EXTRAVERT CAPSULES

Indications

• Vitamin D deficiency
• Osteomalacia
• Rickets
• Prevention of osteoporosis
• Adjuvant treatment for certain cancers

Dosage

Children: Refer to the BNF for Children for specific dosing recommendations, which depend on age, weight, and clinical circumstances.

Adults: Refer to specific clinical guidelines for dosing, as it varies based on indication and patient condition.

Mechanism of action

Colecalciferol is converted in the body to its active form, calcitriol, in the liver and kidneys. Calcitriol then binds to vitamin D receptors (VDR) in various tissues, leading to increased intestinal absorption of calcium and phosphate, reabsorption of calcium in the kidneys, and mobilization of calcium from bone, thereby promoting mineralization and bone health.

Pharmacodynamics

Colecalciferol enhances the intestinal absorption of calcium and phosphate, which are vital for bone formation and maintenance. It also modulates the immune response and has been shown to have effects on cell differentiation and proliferation, contributing to the overall health of various tissues.

Pharmacokinetics

Colecalciferol is absorbed in the intestines and is highly lipophilic, leading to its accumulation in body fat. It has a half-life of several weeks and is metabolized primarily in the liver, where it is converted to 25-hydroxyvitamin D (calcidiol), and then in the kidneys to its active form, calcitriol. The excretion of colecalciferol and its metabolites primarily occurs via bile.

Contra-indications

• Hypercalcaemia
• Vitamin D toxicity
• Severe renal impairment

Adverse effects

• Nausea
• Vomiting
• Constipation
• Loss of appetite
• Weight loss
• Weakness
• Confusion
• Hypercalcaemia symptoms (e.g., thirst, frequent urination, kidney stones)

Interactions

• Thiazide diuretics (may increase the risk of hypercalcaemia)
• Anticonvulsants (may increase the metabolism of vitamin D)
• Cholestyramine (may impair absorption of vitamin D)
• Mineral oil (may impair absorption of vitamin D)

Precautions

• Monitor calcium levels in patients with renal impairment
• Use caution in patients with granulomatous diseases (e.g., sarcoidosis) as they may have increased sensitivity to vitamin D
• Consider dietary intake of calcium and vitamin D when prescribing

Pregnancy

Colecalciferol is generally considered safe in pregnancy, but high doses should be avoided due to the risk of hypercalcaemia.

Breast-feeding

Colecalciferol is excreted in breast milk, but normal doses are considered safe during breastfeeding.

Storage

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

Formulations

• Capsules
• Tablets
• Oral solution
• Injections

Indications

• Thiamine deficiency
• Wernicke's encephalopathy
• Beriberi
• Neuropathy
• Alcoholism-related deficiencies

Dosage

Children: Refer to established pediatric dosing guidelines based on clinical condition or specific recommendations for age and weight.

Adults: Refer to specific guidelines for dosing based on the condition being treated. Typically, doses range from 50 mg to 100 mg daily for deficiency.

Mechanism of action

Thiamine is converted into thiamine pyrophosphate (TPP), which acts as a coenzyme for several critical enzymatic reactions, including the conversion of pyruvate to acetyl-CoA through the pyruvate dehydrogenase complex. TPP is also essential for the metabolism of branched-chain amino acids and the pentose phosphate pathway, which is important for nucleotide synthesis and cellular function.

Pharmacodynamics

Thiamine's pharmacodynamic effects are primarily related to its role in energy metabolism. Supplementation can improve symptoms associated with thiamine deficiency, including neurological disturbances. Increased thiamine levels enhance carbohydrate utilization and promote the synthesis of neurotransmitters, thereby supporting cognitive function and neurological health.

Pharmacokinetics

Thiamine is absorbed in the small intestine and is distributed throughout the body, primarily in the liver, heart, and kidneys. It has a short half-life, approximately 1-2 hours, and excess amounts are excreted renally. The bioavailability of thiamine can be affected by factors such as gastrointestinal health and the presence of certain medications that may influence absorption.

Pregnancy

Thiamine is generally considered safe during pregnancy.

Breast-feeding

Thiamine is excreted in breast milk but is considered safe for use during breastfeeding.

Storage

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

Indications

• Vitamin deficiency syndromes (e.g., scurvy for vitamin C deficiency, rickets for vitamin D deficiency)
• Support for immune function
• Antioxidant support
• Bone health maintenance
• Vision health
• Energy metabolism support

Dosage

Children: Refer to the BNF for Children for specific vitamin dosing guidelines, which depend on age and nutritional requirements.

Adults: Refer to specific vitamin guidelines as dosage varies significantly depending on the type of vitamin and individual needs.

Mechanism of action

Vitamins function primarily as coenzymes or precursors for coenzymes in enzymatic reactions. For instance, B vitamins are involved in energy metabolism, while vitamins A, C, D, E, and K support various physiological functions including vision, antioxidant activity, calcium regulation, and blood clotting. Each vitamin has a unique mechanism of action based on its structure and role in the body.

Pharmacodynamics

Vitamins exert their effects at the cellular level, influencing metabolic pathways, gene expression, and immune responses. For example, vitamin D regulates calcium and phosphate homeostasis, while vitamin A is crucial for vision and immune function. Deficiencies in vitamins can lead to a range of disorders, highlighting their importance in maintaining health.

Pharmacokinetics

The pharmacokinetics of vitamins vary widely. Fat-soluble vitamins (A, D, E, and K) are stored in liver and adipose tissues and can be released into circulation as needed. Water-soluble vitamins (B-complex and C) are not stored and must be consumed regularly, with excess amounts excreted in urine. Absorption rates, half-lives, and distribution can also differ based on the specific vitamin and individual metabolic factors.

Interactions

• tretinoin+vitamin: Severe (increases risk of vitamin toxicity)
• retinoids+vitamin: Severe (increases risk of vitamin toxicity)
• retinoids+vitamin: Moderate (increases risk of toxicity)
• carbamazepine+vitamin: Unknown (decreases effects)
• cobicistat+vitamin: Unknown (increases exposure)
• vitamin D substances+digoxin: Unknown (increases risk of toxicity)
• idelalisib+vitamin: Unknown (increases exposure)
• clarithromycin+vitamin: Unknown (increases exposure)

Pregnancy

Consult healthcare professional before use. Vitamin supplementation during pregnancy should be carefully managed to avoid hypervitaminosis.

Breast-feeding

Consult healthcare professional before use. Some vitamins can pass into breast milk and may affect the infant.

Storage

Store in a cool, dry place, away from direct sunlight. Ensure it is kept out of reach of children.

Formulations

• {'name': 'Vitamin A', 'form': 'Capsule', 'strength': '10000 IU'}
• {'name': 'Vitamin D', 'form': 'Tablet', 'strength': '1000 IU'}
• {'name': 'Vitamin E', 'form': 'Softgel', 'strength': '400 IU'}