Lorazepam
Lorazepam has sedative, anxiolytic and anticonvulsant actions; repeated administration may cause dependence.
Group
Benzodiazepine anticonvulsant and anxiolytic
Mechanism of Action
Enhances GABA-A receptor-mediated inhibitory neurotransmission.
Dose Rates
Dogs
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Anxiety | 0.05 mg/kg | PO | Every 12 h | |
| Seizures | 0.2 mg/kg | IV | Every 3–4 h | Repeat only if needed for seizure control. |
| Seizure infusion — Loading | 0.2 mg/kg | IV | ||
| Seizure infusion — Maintenance | 0.2–0.4 mg/kg/hour | IV | Continuous | |
| Status epilepticus rescue | 0.2 mg/kg | IM, IN | Once | |
| Anxiety | 0.02–0.1 mg/kg | PO | Every 8–24 h | Use the lowest effective amount and frequency; taper sustained treatment. |
| Anxiety | 0.05–0.25 mg/kg | PO | Every 12–24 h | Use the lowest effective amount and frequency; taper sustained treatment. |
| Anxiety | 0.02–0.5 mg/kg | PO | Every 8 h | Use the lowest effective amount and frequency; taper sustained treatment. |
Cats
| Use / stage | Dose | Route | Schedule | Instructions |
|---|---|---|---|---|
| Anxiety | 0.05 mg/kg | PO | Every 12–24 h | |
| Anxiety | 0.03–0.08 mg/kg | PO | Every 12 h | |
| Anxiety | 0.05–0.25 mg/kg | PO | Every 12–24 h | |
| Anxiety | 0.125–0.25 mg/animal | PO | Every 12–24 h |
Indications
- Selected anxiety disorders
- Seizure control
Contraindications
- Taper prolonged treatment to avoid withdrawal.
- Use cautiously during pregnancy and with respiratory compromise.
Interactions
- Other sedatives increase central depression.
- Do not mix with buprenorphine.
Adverse effects
- Sedation, polyphagia and paradoxical excitement
- Dependence and withdrawal signs
Toxicity
Support respiration and circulation; flumazenil may reverse benzodiazepine effects but can precipitate seizures in susceptible or dependent patients.
Preparations
| Preparation | Form | Strength | Route |
|---|---|---|---|
| Lorazepam 0.5 mg tablet | Tablet | 0.5 mg / tablet | PO |
| Lorazepam 1 mg tablet | Tablet | 1 mg / tablet | PO |
| Lorazepam 2 mg tablet | Tablet | 2 mg / tablet | PO |
| Lorazepam 2 mg/mL injection | Injection | 2 mg / mL | IV |
| Lorazepam 4 mg/mL injection | Injection | 4 mg / mL | IV |
| Lorazepam 2 mg/mL oral concentrate | Oral Liquid | 2 mg / mL | PO |
Monitoring and Administration
Monitor respiratory and neurologic response during IV treatment.
Dilute injection 1:1 with saline or 5% dextrose immediately before IV use.
Protect from light and discard discoloured or precipitated solution.
Store the listed oral concentrate and injection refrigerated at 2-8°C and protected from light; tablets remain at room temperature. Before IV injection dilute 1:1 with saline, D5W or sterile water, mix gently and administer slowly. Discard precipitated/discoloured solution. Do not give intra-arterially.