Novocetrin (Levocetirizine Dihydrochloride)

• Novocetrin (levocetirizine) acts on histamine‑mediated allergic pathways to alleviate symptoms of common allergic conditions.
• Allergic rhinitis: reduces nasal congestion, itching, sneezing and watery discharge.
• Seasonal allergic rhinitis: provides symptom control during pollen seasons.
• Chronic idiopathic urticaria: diminishes the frequency and severity of hives and associated itching.

• Levocetirizine selectively blocks peripheral H1‑histamine receptors, preventing histamine from binding and triggering the cascade that leads to vasodilation, increased vascular permeability, and sensory nerve stimulation. By inhibiting this receptor activity, the drug reduces the classic signs of allergic inflammation without readily crossing the blood‑brain barrier, thereby limiting central sedation.

Levocetirizine is generally well tolerated, but adverse reactions can occur.

Common Side Effects

• Drowsiness: mild sleepiness reported by some patients.
• Headache: occasional tension‑type headache.
• Dry mouth: reduced salivation.
• Fatigue: feeling of reduced energy.
• Nausea: mild stomach upset.
• Altered taste: transient metallic or bitter sensation.

Serious or Rare Side Effects

• Angioedema: swelling of face, lips or tongue.
• Severe skin reactions: such as Stevens‑Johnson syndrome.
• Anaphylaxis: rare systemic allergic response.
• Liver enzyme elevation: abnormal hepatic function tests.
• Blood dyscrasias: rare cases of neutropenia or thrombocytopenia.

Before initiating therapy, consider patient‑specific factors and safety measures.

• Renal function assessment: dose may need adjustment in severe renal impairment.
• Hepatic impairment: use with caution in patients with liver disease.
• Known hypersensitivity: avoid if the patient has previously reacted to levocetirizine or related antihistamines.
• Sedation risk: advise patients to avoid operating machinery until they know how the drug affects them.
• Elderly patients: monitor for increased sensitivity to side effects.
• Store at room temperature: keep in the original packaging, protect from moisture and direct sunlight.

Levocetirizine may interact with other medicines, requiring attention to avoid reduced efficacy or increased toxicity.

Major Interactions (Avoid)

• Other H1 antihistamines: additive sedation and anticholinergic effects.
• Central nervous system depressants (e.g., benzodiazepines, opioids): heightened drowsiness.
• Alcohol: potentiates sedative properties.

Moderate Interactions (Monitor Closely)

• Cimetidine: may increase levocetirizine plasma levels.
• Ritonavir: can raise exposure to levocetirizine.
• Theophylline: potential for increased theophylline concentrations.
• Antifungal agents (ketoconazole, itraconazole): may modestly elevate levocetirizine levels.