Are Haldol (haloperidol), Ativan (lorazepam), and diphenhydramine compatible in the same intramuscular (IM) syringe?

Compatibility of Haloperidol, Lorazepam, and Diphenhydramine in the Same IM Syringe

Haloperidol and lorazepam can be combined in the same syringe for intramuscular injection, and this combination is compatible with diphenhydramine as well, making all three medications compatible in the same syringe. 1

Compatible Combinations

• Haloperidol and lorazepam are physically compatible in the same syringe and can be administered together intramuscularly 2
• The triple combination of haloperidol, lorazepam, and diphenhydramine has been validated as physically compatible through both visual inspection and particle counter evaluation 1
• Combinations of a butyrophenone (e.g., haloperidol) and a benzodiazepine (e.g., lorazepam) may be given together for an additive effect and can be administered in the same syringe 2

Clinical Benefits of Combined Administration

• The combination of haloperidol and lorazepam produces more rapid tranquilization than either medication alone in agitated patients 3
• Adding diphenhydramine to haloperidol helps reduce the risk of extrapyramidal symptoms (EPS) that can occur with haloperidol administration 2
• Using a single syringe for multiple medications reduces the number of injections needed, improving patient comfort and compliance 1

Efficacy Considerations

• The combination of haloperidol and lorazepam has been shown to reduce agitation significantly when compared to either drug alone 2
• Fewer repeat doses are typically required when using combination therapy compared to monotherapy 2
• Data from adult studies suggest that coadministration of haloperidol with lorazepam may be more effective than either medication alone 2

Administration Guidelines

• When combining medications in a syringe, it's important to follow standardized procedures to ensure proper dilution and administration 2
• Syringes should be labeled according to pharmacological class and administration route to prevent medication errors 2
• The combination should be administered immediately after preparation for optimal stability 1

Practical Considerations

• When drawing up multiple medications into the same syringe, draw them up in order of increasing irritant potential 2
• Visually inspect the combined solution for any signs of precipitation, cloudiness, or color change before administration 1
• Combinations should be administered promptly after preparation to minimize the risk of compatibility issues developing over time 1

Potential Adverse Effects

• Even when compatible, the combination may increase the risk of respiratory depression and sedation compared to single agents 2
• Monitor patients who have received this combination for potential side effects including respiratory depression, hypotension, and excessive sedation 2
• Be aware that the combination of sedative and analgesic agents may cause respiratory depression and airway obstruction, emphasizing the need to appropriately reduce the dose of each component 2

Alternative Combinations

• For patients where this specific combination is contraindicated, alternative combinations such as risperidone with diphenhydramine or risperidone with lorazepam may be considered 2
• Droperidol combined with midazolam is another alternative that has been shown to achieve adequate sedation more rapidly than haloperidol with lorazepam 4