Diphenhydramine Hydrochloride is an antihistamine drug having the chemical name 2-(diphenylmethoxy)-N, N-dimethylethylamine hydrochloride. It occurs as a white, odorless crystalline powder and is freely soluble in water and alcohol. The structural formula is as follows:
Each capsule contains 50 mg of diphenhydramine hydrochloride for oral administration.
Anhydrous lactose, lactose monohydrate and magnesium stearate.
The 50 mg capsule shell contains D&C red no. 28, FD&C blue no. 1, FD&C red no. 40, gelatin, silicon dioxide and sodium lauryl sulfate.
The imprinting ink contains D&C yellow no. 10 aluminum lake, FD&C blue no. 1 aluminum lake, FD&C blue no. 2 aluminum lake, FD&C red no. 40 aluminum lake, pharmaceutical glaze, propylene glycol and synthetic black iron oxide.
Diphenhydramine hydrochloride is an antihistamine with anticholinergic (drying) and sedative effects. Antihistamines appear to compete with histamine for cell receptor sites on effector cells.
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. Diphenhydramine is widely distributed throughout the body, including the CNS. Little, if any, is excreted unchanged in the urine; most appears as the degradation products of metabolic transformation in the liver, which are almost completely excreted within 24 hours.
Diphenhydramine hydrochloride in the oral form is effective for the following indications:
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.
For active and prophylactic treatment of motion sickness.
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.
This drug should not be used in newborn or premature infants.
Because of the higher risk of antihistamines for infants generally, and for newborns 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.
In infants and children, especially, antihistamines in overdosage may cause hallucinations, convulsions, or death.
As in adults, antihistamines may diminish mental alertness in children. In the young child, particularly, they may produce excitation.
Antihistamines are more likely to cause dizziness, sedation, and hypotension in elderly patients.
Diphenhydramine hydrochloride has an atropine-like action and therefore should be used with caution in patients with a history of lower respiratory disease including asthma, increased intraocular pressure, hyperthyroidism, cardiovascular disease or hypertension.
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.
Long-term studies in animals to determine mutagenic and carcinogenic potential have not been performed.
The most frequent adverse reactions are underscored.
Antihistamine overdosage reactions may vary from central nervous system depression to stimulation. Stimulation is particularly likely in children. Atropine-like signs and symptoms, dry mouth; fixed, dilated pupils; flushing; and gastrointestinal symptoms may also occur.
If vomiting has not occurred spontaneously the patient should be induced to vomit. This is best done by having him drink a glass of water or milk after which he should be made to gag. Precautions against aspiration must be taken, especially in infants and children.
If vomiting is unsuccessful gastric lavage is indicated within 3 hours after ingestion and even later if large amounts of milk or cream were given beforehand. Isotonic or (½) isotonic saline is the lavage solution of choice.
Saline cathartics, as milk of magnesia, by osmosis draw water into the bowel and therefore are valuable for their action in rapid dilution of bowel span.
Stimulants should not be used.
Vasopressors may be used to treat hypotension.
DOSAGE SHOULD BE INDIVIDUALIZED ACCORDING TO THE NEEDS AND 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.
25 to 50 mg three or four times daily. The nighttime sleep-aid dosage is 50 mg at bedtime.
(over 20 lb): 12.5 to 25 mg three to 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/m2/24 hours.
Data are not available on the use of diphenhydramine hydrochloride as a nighttime sleep-aid in children under 12 years.
The basis for determining the most effective dosage regimen will be the response of the patient to medication and the condition under treatment.
In motion sickness, full dosage is recommended for prophylactic use, the first dose to be given 30 minutes before exposure to motion and similar doses before meals and upon retiring for the duration of exposure.
Diphenhydramine Hydrochloride Capsules, USP are available as:
|50 mg:||Pink clear cap/pink clear body filled with white powder. Imprinted in black ink stylized barr 059.|
|Available in bottles of:|
Dispense with a child-resistant closure in a tight container as defined in the USP/NF.
Store at controlled room temperature 15°-30°C (59°-86°F).
BARR LABORATORIES, INC.
POMONA, NY 10970