
• Aesthetic enhancement of pharmaceuticals

Dosage

Children: Dosage will depend on the specific formulation and active ingredients of the medication being coated. Refer to the specific product information for guidance.

Adults: Dosage will depend on the specific formulation and active ingredients of the medication being coated. Refer to the specific product information for guidance.

Mechanism of action

Opadry functions primarily as a coating polymer that adheres to the surface of tablets or granules, creating a protective layer. This layer can control the release of the active ingredient and protect it from environmental factors such as moisture and light. The specific composition of Opadry can vary, but it typically includes film-forming agents, plasticizers, and colorants that work together to achieve the desired coating characteristics.

Pharmacodynamics

The pharmacodynamics of Opadry is largely focused on its physical and chemical properties rather than specific biological interactions. The coating alters the dissolution characteristics of the drug, potentially leading to modified release profiles. This can enhance drug bioavailability or control the release rate of the active ingredient, thereby impacting the therapeutic effect.

Pharmacokinetics

As a coating agent, Opadry itself is not absorbed into the systemic circulation and does not have pharmacokinetic properties related to absorption, distribution, metabolism, or excretion of an active pharmaceutical ingredient. Its impact on pharmacokinetics is indirect, as it affects how the active drug is released and absorbed in the gastrointestinal tract.

Pregnancy

Opadry is a film-coating agent, and specific studies on its effects during pregnancy are not well-documented. Generally, it is advisable to use medications cautiously during pregnancy. Consult a healthcare provider for guidance.

Breast-feeding

Limited data are available regarding the safety of Opadry during breastfeeding. It is recommended to consult a healthcare provider before use.

Storage

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

Formulations

• Opadry OY - a coating system for oral solid dosage forms
• Opadry II - a polymer-based coating system for tablet and capsule applications

Indications

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

Dosage

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

Mechanism of action

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

Pharmacodynamics

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

Pharmacokinetics

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

Adverse effects

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

Precautions

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

Pregnancy

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

Breast-feeding

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

Storage

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

Formulations

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

Mechanism of action

Sildenafil is an oral therapy for erectile dysfunction. In the natural setting, i.e. with sexual stimulation, it restores impaired erectile function by increasing blood flow to the penis. The physiological mechanism responsible for the erection of the penis involves the release of nitric oxide (NO) in the corpus cavernosum during sexual stimulation. Nitric oxide then activates the enzyme guanylate cyclase, which results in increased levels of cyclic guanosine monophosphate (cGMP), producing smooth muscle relaxation in the corpus cavernosum and allowing inflow of blood. Sildenafil is a potent and selective inhibitor of cGMP specific phosphodiesterase type 5 (PDE5) in the corpus cavernosum, where PDE5 is responsible for degradation of cGMP. Sildenafil has a peripheral site of action on erections. Sildenafil has no direct relaxant effect on isolated human corpus cavernosum but potently enhances the relaxant effect of NO on this tissue. When the NO/cGMP pathway is activated, as occurs with sexual stimulation, inhibition of PDE5 by sildenafil results in increased corpus cavernosum levels of cGMP. Therefore sexual stimulation is required in order for sildenafil to produce its intended beneficial pharmacological effects. Moreover, apart from the presence of PDE5 in the corpus cavernosum of the penis, PDE5 is also present in the pulmonary vasculature. Sildenafil, therefore, increases cGMP within pulmonary vascular smooth muscle cells resulting in relaxation. In patients with pulmonary arterial hypertension, this can lead to vasodilation of the pulmonary vascular bed and, to a lesser degree, vasodilatation in the systemic circulation. Sildenafil is a selective inhibitor of phosphodiesterase type 5 (PDE5), an enzyme responsible for degrading cyclic guanosine monophosphate (cGMP) in the corpus cavernosum. By diminishing the effect of PDE5, sildenafil facilitates the effect of nitric oxide during sexual stimulation; cGMP levels increase, smooth muscle relaxes, and blood flows into the corpus cavernosum, producing an erection. Without sexual stimulation, sildenafil has no effect on erections. It has been extensively demonstrated that hydrogen sulfide (H2S) is implicated is several physiological and pathological conditions. In particular, it has been shown that H2S causes relaxation in human penile tissues and inhibits phosphodiesterase (PDE) activity in vessels. Beside sildenafil increases H2S generation in human bladder and tadalafil in myocardial tissues. Therefore, /the/ aim /of the study/ was to demonstrate the link between H2S and PDE-5 in mice corpus cavernosum tissues. ... The effects of sildenafil (10 uM, 0.5 hr); PDE-5 inhibitor, on H2S production as well as the H2S -induced relaxations in mice penile tissues /was investigated/. Penile tissues from CD1 mouse corpus cavernosum (MCC) were used. Functional studies were performed by myograph in Krebs solution. Western blot analysis was performed in order to evaluate CBS and CSE expression and methylene blue assay for measurement of H2S levels. In order to investigate functional significance of H2S on sildenafil-induced augmentation of endothelial relaxation in MCC the sildenafil effect was evaluated on acetylcholine (ACh), L-cysteine and NaHS-induced relaxations in presence or not of CSE enzyme inhibitor PPG (10 uM, 0.5 hr). In order to achieve this issue the H2S production in MCC tissues was also evaluated by incubating the penile tissue with sildenafil in presence or absence of the CSE inhibitor PPG (10 uM, 0.5 hr) Both CBS and CSE were expressed in MCC and the enzymes efficiently converted L-cysteine into H2S. Further /it was shown/ that sildenafil caused a significant increase in H2S production and this augmentation was reversed by CSE inhibition. /It was/ found that sildenafil induced an increase in both ACh and L-cysteine-induced relaxations and these augmentations reversed by CSE inhibitor PPG in MCC pre-contracted with phenylephrine (3.10-5M). Beside sildenafil did not sign

Pharmacodynamics

In vitro studies have shown that sildenafil is selective for phosphodiesterase-5 (PDE5). Its effect is more potent on PDE5 than on other known phosphodiesterases. In particular, there is a 10-times selectivity over PDE6 which is involved in the phototransduction pathway in the retina. There is an 80-times selectivity over PDE1, and over 700-times over PDE 2, 3, 4, 7, 8, 9, 10 and 11. And finally, sildenafil has greater than 4,000-times selectivity for PDE5 over PDE3, the cAMP-specific phosphodiesterase isoform involved in the control of cardiac contractility. In eight double-blind, placebo-controlled crossover studies of patients with either organic or psychogenic erectile dysfunction, sexual stimulation resulted in improved erections, as assessed by an objective measurement of hardness and duration of erections (via the use of RigiScan®), after sildenafil administration compared with placebo. Most studies assessed the efficacy of sildenafil approximately 60 minutes post-dose. The erectile response, as assessed by RigiScan®, generally increased with increasing sildenafil dose and plasma concentration. The time course of effect was examined in one study, showing an effect for up to 4 hours but the response was diminished compared to 2 hours. Sildenafil causes mild and transient decreases in systemic blood pressure which, in the majority of cases, do not translate into clinical effects. After chronic dosing of 80 mg, three times a day to patients with systemic hypertension the mean change from baseline in systolic and diastolic blood pressure was a decrease of 9.4 mmHg and 9.1 mmHg respectively. After chronic dosing of 80 mg, three times a day to patients with pulmonary arterial hypertension lesser effects in blood pressure reduction were observed (a reduction in both systolic and diastolic pressure of 2 mmHg) . At the recommended dose of 20 mg three times a day no reductions in systolic or diastolic pressure were seen. Single oral doses of sildenafil up to 100 mg in healthy volunteers produced no clinically relevant effects on ECG. After chronic dosing of 80 mg three times a day to patients with pulmonary arterial hypertension no clinically relevant effects on the ECG were reported either. In a study of the hemodynamic effects of a single oral 100 mg dose of sildenafil in 14 patients with severe coronary artery disease (CAD) (> 70 % stenosis of at least one coronary artery), the mean resting systolic and diastolic blood pressures decreased by 7 % and 6 % respectively compared to baseline. Mean pulmonary systolic blood pressure decreased by 9%. Sildenafil showed no effect on cardiac output and did not impair blood flow through the stenosed coronary arteries. Mild and transient differences in color discrimination (blue/green) were detected in some subjects using the Farnsworth-Munsell 100 hue test at 1 hour following a 100 mg dose, with no effects evident after 2 hours post-dose. The postulated mechanism for this change in color discrimination is related to inhibition of PDE6, which is involved in the phototransduction cascade of the retina. Sildenafil has no effect on visual acuity or contrast sensitivity. In a small size placebo-controlled study of patients with documented early age-related macular degeneration (n = 9), sildenafil (single dose, 100 mg) demonstrated no significant changes in visual tests conducted (which included visual acuity, Amsler grid, color discrimination simulated traffic light, and the Humphrey perimeter and photostress test).

Mechanism of action

Substantial evidence indicates that molecular hydrogen (H2) has beneficial vascular effects because of its antioxidant and/or anti-inflammatory effects. Thus, hydrogen-rich water may prove to be an effective anti-aging drink. This study examined the effects of H2 on endothelial senescence and clarified the mechanisms involved. Hydrogen-rich medium was produced by a high-purity hydrogen gas generator. Human umbilical vein endothelial cells (HUVECs) were incubated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) for various time periods in normal or hydrogen-rich medium. The baseline H2concentration in hydrogen-rich medium was 0.55 +/- 0.07 mmol/L. This concentration gradually decreased, and H2 was almost undetectable in medium after 12 hr. At 24 hr after TCDD exposure, HUVECs treated with TCDD exhibited increased 8OHdG and acetyl-p53 expression, decreased nicotinamide adenine dinucleotide (NAD(+))/NADH ratio, impaired Sirt1 activity, and enhanced senescence-associated beta-galactosidase. However, HUVECs incubated in hydrogen-rich medium did not exhibit these TCDD-induced changes accompanying Nrf2 activation, which was observed even after H2 was undetectable in the medium. Chrysin, an inhibitor of Nrf2, abolished the protective effects of H2 on HUVECs. H2 has long-lasting antioxidant and anti-aging effects on vascular endothelial cells through the Nrf2 pathway, even after transient exposure to H2. Hydrogen-rich water may thus be a functional drink that increases longevity. /Hydrogen-rich water/ Amyloid beta (Abeta) peptides are identified /as a/ cause of neurodegenerative diseases such as Alzheimer's disease (AD). Previous evidence suggests Abeta-induced neurotoxicity is linked to the stimulation of reactive oxygen species (ROS) production. The accumulation of Abeta-induced ROS leads to increased mitochondrial dysfunction and triggers apoptotic cell death. This suggests antioxidant therapies may be beneficial for preventing ROS-related diseases such as AD. Recently, hydrogen-rich water (HRW) has been proven effective in treating oxidative stress-induced disorders because of its ROS-scavenging abilities. However, the precise molecular mechanisms whereby HRW prevents neuronal death are still unclear. In the present study, we evaluated the putative pathways by which HRW protects against Abeta-induced cytotoxicity /in SK-N-MC cells/. Our results indicated that HRW directly counteracts oxidative damage by neutralizing excessive ROS, leading to the alleviation of Abeta-induced cell death. In addition, HRW also stimulated AMP-activated protein kinase (AMPK) in a sirtuin 1 (Sirt1)-dependent pathway, which upregulates forkhead box protein O3a (FoxO3a) downstream antioxidant response and diminishes Abeta-induced mitochondrial potential loss and oxidative stress. Taken together, our findings suggest that HRW may have potential therapeutic value to inhibit Abeta-induced neurotoxicity. /Hydrogen-rich water/ The NLRP3 inflammasome, an intracellular multi-protein complex controlling the maturation of cytokine interleukin-1beta, plays an important role in lipopolysaccharide (LPS)-induced inflammatory cascades. Recently, the production of mitochondrial reactive oxygen species (mtROS) in macrophages stimulated with LPS has been suggested to act as a trigger during the process of NLRP3 inflammasome activation that can be blocked by some mitochondria-targeted antioxidants. Known as a ROS scavenger, molecular hydrogen (H2) has been shown to possess therapeutic benefit on LPS-induced inflammatory damage in many animal experiments. Due to the unique molecular structure, H2 can easily target the mitochondria, suggesting that H2 is a potential antagonist of mtROS-dependent NLRP3 inflammasome activation. Here we have showed that, in mouse macrophages, H2 exhibited substantial inhibitory activity against LPS-initiated NLRP3 inflammasome activation by scavenging mtROS. Moreover, the elimination of mtROS by H2 resultantly inhibited mtROS-mediated NLRP3 deubi

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