Lorazepam

Action

Unknown. Thought to depress CNS at limbic system and disrupt neurotransmission in reticular activating system.

Availability

Injection: 2 mg/ml, 4 mg/ml

Solution (concentrated): 2 mg/ml

Tablets: 0.5 mg, 1 mg, 2 mg

Indications and dosages

➣ Anxiety

Adults: 2 to 3 mg P.O. daily in two or three divided doses. Maximum dosage is 10 mg daily.

➣ Insomnia

Adults: 2 to 4 mg P.O. at bedtime

➣ Premedication before surgery (as antianxiety agent, sedative-hypnotic, or amnestic)

Adults: 0.05 mg/kg (not to exceed 4 mg) deep I.M. injection at least 2 hours before surgery, or 0.044 mg/kg (not to exceed 2 mg) I.V. 15 to 20 minutes before surgery. For greater amnestic effect, give up to 0.05 mg/kg (not to exceed 4 mg) I.V. 15 to 20 minutes before surgery.

➣ Status epilepticus

Adults: 4 mg I.V. given slowly (no faster than 2 mg/minute). If seizures continue or recur after 10 to 15 minutes, repeat dose. If seizure control isn't established after second dose, other measures should be used. Don't exceed 8 mg in 12 hours.

Dosage adjustment

• Elderly or debilitated patients

Off-label uses

• Acute alcohol withdrawal syndrome

Contraindications

• Hypersensitivity to drug, other benzodiazepines, polyethylene or propylene glycol, or benzyl alcohol

• Acute angle-closure glaucoma

• Coma or CNS depression

• Hepatic or renal failure

Precautions

Use cautiously in:

• hepatic or renal impairment

• history of suicide attempt, drug abuse, depressive disorder, or psychosis

• elderly patients

• pregnant or breastfeeding patients.

Administration

• For I.V. use, dilute with equal volume of compatible diluent, such as normal saline solution or dextrose 5% in water. Keep resuscitation equipment and oxygen at hand.

☞ Give each 2 mg of I.V. dose slowly, over 2 to 5 minutes. Don't exceed rate of 2 mg/minute.

• Don't give parenteral form to children younger than age 18.

Adverse reactions

CNS: amnesia, agitation, ataxia, depression, disorientation, dizziness, drowsiness, headache, incoordination, asthenia

CV (with too rapid I.V. administration): hypotension, bradycardia, tachycardia, apnea, cardiac arrest, cardiovascular collapse

EENT: blurred vision, diplopia, nystagmus

GI: nausea, abdominal discomfort

Other: increased or decreased appetite

Interactions

Drug-drug. CNS depressants (including antidepressants, antihistamines, benzodiazepines, sedative-hypnotics): additive CNS depression

Hormonal contraceptives: increased lorazepam clearance

Drug-herbs. Chamomile, hops, kava, skullcap, valerian: increased CNS depression

Drug-behaviors. Alcohol use: increased CNS depression

Smoking: increased metabolism and decreased efficacy of lorazepam

Patient monitoring

☞ During I.V. administration, monitor ECG and cardiovascular and respiratory status.

• Monitor vital signs closely.

• Evaluate for amnesia.

• Watch closely for CNS depression. Institute safety precautions as needed to prevent injury.

☞ Monitor for signs and symptoms of overdose (such as confusion, hypotension, coma, and labored breathing).

• Assess liver function tests and CBC.

Patient teaching

• Tell patient and family about drug's possible CNS effects. Recommend appropriate safety precautions.

• Explain that with long-term use, drug must be discontinued slowly (typically over 8 to 12 weeks).

• Instruct patient to avoid alcohol, because it increases drowsiness and other CNS effects.

• Caution patient to avoid smoking, because it speeds drug breakdown in body.

• Advise female patient to inform prescriber if she is pregnant or breastfeeding.

• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, herbs, and behaviors mentioned above.