Benadryl (Diphenhydramine hydrochloride) is an antihistamine drug having the chemical name 2-(Diphenylmethoxy)-N,N-dimethylethylamine hydrochloride. It occurs as a white, crystalline powder, is freely soluble in water and alcohol and has a molecular weight of 291.82. The molecular formula is CHNO • HCl. The structural formula is as follows:

Benadryl (Diphenhydramine hydrochloride) in the parenteral form is a sterile, pyrogen-free solution available in a concentration of 50 mg of diphenhydramine hydrochloride per mL. The solutions for parenteral use have been adjusted to a pH between 5.0 and 6.0 with either sodium hydroxide or hydrochloric acid. The multidose Steri-Vials® contain 0.1 mg/mL benzethonium chloride as a germicidal agent.

Diphenhydramine hydrochloride is an antihistamine with anticholinergic (drying) and sedative side effects. Antihistamines appear to compete with histamine for cell receptor sites on effector cells.

Benadryl (Diphenhydramine hydrochloride) in the injectable form has a rapid onset of action. Diphenhydramine hydrochloride is widely distributed throughout the body, including the CNS. A portion of the drug is excreted unchanged in the urine, while the rest is metabolized via the liver. Detailed information on the pharmacokinetics of Diphenhydramine Hydrochloride Injection is not available.

Benadryl (Diphenhydramine hydrochloride) in the injectable form is effective in adults and pediatric patients, other than premature infants and neonates, for the following conditions when Benadryl (Diphenhydramine hydrochloride) in the oral form is impractical.

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.

Local necrosis has been associated with the use of subcutaneous or intradermal use of intravenous Benadryl (Diphenhydramine hydrochloride) .

The most frequent adverse reactions are underscored.

Antihistamine overdosage reactions may vary from central nervous system depression to stimulation. Stimulation is particularly likely in pediatric patients. Atropine-like signs and symptoms; dry mouth; fixed, dilated pupils; flushing; and gastrointestinal symptoms may also occur.

Vasopressors may be used to treat hypotension.

THIS PRODUCT IS FOR INTRAVENOUS OR INTRAMUSCULAR ADMINISTRATION ONLY.

Benadryl (Diphenhydramine hydrochloride) in the injectable form is indicated when the oral form is impractical.

Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.

DOSAGE SHOULD BE INDIVIDUALIZED ACCORDING TO THE NEEDS AND THE RESPONSE OF THE PATIENT.

—sterile, pyrogen-free solution containing 50 mg diphenhydramine hydrochloride in each milliliter of solution. Available in packages of twenty-five 1-mL (N 0071-4259-13) Steri-Vials.