Precedex (Dexmetatomidine)
Dexmedetomidine is a specific and selective alpha-2 adrenoceptor agonist. By binding to the presynaptic alpha-2 adrenoceptors, it inhibits the release if norepinephrine, therefore, terminate the propagation of pain signals. Activation of the postsynaptic alpha-2 adrenoceptors inhibits the sympathetic activity decreases blood pressure and heart rate.
Benzodiazepines
In order for GABAA receptors to be sensitive to the action of benzodiazepines they need to contain an α and a γ subunit, between which the benzodiazepine binds. Once bound, the benzodiazepine locks the GABAA receptor into a conformation where the neurotransmitter GABA has much higher affinity for the GABAA receptor, increasing the frequency of opening of the associated chloride ion channel and hyperpolarising the membrane. This potentiates the inhibitory effect of the available GABA leading to sedative and anxiolytic effects.
Flumazenil
- onset: 1-2 min
- peaks effect: 2-10 min
- duration: 45-90 min
Naloxone
- onset: 1-2 min
- peaks effect: 5-15 min
- duration: 60-240 min
Myasthenia Gravis
- autoimmune disorder of the motor endplate
- patients often have 70-80% reduction in the number of acetylcholine motor-endplate receptors
- Approximately 25% of these receptors are required for functional neuromuscular transmission
Cholinergic crisis
- bradycardia
- hypotension
- increased secretions
- lacrimation
- wheezing
- muscle weakness
- nausea & vomiting
- constricted pupils
Malignant Hyperthermia
- most sensitive indicator: hypercapnia
- Early signs: tachycardia
Cocaine
- Half life 0.5 to 1.5 hrs
Alcohol Withdrawal
- 1st line: benzodiazepine (eg. lorazepam)
- if agitated due to poor analgesia: morphine
- if postoperative delirium only: haloperidol
