Benzodiazepine: Mechanism of action
Anesthetic composed of a fused benzene and diazepine ring that is administered orally or intravenously to produce a sedative or hypnotic effect
Ex. Lorazepam, Midazolam, Diazepam
Binds to Gamma- aminobutyric acid (GABAA) receptor in vascular smooth muscle and the central nervous system (CNS)
APs inhibited in
vascular smooth muscle
Vascular smooth muscle relaxes
Vasodilation ↓ Blood pressure
Authors: Victoria Silva Travis Novak Reviewers: Billy Sun Mao Ding Melinda Davis* *MD at time of publication
↑ Frequency of chloride channel opening
Hyperpolarization of nerve membrane
Action potential (AP) inhibited
APs inhibited in the
medulla oblongata
(the respiratory center)
↓ Respiratory drive: the body fails to ↑ depth and rate of respirations when arterial CO2 ↑
General CNS inhibition
Anti-convulsion
(Seizures are caused by a burst of uncontrollable, electrical activity in the brain)
APs inhibited in the thalamus and hypothalamus (play a role in memory)
APs inhibited in the limbic system (the behavioral and emotional response centers in the brain)
Hypotension
↓ Cerebral blood flow
↓CO2 diffusion from arterial blood to alveoli
↓O2 diffusion from alveoli to arterial blood
Pharyngeal muscle relaxation
↑ Arterial CO2
↓ Arterial O2
Airway obstruction
Amnesia
↑ PaCO2
↓ PaO2
↓ Anxiety
Anxiolysis Hypercapnia
Hypoxemia
In high doses:
Depression of arousal and loss of consciousness
Induction of general anesthesia
(No analgesic effect)
↓ Intracranial pressure Benzodiazepine reversal:
Temporary cessation of breathing
Apnea
Flumazenil competitively binds to GABAA
Flumazenil reverses the binding of benzodiazepine to GABAA
↓ Frequency of chloride channel opening
Depolarization of nerve membrane
Benzodiazepine reversal
Legend:
Pathophysiology
Mechanism
Sign/Symptom/Lab Finding
Complications
Published Aug 09, 2018, updated April 25, 2023 on www.thecalgaryguide.com