Diphenhydramine hydrochloride

Diphenhydramine hydrochloride ( Allerdryl, Allermed, Benadryl, Diphenadryl, Hydramine, Tusstat)

 

AVAILABLE FORMS:
Capsules: 25mg; 50mg
Injection: 10mg/ml; 50 mg/ml
Elixir: 12.5 mg/5ml

 

INDICATIONS:

• Rhinitis,allergic symptoms, motion sickness
• Parkinson's Disease
• Extrapyramidal Symptoms
• Nighttime sleep aid / sedation

MECHANISM OF ACTION:
Competes with histamine for H1-receptor sites on effector cells. Diphenhydramine blocks the effects of H1 receptor stimulation (bronchoconstriction, visceral contractions) and that of H2 receptor stimulation (peripheral vasodilation and secretion of gastric acids). It provides local anesthesia by preventing transmission of nerve impulses.

 

ADVERSE REACTIONS:
CNS: drowsiness, dizziness, headache, fatigue, sedation, sleepiness, incoordination, confusion, restlessness, insomia, nervousness, tremor, seizures.
CV: hypotension, palpitations, tachycardia.
GI: nausea, vomiting, epigastric distress, dry mouth, diarrhea, constipation.
GU: urine retention, urinary frequency.
Hematologic: hemolytic anemia, leukopenia, agranulocytosis, thrombocytopenia.
Metabolic: weight gain.
Skin: rash, urticaria, photosensitivity.
Other: anaphylactic shock.

 

CONTRAINDICATIONS:
Topically to treat chickenpox, poison ivy, or sunburn. Topically on large areas of the body or on blistered or oozing skin. Contraindicated in patients hypersensitive to drug or other drugs of similar chemical structure and in those with acute asthma, angle-closure glaucoma, stenosing peptic ulcer, symptomatic prostatic hyperplasia, bladder-neck obstruction, or pyloroduodenal obstruction. Alsso contraindicated in those taking MAO inhibitors, in neonates or premature infants, in elderly or debilitated patients, and in breast-feeding women.

NURSING CONSIDERATIONS

• Use cautiously in patients with increased intraocular pressure, hyperthyroidism, CV disease, hypertension or bronchial asthma.
• Children younger than age 14 should use drug only as directed by prescriber.
• Discontinue drug 4 days before patient undergoes diagnostic skin test.Antihistamines can prevent, reduce, or mask positive skin test response.
• Alert: Don't confuse cyproheptadine with cyclobenzaprine.