APCALIS SX 20

Indications

• Erectile dysfunction (ED)
• Pulmonary arterial hypertension (PAH)
• Benign prostatic hyperplasia (BPH)

Dosage

Children: Not established; refer to the BNF for Children for further guidance.

Adults: Refer to the specific guidelines in the BNF for appropriate dosage.

Mechanism of action

Tadalafil selectively inhibits phosphodiesterase-5 (PDE5), leading to increased levels of cyclic guanosine monophosphate (cGMP). This enhances smooth muscle relaxation in penile tissues during sexual arousal by preventing the breakdown of cGMP, thereby facilitating increased blood flow and erection. In PAH, tadalafil promotes vasodilation of the pulmonary arteries, reducing blood pressure in these vessels. In BPH, it may decrease smooth muscle cell proliferation, alleviating urinary symptoms.

Pharmacodynamics

Tadalafil enhances sexual stimulation-dependent smooth muscle relaxation in the penis, resulting in increased blood flow and erection. In PAH, it produces vasodilation in the pulmonary vasculature, lowering pulmonary artery pressure. For BPH, tadalafil may alleviate urinary symptoms by reducing prostate size and relieving anatomical obstruction. Its lower affinity for PDE6 compared to other PDE5 inhibitors results in fewer visual side effects.

Pharmacokinetics

Tadalafil is well absorbed orally, with peak plasma concentrations occurring within 2 hours. Its bioavailability is approximately 80%, and it has a half-life of approximately 17.5 hours, allowing for once-daily dosing for some indications. Tadalafil is metabolized primarily in the liver via the cytochrome P450 system, mainly CYP3A4, and is excreted as metabolites in the feces and urine. The presence of food does not significantly affect its absorption.

Contra-indications

• Systolic blood pressure less than 90 mmHg
• Concurrent use of nitrates for angina

Adverse effects

• Headache
• Flushing
• Dyspepsia
• Nausea
• Back pain
• Myalgia
• Visual disturbances
• Hearing impairment
• Priapism
• Hypotension

Interactions

• Cobicistat + tadalafil: Moderate (increases exposure)
• Antifungals, azoles + tadalafil: Unknown (increases exposure)
• Crizotinib + tadalafil: Unknown (increases exposure)
• Idelalisib + tadalafil: Unknown (increases exposure)
• Imatinib + tadalafil: Unknown (increases exposure)
• Letermovir + tadalafil: Unknown (increases exposure)
• Nilotinib + tadalafil: Unknown (increases exposure)

Precautions

• Caution in patients with hepatic impairment
• Consider dose adjustment in mild to moderate impairment
• Discontinue if sudden visual impairment occurs

Pregnancy

Use only if potential benefit outweighs risk; no evidence of harm in animal studies.

Breast-feeding

Manufacturer advises avoiding use; no information available.

Storage

Store in a cool, dry place away from light.

Formulations

• Tadalafil 2.5 mg tablets
• Tadalafil 5 mg tablets
• Tadalafil 10 mg tablets
• Tadalafil 20 mg tablets

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

• 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

• Used as an excipient in pharmaceutical formulations
• Improves solubility and stability of active ingredients
• Facilitates drug absorption

Dosage

Children: Refer to specific product guidelines as hydroxypropyl is typically used as an excipient and not dosed independently.

Adults: Refer to specific product guidelines as hydroxypropyl is typically used as an excipient and not dosed independently.

Mechanism of action

Hydroxypropyl functions primarily as a solubilizing agent, which aids in the dissolution of poorly soluble drugs. It interacts with water and other solvents to improve the dispersion of pharmaceutical compounds, thereby enhancing their bioavailability. Hydroxypropyl may also facilitate the permeability of drug molecules through biological membranes, contributing to their overall efficacy.

Pharmacodynamics

The pharmacodynamics of hydroxypropyl relate to its role in improving the physicochemical properties of drug formulations. By increasing solubility and stability, hydroxypropyl can enhance the absorption of drugs administered via various routes, including oral and topical. Its non-toxic nature allows for safe incorporation into formulations, making it suitable for a wide range of applications.

Pharmacokinetics

The pharmacokinetics of hydroxypropyl have not been extensively studied as it primarily acts as an excipient rather than an active pharmaceutical ingredient. When used in formulations, it is typically not absorbed into systemic circulation in significant amounts, thereby minimizing potential systemic effects. Hydroxypropyl is generally regarded as safe when used in appropriate amounts in drug formulations.

Pregnancy

Hydroxypropyl is not classified for use during pregnancy, and its safety has not been established. Caution is advised.

Breast-feeding

There is limited information on the excretion of hydroxypropyl in human milk. Caution is advised when administering to breastfeeding women.

Storage

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

Indications

• Improvement of drug solubility
• Controlled release of active pharmaceutical ingredients
• Enhancement of bioavailability for poorly soluble drugs

Dosage

Children: Refer to the specific API's dosing guidelines as Insacoat does not have a standalone dosage recommendation.

Adults: Refer to the specific API's dosing guidelines as Insacoat does not have a standalone dosage recommendation.

Mechanism of action

Insacoat functions by forming a protective layer around the API, allowing for improved solubility and stability. This coating can also facilitate the targeted release of the drug at specific sites in the gastrointestinal tract, enhancing the therapeutic effect while minimizing side effects.

Pharmacodynamics

The pharmacodynamics of Insacoat relates to its ability to modify the release profile of the drug it coats. By controlling the dissolution of the API, Insacoat can prolong the duration of action and improve the efficacy of the medication. This is particularly beneficial for drugs that have a narrow therapeutic index or those that require sustained release to maintain effective plasma concentrations.

Pharmacokinetics

The pharmacokinetics of Insacoat are influenced by the characteristics of the API it encapsulates. Generally, the coating can affect the absorption rate and the onset of action of the drug. Insacoat aims to improve the bioavailability of poorly soluble drugs by enhancing their solubility in the gastrointestinal fluids. However, specific pharmacokinetic profiles will vary depending on the API, the formulation, and the route of administration.

Pregnancy

There is limited data on the safety of Insacoat during pregnancy. It is advisable to only use this medication if the benefits outweigh the risks.

Breast-feeding

Caution is advised when using Insacoat while breastfeeding, as it is unclear whether it passes into breast milk. Consult a healthcare provider before use.

Storage

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

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

• Cleansing agent in topical formulations
• Emulsifying agent in cosmetic products
• Foaming agent in shampoos and body washes

Dosage

Children: Refer to specific product formulations for appropriate concentrations and application methods.

Adults: Refer to specific product formulations for appropriate concentrations and application methods.

Mechanism of action

Lauryl sulfate functions as an anionic surfactant. It reduces the surface tension between different substances, allowing for better spreading and wetting. In the context of cleansing, it facilitates the removal of dirt and oils from the skin and hair by emulsifying these substances, thus making them easier to rinse away with water.

Pharmacodynamics

As a surfactant, lauryl sulfate displays properties that can disrupt cellular membranes and alter permeability. This mechanism is beneficial in enhancing the penetration of other therapeutic agents in topical formulations. However, its irritant potential on skin and mucous membranes should be noted, as it can lead to dryness and irritation with prolonged exposure.

Pharmacokinetics

Lauryl sulfate is primarily applied topically and is not intended for systemic absorption. When used in formulations, it acts locally at the site of application. Its absorption through the skin is minimal, and any systemic exposure is limited. Metabolism and excretion pathways are not well-defined for topical applications, as it is largely washed away after use.

Pregnancy

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

Breast-feeding

Unknown whether lauryl is excreted in human milk. Caution should be exercised when administering to nursing mothers.

Storage

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

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.

Dosage

Children: Refer to specific drug formulations and product labels as purified substances can vary widely in their use and dosing.

Adults: Refer to specific drug formulations and product labels as purified substances can vary widely in their use and dosing.

Mechanism of action

The mechanism of action for purified compounds varies widely depending on the specific substance. Generally, purified drugs exert their effects by interacting with specific biological targets, such as receptors, enzymes, or ion channels, leading to a desired therapeutic effect. This interaction can involve binding to receptors to activate or inhibit signaling pathways, modulating enzymatic activity, or altering physiological processes.

Pharmacodynamics

Pharmacodynamics describes the effects of a drug on the body and the relationship between drug concentration and effect. For purified drugs, this can involve dose-response relationships and the time course of their action. The purified form often enhances potency and reduces variability in response among patients, which can lead to more predictable therapeutic outcomes. The overall effect is determined by the drug's affinity for its target, the efficacy of the drug-receptor interaction, and the downstream signaling pathways activated as a result of this interaction.

Pharmacokinetics

Pharmacokinetics involves the absorption, distribution, metabolism, and excretion (ADME) of a drug. For purified substances, absorption can be more efficient due to the absence of impurities that may affect solubility or stability. Distribution may also be enhanced, leading to higher bioavailability. Metabolism can be influenced by the structure of the purified compound, as it may be metabolized more readily by liver enzymes. Excretion typically occurs through the kidneys or liver, depending on the molecular characteristics of the purified drug.

Pregnancy

Consult with a healthcare professional, as the safety of purified forms of medications during pregnancy may vary depending on the specific substance.

Breast-feeding

Consult with a healthcare professional, as the safety of purified forms of medications during breastfeeding may vary depending on the specific substance.

Storage

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

Dosage

Children: Refer to specific product formulations for guidelines, as dosing can vary based on the formulation and therapeutic context.

Adults: Refer to specific product formulations for guidelines, as dosing can vary based on the formulation and therapeutic context.

Mechanism of action

Stearates, such as magnesium stearate, function primarily by reducing friction during tablet manufacturing and enhancing the flow properties of powders. They do not exert a therapeutic pharmacological action in the body but facilitate the delivery of other active substances.

Pharmacodynamics

Given that stearates are primarily excipients, they do not exhibit traditional pharmacodynamic properties as active drugs do. Their role is to optimize the formulation of drugs, enhancing physical characteristics such as texture and consistency, which indirectly affect the performance of the active ingredients.

Pharmacokinetics

Stearates are poorly absorbed in the gastrointestinal tract due to their lipid nature. When ingested, they may pass through the digestive system with minimal systemic absorption. Their primary action occurs at the site of formulation, where they assist in the dispersion and release of active ingredients rather than being metabolized or exerting effects in the body.

Pregnancy

The safety of sterate during pregnancy has not been established. It should only be used if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

It is not known whether sterate is excreted in human milk. Caution should be exercised when administering to nursing mothers.

Storage

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

Dosage

Children: Refer to BNF for Children for appropriate dosing guidelines for paediatric patients.

Adults: Refer to specific guidelines or BNF for the appropriate dosing of substituted drugs as they vary widely based on the specific compound and its clinical use.

Mechanism of action

The mechanism of action for substituted drugs typically involves interaction with specific biological targets such as receptors, enzymes, or ion channels. By binding to these targets, substituted drugs can modulate various physiological processes, leading to desired therapeutic effects, such as analgesia, anti-inflammatory action, or modulation of neurotransmitter activity.

Pharmacodynamics

Pharmacodynamics of substituted drugs depends on their specific structure and target interactions. Generally, they exert effects through receptor activation or inhibition, leading to alterations in signaling pathways. This can result in enhanced or diminished cellular responses, contributing to the overall therapeutic outcome. The potency and efficacy of these drugs can vary widely based on their chemical modifications.

Pharmacokinetics

The pharmacokinetics of substituted drugs involves absorption, distribution, metabolism, and excretion (ADME). Factors such as the lipophilicity, molecular weight, and chemical stability of the substituents can affect how the drug is absorbed in the gastrointestinal tract, distributed throughout the body, metabolized by the liver, and ultimately excreted through the kidneys. Variations in these parameters will influence the drug's bioavailability, half-life, and duration of action.

Pregnancy

Consult healthcare provider before use. Safety during pregnancy has not been established.

Breast-feeding

Consult healthcare provider before use. Limited data available on safety during breastfeeding.

Storage

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

Mechanism of action

Tadalafil is a selective phosphodiesterase-5 (PDE5) inhibitor that produces several downstream effects with the most common therapeutic effect being smooth muscle relaxation. Patients may experience ED due to a variety of causes including psychogenic, neurogenic, vasculogenic, iatrogenic, or endocrine. These causes result in dysfunction of penile smooth muscle relaxation through either disrupted neuronal signaling or direct influence on smooth muscle cells. During sexual arousal, non-adrenergic non-cholinergic (NANC) neurons release nitric oxide (NO). Nitric oxide stimulates guanylate cyclase which converts guanosine triphosphate to cyclic guanosine monophosphate (cGMP). cGMP activates the cGMP-dependent kinase (PKG) in a signal cascade which activates K+ channels leading to inhibition of Ca2+ channels, inhibits platelet activation, and inhibits smooth muscle cell proliferation while inducing apoptosis. This signal cascade is attenuated by PDE5 which breaks the phosphodiester bond of cGMP, converting it to GMP. Inhibition of PDE5 by tadalafil increases signaling via the PKG cascade which supports penile smooth muscle relaxation during sexual arousal by decreasing Ca2+ entry into smooth muscle cells. This smooth muscle relaxation allows blood to fill the corpus cavernosum thereby producing an erection. In PAH, blood pressure in the pulmonary arteries is raised due to a variety of mechanisms stemming from endothelial dysfunction. Decreased production of NO and prostacyclin reduce vasodilatory signaling while overproduction of endothelin-1 and thromboxane increase vasoconstriction. Inflammation, thromboses, and hypoxia later contribute to vascular remodeling which further reduces luminal size. The resultant increase in blood pressure reduces the capacity for gas exchange and increases afterload at the right ventricle, producing symptoms of dyspnea, fatigue, and dizziness as well as leading to right-sided heart failure. Tadalafil exerts its therapeutic effect in PAH through boosting NO-cGMP signaling to contribute to smooth muscle relaxation as with ED. Lastly, tadalafil is used to treat BPH. BPH produces urinary dysfunction through hyperproliferation of the epithelial and smooth muscle layers of the prostate. The increased size of the prostate blocks urine flow through the urethra resulting in higher residual volumes due to incomplete emptying. Tadalafil does not appear to exert its benefit via smooth muscle relaxation of the prostate. It may instead exert its effect through a mix of increased oxygenation and decreased inflammation, which decreases tissue remodeling, and inhibition of cell proliferation through the cGMP cascade. The decreased affinity for PDE6 compared to other PDE5 inhibitors may explain the decreased incidence of visual side effects as PDE6 is present in the eye and contributes to color vision. In vitro studies have shown that the effect of tadalafil is more potent on phosphodiesterase type 5 (PDE5) than on other phosphodiesterases. These studies have shown that tadalafil is >10,000-fold more potent for PDE5 than for PDE1, PDE2, PDE4, and PDE7 enzymes, which are found in the heart, brain, blood vessels, liver, leukocytes, skeletal muscle, and other organs. Tadalafil is >10,000-fold more potent for PDE5 than for PDE3, an enzyme found in the heart and blood vessels. Additionally, tadalafil is 700-fold more potent for PDE5 than for PDE8, PDE9, PDE10 and 14-fold more potent for PDE5 than for PDE11A1, an enzyme found in human skeletal muscle. Tadalafil inhibits human recombinant PDE11A1 activity at concentrations within the therapeutic range. The physiological role and clinical consequence of PDE11 inhibition in humans have not been defined. Studies in vitro have demonstrated that tadalafil is a selective inhibitor of phosphodiesterase type 5 (PDE5). PDE5 is found in corpus cavernosum smooth muscle, vascular and visceral smooth muscle, skeletal muscle, platelets, kidney, lung, cerebellum, and pancreas. Penile ere

Pharmacodynamics

Tadalafil exerts a therapeutic effect in ED by increasing sexual stimulation-dependant smooth muscle relaxation in the penis, allowing the corpus cavernosum to fill with blood to produce an erection. Smooth muscle relaxation in the pulmonary vasculature helps to produce vasodilation in PAH which reduces blood pressure in the pulmonary arteries. In BPH, tadalafil may contribute to decreased smooth muscle cell proliferation which may reduce the size of the prostate and relieve the anatomical obstruction which produces urinary symptoms of BPH. The decreased affinity of tadalafil for PDE6 compared to other PDE5 inhibitors may explain the reduced incidence of visual side effects.