Pharmacology of benzodiazepines Flashcards
What are ideal agents that we want in a drug for sedation
- Rapid onset
- Predictable
- Enough working time
- Rapid recovery
- Reduce anxiety
- Amnesia – will not remember the tx
- Affordable
If a sedation agent is given in very high dose what would this lead to
indue GA
What are ways to deliver sedation drug
- Inhalation sedation – mask is put around the nose and pt inhales the drug
- Oral – tablet – not common
- Intravenous sedation – given through injection the vein
- Intranasal sedation – drug is placed near pt’s nose and pt inhales the drug
What is the routine drugs used in sedation?
- Benzodiazepines – midazolam
- Nitrous oxide
How is NO delivered
inhalation
How can midazolam be delivered?
Intra-nasal, oral or IV
Nitrous oxide: clinical effects
- Poorly soluble in blood
- poor anaesthetic
- good analgesic so used for muscle pain and in delivering baby
- causes CNS depression
- when given in combination with oxygen it does not affect cardiovascular and respiratory efforts
- rapid metabolism
- rapid recovery
- predictable action and duration
- rapid onset
What are the side effects of NO
- very few – generally safe
- overdose – nausea, vomiting, unpleasant
- high dose – mild depression of alveolar ventilation
- chronic exposure can lead to pregnancy issues – this is why it is important to scavenge gasses
What are the pharmacodynamics of a drug?
Effects of the therapeutic and side effects
what are the pharmacokinetics of a drug
the absorption, distribution and elimination of the drug
what are the key effects of BZD
- reduces anxiety and aggression
- anticonvulsant effect
- sedation and induction of sleep
- reduces muscle tone and coordination
what can high dose of BZD lead to
high dose can lead to respiratory depression – stop them from breathing
if you keep increasing the dose of BZD you will get GA
How is the BZD drug activated
- specific BZD receptors on nerve cells within the brain
- GABA INHIBITORY NEURORECTOR which is released attaches to the postsynaptic neuron and the number of sensory messages perceived by the brain is reduced – BZD prolongs the effect of GABA
What are the disadvantages of BZD
- Respiratory depression affects all pt so need to monitor RR – it’s due to the reduction in sensitivity of chemoreceptor
- cardiovascular depression – reduces CO and BP – effects of this are minor in healthy pts as they can compensate for this using baroreceptors – in pts who are cardiovascular compromised this will be more of an issue
- drug interactions: alcohol, antihistamines, opioids and some calcium channel blockers, anti-psychotics
When and how is diazepam given
- given orally as a premed night before tx or morning of – need to have sedation training to administer this
