Pharmacology of Sedation Drugs Flashcards
Define conscious sedation
Reduction or abolition of physiological and psychological responses to the stress of dentistry, without loss of consciousness, cooperation or protective reflexes
List 3 routes of drug administration?
Intravenous
Inhalation
Oral
Advantages of IV administration?
Certain absorption
Advantages of inhalation administration?
Rapid absorption and onset fo sedation, rapid elimination and recovery
Disadvantages of oral route of administration?
Slow onset, gastric absorption
Describe benzodiazepines mode of action?
Act on receptors in CNS to enhance effect of GABA
What is the effect of GABA?
Inhibit neurotransmission
Where are GABA receptors located?
Cerebral cortex and motor circuits
Where are benzodiazepine receptors located?
Also to GABA receptors
Clinical effects of benzodiazepines?
Anxiolysis (reduced fear) Sedation Detachment Amnesia Muscle relaxation Disinhibitiion (more agitated, violent - more common in teenagers) Anti-convulsion
Benzodiazepines effect on pain?
They are not analgesics - may influence the pain response (psychologically)
Midazolam is water soluble at pH<4 and lipid solute at physiological pH, why is this important?
Allows penetration of blood-brain barrier
Why is midazlolam chosen over diazepam?
2-3 times more potent
Why are elderly more sensitive to midazlolam?
Decreased protein binding
Where is midazlolam metabolised?
Liver
Where is midazlolam excreted?
Kidney
What are the side-effects of benzodiazepines?
Respiratory depression
Cardiovascular effect - reduced BP
Drug interactions
How do benzodiazepines cause respiratory depression?
CNS depression and muscle relaxation, causing decreased cerebral response to CO2
How do benzodiazepine effect cardiovascular system?
Reduced BP by decrease in vascular resistance, increased HR due to baroreceptor response
Cardiac output unaffected
What kind of drug interactions re important with BZP?
Synergistic CNS depression with other CNS depressants e.g. opiates, alcohol
Erythromycin and cimetidine inhibit metabolism
Clinical use of nitrous oxide?
Inhalation sedation
Describe nitrous oxide gas?
Colourless, with sweet odour
Clinical effects of nitrous oxide?
a) sedation
b) cardiovascular
c) respiratory system
a) Depressive and euphoriant effects
Depressed sensation: touch, pain, hearing, vision
b) minimal, myocardial depressant at high dose
c) mild depression of alveolar ventilation and co2 response
List side-effects of nitrous oxide
Hazards to professional with chronic exposure
Haematological problems - oxidises B12
causing pernicious anaemia
Neurological disease and hepatic disease with chronic exposure
Decreased fertility
