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RESPIRATORY SYSTEM › ANTIHISTAMINES FOR SYSTEMIC USE › ANTIHISTAMINES FOR SYSTEMIC USE › Other antihistamines for systemic use
thenalidine, combinations
R06AX53
Forms & Strengths
- Oral tablets 25 mg
- Oral tablets 50 mg
- Oral tablets 25 mg + pseudoephedrine 60 mg (combination)
- Oral syrup 5 mg/5 mL
Adult Dosing
- Allergic rhinitis/urticaria: 25‑50 mg PO 2‑3 times daily
- Combination product (with pseudoephedrine): 1 tablet PO every 6‑8 h, max 3 doses/24 h
Pediatric Dosing
- 6‑12 yr: 12.5‑25 mg PO 2‑3 times daily
- <6 yr: not recommended
Indications
- Symptomatic relief of seasonal/perennial allergic rhinitis
- Urticaria and other histamine‑mediated skin itching
- Adjunct in common‑cold formulas containing a decongestant
Mechanism of Action
- Competitive antagonism of peripheral H1 histamine receptors
- Additional anticholinergic activity reduces nasal secretions
Contraindications
- Known hypersensitivity to thenalidine or excipients
- Narrow‑angle glaucoma
- Severe urinary retention or prostatic hypertrophy
- Severe hepatic impairment
- Neonates and premature infants
Adverse Reactions
- Sedation/drowsiness
- Dry mouth, thirst, constipation
- Blurred vision, photophobia
- Tachycardia or palpitations
- Dizziness, headache
- Nausea or abdominal discomfort
Drug Interactions
- Additive CNS depression with alcohol, benzodiazepines, opioids, antihistamines
- Enhanced anticholinergic effects with tricyclic antidepressants, antispasmodics
- Reduced efficacy of sympathomimetics (e.g., pseudoephedrine) if given with MAO‑inhibitors
- Potential CYP2D6 inhibition may increase levels of metoprolol, codeine
Curated Content: Needs Vetting Before Put to Clinical Use