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.
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.

INDICATIONS AND USAGE
Diphenhydramine hydrochloride in the injectable
form is effective in adults and pediatric patients,
other than premature infants and neonates, for the
following conditions when diphenhydramine hydrochloride
in the oral form is impractical.
Antihistaminic: For amelioration of allergic reactions
to blood or plasma, in anaphylaxis as an adjunct to
epinephrine and other standard measures after the
acute symptoms have been controlled, and for other
uncomplicated allergic conditions of the immediate
type when oral therapy is impossible or contraindicated.
Motion Sickness: For active treatment of motion sickness.
Antiparkinsonism: For use in parkinsonism, when oral
therapy is impossible or contraindicated, as follows:
parkinsonism in the elderly who are unable to tolerate
more potent agents; mild cases of parkinsonism
in other age groups, and in other cases of parkinsonism
in combination with centrally acting anticholinergic
agents.

CONTRAINDICATIONS
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.
Use as a Local Anesthetic: 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: Hyper sensitivity to diphenhydramine
hydrochloride and other antihistamines of similar
chemical structure.

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
diphenhydramine.
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 more likely to cause dizziness,