Benadryl Information
Benadryl (Diphenhydramine) Description
Benadryl (Diphenhydramine) (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) 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.
Benadryl (Diphenhydramine) Clinical Pharmacology
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) 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) Indications And Usage
Benadryl (Diphenhydramine) in the injectable form is effective in adults and pediatric patients, other than premature infants and neonates, for the following conditions when Benadryl (Diphenhydramine) in the oral form is impractical.
Benadryl (Diphenhydramine) Contraindications
Because of the risk of local necrosis, this drug should not be used as a local anesthetic.
Antihistamines are also contraindicated in the following conditions:
Benadryl (Diphenhydramine) Warnings
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) .
Benadryl (Diphenhydramine) Precautions
Patients taking diphenhydramine hydrochloride should be advised that this drug may cause drowsiness and has an additive effect with alcohol.
Patients should be warned about engaging in activities requiring mental alertness such as driving a car or operating appliances, machinery, etc.
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.
Benadryl (Diphenhydramine) should not be used in neonates and premature infants (see ).
Benadryl (Diphenhydramine) may diminish mental alertness, or, in the young pediatric patient, cause excitation. Overdosage may cause hallucinations, convulsions, or death (see and ).
See also section.
Benadryl (Diphenhydramine) Adverse Reactions
The most frequent adverse reactions are underscored.
Benadryl (Diphenhydramine) Overdosage
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.
Benadryl (Diphenhydramine) Dosage And Administration
THIS PRODUCT IS FOR INTRAVENOUS OR INTRAMUSCULAR ADMINISTRATION ONLY.
Benadryl (Diphenhydramine) 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.
Benadryl (Diphenhydramine) How Supplied
—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.
Benadryl (Diphenhydramine)
