Diphenhydramine
Mechanism :
Diphenhydramine is an antihistamine with anticholinergic and sedative side effects. Antihistamines appear to compete with histamine for cell receptor sites on effector cells.
Indication :
- Sedation
- Allergic Rhinitis
- Dystonic reactions
- Motion Sickness
- Allergic reactions
Contraindications :
Hypersensitivity to diphenhydramine hydrochloride and other antihistamines of similar chemical structure. This drug should not be used in new-born or premature infants.
Dosing :
2-6 years:
6.25 mg orally every 4 to 6 hours, not to exceed 37.5 mg/24 hours.
6-12 years:
12.5 to 25 mg orally every 4 to 6 hours, not to exceed 150 mg/24 hours.
>12 years:
25 to 50 mg orally every 4 to 6 hours, not to exceed 300 mg/24 hours.
Adverse Effect :
Chills, dryness of mouth, nose, and throat, hypotension, headache, palpitations, tachycardia, hemolytic anemia, thrombocytopenia, agranulocytosis, sedation, dizziness, fatigue, confusion, restlessness, excitation, nervousness, tremor, irritability, blurred vision, diplopia, vertigo, tinnitus, anorexia, nausea, vomiting, urinary frequency, urinary retention, early menses.
Interaction :
Alcohol and other CNS depressants: Diphenhydramine hydrochloride has additive effects.
MAO inhibitors: Prolong and intensify the anticholinergic effects of antihistamines.
Hepatic Dose :
Dose reduction may be required as diphenhydramine is eliminated primarily by hepatic metabolism.