Capetero 500

Indications

• Dry eye conditions
• Tear deficiency
• Keratoconjunctivitis sicca

Dosage

Children: Apply as required, typically in the form of eye drops.

Adults: Apply as required, typically in the form of eye drops.

Mechanism of action

Hypromellose acts by forming a viscous gel upon contact with the ocular surface, which helps to retain moisture and protect against irritants. This gel-like property enhances the stability of the tear film and reduces evaporation, thereby alleviating symptoms associated with dry eye conditions.

Pharmacodynamics

The pharmacodynamic effects of hypromellose are primarily related to its ability to mimic natural tears, providing lubrication to the ocular surface. This lubrication reduces friction during blinking and maintains corneal hydration, which is critical for ocular comfort and health. Its high viscosity also contributes to prolonged retention time on the eye surface.

Pharmacokinetics

Hypromellose is administered topically as eye drops and is not significantly absorbed systemically. The retention time of hypromellose on the ocular surface is enhanced due to its viscosity, allowing for extended relief of dry eye symptoms. The elimination of hypromellose occurs primarily through drainage from the eye and dilution by the natural tear fluid.

Adverse effects

• Temporary visual disturbance
• Eye irritation

Precautions

• Should not be used during contact lens wear
• Use with caution in patients with known hypersensitivity to any component of the formulation

Pregnancy

Hypromellose is generally considered safe for use during pregnancy. However, it should be used only if clearly needed and after consulting a healthcare provider.

Breast-feeding

Hypromellose is unlikely to affect breastfed infants when used as directed, but consultation with a healthcare provider is advisable.

Storage

Store in a cool, dry place away from direct sunlight. Once opened, use within a specified period as indicated on the packaging.

Formulations

• {'name': 'Teardew', 'concentration': '0.3%', 'form': 'eye drops', 'volume': '10 ml'}
• {'name': 'Xailin Hydrate', 'concentration': '0.3%', 'form': 'eye drops', 'volume': '10 ml'}
• {'name': 'AacuLose', 'concentration': '0.3%', 'form': 'eye drops', 'volume': '10 ml'}
• {'name': 'Artelac', 'concentration': '0.32%', 'form': 'eye drops', 'volume': '10 ml'}
• {'name': 'Lacrilube', 'concentration': '2 mg/g', 'form': 'eye ointment', 'volume': '3.5 g'}
• {'name': 'Celluvisc', 'concentration': '1%', 'form': 'eye drops', 'volume': '0.4 ml unit dose'}

Indications

• Stage III colon cancer, adjuvant following surgery
• Locally advanced or metastatic breast cancer, as second-line treatment after failure of taxane and anthracycline regimens

Dosage

Adults: 1.25 g/m2 twice daily for 14 days, subsequent courses repeated after a 7

Mechanism of action

Capecitabine is metabolized to 5-fluorouracil in vivo through a series of enzymatic reactions involving carboxylesterases, cytidine deaminase, and thymidine phosphorylase. The active metabolites of 5-FU, including FdUMP, interact with thymidylate synthase, inhibiting its activity and leading to the depletion of dTMP necessary for DNA synthesis. This mechanism of action disrupts cell proliferation and induces apoptosis in cancer cells, providing an effective treatment for tumors.

Pharmacodynamics

Capecitabine exerts its antitumor effects by interfering with DNA synthesis and function. As an antimetabolite, its primary action is through inhibition of thymidylate synthase, which is crucial for DNA replication. The selective conversion of capecitabine to 5-FU within tumor tissues enhances its therapeutic index, reducing gastrointestinal toxicity while maintaining efficacy. This drug leads to cell cycle arrest and eventual cancer cell death, primarily affecting rapidly dividing cells.

Pharmacokinetics

Capecitabine is absorbed well from the gastrointestinal tract, with peak plasma concentrations occurring approximately 1-2 hours after oral administration. It is extensively metabolized by the liver and other tissues, with a half-life of about 0.5 to 2 hours. The drug's metabolites are primarily excreted through urine. Dosage adjustments may be necessary in patients with hepatic or renal impairment, and monitoring of liver function and renal parameters is essential during treatment.

Contra-indications

• Complete dihydropyrimidine dehydrogenase deficiency

Adverse effects

• Severe and fatal toxicity
• Diarrhea
• Dehydration
• Bleeding

Interactions

• Capecitabine + coumarins: Moderate (increases effects)
• Allopurinol + capecitabine: Unknown (decreases effects)
• Capecitabine + antiepileptics: Unknown (increases concentration)
• Capecitabine + fosphenytoin: Unknown (increases concentration)
• Capecitabine + phenytoin: Unknown (increases concentration)
• Live vaccines + capecitabine: Unknown (increases risk of generalized infection, possibly life-threatening)
• Metronidazole + capecitabine: Unknown (increases risk of capecitabine toxicity)
• Cimetidine + capecitabine: Unknown (increases exposure)

Precautions

• Monitor liver function tests, serum creatinine, and serum bicarbonate before initiation and before each treatment cycle
• Monitor full blood count before initiation and before each treatment cycle
• Caution in patients with diabetes mellitus

Pregnancy

Use in pregnancy only if the potential benefit justifies the potential risk to the fetus. There is a risk of fetal harm.

Breast-feeding

Capecitabine is not recommended during breastfeeding due to potential risk to the infant.

Storage

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

Formulations

• Capecitabine 500 mg tablet
• Capecitabine 150 mg tablet

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

• 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.

Mechanism of action

Capecitabine is metabolized to 5-fluorouracil in vivo by carboxylesterases, cytidine deaminase, and thymidine phosphorylase/uridine phosphorylase sequentially. 5-fluorouracil is further metabolized through a series of enzymatic reactions into 3 main active metabolites: 5-fluorouridine triphosphate (5-FUTP), 5-fluoro-2’-deoxyuridine monophosphate (5-FdUMP), and 5-fluorodeoxyuridine triphosphate (5-FdUTP).. These metabolites cause cell injury by two different mechanisms. First, FdUMP and the folate cofactor, N5-10-methylenetetrahydrofolate (CH₂THF), bind to thymidylate synthase (TS) to form a covalently bound ternary complex. TS is an enzyme that catalyzes the methylation of deoxyuridine monophosphate (dUMP) to deoxythymidine monophosphate (dTMP). Under normal physiological conditions, dUMP binds to TS first before CH₂THF, followed by a 1,4 or Michael addition from the pyrimidine C (6)atom to the Cys146 nucleophile. If correctly positioned, dUMP, CH₂THF, and TS would form a ternary complex to facilitate the donation of the methyl group from CH₂THF to dUMP. However, the substitution of dUMP with FdUMP results in a new time-dependent TS–FdUMP–CH2THF complex. Since the fluorine group prevents dissociation of FdUMP from the pyrimidine ring, the whole complex is rendered irreversibly deactivated, terming this reaction "suicide inhibition". TS inhibition prevents the conversion of dUMP to dTMP, depleting the pool of dTMP that could be phosphorylated into dTTP to be incorporated as DNA nucleotides. This disrupts the nucleotides balance, particularly the the ATP/dTTP ratio, thus impairing DNA synthesis and repair and causing apoptosis. 5-FdUMP can also be phosphorylated into 5-FdUTP, further increasing the pool of dUTP base to potentially overwhelm the activity of dUTPase. Coupled with the decrease in dTTP, 5-FdUMP, and 5-FdUTP increase the probability of mistakenly incorporating a uracil base into DNA strands in place of thymine. Although this mistake can often be resolved by the nucleotide excision repair enzyme uracil-DNA-glycosylase (UDG), the high (F)dUTP/dTTP ratio would result in re-incorporation of uracil into DNA, leading to a futile cycle of misincorporation, excision, and repair. Repeated base excision repair can result in abasic sites, which can lead to DNA mutagenesis and thus protein miscoding, replication forks collapse, and DNA fragmentation through single or double strand breaks However, several reports have found that the incorporation of uracil in genomic DNA does not significantly affect the cytotoxicity of 5-FU, suggesting that the cytotoxic effect of 5-FU is dominated by the perturbation of RNA through 5-FUTP. Similar to 5-dFUTP, 5-FUTP can be mistakenly incorporated into RNA in place of regular UTP and disrupt regular RNA biology through various mechanisms. 5-FUTP can be incorporated into the spliceosomal U2 snRNA at pseudouridylated sites to prevent further pseudouridylation and thus pre-mrNA splicing. 5-FUTP can also change the structure of U4 and U6 snRNA and reduce the turnover rate of U1 snrNA once incorporated. For tRNA, 5-FUTP can affect tRNA's post-transcriptional RNA modifications activity, particularly by inhbiting pseudouridine synthase through formation of covalent complex. Recently, the effect of 5-FUTP on miRNAs and lncRNA was also observed through profound changes in expression, although the precise mechanism is still unknown. Although the main mechanism of 5-FU cytotoxicity was thought to be attributed to DNA damages, recent reports have shown that the majority of 5-FU pharmacological action is mediated through RNA, since 5-FU is accumulated ~3000- to 15 000-fold more in RNA compared to that of DNA. Capecitabine is a prodrug and has little pharmacologic activity until it is converted to fluorouracil, an antimetabolite. Because capecitabine is converted to fluorouracil by enzymes that are expressed at higher concentrations in many tumors than in adjac

Pharmacodynamics

Capecitabine is a fluoropyrimidine carbamate belonging to a group of antineoplastic agents called antimetabolites, which kill cancerous cells by interfering with DNA synthesis. It is an orally administered systemic prodrug that has little pharmacologic activity until it is converted to 5-fluorouracil (5-FU) by enzymes that are expressed in higher concentrations in many tumors. Capecitabine was designed specifically to overcome the disadvantages of 5-FU and to mimic the infusional pharmacokinetics of 5-FU without the associated complexity and complications of central venous access and infusion pumps. Particularly, since the enzymes converting 5-FU into active metabolites exist in the gastrointestinal tract, infusion of 5-FU can have gastrointestinal toxicity while also losing efficacy. Since capecitabine can be transported intact across the intestinal mucosa, it can be selectively delivered 5-FU to tumor tissues through enzymatic conversion preferentially inside tumor cells. 5-FU exerts its pharmacological action through the inhibition and interference of 3 main targets: thymidylate synthase, DNA, and RNA, leading through protein synthesis disruption and apoptosis. Population-based exposure-effect analyses demonstrated a positive association between AUC of 5-FU and grade 3-4 hyperbilirubinemia.