WELTEK NEURO CAPSULES

Indications

• Vitamin B6 deficiency
• Isoniazid-induced neuropathy (prophylaxis and treatment)
• Idiopathic sideroblastic anaemia
• Prevention of penicillamine-induced neuropathy in Wilson's disease
• Metabolic diseases such as cystathioninuria and homocystinuria
• Premenstrual syndrome

Mechanism of action

Pyridoxine hydrochloride is converted in the body to pyridoxal phosphate, which is the active form of vitamin B6. It serves as a cofactor for more than 100 enzymatic reactions, particularly those involved in the metabolism of amino acids, the synthesis of neurotransmitters (such as serotonin, dopamine, and gamma-aminobutyric acid), and the production of hemoglobin. Its role in neurotransmitter synthesis makes it crucial for normal brain function and mood regulation.

Pharmacodynamics

Pyridoxine hydrochloride exerts its effects by facilitating the conversion of amino acids into neurotransmitters and is involved in the synthesis of heme. It impacts the metabolism of tryptophan to serotonin and is essential for the production of norepinephrine and gamma-aminobutyric acid, which are vital for proper neurological function. Deficiency of vitamin B6 can lead to neurological symptoms, including peripheral neuropathy and cognitive disturbances.

Pharmacokinetics

Pyridoxine hydrochloride is readily absorbed from the gastrointestinal tract. It is primarily metabolized in the liver, where it is converted to its active form, pyridoxal phosphate. The elimination half-life of pyridoxine is approximately 15-20 days, and it is excreted primarily through the urine. Renal impairment may affect the metabolism and excretion of pyridoxine, necessitating dose adjustments.

Contra-indications

• Hyperkalaemia
• Severe liver damage

Adverse effects

• Peripheral neuritis
• Hepatitis
• Hypoglycaemia
• Urine discolouration

Interactions

• Potassium aminobenzoate
• Isoniazid

Precautions

• Caution in renal impairment (increased risk of hyperkalaemia)
• Interrupt treatment during periods of low food intake (such as fasting, anorexia, and nausea) to reduce risk of hypoglycaemia
• Monitor liver function tests monthly during high-dose therapy

Pregnancy

Manufacturer advises avoiding use in pregnancy due to potential risk of birth defects; however, no adverse effects have been reported at normal dietary levels.

Breast-feeding

Theoretical risk of toxicity in infants if mothers take large doses.

Storage

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

Formulations

• Pyridoxine hydrochloride 10 mg tablets
• Pyridoxine hydrochloride 20 mg tablets
• Pyridoxine hydrochloride 50 mg tablets
• Pyridoxine hydrochloride oral solution 20 mg per 1 ml

Indications

• Hypertension
• Benign prostatic hyperplasia
• Urinary retention related to prostate enlargement

Dosage

Children: Refer to the BNF for Children for appropriate dosing guidelines in the paediatric population.

Adults: Refer to the BNF for specific dosing recommendations based on individual clinical scenarios.

Mechanism of action

Alpha acts by selectively blocking alpha-1 adrenergic receptors, which are responsible for mediating vasoconstriction in blood vessels. By inhibiting these receptors, alpha promotes vasodilation, leading to a decrease in peripheral vascular resistance and subsequently lowering blood pressure. Additionally, this action can help alleviate urinary symptoms associated with an enlarged prostate.

Pharmacodynamics

The pharmacodynamics of alpha involve its competitive antagonism at alpha-1 adrenergic receptors, resulting in decreased vasoconstriction and increased blood flow. This mechanism is beneficial in conditions characterized by high blood pressure and urinary retention due to prostatic enlargement. The onset of action typically occurs within hours, with peak effects observed within a few days of consistent dosing.

Pharmacokinetics

Alpha is absorbed well from the gastrointestinal tract, with peak plasma concentrations achieved within 1-3 hours post-administration. The drug undergoes hepatic metabolism, primarily via cytochrome P450 enzymes, resulting in active and inactive metabolites. The elimination half-life varies, but it generally is around 6-12 hours, allowing for once-daily dosing in many cases. Renal excretion is a significant route for its metabolites, necessitating caution in patients with renal impairment.

Interactions

• maois, irreversible + alpha blockers: Severe (increases effects)
• ribociclib + alpha blockers: Severe (increases exposure)
• cobicistat + alpha blockers: Moderate (increases exposure)
• idelalisib + alpha blockers: Moderate (increases exposure)
• dronedarone + alpha blockers: Unknown (increases exposure)
• antifungals, azoles + alpha blockers: Unknown (increases exposure)
• crizotinib + alpha blockers: Unknown (increases exposure)
• imatinib + alpha blockers: Unknown (increases exposure)
• letermovir + alpha blockers: Unknown (increases exposure)
• clarithromycin + alpha blockers: Unknown (increases exposure)

Indications

• Diabetic neuropathy
• Diabetic complications
• Nutritional supplementation in thiamine deficiency

Dosage

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

Adults: The usual adult dosage is 300 mg to 600 mg per day, divided into 2 to 3 doses.

Mechanism of action

Benfotiamine is converted into thiamine in the body, where it serves as a cofactor for several enzymes involved in carbohydrate metabolism. It helps to reduce the formation of advanced glycation end-products (AGEs) and modulates pathways involved in diabetic complications, including the hexosamine pathway and the polyol pathway.

Pharmacodynamics

Benfotiamine enhances the activity of thiamine-dependent enzymes, which play critical roles in energy metabolism. This action may lead to improved glucose utilization and reduced oxidative stress, which is particularly beneficial in conditions such as diabetes mellitus. By inhibiting the accumulation of toxic metabolites associated with hyperglycemia, benfotiamine may help mitigate diabetic complications.

Pharmacokinetics

Benfotiamine is well-absorbed from the gastrointestinal tract due to its lipophilic nature. After absorption, it is metabolized to thiamine and its active metabolites. The elimination half-life and excretion pathways are not well established but are thought to involve renal excretion, similar to other thiamine metabolites.

Pregnancy

Benfotiamine should be used in pregnancy only if the potential benefit justifies the potential risk to the fetus.

Breast-feeding

There are no data on the excretion of benfotiamine in human milk. Caution should be exercised when administering to breastfeeding women.

Storage

Store in a cool, dry place, protected from light.

Formulations

• {'form': 'Capsules', 'strength': '300 mg'}
• {'form': 'Tablets', 'strength': '150 mg'}

Indications

• Folate deficiency
• Megaloblastic anemia
• Prevention of neural tube defects in pregnancy
• Supplementation in patients on certain medications (e.g., methotrexate)

Dosage

Children: Refer to the BNF for Children for appropriate pa

Adults: Refer to specific guidelines or the BNF for appropriate adult dosing based on the indication.

Mechanism of action

Folate functions as a coenzyme in the conversion of homocysteine to methionine, a process that is vital for DNA synthesis and repair. It is involved in the one-carbon metabolism pathway, where it acts as a carrier of one-carbon units necessary for the synthesis of purines and thymidylate, thus supporting the production of nucleotides and DNA. This mechanism is particularly important in rapidly dividing cells.

Pharmacodynamics

Folate is critical for the formation of red blood cells and the proper functioning of the nervous system. It aids in the production of nucleic acids, which are essential for cell proliferation. Folate deficiency can lead to impaired DNA synthesis, resulting in megaloblastic anemia characterized by the presence of large, immature red blood cells in the bloodstream. Adequate folate levels are also associated with reduced risk of neural tube defects in developing fetuses.

Pharmacokinetics

Folate is absorbed in the proximal part of the small intestine, primarily in the jejunum, and is transported in the bloodstream bound to plasma proteins. It undergoes hepatic metabolism and is stored mainly in the liver. The elimination half-life varies, but dietary folate can be retained in the body for several weeks. Excess folate is excreted through the urine. The bioavailability of folate from food sources is lower compared to synthetic folic acid found in supplements.

Interactions

• folates+fluorouracil: Severe (increases risk of toxicity)
• folates+antiepileptics: Moderate (decreases concentration)
• folates+fosphenytoin: Moderate (decreases concentration)
• folates+phenobarbital: Moderate (decreases concentration)
• folates+phenytoin: Moderate (decreases concentration)
• folates+primidone: Moderate (decreases concentration)
• sulfasalazine+folates: Unknown (decreases absorption)

Pregnancy

Folate is essential for fetal development and is often recommended to prevent neural tube defects.

Breast-feeding

Folate is generally safe during breastfeeding, as it is important for both maternal and infant health.

Storage

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

Formulations

• Tablets
• Injection

Indications

• Polycystic ovary syndrome (PCOS)
• Generalized anxiety disorder
• Depression
• Obsessive-compulsive disorder
• Insulin resistance

Dosage

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

Adults: Refer to the BNF for specific dosing recommendations, as doses may vary based on the condition being treated.

Mechanism of action

Inositol functions primarily as a precursor for the synthesis of phosphoinositides, which are key components of cell membranes. These phosphoinositides are involved in various intracellular signaling pathways, particularly those mediated by G-protein coupled receptors. Inositol also influences the action of neurotransmitters such as serotonin and has been shown to enhance insulin sensitivity and glucose metabolism.

Pharmacodynamics

Inositol has been observed to have mood-stabilizing effects and may improve insulin sensitivity. Its role in cell signaling impacts various physiological processes, including cellular communication and metabolic regulation. The therapeutic effects of inositol in psychiatric conditions may be attributed to its ability to modulate neurotransmitter systems, particularly involving serotonin and dopamine.

Pharmacokinetics

Inositol is well-absorbed from the gastrointestinal tract, with peak plasma levels occurring within 1 to 2 hours after ingestion. It is distributed throughout the body and can cross the blood-brain barrier. Inositol is predominantly excreted in the urine, with a half-life that varies based on dosage and individual metabolism. Metabolism occurs primarily through dephosphorylation to form various inositol phosphates.

Pregnancy

Inositol is generally considered safe during pregnancy but should be used under medical supervision.

Breast-feeding

Inositol is likely safe during breastfeeding, but consult a healthcare provider for specific recommendations.

Storage

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

Formulations

• Powder
• Capsules

Indications

• Diabetic neuropathy
• Oxidative stress-related disorders
• Metabolic syndrome
• Weight management
• Liver health

Dosage

Children: Refer to specific product guidelines, as safety and efficacy in children have not been established.

Adults: Refer to specific product guidelines, as dosages may vary based on the formulation and indication.

Mechanism of action

Lipoic acid acts as a cofactor for mitochondrial enzyme complexes, particularly those involved in the Krebs cycle, enhancing energy production. It also possesses antioxidant properties, neutralizing free radicals and regenerating other antioxidants such as vitamins C and E. Additionally, lipoic acid can modulate various signaling pathways, including those related to insulin sensitivity and inflammation.

Pharmacodynamics

Lipoic acid has a dual role as a coenzyme and an antioxidant. By participating in the decarboxylation of alpha-keto acids, it aids in energy production. Its antioxidant properties contribute to the protection of cells from oxidative stress, which is implicated in various chronic diseases. Lipoic acid can improve insulin sensitivity, making it beneficial in managing glucose metabolism disorders.

Pharmacokinetics

After oral administration, lipoic acid is absorbed in the gastrointestinal tract, with peak plasma concentrations occurring within 30 to 60 minutes. It undergoes hepatic metabolism, primarily via reduction and conjugation, resulting in various metabolites. The elimination half-life is approximately 30 minutes to 2 hours, and it is excreted primarily in urine. The bioavailability of lipoic acid can be affected by food intake.

Adverse effects

• Nausea
• Vomiting
• Abdominal pain
• Skin rash
• Hypoglycemia

Interactions

• May enhance the effects of insulin and other antidiabetic medications
• May interact with heavy metal chelators

Precautions

• Use with caution in patients with diabetes due to the risk of hypoglycemia
• Monitor blood sugar levels in diabetic patients

Pregnancy

Safety during pregnancy has not been established; use only if clearly needed.

Breast-feeding

It is not known whether lipoic acid is excreted in human breast milk; caution is advised.

Storage

Store in a cool, dry place away from light.

Formulations

• Capsules
• Tablets
• Injectable solutions

Indications

• Vitamin B12 deficiency
• Megaloblastic anemia
• Peripheral neuropathy
• Neuropathic pain
• Multiple sclerosis

Dosage

Children: For paediatric patients, refer to the BNF for Children for appropriate dosing guidelines.

Adults: The typical adult dosage for methylcobalamin is 500 micrograms to 1,000 micrograms administered intramuscularly or subcutaneously, usually once daily for the initial treatment, followed by maintenance doses as needed.

Mechanism of action

Methylcobalamin serves as a cofactor for the enzyme methionine synthase, which catalyzes the conversion of homocysteine to methionine. This reaction is crucial in the synthesis of S-adenosylmethionine (SAMe), an important methyl donor in numerous methylation reactions within the body. Methylcobalamin also plays a role in myelin formation and the maintenance of nerve cells.

Pharmacodynamics

Methylcobalamin exhibits neuroprotective effects, promoting nerve regeneration and repair in peripheral neuropathy. It is believed to enhance nerve conduction and improve neurological function. The physiological effects are primarily attributed to its role in methylation processes and the synthesis of neurotransmitters.

Pharmacokinetics

Methylcobalamin is water-soluble and is absorbed in the intestine. The bioavailability can be affected by gastrointestinal health, and intrinsic factor is not required for its absorption. It is distributed throughout the body, with high concentrations in the liver, kidneys, and brain. The elimination half-life of methylcobalamin is approximately 6 hours, and it is excreted primarily in the urine.

Adverse effects

• Nausea
• Diarrhea
• Headache
• Dizziness
• Anxiety
• Rash
• Pruritus

Precautions

• Monitor patients with Leber's disease due to potential optic nerve damage.
• Caution in patients with allergies to cobalt or vitamin B12.
• Use with caution in patients with renal impairment.

Pregnancy

Methylcobalamin is classified as a category A drug. It is generally considered safe during pregnancy, but consultation with a healthcare provider is recommended.

Breast-feeding

Methylcobalamin is excreted in breast milk. It is generally considered safe during breastfeeding, but consultation with a healthcare provider is recommended.

Storage

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

Formulations

• Tablets
• Injections
• Sublingual tablets
• Oral solutions

Indications

• Vitamin B6 deficiency
• Peripheral neuropathy associated with isoniazid therapy
• Supplementation in specific dietary deficiencies

Dosage

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

Adults: Refer to the BNF for specific dosing details, typically 10-50 mg daily for deficiency.

Mechanism of action

Pyridoxine, mainly in its active form pyridoxal 5'-phosphate, is involved in numerous biochemical reactions, including amino acid metabolism, glycogen breakdown, nucleic acid synthesis, and the production of key neurotransmitters. It aids in the synthesis of hemoglobin and sphingolipids, and its deficiency can impair several physiological processes, including immune response and vascular health.

Pharmacodynamics

Pyridoxine is utilized for the prevention and treatment of vitamin B6 deficiency, particularly in individuals undergoing treatment with isoniazid, which can deplete vitamin B6 levels. It may also have beneficial effects on blood pressure and lipid profiles, as studies have shown it can lower both systolic and diastolic blood pressure, inhibit platelet aggregation, and improve cholesterol levels. Additionally, it plays a role in enhancing immune function and protecting endothelial cells from injury.

Pharmacokinetics

Pyridoxine is rapidly absorbed from the gastrointestinal tract. It is transported to tissues where it is phosphorylated to its active form, pyridoxal 5'-phosphate. The vitamin is primarily excreted in urine as pyridoxine and its metabolites. Its half-life varies depending on the individual’s nutritional status and other factors. Adequate dietary intake is essential for maintaining optimal levels in the body.

Pregnancy

Pyridoxine is generally considered safe during pregnancy. However, high doses should be avoided unless specifically prescribed.

Breast-feeding

Pyridoxine is excreted in breast milk, but at normal dietary levels it is considered safe for breastfeeding mothers.

Storage

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

Formulations

• Tablets
• Oral solution
• Injectable form

Mechanism of action

Vitamin B6 is the collective term for a group of three related compounds, pyridoxine (PN), pyridoxal (PL) and pyridoxamine (PM), and their phosphorylated derivatives, pyridoxine 5'-phosphate (PNP), pyridoxal 5'-phosphate (PLP) and pyridoxamine 5'-phosphate (PMP). Although all six of these compounds should technically be referred to as vitamin B6, the term vitamin B6 is commonly used interchangeably with just one of them, pyridoxine. Vitamin B6, principally in its biologically active coenzyme form pyridoxal 5'-phosphate, is involved in a wide range of biochemical reactions, including the metabolism of amino acids and glycogen, the synthesis of nucleic acids, hemogloblin, sphingomyelin and other sphingolipids, and the synthesis of the neurotransmitters serotonin, dopamine, norepinephrine and gamma-aminobutyric acid (GABA).

Pharmacodynamics

Vitamin B6 (pyridoxine) is a water-soluble vitamin used in the prophylaxis and treatment of vitamin B6 deficiency and peripheral neuropathy in those receiving isoniazid (isonicotinic acid hydrazide, INH). Vitamin B6 has been found to lower systolic and diastolic blood pressure in a small group of subjects with essential hypertension. Hypertension is another risk factor for atherosclerosis and coronary heart disease. Another study showed pyridoxine hydrochloride to inhibit ADP- or epinephrine-induced platelet aggregation and to lower total cholesterol levels and increase HDL-cholesterol levels, again in a small group of subjects. Vitamin B6, in the form of pyridoxal 5'-phosphate, was found to protect vascular endothelial cells in culture from injury by activated platelets. Endothelial injury and dysfunction are critical initiating events in the pathogenesis of atherosclerosis. Human studies have demonstrated that vitamin B6 deficiency affects cellular and humoral responses of the immune system. Vitamin B6 deficiency results in altered lymphocyte differentiation and maturation, reduced delayed-type hypersensitivity (DTH) responses, impaired antibody production, decreased lymphocyte proliferation and decreased interleukin (IL)-2 production, among other immunologic activities.