Pharmacology of Sedation Drugs

Question 1

Define conscious sedation

Answer 1

Reduction or abolition of physiological and psychological responses to the stress of dentistry, without loss of consciousness, cooperation or protective reflexes

Question 2

List 3 routes of drug administration?

Answer 2

Intravenous
Inhalation
Oral

Question 3

Advantages of IV administration?

Answer 3

Certain absorption

Question 4

Advantages of inhalation administration?

Answer 4

Rapid absorption and onset fo sedation, rapid elimination and recovery

Question 5

Disadvantages of oral route of administration?

Answer 5

Slow onset, gastric absorption

Question 6

Describe benzodiazepines mode of action?

Answer 6

Act on receptors in CNS to enhance effect of GABA

Question 7

What is the effect of GABA?

Answer 7

Inhibit neurotransmission

Question 8

Where are GABA receptors located?

Answer 8

Cerebral cortex and motor circuits

Question 9

Where are benzodiazepine receptors located?

Answer 9

Also to GABA receptors

Question 10

Clinical effects of benzodiazepines?

Answer 10

Anxiolysis (reduced fear)
Sedation
Detachment
Amnesia
Muscle relaxation 
Disinhibitiion (more agitated, violent - more common in teenagers)
Anti-convulsion

Question 11

Benzodiazepines effect on pain?

Answer 11

They are not analgesics - may influence the pain response (psychologically)

Question 12

Midazolam is water soluble at pH<4 and lipid solute at physiological pH, why is this important?

Answer 12

Allows penetration of blood-brain barrier

Question 13

Why is midazlolam chosen over diazepam?

Answer 13

2-3 times more potent

Question 14

Why are elderly more sensitive to midazlolam?

Answer 14

Decreased protein binding

Question 15

Where is midazlolam metabolised?

Answer 15

Liver

Question 16

Where is midazlolam excreted?

Answer 16

Kidney

Question 17

What are the side-effects of benzodiazepines?

Answer 17

Respiratory depression
Cardiovascular effect - reduced BP
Drug interactions

Question 18

How do benzodiazepines cause respiratory depression?

Answer 18

CNS depression and muscle relaxation, causing decreased cerebral response to CO2

Question 19

How do benzodiazepine effect cardiovascular system?

Answer 19

Reduced BP by decrease in vascular resistance, increased HR due to baroreceptor response
Cardiac output unaffected

Question 20

What kind of drug interactions re important with BZP?

Answer 20

Synergistic CNS depression with other CNS depressants e.g. opiates, alcohol
Erythromycin and cimetidine inhibit metabolism

Question 21

Clinical use of nitrous oxide?

Answer 21

Inhalation sedation

Question 22

Describe nitrous oxide gas?

Answer 22

Colourless, with sweet odour

Question 23

Clinical effects of nitrous oxide?

a) sedation
b) cardiovascular
c) respiratory system

Answer 23

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

Question 24

List side-effects of nitrous oxide

Answer 24

Hazards to professional with chronic exposure
Haematological problems - oxidises B12
causing pernicious anaemia
Neurological disease and hepatic disease with chronic exposure
Decreased fertility