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Diphenhydramine (Diphenhydramine Hydrochloride) - Summary



Diphenhydramine Hydrochloride Injection is a sterile, nonpyrogenic solution for intravenous or deep intramuscular use as an antihistaminic agent. Each mL contains diphenhydramine hydrochloride 50 mg and benzethonium chloride 100 mcg in Water for Injection. pH 4.0-6.5; sodium hydroxide and/or hydrochloric acid added, if needed, for pH adjustment.

Diphenhydramine Hydrochloride Injection is effective in adults and pediatric patients, other than premature infants and neonates, for the following conditions when the oral form is impractical:


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.


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.

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Published Studies Related to Diphenhydramine

A trial of midazolam vs diphenhydramine in prophylaxis of metoclopramide-induced akathisia. [2012.01]
STUDY OBJECTIVE: The study aimed to evaluate the effects of midazolam and diphenhydramine for the prevention of metoclopramide-induced akathisia... CONCLUSION: Coadministered midazolam reduced the incidence of akathisia induced by metoclopramide compared to placebo but increased the rate of sedation. No difference was detected from diphenhydramine. Routine coadministered 20 mg diphenhydramine did not prevent metoclopramide-induced akathisia. Copyright (c) 2012 Elsevier Inc. All rights reserved.

Effect of short-term diphenhydramine administration on aqueous tear production in normal dogs. [2011.11]
Objective To perform a randomized, placebo-controlled, masked clinical trial using a cross-over design to determine the effect of oral diphenhydramine on aqueous tear production in normal dogs. Animals studied Seventeen dogs with normal ophthalmic examinations...

Evaluation of the subjective and reinforcing effects of diphenhydramine, levetiracetam, and valproic acid. [2011.06]
Few unscheduled sedating medications have been evaluated for their subjective and reinforcing effects in humans. To increase the information available about unscheduled sedating medications and to evaluate the ability of human laboratory measures to discriminate between scheduled and unscheduled sedating drugs, 24 subjects with a history of experience with several classes of drugs of abuse, including sedatives and/or alcohol, and who reported liking a test dose of pentobarbital 300 mg, were randomized to single doses of diphenhydramine 400 mg, levetiracetam 4000 mg, valproic acid 1500 mg, diazepam 30 mg or placebo in a double-blind, 5-way crossover study...

Efficacy of intramuscular nalbuphine versus diphenhydramine for the prevention of epidural morphine-induced pruritus after cesarean delivery. [2011.03]
BACKGROUND: Pruritus is the most common side effect of epidural morphine analgesia. Diphenhydramine is a widely used agent for the treatment of urticarial pruritus. Nalbuphine is a mixed opioid agonist-antagonist and has been reported to be effective in treating opioid-induced pruritus. We compared the effectiveness of intramuscular diphenhydramine and nalbuphine for the prevention of epidural morphine-induced pruritus after cesarean section... CONCLUSION: Nalbuphine proved better than diphenhydramine for prevention of epidural morphine-induced pruritus in patients who underwent cesarean section. Prophylactic intramuscular nalbuphine (10 mg) is effective in decreasing the incidence and severity of pruritus and does not affect analgesia.

Next-day residual sedative effect after nighttime administration of an over-the-counter antihistamine sleep aid, diphenhydramine, measured by positron emission tomography. [2010.12]
Antihistamines often are self-administered at night as over-the-counter (OTC) sleep aids, but their next-day residual sedative effect has never been evaluated using a reliable quantitative method such as positron emission tomography (PET). We performed a double-blind, placebo-controlled, crossover study in which we evaluated the residual effect the next day after nighttime administration of diphenhydramine, a commonly used OTC sleep aid, in terms of brain H receptor occupancy (HRO) measured using (1)(1)C-doxepin-PET...

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Clinical Trials Related to Diphenhydramine

Pharmacogenetic Factors and Side Effects of Metoclopramide and Diphenhydramine [Active, not recruiting]

Diphenhydramine for Acute Migraine [Completed]
Parenteral diphenhydramine is commonly used as adjuvant therapy for acute migraine despite the fact that data supporting this practice do not exist. The investigators propose a randomized double blind study to test the hypothesis that 50mg of intravenous diphenhydramine, when added to standard migraine therapy, will result in a greater rate of sustained headache relief than standard migraine therapy alone. For this study, standard migraine therapy will be 10mg of intravenous metoclopramide. Sustained headache relief is defined as achieving a headache level of "mild" or "none" within two hours and maintaining a level of "mild" or "none" for 48 hours. Patients who present to the Montefiore emergency room (Bronx, NY) with an acute migraine will be approached for participation. They will be screened for medication contra-indications and non-migraine etiologies of headache. The study will be randomized. Assignment will be concealed. Participants and researchers will be blinded. Efficacy outcomes and adverse events will be assessed every half hour for two hours in the ED and by telephone 48 hours after medication administration. A sample size calculation, based on pilot data, revealed the need for 374 participants. An interim analysis will be performed after 200 participants have been enrolled with the goal of assessing for lack of conditional power.

Bioequivalence Study of Dr.Reddy's Ibuprofen and Diphenhydramine Citrate 200 mg/38 mg Caplets Under Fed Condition [Completed]

Bioequivalence Study of Dr.Reddy's Ibuprofen and Diphenhydramine Citrate 200 mg/38 mg Caplets Under Fasting Condition [Completed]

Antitussive Effect of a Naturally Flavored Syrup Containing Diphenhydramine, Compared With Dextromethorphan and Placebo [Completed]
The purpose of this study is to evaluate the antitussive (cough-suppressing) effects of two liquid medications: a combination of diphenhydramine and phenylephrine in a naturally cocoa flavoring, and, dextromethorphan syrup, compared with placebo.

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Reports of Suspected Diphenhydramine Side Effects

Completed Suicide (3)Respiratory Arrest (3)Cardiac Arrest (3)Drug Abuse (2)Injury (2)Electrocardiogram QT Prolonged (1)Coma (1)Hepatic Failure (1)Overdose (1)Medication Error (1)more >>

Page last updated: 2011-12-09

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