MERIONAL

Indications

• Hypothyroidism
• Thyroid cancer
• Follicular lymphoma
• Ovarian dysfunction

Dosage

Children: Refer to specific treatment guidelines and protocols for dosing of thyroid hormones or chemotherapeutic agents based on the individual condition.

Adults: Refer to specific treatment guidelines and protocols for dosing of thyroid hormones or chemotherapeutic agents based on the individual condition.

Mechanism of action

Follicular cells in the thyroid gland synthesize and secrete thyroid hormones (T3 and T4) in response to thyroid-stimulating hormone (TSH) from the anterior pituitary. In the case of follicular lymphoma, the mechanism involves the proliferation of B-cells, leading to the accumulation of malignant cells within lymphoid follicles. These cancers often involve genetic mutations affecting growth signaling pathways, such as the BCL2 gene which prevents apoptosis.

Pharmacodynamics

Follicular cells primarily influence metabolism and growth through the regulation of thyroid hormones, which increase basal metabolic rate, enhance protein synthesis, and promote growth in the body. In terms of oncological implications, follicular lymphoma and thyroid carcinoma are characterized by dysregulation of cell cycle and apoptosis, leading to uncontrolled cellular proliferation.

Pharmacokinetics

In the context of thyroid hormones produced by follicular cells, T3 and T4 are absorbed through the gastrointestinal tract and have high protein binding capacities. They are metabolized in the liver and excreted primarily through the kidneys. The half-life of T4 is approximately 7 days, while T3 has a shorter half-life of about 1 day. In lymphomas, pharmacokinetics would depend on the specific chemotherapeutic agents used for treatment.

Pregnancy

The safety of follicular for use during pregnancy has not been established. It is advised to be used only if potential benefits justify potential risks to the fetus.

Breast-feeding

It is not known whether follicular is excreted in human milk. Caution should be exercised when administering to breastfeeding women.

Storage

Store at room temperature, away from moisture and heat. Keep out of reach of children.

Indications

• Menopausal symptoms (e.g., hot flashes, vaginal dryness)
• Hypogonadism
• Thyroid disorders (e.g., hypothyroidism)
• Adrenal insufficiency
• Growth hormone deficiency
• Polycystic ovary syndrome (PCOS)

Dosage

Children: Refer to the BNF for Children for specific paediatric dosing guidelines, as these depend on the type of hormone and the condition being treated.

Adults: Refer to the specific hormone type and formulation for dosing guidance in adults, as dosages may vary significantly based on individual patient needs and specific conditions being treated.

Mechanism of action

Hormones exert their effects through binding to specific receptors on target cells, initiating a cascade of intracellular signaling pathways. This may involve the activation of gene expression, modulation of enzyme activity, or alteration of cell membrane permeability. The specific mechanism varies depending on the type of hormone and its target tissues.

Pharmacodynamics

Hormones have varied effects depending on their class and the target tissues involved. They can influence metabolic pathways, regulate growth and development, and affect mood and cognition. Hormones typically act through either genomic mechanisms, involving changes in gene transcription, or non-genomic pathways, which may involve rapid signaling via second messengers.

Pharmacokinetics

The pharmacokinetics of hormones vary widely based on their chemical structure, route of administration, and formulation. Generally, hormones are absorbed into circulation after administration, with peak plasma concentrations occurring at variable times depending on the specific hormone. They may be metabolized in the liver or other tissues, with elimination typically occurring through renal or biliary excretion. Half-lives can range from minutes to hours, influencing dosing frequency.

Interactions

• antiepileptics (carbamazepine, eslicarbazepine, fosphenytoin, oxcarbazepine, perampanel, phenobarbital, phenytoin, primidone, rufinamide, topiramate) + hormone replacement therapy: Unknown (decreases effects)
• bosentan + hormone replacement therapy: Unknown (decreases effects)
• ritonavir + hormone replacement therapy: Unknown (decreases effects)
• modafinil + hormone replacement therapy: Unknown (decreases effects)
• rifamycins + hormone replacement therapy: Unknown (decreases effects)
• St John's Wort + hormone replacement therapy: Unknown (decreases efficacy)
• etoricoxib + hormone replacement therapy: Unknown (increases exposure)

Indications

• Infertility in women (as part of ovulation induction)
• Hypogonadism in men
• Assisted reproductive technologies (ART)
• Hormone replacement therapy in specific cases

Dosage

Children: Dosing in children should only be determined by a healthcare professional based on individual needs and clinical guidelines.

Adults: Follow established guidelines and dosing recommendations based on clinical context. Refer to specific clinical protocols for detailed dosing.

Mechanism of action

Luteinizing hormone functions by binding to specific receptors on the surface of Leydig cells in males and ovarian cells in females. This binding activates adenylate cyclase, leading to an increase in intracellular cyclic AMP (cAMP), which subsequently stimulates steroidogenesis. In females, LH triggers ovulation and the formation of the corpus luteum, while in males, it promotes the production of testosterone.

Pharmacodynamics

LH is crucial for normal reproductive physiology. In females, its peak levels induce ovulation and are necessary for the maintenance of the corpus luteum and progesterone secretion. In males, LH stimulates testosterone production, which is vital for spermatogenesis and the maintenance of secondary sexual characteristics. The levels of LH are regulated by gonadotropin-releasing hormone (GnRH) from the hypothalamus and feedback mechanisms involving estrogen and testosterone.

Pharmacokinetics

LH has a short half-life, typically ranging from 20 to 30 minutes. It is primarily eliminated via renal clearance. The pharmacokinetics can vary based on the formulation used (e.g., recombinant LH) and the route of administration. Peak plasma concentrations are achieved shortly after administration, and the hormone is detected in the circulation within minutes. Its activity is influenced by factors such as age, sex, and the presence of other hormones.

Adverse effects

• Headache
• Nausea
• Vomiting
• Abdominal pain
• Injection site reactions
• Mood changes

Precautions

• Use with caution in patients with a history of hormonal disorders.
• Monitor for signs of ovarian hyperstimulation syndrome in females.
• Assess for potential allergic reactions prior to administration.

Pregnancy

The use of luteinizing hormone during pregnancy should be closely monitored due to its role in reproductive hormone regulation.

Breast-feeding

Luteinizing hormone is generally not recommended during breastfeeding unless clearly needed and prescribed by a healthcare professional.

Storage

Store at 2°C to 8°C (36°F to 46°F). Do not freeze. Protect from light.

Formulations

• Injectable solution

Indications

• Attention Deficit Hyperactivity Disorder (ADHD)
• Narcolepsy
• Obesity (as part of a comprehensive weight management program)
• Treatment-resistant depression
• Cognitive enhancement in certain disorders

Dosage

Children: Refer to the BNF for Children for appropriate dosing guidelines based on age and weight.

Adults: Refer to the specific BNF for individual stimulant medications for appropriate dosing guidelines.

Mechanism of action

Stimulants enhance the release of neurotransmitters such as dopamine and norepinephrine in the brain. They inhibit the reuptake of these neurotransmitters, leading to increased synaptic concentrations and prolonged effects. This mechanism is particularly relevant in the treatment of ADHD, where increased dopamine activity in the prefrontal cortex can improve attention and behavior regulation.

Pharmacodynamics

Stimulants generally exert their effects by increasing neurotransmitter availability in the synaptic cleft, leading to enhanced neuronal firing rates. This results in improved cognitive function, mood elevation, and increased physical activity. The specific pharmacodynamic profile can vary between different stimulant medications, with some exhibiting a more pronounced effect on dopamine versus norepinephrine pathways.

Pharmacokinetics

Stimulants are typically well absorbed in the gastrointestinal tract and may have varying half-lives depending on the formulation (immediate vs extended release). They are metabolized primarily in the liver, and their elimination is often through the kidneys. The onset of action can range from minutes to hours, with effects lasting from a few hours to over 12 hours in some extended-release forms.

Pregnancy

The use of stimulating agents during pregnancy should be approached with caution due to potential risks to fetal development. It is essential to weigh the benefits against possible adverse effects.

Breast-feeding

Caution is advised when using stimulating agents while breastfeeding, as they may pass into breast milk and affect the infant.

Storage

Store in a cool, dry place away from direct sunlight. Ensure the container is tightly closed to maintain stability.