L-MONTY

Indications

• Allergic rhinitis
• Chronic idiopathic urticaria

Dosage

Children: For children aged 6 to 12 years, the usual dose is 2.5 mg once daily. For children aged 12 years and older, the usual dose is 5 mg once daily.

Adults: The usual dose is 5 mg once daily.

Mechanism of action

Levocetirizine selectively inhibits histamine H1 receptors. This action prevents histamine from activating this receptor and causing effects like smooth muscle contraction, increased permeability of vascular endothelium, histidine uptake in basophils, stimulation of cough receptors, and stimulation of flare responses in the nervous system.

Pharmacodynamics

Levocetirizine is a second-generation histamine H1 antagonist used to treat various allergic symptoms. It has a long duration of action as it is generally taken once daily, and a wide therapeutic window as animal studies show the maximal nonlethal dose is over 100 times a normal dose. Patients are cautioned to avoid tasks that require complete alertness and to use caution in those with factors predisposing to urinary retention.

Pharmacokinetics

Levocetirizine is well absorbed from the gastrointestinal tract, with peak plasma concentrations occurring approximately 0.9 hours after oral administration. It has a volume of distribution of about 0.4 L/kg and is approximately 90% protein-bound. The elimination half-life is about 8 hours, and it is primarily excreted unchanged in the urine. Renal impairment may necessitate dosage adjustments.

Adverse effects

• Drowsiness
• Dry mouth
• Fatigue
• Headache
• Gastrointestinal disturbances

Precautions

• Use caution in patients with a history of urinary retention
• Patients should be advised to avoid tasks requiring full alertness

Pregnancy

The safety of levocetirizine in pregnancy has not been established. It should only be used if clearly needed.

Breast-feeding

Levocetirizine is excreted in breast milk. Caution is advised when administered to nursing women.

Storage

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

Formulations

• Tablets
• Oral solution

Indications

• Asthma (prophylaxis and chronic treatment)
• Seasonal allergic rhinitis
• Perennial allergic rhinitis
• Exercise-induced bronchoconstriction

Dosage

Children: Refer to the BNF for Children for pediatric dosing instructions, as this may differ based on the child's age and weight.

Adults: Refer to the BNF for specific dosing information as it may vary based on individual patient needs and clinical guidelines.

Mechanism of action

Montelukast selectively binds to the cysteinyl leukotriene receptor (CysLT1) on target cells, blocking the action of leukotrienes like leukotriene D4. This inhibition leads to a reduction in bronchoconstriction, mucus secretion, and vascular permeability, thus alleviating the symptoms associated with asthma and allergic rhinitis.

Pharmacodynamics

Montelukast demonstrates anti-inflammatory effects by modulating the leukotriene pathway, leading to decreased airway inflammation and hyperreactivity. It also contributes to the improvement of lung function and reduction of asthma exacerbations. Montelukast's effects on respiratory function and quality of life in patients with asthma have been well documented.

Pharmacokinetics

Montelukast is well absorbed following oral administration, with peak plasma concentrations occurring within 2 to 4 hours. It has a bioavailability of approximately 64%, with a half-life of about 2.7 to 5.5 hours. The drug is extensively metabolized in the liver via cytochrome P450 enzymes, primarily CYP3A4, and is excreted mainly in the feces. Renal excretion of unchanged montelukast is minimal.

Contra-indications

• Hypersensitivity to montelukast or any of its components

Adverse effects

• Headache
• Gastrointestinal disturbances
• Fatigue
• Dizziness
• Mood changes, including depression and suicidal thoughts
• Respiratory infections

Interactions

• May interact with phenobarbital, a CYP450 enzyme inducer, reducing montelukast levels
• Aspirin may increase the risk of respiratory adverse effects in patients with asthma

Precautions

• Use with caution in patients with a history of depression or suicidal behavior
• Regular monitoring is advised for patients with asthma
• Not a rescue medication for acute asthma attacks

Pregnancy

Montelukast is categorized as a pregnancy category B drug. Animal studies have not shown any harm, but adequate and well-controlled studies in pregnant women are lacking. Use only if clearly needed.

Breast-feeding

Montelukast is excreted in human milk. Caution is advised when administered to nursing mothers.

Storage

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

Formulations

• Tablets
• Chewable tablets
• Granules

Mechanism of action

Levocetirizine selectively inhibits histamine H₁ receptors. This action prevents histamine from activating this receptor and causing effects like smooth muscle contraction, increased permeability of vascular endothelium, histidine uptake in basophils, stimulation of cough receptors, and stimulation of flare responses in the nervous system.

Pharmacodynamics

Levocetirizine is a second generation histamine H₁ antagonist used to treat various allergic symptoms. It has a long duration of action as it is generally taken once daily, and a wide therapeutic window as animal studies show the maximal nonlethal dose is over 100x a normal dose. Patients are cautioned to avoid tasks that require complete alertness, avoid alertness, and use caution in patients with factors predisposing urinary retention.