CABERLIN 0.5

Indications

• Parkinson's disease
• Prolactin-secreting tumors (prolactinomas)
• Suppression of lactation

Dosage

Adults: Initially 1 mg daily, increased in steps of 0.5–1 mg

Mechanism of action

Cabergoline acts primarily as an agonist at dopamine D2 receptors, which are G-protein coupled receptors. Activation of these receptors inhibits adenylyl cyclase activity, leading to decreased intracellular cAMP levels. This results in reduced release of prolactin from lactotrophs in the pituitary gland and improved muscle coordination in individuals with movement disorders. Additionally, cabergoline has a high affinity for D2 receptors and lower affinity for D1, adrenergic, and serotonin receptors, contributing to its therapeutic effects.

Pharmacodynamics

Cabergoline stimulates dopaminergic receptors, particularly D2 and D3 subtypes, which are critical in managing symptoms of Parkinson's disease. The drug enhances motor function by modulating neurotransmitter release in the nigrostriatal pathway. Its effects include reduced prolactin secretion and improved motor control, as well as potential neuroprotective benefits through presynaptic D2 receptor stimulation. Cabergoline is associated with various side effects, including impulse control disorders and fibrotic reactions, necessitating careful monitoring during treatment.

Pharmacokinetics

Cabergoline is administered orally and is well absorbed, with peak plasma concentrations reached within 1 to 4 hours post-dose. It has a long half-life, allowing for once or twice weekly dosing. The drug undergoes hepatic metabolism, mainly via CYP3A4, and is excreted primarily in feces. Dose adjustments may be necessary in patients with hepatic impairment due to increased plasma concentrations. Regular monitoring is required to evaluate for potential cardiac and pulmonary fibrotic complications associated with long-term use.

Contra-indications

• history of puerperal psychosis
• pulmonary fibrotic disorders
• retroperitoneal fibrotic disorders
• severe cardiovascular disease
• history of serious mental disorders, especially psychotic disorders
• pre-eclampsia

Adverse effects

• pulmonary fibrotic reactions
• retroperitoneal fibrotic reactions
• pericardial fibrotic reactions
• hypotensive reactions
• excessive daytime sleepiness
• sudden onset of sleep
• impulse control disorders such as pathological gambling, binge eating, and hypersexuality

Interactions

• dronedarone: increases concentration of cabergoline
• cobicistat: increases concentration of cabergoline
• crizotinib: increases concentration of cabergoline
• idelalisib: increases concentration of cabergoline
• imatinib: increases concentration of cabergoline
• memantine: increases effects of cabergoline
• metoclopramide: decreases effects of cabergoline
• nilotinib: increases concentration of cabergoline

Precautions

• monitor for pituitary enlargement, particularly during pregnancy
• monitor visual field to detect secondary field loss in macroprolactinoma
• monitor blood pressure for a few days after starting treatment and following dosage increase
• caution in patients with a history of peptic ulcer
• caution in patients with Raynaud's syndrome
• monitor for dyspnoea, persistent cough, chest pain, and cardiac failure

Pregnancy

Avoid use during pregnancy due to potential risks; monitoring for fibrotic reactions is advised.

Breast-feeding

Suppresses lactation; avoid breastfeeding for about 5 days if lactation prevention fails.

Storage

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

Formulations

• tablets
• oral suspension

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

• Protein supplementation in athletes
• Muscle recovery post-injury
• Support in conditions causing muscle wasting
• Management of metabolic disorders such as phenylketonuria

Dosage

Children: Refer to the BNF for Children for specific paediatric dosing guidelines.

Adults: Refer to the BNF for specific adult dosing guidelines.

Mechanism of action

Leucine undergoes catabolism primarily in muscle tissue, where it is transaminated by branched-chain amino acid aminotransferase, resulting in the formation of various keto acids. These products are further oxidized by branched-chain alpha-keto acid dehydrogenase, leading to the production of acetyl-CoA and acetoacetyl-CoA, classifying leucine as a strictly ketogenic amino acid. The metabolic pathways diverge thereafter, producing multiple intermediates necessary for various physiological functions.

Pharmacodynamics

As an essential amino acid, leucine aids in the regulation of blood sugar levels, supports muscle tissue growth and repair, enhances growth hormone production, and promotes wound healing. It is also known to help prevent muscle protein breakdown that can occur after physical trauma or stress. Leucine may have therapeutic potential for individuals with metabolic disorders such as phenylketonuria, where amino acid metabolism is impaired.

Pharmacokinetics

Leucine is absorbed in the intestines after dietary intake and is transported to tissues where it is utilized. Its bioavailability is influenced by dietary composition and the presence of other amino acids. Once in the muscle tissue, leucine is readily catabolized to produce energy substrates, contributing to muscle metabolism and repair processes. The half-life and excretion routes of leucine are not extensively documented but are primarily through urine in the form of metabolites.

Pregnancy

Leucine is considered safe during pregnancy when consumed in normal dietary amounts. However, high doses should be avoided unless prescribed by a healthcare professional.

Breast-feeding

Leucine is also considered safe during breastfeeding when taken in dietary amounts. High doses should be approached with caution and discussed with a healthcare provider.

Storage

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

Formulations

• Capsule
• Tablet
• Powder

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

The dopamine D₂ receptor is a 7-transmembrane G-protein coupled receptor associated with G_i proteins. In lactotrophs, stimulation of dopamine D₂ causes inhibition of adenylyl cyclase, which decreases intracellular cAMP concentrations and blocks IP3-dependent release of Ca²⁺ from intracellular stores. Decreases in intracellular calcium levels may also be brought about via inhibition of calcium influx through voltage-gated calcium channels, rather than via inhibition of adenylyl cyclase. Additionally, receptor activation blocks phosphorylation of p42/p44 MAPK and decreases MAPK/ERK kinase phosphorylation. Inhibition of MAPK appears to be mediated by c-Raf and B-Raf-dependent inhibition of MAPK/ERK kinase. Dopamine-stimulated growth hormone release from the pituitary gland is mediated by a decrease in intracellular calcium influx through voltage-gated calcium channels rather than via adenylyl cyclase inhibition. Stimulation of dopamine D₂ receptors in the nigrostriatal pathway leads to improvements in coordinated muscle activity in those with movement disorders. Cabergoline is a long-acting dopamine receptor agonist with a high affinity for D2 receptors. Receptor-binding studies indicate that cabergoline has low affinity for dopamine D1, α₁,- and α₂- adrenergic, and 5-HT₁- and 5-HT₂-serotonin receptors.

Pharmacodynamics

Cabergoline stimulates centrally-located dopaminergic receptors resulting in a number of pharmacologic effects. Five dopamine receptor types from two dopaminergic subfamilies have been identified. The dopaminergic D1 receptor subfamily consists of D₁ and D₅ subreceptors, which are associated with dyskinesias. The dopaminergic D2 receptor subfamily consists of D₂, D₃ and D₄ subreceptors, which are associated with improvement of symptoms of movement disorders. Thus, agonist activity specific for D2 subfamily receptors, primarily D₂ and D₃ receptor subtypes, are the primary targets of dopaminergic antiparkinsonian agents. It is thought that postsynaptic D2 stimulation is primarily responsible for the antiparkinsonian effect of dopamine agonists, while presynaptic D2 stimulation confers neuroprotective effects. This semisynthetic ergot derivative exhibits potent agonist activity on dopamine D₂- and D₃-receptors. It also exhibits: agonist activity (in order of decreasing binding affinities) on 5-hydroxytryptamine (5-HT)_2B, 5-HT_2A, 5-HT_1D, dopamine D₄, 5-HT_1A, dopamine D₁, 5-HT_1B and 5-HT_2C receptors and antagonist activity on α_2B, α_2A, and α_2C receptors. Parkinsonian Syndrome manifests when approximately 80% of dopaminergic activity in the nigrostriatal pathway of the brain is lost. As this striatum is involved in modulating the intensity of coordinated muscle activity (e.g. movement, balance, walking), loss of activity may result in dystonia (acute muscle contraction), Parkinsonism (including symptoms of bradykinesia, tremor, rigidity, and flattened affect), akathesia (inner restlessness), tardive dyskinesia (involuntary muscle movements usually associated with long-term loss of dopaminergic activity), and neuroleptic malignant syndrome, which manifests when complete blockage of nigrostriatal dopamine occurs. High dopaminergic activity in the mesolimbic pathway of the brain causes hallucinations and delusions; these side effects of dopamine agonists are manifestations seen in patients with schizophrenia who have overractivity in this area of the brain. The hallucinogenic side effects of dopamine agonists may also be due to 5-HT_2A agonism. The tuberoinfundibular pathway of the brain originates in the hypothalamus and terminates in the pituitary gland. In this pathway, dopamine inhibits lactotrophs in anterior pituitary from secreting prolactin. Increased dopaminergic activity in the tuberoinfundibular pathway inhibits prolactin secretion.

Mechanism of action

This group of essential amino acids are identified as the branched-chain amino acids, BCAAs. Because this arrangement of carbon atoms cannot be made by humans, these amino acids are an essential element in the diet. The catabolism of all three compounds initiates in muscle and yields NADH and FADH2 which can be utilized for ATP generation. The catabolism of all three of these amino acids uses the same enzymes in the first two steps. The first step in each case is a transamination using a single BCAA aminotransferase, with a-ketoglutarate as amine acceptor. As a result, three different a-keto acids are produced and are oxidized using a common branched-chain a-keto acid dehydrogenase, yielding the three different CoA derivatives. Subsequently the metabolic pathways diverge, producing many intermediates. The principal product from valine is propionylCoA, the glucogenic precursor of succinyl-CoA. Isoleucine catabolism terminates with production of acetylCoA and propionylCoA; thus isoleucine is both glucogenic and ketogenic. Leucine gives rise to acetylCoA and acetoacetylCoA, and is thus classified as strictly ketogenic. There are a number of genetic diseases associated with faulty catabolism of the BCAAs. The most common defect is in the branched-chain a-keto acid dehydrogenase. Since there is only one dehydrogenase enzyme for all three amino acids, all three a-keto acids accumulate and are excreted in the urine. The disease is known as Maple syrup urine disease because of the characteristic odor of the urine in afflicted individuals. Mental retardation in these cases is extensive. Unfortunately, since these are essential amino acids, they cannot be heavily restricted in the diet; ultimately, the life of afflicted individuals is short and development is abnormal The main neurological problems are due to poor formation of myelin in the CNS. The mechanism of intracellular protein degradation, by which protein is hydrolyzed to free amino acids, is more complex and is not as well characterized at the mechanistic level as that of synthesis. A wide variety of different enzymes that are capable of splitting peptide bonds are present in cells. However, the bulk of cellular proteolysis seems to be shared between two multienzyme systems: the lysosomal and proteasomal systems. The lysosome is a membrane-enclosed vesicle inside the cell that contains a variety of proteolytic enzymes and operates mostly at acid pH. Volumes of the cytoplasm are engulfed (autophagy) and are then subjected to the action of the protease enzymes at high concentration. This system is thought to be relatively unselective in most cases, although it can also degrade specific intracellular proteins. The system is highly regulated by hormones such as insulin and glucocorticoids, and by amino acids. The second system is the ATP-dependent ubiquitin-proteasome system, which is present in the cytoplasm. The first step is to join molecules of ubiquitin, a basic 76-amino acid peptide, to lysine residues in the target protein. Several enzymes are involved in this process, which selectively targets proteins for degradation by a second component, the proteasome. Dietary leucine transported into the brain parenchyma serves several functions. Most prominent is the role of leucine as a metabolic precursor of fuel molecules, alpha-ketoisocaproate and ketone bodies. As alternatives to glucose, these compounds are forwarded by the producing astrocytes to the adjacent neural cells. Leucine furthermore participates in the maintenance of the nitrogen balance in the glutamate/glutamine cycle pertinent to the neurotransmitter glutamate. Leucine also serves as a regulator of the activity of some enzymes important for brain energy metabolism. Another role of leucine as an informational molecule is in mTOR signaling that participates in the regulation of food ingestion. The importance of leucine for brain function is stressed by the fact that inborn errors in its metabolism cause metabolic dis

Pharmacodynamics

An essential amino acid. (Claim) Leucine helps with the regulation of blood-sugar levels, the growth and repair of muscle tissue (such as bones, skin and muscles), growth hormone production, wound healing as well as energy regulation. It can assist to prevent the breakdown of muscle proteins that sometimes occur after trauma or severe stress. It may also be beneficial for individuals with phenylketonuria - a condition in which the body cannot metabolize the amino acid phenylalanine