Sedatives

What is a sedative?

A substance that depresses the (CNS), resulting in calmness, relaxation, reduction of anxiety, sleepiness, slowed breathing, slurred speech, staggering gait, poor judgement, and slow, uncertain reflexes

Common properties of sedatives

• Dissolved in the blood

• Cross the blood brain barrier

• Act on receptors in the synapse

Sedatives depress brain areas that make you awake and alert by blocking dopamine

And/or enhance the action of receptors that depress the nervous system by activating GABA

What are the two neurotransmitters we are concerned about when considering sedation?

Dopamine and Gamma-aminobutyric acid - GABA

→ Dopamine excites the brain. Stimulant - agonist - Involved emotional and motivational behaviour, as well as the control of movement

→ GABA provides an antagonistic action to counter balance the dopamine within the brain. Blocker

How do sedatives work?

Block dopamine and stimulate GABA

The nervous system is like a car, the faster it goes the more stimulated and excited you are. Sedatives press on the brakes (stimulate GABA) or make it harder to press on the accelerator (block dopamine) or both.

Why do you give sedatives in your area of work?

Agitated patient, intubation, operations, pain relief, comfort, Facilitate ventilation, stop aggressive behaviour, treat psychosis, sleep, facilitate withdrawl, seizure treatment, mental illness

Which sedatives do you administer in your area of worK?

There are five major indications for the use of sedatives in seriously ill patients:

1. To allay anxiety

2. To manage acute confusional states

3. To faciltate mechanical ventialtion

4. To implement treatment or diagnostic procedures

5. To reduce tachycardia, hypertension or raised intracranial pressure

Sedative groups in terms of properties

Anxiolytics - benzodiazepines → loraz and diaz

Hypnotics - benzodiazepines → loraz, diaz and nitrazepam

Neuroleptics/antipsychotics → chlorpromazine, haloperidol

Anaesthetics → etomidate, propofol, ketamine, barbiturates

Analgesics → morphine, fentanyl, remifentanil

Fentanyl

• is 100x more potent than morphine

• it has a faster onset of action than morphine and does not produce a histamine release

• it has a shorter duration of action than morphine when used on a prn basis or when infused for a short duration

• it is the analgesic of choice in patients with renal dysfunction, morphine allergy or ongoing haemodynamic instability

• metabolised by the liver

Benzodiazepines

• Depression of CNS → increases inhibition of the CNS by the neurotransmitter GABA

• Paradoxical effects → increased hostility, aggression, talkative, excitable

• Withdrawal and dependence

• Impaired judgement

• Slow reaction time

• Impaired renal and hepatic clearance in elderly

Midazolam adverse effects

Respiratory depression and airway obstruction

Hypertension or hypotension

Headache, drowsiness, dizziness, excessive sedation

Thrombophlebitis

Midazolam antidote

Flumazenil

Midazolam monitoring

HR, ECG, Arterial blood pressure, RR

Midazolam side effects

There are lots of side effects and problems with midaz but considering the range of uses this drug has it would be pertinent to say the one things of paramount is the importance of ABC

Propofol

• Short acting general anaesthetic agent

• Induction/maintenance of general anaesthesia

• Mechanically ventilated adults

• Procedures

• Mania, agitated depression

• Metabolised by the liver

Haloperidol

• Sever anxiety

• Quieten disturbed patients

• Brain damage, mania, agitated depression

Haloperidol adverse effects

Tachycardia, hypotension, hypertension, ataxia, restlessness, agitation, seizures, exacerbation of psychotic symptoms, dry mouth or hyper-salivation, QT interval prolongation, elevated liver enzymes