Benadryl (diphenhydramine hydrochloride) is an antihistamine. Benadryl in the parenteral form is a sterile, pyrogen-free solution available in a concentration of 50 mg of diphenhydramine hydrochloride per mL.
Benadryl in the injectable form is effective in adults and pediatric patients, other than premature infants and neonates, for the following conditions when Benadryl 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.
Published Studies Related to Benadryl Injection (Diphenhydramine Injection)
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.
Antiemetic efficacy of metoclopramide and diphenhydramine added to patient-controlled morphine analgesia: a randomised controlled trial. [2010.12]
BACKGROUND AND OBJECTIVE: the objective of this study was to assess whether antiemetic drugs metoclopramide and diphenhydramine, administered together as opposed to alone, can have better efficacy in preventing postoperative nausea and vomiting when added to patient-controlled morphine analgesia... CONCLUSION: results of this study showed that a combination of metoclopramide with diphenhydramine in patients treated with dexamethasone at anaesthesia induction decreased postoperative nausea and vomiting compared to metoclopramide or diphenhydramine in these patients, when added to patient-controlled anaesthesia with morphine.
Effect of morphine and pregabalin compared with diphenhydramine hydrochloride and placebo on hyperalgesia and allodynia induced by intradermal capsaicin in healthy male subjects. [2008.12]
Intradermal (ID) capsaicin injection in humans induces spontaneous pain, flare, primary hyperalgesia, secondary hyperalgesia, and allodynia... This platform may provide a means to rapidly assess new analgesics and enhance dose selection and decision-making during clinical development.
Time-dependent inhibition of histamine-induced cutaneous responses by oral and intramuscular diphenhydramine and oral fexofenadine. [2008.05]
BACKGROUND: Diphenhydramine is often the treatment of choice for acute urticarial or allergic reactions despite its adverse effects of sedation and impairment. Second- and third-generation histamine1-antihistamines are generally devoid of these adverse effects but are typically not used because of a perceived slower onset of action. OBJECTIVE: To examine the time-dependent effects of oral fexofenadine and oral and intramuscular diphenhydramine to reduce histamine-induced wheal-and-flare responses... CONCLUSION: Diphenhydramine tended to work more rapidly than fexofenadine, but the differences were not statistically significant. Given the adverse effect profile of diphenhydramine, but only marginal onset of action advantage, the risk-to-benefit ratio may be more favorable for oral fexofenadine when treating an acute urticarial or allergic reaction.
A clinical trial of trimethobenzamide/diphenhydramine versus sumatriptan for acute migraines. [2006.06]
BACKGROUND: Although various classes of medication are used to treat acute migraine in the emergency department (ED), no treatment offers complete pain relief without side effects or recurrence of headache. Consequently, even though several antiemetic medications as well as SQ sumatriptan have demonstrated efficacy and tolerability for the ED treatment of migraine, there remains a need for more effective parenteral therapies. Open-label studies suggest that the combination of trimethobenzamide and diphenhydramine (TMB/DPH) may provide effective relief in a high proportion of migraineurs. OBJECTIVE: To test the hypothesis that ED patients with acute migraine, given intramuscular TMB/DPH, would have a larger reduction in their pain scores than patients given SQ sumatriptan... CONCLUSIONS: SQ sumatriptan is probably superior to TMB/DPH for treating the pain of acute migraine at 2 hours. However, TMB/DPH was well-tolerated, efficacious, and relieved pain comparably to sumatriptan at 24 hours. TMB/DPH might have a role in select populations in which sumatriptan is contraindicated or likely to be ineffective.
Clinical Trials Related to Benadryl Injection (Diphenhydramine Injection)
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.
Diphenhydramine, Lorazepam, and Dexamethasone in Treating Nausea and Vomiting Caused By Chemotherapy [Terminated]
RATIONALE: Diphenhydramine, lorazepam, and dexamethasone may help lessen or prevent nausea
and vomiting in patients treated with chemotherapy. It is not yet known whether
diphenhydramine, lorazepam, and dexamethasone are more effective than standard therapy in
treating nausea and vomiting caused by chemotherapy.
PURPOSE: This randomized phase II trial is studying diphenhydramine, lorazepam, and
dexamethasone to see how well they work compared with standard therapy in treating nausea
and vomiting caused by chemotherapy in young patients with newly diagnosed cancer.
Study to Evaluate Diphenhydramine in Children and Adolescents [Completed]
To characterize the pharmacokinetics of diphenhydramine in two pediatric populations:
children, ages 2 to < 12 years, and adolescents, ages 12 to < 18 years.
Study of Promethazine for Treatment of Diabetic Gastroparesis [Recruiting]
Adult diabetic patients (ages 18-65) with gastric emptying scintigraphy-confirmed delayed
gastric emptying will be recruited to participate in the study. Using double-blinded
methodology, study participants will be randomly assigned to one of two treatment arms:
promethazine 12. 5 mg three times daily for 28 days or placebo three times daily for 28 days.
The primary outcome will be the change in gastroparesis symptom severity, as measured by
the Gastroparesis Cardinal Symptom Index (GCSI) at four weeks compared to baseline.
Participants will be seen for a clinic evaluation at weeks 0, 2 and 4, during which symptom
scores, adverse events and treatment compliance will be assessed. It is hypothesized
promethazine treatment will be superior to placebo in improving symptoms of gastroparesis.
Page last updated: 2011-12-09