From the Guidelines
Intravenous (IV) Benadryl (diphenhydramine) can be used to prevent dystonic reactions from compazine (prochlorperazine), with a typical preventive dose of 25-50 mg administered before giving compazine. According to the guidelines, diphenhydramine can be used for dystonic reactions 1. Dystonic reactions are involuntary muscle contractions that can occur as side effects of certain medications, particularly antipsychotics and antiemetics like compazine. These reactions happen because compazine blocks dopamine receptors, creating an imbalance between dopamine and acetylcholine in the brain. Benadryl works by blocking acetylcholine receptors, which helps restore this balance and prevents the abnormal muscle movements.
Some key points to consider when using IV Benadryl to prevent dystonic reactions from compazine include:
- The dose of IV Benadryl can range from 25-50 mg, depending on the patient's specific needs and medical history 1.
- IV Benadryl can be administered before giving compazine to prevent dystonic reactions, or it can be given as treatment if a reaction occurs.
- For patients receiving regular compazine doses, oral Benadryl may also be prescribed as a preventive measure, typically 25-50 mg taken 30 minutes before each compazine dose.
- Benztropine may be used in patients who are allergic to diphenhydramine, as an alternative treatment for dystonic reactions 1.
It's essential to monitor patients for dystonic reactions when using prochlorperazine or metoclopramide, and to have a plan in place for preventing and treating these reactions, such as using IV Benadryl 1.
From the Research
IV Benadryl and Dystonic Reactions
- There is no direct evidence that IV Benadryl prevents dystonic reactions from Compazine.
- However, studies have shown that diphenhydramine (Benadryl) can be effective in treating dystonic reactions, including those induced by other medications 2, 3.
- One study found that benztropine mesylate was more effective than diphenhydramine in reducing recovery time for drug-induced dystonic reactions 2.
- Another study reported a case of acute dystonia induced by diphenhydramine itself, highlighting the potential for antihistamines to cause dystonic reactions 4.
- Compazine (prochlorperazine) is known to cause dystonic reactions, with an incidence of 4% in one study 5.
- A case report described a patient who developed acute dystonia after taking prochlorperazine, which was successfully treated with orphenadrine 6.
Treatment of Dystonic Reactions
- Diphenhydramine has been shown to be effective in treating idiopathic truncal dystonia, with minimal side effects 3.
- Benztropine mesylate is also effective in treating drug-induced dystonic reactions, and may be more effective than diphenhydramine in some cases 2.
- Orphenadrine has been used to treat acute dystonia induced by prochlorperazine 6.