ABH Gel Is Not Recommended for Sedation Due to Lack of Absorption and Potential Risks
ABH Gel (Ativan/lorazepam, Benadryl/diphenhydramine, Haldol/haloperidol) should not be used for sedation as research demonstrates the medications are not absorbed in sufficient quantities to be effective, while carrying potential risks associated with each component.
Absorption and Efficacy Issues
ABH gel applied topically fails to achieve therapeutic systemic levels of any of its components, with studies showing no detectable lorazepam or haloperidol in plasma and only erratic, subtherapeutic levels of diphenhydramine 1.
Laboratory studies confirm that the theoretical steady-state plasma concentrations achieved with ABH gel (diphenhydramine 1.6 ng/mL, haloperidol 0.13 ng/mL, and lorazepam 2.30 ng/mL) are significantly below therapeutic levels required for clinical effect 2.
Despite its continued use in some hospice and palliative care settings, ABH gel represents a "pricey placebo" that delays effective treatment with more reliable modalities 3.
Risks Associated with Individual Components
Lorazepam (Ativan)
Lorazepam carries FDA black box warnings regarding risks of respiratory depression, sedation, and death when used with opioids 4.
It poses risks of abuse, misuse, addiction, and physical dependence with potential for life-threatening withdrawal reactions 4.
Lorazepam should be used cautiously in patients with compromised respiratory function (e.g., COPD, sleep apnea) and may cause paradoxical reactions, especially in children and the elderly 4.
Diphenhydramine (Benadryl)
First-generation antihistamines like diphenhydramine are associated with significant sedation, performance impairment, and anticholinergic effects 5.
Diphenhydramine can impair driving ability, with studies showing drivers taking first-generation antihistamines were 1.5 times more likely to be responsible for fatal accidents 5.
It is listed as a medication to avoid in older adults due to its anticholinergic properties that can cause CNS impairment, delirium, vision problems, urinary retention, constipation, and increased fall risk 5.
Haloperidol (Haldol)
Haloperidol can cause extrapyramidal symptoms (EPSEs) and should not be used in patients with Parkinson's disease or Lewy body dementia 5.
It may prolong QTc interval, requiring ECG monitoring when administered intravenously 5.
Antipsychotics like haloperidol carry an FDA black box warning regarding increased risk of death when used for dementia-related behavioral disorders 5.
Alternative Approaches for Sedation
For agitation management, intravenous administration of medications is preferred over topical application for reliable absorption and effect 5.
When sedation is required in delirious patients, guidelines suggest using dexmedetomidine rather than benzodiazepine infusions, unless delirium is related to alcohol or benzodiazepine withdrawal 5.
For acute agitation requiring medication, parenteral administration of haloperidol and lorazepam has shown efficacy, with evidence suggesting that adding diphenhydramine (as in B52 combinations) may result in more adverse effects including oxygen desaturation, hypotension, and longer hospital stays 6.
In cases where symptoms of acute delirium prevail, neuroleptic drugs (e.g., haloperidol) are preferred over benzodiazepines 5.
Monitoring and Safety Considerations
When using sedative medications, patients should be monitored for respiratory depression, which often precedes respiratory arrest 5.
Naloxone should be available when opioids are administered, and flumazenil when benzodiazepines are used, though routine reversal is discouraged 5.
Caution is warranted when combining medications with sedating effects (e.g., benzodiazepines with opioids) due to increased risk of respiratory depression and death 5.
Conclusion
For sedation purposes, clinicians should avoid ABH gel due to its proven lack of systemic absorption and instead use evidence-based parenteral medications with appropriate monitoring. When sedation is necessary, the benefits must clearly outweigh the risks, with careful consideration of patient-specific factors and close monitoring for adverse effects.