Salient pharmacological features of benzodiazepines
| Class/molecule | Pharmacological features |
|---|---|
| Benzodiazepines | Act by facilitating the activity of GABA, which is a major inhibitory neurotransmitter |
| Therapeutic effects due to decreased arousal | |
| Target symptom anxiety | |
| Can be used alone or in combination with antipsychotics | |
| Preferred in a patient in whom agitation is secondary to alcohol or sedative withdrawal | |
| Side effects to consider | |
| Excessive sedation; added sedation when combined with CNS depressant | |
| Respiratory depression; to avoid in patients with risk for CO2 retention | |
| Paradoxical disinhibition in high doses in patients with structural brain damage, mental retardation, or dementia | |
| Ataxia | |
| Typical antipsychotics (FGA) | Dopamine antagonist |
| Advantageous effects: as antipsychotic and for agitation | |
| Preferred in acute agitation | |
| Low potency FGA: Not recommended | |
| High potency FGA (haloperidol): virtually no anticholinergic properties, little risk of hypotension, no respiratory depression, can be given IV, the onset of action is within 30 min and lasts up to 12-24 h | |
| Side effects to consider | |
| EPS | |
| Neuroleptic Malignant Syndrome (NMS) | |
| Dystonia | |
| Akathisia | |
| Parkinson-like effects | |
| QTc prolongation | |
| May lower the seizure threshold | |
| Atypical antipsychotics (SGA) | Broader spectrum of response |
| Different side effect profile | |
| Fewer EPS and akathisia | |
| QTc concern remains | |
| Metabolic syndrome on prolonged use | |
| Olanzapine | |
| IM dose range of 5-10 mg | |
| Maximum of 30 mg/day | |
| 15-45 min until peak plasma concentration | |
| 21-54 h elimination half-life | |
| Oral dose range 5-10 mg and flexible-dose up to 40 mg/day | |
| Risperidone | |
| 1–6 mg PO or ODT | |
| Oral risperidone concentrate 2 mg+oral lorazepam 2 mg equivalent to IM haloperidol 5mg+IM lorazepam 2 mg | |
| Oral risperidone 2 mg equally effective as oral haloperidol 5 mg | |
| Risk of EPS | |
| Aripiprazole | |
| Partial dopamine agonist | |
| Oral aripiprazole 15 mg as effective as oral olanzapine 20 mg | |
| Low risk for QT interval prolongation (<1%) | |
| Quetiapine | |
| 25 mg onwards up to 400 mg | |
| 1–3 h to peak plasma concentrations | |
| Shallow risk of EPS | |
| Sedation and orthostasis are side effects |
FGA – First generation antipsychotics; EPS – Extrapyramidal symptoms; SGA – Second generation antipsychotics; CNS – Central nervous system; IV – Intravenous