which IV drugs use the chloride (GABA-A) channel mechanism?
Benzodiazapam Barbiturates. Inhaled anesthetics Propofol Etomidate
methohexital and thiopental Mechanism: Prolong GABA effect on GABA-A receptors. Clinical use: Induction of anesthesia. Characteristics: 1. Ultra short actin: Rapid onset (30sec): 5-10min duration. - Fast recovery after single dose due to redistriubtion. - SLow recovery due to accumulation in tissue following repeated doses. - Potent anesthetic but weak analgesic Kinetics: Liver and enzyme inducer Adverse: Hypotension apnea Spasms of chest, laryngo and broncho. Repsiratory depression cerebral vasoconstrion WIth minimal CV effect: - Increases HR.
lorazapam, midazolam and diazapam Action: 1) Potentiate GABA effect on GABAA receptors 2) Facilitation of amnesia (retrograde), while causing sedation in conjunction with anesthetics Indication: 1) Induction of anesthesia (midazolam, lorazepam) 2) Premedication to decrease anxiety before anesthesia (diazepam) Char: -Short-acting (midazolam, lorazepam) for short interventions -Long acting (diazepam) Adverse: -Minimal cardiovascular depression -Respiratory depres
fentanyl, alfentanil, remifentanil and sulfentanil Action: Analgesic Clinical use: During anestheisa. Char: Combined with anesthetics ANTAGONIZED by naloxone. ADverse hypotension, respiratory dperession muscle rigidity. Alpha 2 antagonist:
Alpha 2 antagonist:
Clonidine and dexmetomidine Action: Decrease BP (good for HTN patients). Clonidine: ICU for short term sedation of intubated and ventilated patients.
Etomidate: Hypnotic agent for anesthesia. Clinical use: Anesthesia in coronary artery disease Anesthesia in hypovolemic patients Char: Short acting (rapid onset) No analgesic activity. Advantage: Ability to preserve CV and respiratory stability. Adverse: Cortisol ad aldosterone are reduced in plasma. Pain at site of injection Involuntary skeletal muscle movements (Treated with BZ)
Propofol Mechanism: -Enhances GABAA receptor activity -Sedative/hypnotic Clinical use: 1) Antiemetic 2) Induction for outpatient anesthesia (1st choice) - 3) It is a component of balance anesthesia and TIVA (total IV anesthesia). 4) Sedation in mechanically ventilated patients in ICU/ Char: - Short-acting: rapid onset (30s): 5-10min duration - Fast recovery - Ø analgesic effect. Pharmacokinetics: -Fast metabolism in liver conjugation -High protein binding -Pain in site of infusion Adverse: -Hypotension -Transient apnea after induction -Respiratory depression -Propofol infusion syndrome: after long application in higher dose-> lipid metabolism disturbances -> metabolic acidosis- -Synergistic interaction with opioids -> (-) inotropic effect, veno- and vasoconstriction + inhibition of baroreceptor reflex -Cerebral vasoconstriction -> reduced cerebral blood flow-> ICP reduced.
Ketamin IV or IM
Ketamine Mechanism: -NMDA receptor antagonist (at phencyclidine (PCP, other drug) site): A. Dissociate state where patient is unconscious (may appear to be awake) and doesn’t feel pain. It provides: ØSedation ØAmnesia ØImmobility B. Stimulation of central SY outflow: Increases blood pressure via heart. Bronchodialator. Indication: A. Anesthesia in hypovolemic or cardiogenic shock and asthmatic patients. B. Anesthesia for children and elderly for short procedures Char: -BOTH analgesia and anesthesia -Produces surgical anesthesia alone (induction and maintenance) -Short-acting (minutes) with a moderately rapid onset and recovery, but slower than the others. -Given IM or IV Pharmacokinetics: -Liver (norketamine). Adverse: - ICP increased. hallucinogenic BP increase Convulsions unpleasent recovery.
Total inahalational anesthesia
Sevoflurane for induction and maintenance
Preoperative: Sedation and analgesia
Intraoperative: NMJ blocking agents
IV and inhalaed anesthetic agents.
TIVA (Total IV anesthesia)
1. Hypnosis (e.g. popofol as short acting
2. analgesia (e.g. remifentanil as short acting).
3. Muscle relaxation (e.g. atracurium, verocurium for intermediate acting; e.g. mivacurium for short acing; inhition fo these by sugammedex.
adv: avoid potential toxicity of inahled anesthetics.
prefered in neurosurgery and less pollutatnt.
secure, reliable IV acess is required
Neuroleptic analgesia and anesthesia
an anesthetic process that involves combining a major neuroleptic tranquilizer/antipsychotic with a potent opioid analgesic to produce a detached, pain-free state.
Achieved by fentanyl and droperidol
WIth nitric oxide it is called neuroleptanesthesia (fentanyl, droperidol and nitrious oxide).
Neuroleptic analgeis ana danesthesia are safe and simple procedures for old, serious ill or weakend patients.
Sedation and amnesia
oral or parental benzodiazepine and local anesthetic
Monitoed anesthesia (conscious, sedation), used for minor procedures where patients can respond to verbal commands.
It has no impat on respiration.
Same day surgery
IV benzo and propofol
Adv: Less post-op complication