REJUNURON

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
• 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
• Peripheral neuropathy
• Cognitive impairment
• Anemia related to Vitamin B12 deficiency
• Neuropathic pain

Dosage

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

Adults: Refer to BNF for specific dosing guidelines.

Mechanism of action

Methylcobalamin acts as a coenzyme in the conversion of homocysteine to methionine and in the synthesis of nucleic acids. It is essential for the maintenance of myelin, which is necessary for the proper functioning of the nervous system. Methylcobalamin contributes to the regeneration of nerve fibers and the repair of damaged nerves, promoting nerve health and functionality.

Pharmacodynamics

The pharmacodynamic effects of methylcobalamin include its role in promoting erythropoiesis, or the production of red blood cells, and its neuroprotective properties. It has been shown to enhance nerve regeneration and function, improve cognitive function, and alleviate symptoms of neuropathy. Methylcobalamin supports cellular metabolism and energy production, facilitating the utilization of carbohydrates and fats.

Pharmacokinetics

Methylcobalamin is absorbed from the gastrointestinal tract, with peak plasma concentrations occurring approximately 2 to 3 hours after administration. It is distributed throughout the body, particularly in the liver and kidneys. The elimination half-life is variable, but it is generally excreted in urine as both unchanged methylcobalamin and its metabolites. Methylcobalamin can cross the blood-brain barrier, allowing it to exert its effects on the central nervous system.

Adverse effects

• Nausea
• Diarrhea
• Headache
• Dizziness
• Allergic reactions

Interactions

• May interact with certain medications that affect blood sugar levels
• Potential interaction with certain antibiotics

Precautions

• Use with caution in patients with known hypersensitivity to cobalamin or cobalt
• Monitor patients with renal impairment
• Consider potential interactions with other medications

Pregnancy

Methylcobalamin is generally considered safe during pregnancy, but it is essential to consult a healthcare provider before use.

Breast-feeding

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

• Oral tablets
• Sublingual tablets
• Injectable solution