Adryl

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.

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.

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.

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

Anti-histamine