Mental Health Drugs Flashcards
Name a acetylcholinesterase inhibitor
Donepezil (aricept), calatamine, rivastagmine
Indications of acetylcholinesterase inhibitors
1) Alzheimer’s disease
Slows down the progression but benefit is often small
Mechanism of acetylcholinesterase inhibitor
Reversible acetylcholinesterase inhibitor
The increased acetylchline at synapses which helps due to a loss chonergic system in alzheimers disease
Adverse effects of acetylcholinesterase inhibitosrs
Nausea, vomiting and diarrhoea
Fatigue
Dizziness/syncope
Urinary Problems
What happens in a cholinergic crisis
Severe nausea, vomiting Abdo pain Sweating Bradycardia Hypotension Collapse
Caution of acetylcholinesterase inhibitors in
People with heart disaese Cardiac conduction problems COPD Asthma Peptic Ulcer Disease Renal Impairment
Interactinos of acetylcholinesterase inhibitors
Theoreteically would interact with CP450 enzymes altering other drugs metabolism but no clinical evidence
Name tricyclic antidepressants
Amitryptiline, lofepramine
Uses of tricyclic antidepressants
1) moderate/severe depression - 2nd line
2) Neuropathic pain –> but at much lower dose e.g. sciatica
Action of tricyclic antidepressants
inhibit the neuronal reuptake of serotonin and noradrenaline from the synaptic cleft
This increases their availbalility for neurotransmittion
Also block a wide range of receptors –> histamine, muscarinic, adrenergic, dopamine –> which accounts for the extensive side effecst
Adverse effects of tricyclic antidepressants
Blockage of antimuscarininc receptors: dry mouth, constipation, urinary retention, blurred vision
Blockade of histamine and adrenergic recpetors: sedatino and hypotension
Cardiac adverse effects –> arrythmias and ECG changes
Neurological effects: convulsions, hallucitations, mania
Blockade of dopamine receptors: breast changes and sexual dysfunction
What happens if you block antimuscarininc receptors
dry mouth, constipation, urinary retention, blurred vision
What happens if you block histamine and adrenergic receptors
Sedation and hypotension
What happens in overdose of tricyclic antidepressants
Extremely dangerous
Lower bp and arrythmias
Coma and repiratory failure –> may be fatal!!!
What happens if you suddenly withdraw tricyclic antidepressants
GI Upset, neurological, influenza-like symptoms and sleep problems
Warnings of tricyclic antidepressants
Caution with people at high risk of adverse effects e.g. elderly, CV disease and epiplepsy
Interactions of tricyclic antidepressatns
DO NOT GIVE WITH MONOAMINE OXIDASE INHIBITORS –> both increase noradrenaline and serotonin at the synapse –. together thye can precipitate hypertension and hyperthermia or SEROTNONIN SYNDROME
TCA can also increase antimuscuranic, sedative or hypotensive effects of other drugs
What line do we usually use TCA?
They are usually 2nd line
This is due to a similar efficacy to other antidepressants but worse side effects and more dangerous in overdose
How should we stop doses of TCA
Reduce dose over a 4 week period to avoid withdrawal symptoms
Name some SSRIs
Citalopram
Fluoxetine
Sertraline
Escitalopram
Uses of SSRIS
1) Depression –> first line for moderate/severe
2) Panic disroder
3) OCD
Action of SSRIS
Preferentially inhibit serotonin reuptake from the synaptic cleft –> increased availability for neurotransmission –> improves mood and physical symptoms
How do SSRIs differ from tricyclcis
They dont inhibit noradrenaline reuptake and cause less blockade of other receptors
Similar efficacy to TCAs but SSRIs are preferred as they have less side effects
Advsere effects of SSRIs
Common: GI disturbance, appetite and weight disturbance and hypersensitivity reactions
Hyponatraemia –> mportant in elderly as may cause confusino and decreased consciousenss
Suicidal thoughts & Behaviours
Lower the threshold and some (citaloprom) prolong the QT interval –> predisposes you to arrhythmias
Increased risk of bleeding
Serotonin syndrome
What is serotonin syndrome
Triad of autonomic hyperatctivity, altered mental state and neuromuscular excitation
Usually responds to treatment withdrawal and supportive therapy
What happens if you suddenly withdraw SSRIs
GI Upset
Neurological & flu-like sympomts
Sleep disturbance
Warnings of using SSRIs
Caution if high risk of adverse effects e.g. epilepsy and peptic ulcer disease
Caution in young people –> poor efficacy and increase suicidal thoughts
Hepatic impairment –> metabolised by liver so may need dose reduction
Interactions of SSRIA
1) MAO –> both increase serotonin –> can cause serotnonin syndrome
2) Avoid in drugs that prolong the QT interval e.g. antipsychotics
3) Give gastroprotection if also taking aspirin/NSAID –> as increased risk of GI bleed
4) Anticoagulants –> both increase thebleeding risk
Name benzodiazepines
Diazepam Midazolam (short-acting) Temazepam (intermiediate) Lorazepam (long-acting) Chlordiazepoxide
Uses of benzodiazepines
1) Seizures and status epilepticus –> 1st line - usually lorazepam
2) Alcohol withdrawal reactions - 1st line, usually chlordiazepoxide
3) Sedation for interventional producers –> use short-acting if GA is unnecessary or undesirable
4) Anxiety or insomina –> ONLY USE SHORT TERM TEMAZEPAM
How do benzodiazepines work?
Facilitate and enhance binding of GABA to the GABAa receptor
Widespread depressent on neurotransmission –> decrease anxiety, sleepiness, sedationa nd anticonvulsant effects
What is GABA
GABAa is a chloride channel that opens when GABA binds
GABA is the main inhibitory neurotransmitter in the brain
Chloride ions flow into the cell to make it more resistent to depolarisation
How does alcohol affect GABA
Alcohol also acts on GABAa receptor and in chronic excessive use the patient becomes tolerant to its presence
Therefore abrupt cessation provokes an excitatory state of alcohol withdrawal –> benzodiazepiens can be used to treat this and then reduce their dose in a gradual and more controlled way!
Adverse effects of benodiazpeines
Dose depndent –> drowsiness, sedation and coma
Overdose –> loss of airway refleces can lead to airway obstruction and death
DEPENDENCE –> if used weeks, then get withdrawal if abrupt cessation
Warnings of benzodiazepiens
a) ELDERLY –> more susceptibly to effects so give a lower dose
b) Avoid in patients with significant respiratory problems or neuromuscuar disease e.g. myasthenia gravis
c) Avoid if liver failure –> may precipitate hepatic encephalopathy, if their use is essential (e.g. alcohol withdrawal) then use lorazepam as it relies less on the liver for its elimination
Interactions of benzodiazepines
1) Additive effect to other sedative drugs e.g. alcohol and opioids
2) CP450 inhibitor (amiodarone, diltiazem, macrolides, fluconazole, protease inhibitors)
As it dependes on CP450 enzymes for elimination, hence inhibitors increase their effect
