University:
Western Sydney University
Course:
MEDI 2003 | Clinical Sciences 2
Academic year:

2024
Views:

468

Pages:

2
Author:

Mariam A. A.

Benzodiazepines Used as: Sedatives Hypnotics Anxiolytics Muscle relaxants Anticonvulsants Dependence is common Potential fatal withdrawal syndrome: tachycardia, psychosis, delirium Can cause rebound insomnia With opioids, risk of respiratory depression is increased Mechanism of Action Bind non-selectively to GABA-A receptors Open Cl- channels ↑ GABAergic inhibition CNS depression Distribution Binding sites found in brain, spinal cord, cerebellum Highest density in cerebral cortex Less sensitive to depression in medulla Pharmacokinetics Half-life varies widely Short-acting: oxazepam, lorazepam Intermediate-acting: alprazolam, clonazepam Long-acting: diazepam, flurazepam Adverse Effects Drowsiness Sedation Ataxia Dizziness Confusion Amnesia Paradoxical reactions Clinical Uses Anxiety Insomnia Muscle relaxation Status epilepticus Adjunct in chronic pain management Premedication for surgical procedures Withdrawal syndrome Benzodiazepines Volume of distribution is large as it is highly lipid soluble Take longer than propofol to equilibrate with the brain All are extensively protein bound (96%) Termination of action occurs largely by redistribution & hepatic metabolism Metabolites are excreted by the kidney 3 main pathways of metabolism: oxidation, conjugation with glucuronide, or hydrolysis More likely to be affected by liver disease, drug interactions, age Lorazepam: less likely to be affected by liver disease Oxazepam: more likely to be affected by liver disease Diazepam: metabolized by CYP3A4 Table 4.7 Properties of benzodiazepines and related agents-cont'd Drug Routes of administration Dose range Onset of clinical action Offset of clinical effect Principal indications Precautions Midazolam IV, buccal, nasal 0.025-0.05 mg/kg, 0.03-0.1 mg/kg infusion, 0.2 mg/kg nasal 90 s 2 h Procedural sedation and anxiolysis May cause residual drowsiness, dizziness, and a hangover effect Significant increase in CSHT with continuous infusion in patients with renal impairment Semazepam Oral, rectal 10-30 mg, 10-20 mg 1-3 h 8-12 h Preoperative anxiolysis, night sedation May cause residual drowsiness, dizziness, and a hangover effect Withdrawal phenomena possible Status epilepticus Lorazepam Oral, sublingual 2-5 mg, 1-2 mg 1-3 h 8-12 h Preoperative anxiolysis, night sedation May cause residual drowsiness, dizziness, and a hangover effect Withdrawal phenomena possible Status epilepticus Diazepam Oral, rectal 5-20 mg, 10-20 mg 30-90 min, 15-30 min 24-36 h Preoperative anxiolysis, night sedation Withdrawal phenomena possible Status epilepticus Should not be used to manage psychosis Chlordiazepoxide Oral, rectal 10-25 mg, 10-20 mg 15-30 min 24-36 h Preoperative anxiolysis, night sedation Withdrawal phenomena possible Status epilepticus Two main pathways of metabolism: oxidation and conjugation with glucuronide