Diphenhydramine

Diphenhydramine hydrochloride in the oral form is effective for the following indications: Antihistaminic For allergic conjunctivitis due to foods, mild, uncomplicated allergic skin manifestations of urticaria and angioedema, amelioration of allergic reactions to blood or plasma, dermatographism, as therapy for anaphylactic reactions adjunctive to epinephrine and other standard measures after the acute manifestations have been controlled. Motion Sickness For active and prophylactic treatment of motion sickness. Antiparkinsonism For parkinsonism (including drug-induced) in the elderly unable to tolerate more potent agents, mild cases of parkinsonism (including drug-induced) in other age groups, in other cases of parkinsonism (including drug-induced) in combination with centrally acting anticholinergic agents. Nighttime Sleep-aid.

DOSAGE SHOULD BE INDIVIDUALIZED ACCORDING TO THE NEEDS AND THE RESPONSE OF THE PATIENT. A single oral dose of diphenhydramine hydrochloride is quickly absorbed with maximum activity occurring in approximately one hour. The duration of activity following an average dose of diphenhydramine hydrochloride is from four to six hours. Adults 25 to 50 mg three or four times daily. The nighttime sleep-aid dosage is 50 mg at bedtime. Pediatric Patients, other than premature infants and neonates 12.5 to 25 mg three or four times daily. Maximum daily dosage not to exceed 300 mg. For physicians who wish to calculate the dose on the basis of body weight or surface area, the recommended dosage is 5 mg/kg/24 hours or 150 mg/m 2 /24 hours. Data are not available on the use of diphenhydramine hydrochloride as a nighttime sleep-aid in children under 12 years.

Use in Neonates or Premature Infants This drug should not be used in neonates or premature infants. Use in Nursing Mothers Because of the higher risk of antihistamines for infants generally, and for neonates and prematures in particular, antihistamine therapy is contraindicated in nursing mothers. Antihistamines are also contraindicated in the following conditions Hypersensitivity to diphenhydramine hydrochloride and other antihistamines of similar chemical structure.

Antihistamines should be used with considerable caution in patients with narrow-angle glaucoma, stenosing peptic ulcer, pyloroduodenal obstruction, symptomatic prostatic hypertrophy, or bladder-neck obstruction. Use in Pediatric Patients In pediatric patients, especially, antihistamines in overdosage may cause hallucinations, convulsions, or death. As in adults, antihistamines may diminish mental alertness in pediatric patients. In the young pediatric patient, particularly, they may produce excitation. Use in the Elderly (approximately 60 years or older) Antihistamines are most likely to cause dizziness, sedation, and hypotension in elderly patients.

The most frequent adverse reactions are underscored. General: Urticaria, drug rash, anaphylactic shock, photosensitivity, excessive perspiration, chills, dryness of the mouth, nose and throat. Cardiovascular System: Hypotension, headache, palpitations, tachycardia, extrasystoles. Hematologic System: Hemolytic anemia, thrombocytopenia, agranulocytosis. Nervous System: Sedation, sleepiness, dizziness, disturbed coordination, fatigue, confusion, restlessness, excitation, nervousness, tremor, irritability, insomnia, euphoria, paresthesia, blurred vision, diplopia, vertigo, tinnitus, acute labyrinthitis, neuritis, convulsions. GI System: Epigastric distress, anorexia, nausea, vomiting, diarrhea, constipation. GU System: Urinary frequency, difficult urination, urinary retention, early menses.

Diphenhydramine hydrochloride has additive effects with alcohol and other CNS depressants (hypnotics, sedatives, tranquilizers, etc.). MAO inhibitors prolong and intensify the anticholinergic (drying) effects of antihistamines.

Store at 20° to 25°C (68° to 77°F). Protect from freezing and light.