Sedno Syrup

Indications

• Allergic rhinitis
• Chronic idiopathic urticaria

Dosage

Children: Children 1–5 years: 1.25 mg once daily. Children 6–11 years: 2.5 mg once daily. Children 12–17 years: 5 mg once daily.

Adults: 5 mg once daily.

Mechanism of action

Desloratadine competes with free histamine for binding at H1-receptors located in the gastrointestinal tract, uterus, large blood vessels, and bronchial smooth muscle. By blocking the action of endogenous histamine, it provides temporary relief from symptoms such as nasal congestion and watery eyes associated with allergic reactions.

Pharmacodynamics

Desloratadine exhibits selective and peripheral H1-antagonist action, effectively preventing histamine-induced activation of cells involved in allergic reactions. Its long-acting properties ensure sustained relief from allergy symptoms without significant sedation, as it does not penetrate the blood-brain barrier to a notable extent.

Pharmacokinetics

Desloratadine is well absorbed from the gastrointestinal tract. It has a half-life of approximately 27 hours, allowing for once-daily dosing. The drug is metabolized primarily in the liver and has a low potential for drug interactions due to its minimal effect on cytochrome P450 enzymes. It is excreted mainly in urine, with a small fraction eliminated unchanged.

Contra-indications

• History of hypersensitivity to loratadine

Adverse effects

• Asthenia
• Dry mouth
• Headache
• Dizziness
• Drowsiness
• Nausea
• Pharyngitis
• Suicidal ideation
• Vertigo
• Abdominal pain
• Appetite increased
• Diarrhoea
• Confusion
• Aggression
• Angioedema
• Hallucination
• Hepatic function abnormal
• Insomnia
• Movement disorders
• Oedema
• Seizure
• Syncope
• Tachycardia
• Altered taste
• Thrombocytopenia
• Tremor
• Urinary disorders
• Vision disorders
• Weight increased
• Akathisia
• Arrhythmias
• Gastrointestinal discomfort
• Photosensitivity reaction
• QT interval prolongation

Interactions

• May interact with other antihistamines and CNS depressants
• Use with caution in severe renal impairment

Precautions

• Caution in patients with epilepsy
• Use with caution in severe renal impairment
• Patients should be advised that drowsiness can occur and may affect performance of skilled tasks

Pregnancy

Most manufacturers of antihistamines advise avoiding their use during pregnancy; however, there is no evidence of teratogenicity.

Breast-feeding

Most antihistamines are present in breast milk in varying amounts; although not known to be harmful, most manufacturers advise avoiding their use in mothers who are breast-feeding.

Storage

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

Formulations

• Tablets: 5 mg
• Oral solution: 2.5 mg/5 mL

Mechanism of action

Like other H1-blockers, Desloratadine competes with free histamine for binding at H₁-receptors in the GI tract, uterus, large blood vessels, and bronchial smooth muscle. This blocks the action of endogenous histamine, which subsequently leads to temporary relief of the negative symptoms (eg. nasal congestion, watery eyes) brought on by histamine.

Pharmacodynamics

Desloratadine is a long-acting second-generation H₁-receptor antagonist which has a selective and peripheral H1-antagonist action. Histamine is a chemical that causes many of the signs that are part of allergic reactions, such as the swelling of tissues. Histamine is released from histamine-storing cells (mast cells) and attaches to other cells that have receptors for histamine. The attachment of the histamine to the receptors causes the cell to be "activated," releasing other chemicals which produce the effects that we associate with allergies. Desloratadine blocks one type of receptor for histamine (the H1 receptor) and thus prevents activation of cells by histamine. Unlike most other antihistamines, Desloratadine does not enter the brain from the blood and, therefore, does not cause drowsiness.