Phenadryl Syrup

Diphenhydramine has anti-histaminic (H1-receptor), anti-emetic, anti-vertigo and sedative and hypnotic properties. The anti-histamine action occurs by blocking the spasmogenic and congestive effects of histamine by competing with histamine for H1 receptor sites on effector cells, preventing but not reversing responses mediated by histamine alone. Such receptor sites may be found in the gut, uterus, large blood vessels, bronchial muscles, and elsewhere. Anti-emetic action is by inhibition at the medullary chemoreceptor trigger zone. Anti-vertigo action is by a central antimuscarinic effect on the vestibular apparatus and the integrative vomiting center and medullary chemoreceptor trigger zone of the midbrain.

Antihistamine and antitussive:
Tablet:

• Adults: 25 mg to 50 mg 3 to 4 times daily.
• Children (10 years or over): 25 mg 3 or 4 times daily or as directed by the physician.

Syrup:

• Children under 2 years: 2.5 mL every 4 to 6 hours.
• Children 2 to under 6 years: 5 mL every 4 to 6 hours.
• Children 6 to 12 years: 10-20 mL every 4 to 6 hours.
• Adults and children≥12 years: 10-20 mL every 4 to 6 hours.

Sleep aid:
Adults and children over 12 years: 50 mg at bedtime.

Antidepressants, particularly of the tricyclic and monoamine oxidase inhibitor types may interact with diphenhydramine. MAO inhibitors prolong and intensify the anticholinergic effects of antihistamines. The CNS effect is increased by alcohol and other CNS depressant drugs.

Diphenhydramine is contraindicated for the premature or newborn infants. Hypersensitivity to any of the component of this drug. Asthma attack, narrow angle glaucoma, prostatic hypertrophy, stenosing peptic ulcer, pyloroduodenal obstructions, bladder neck obstruction, patients receiving antidepressant therapy.

Side-effects include drowsiness, dizziness and dryness of mouth, nausea and vomiting. Other infrequently reported effects are vertigo, palpitation, blurring of vision, headache, restlessness, insomnia and thickening of bronchial secretions. Allergic reactions, diarrhoea, vomiting and excitation may also occur.

Safety for use in pregnancy and lactation has not been established. Its use therefore in such patients should involve consideration of expected benefits and possible risks.

Patients should be cautioned not to operate vehicles or hazardous machinery until their response to the drug has been determined.

Antihistamine over dosage reactions may vary from central nervous system depression to stimulation. Stimulation is particularly likely in children. Atropine-like signs and symptoms such as dryness of mouth, fixed and dilated pupils, flushing and gastrointestinal symptoms may also occur.

Sedating Anti-histamine

Do not store above 30°C temperature. Keep way from light and wet place. Keep out of reach of children.