Mental health drugs Flashcards
Name one tricyclic antidepressant
amitriptyline
What is the mechanism by which amitriptyline exerts its action?
- blocks the re-uptake of 5-HT and noradrenaline - increases availability for neurotransmission
- Also blocks dopamine, histamine, alpha-adrenergic and muscarinic/cholinergic receptors
What are the indications for tricyclic anti-depressants?
- 2nd Line for moderate-severe depression where SSRIs not effective
- Tx option for neuropathic pain (not licensed for use)
What are the CIs for anti-tricyclic drugs?
CV disease Elderly Epileptics (reduces seizure threshold) Prostatic hypertrophy - urinary retention Increased intra-occular pressure Constipation
What are the SEs for tricyclic anti-depressants?
Brain - hallucinations, convulsions, mania
CV - arrthymias, prolongs QT and QRS
Dopamine blockage - breast changes/gynaecomastia, sexual dysfunction, extrapyramidal Sx (dyskinesia, tremor)
Histamine/Alpha-adrenergics - hypotension, drowsiness
Anti-cholinergics effects - constipation, urinary retention, dry mouth, blurry eyes (reduces tears)
What are the potential interactions of amitriptyline?
Should not be combined with MAO inhibitors or any other drugs that increase 5-HT/NA - may cause serotonin syndrome
Should also not be combined with drugs that block dopamine, muscarinic, histamine or hypotensive drugs
What happens if you take an overdose of amitriptyline?
- Hypotension, arrthymias, convulsions, coma, resp failures
What happens if you withdraw amitriptyline too quickly?
GI upset, neurological and flu like symptoms, sleep disturbances
Name 3 SSRIs
Citalopram, sertraline, fluoxetine
What is the mechanism by which SSRIs (citralopram, sertraline, fluoxatine) exert their action?
Inhibits the re-uptake of serotonin back from neural cleft]
Increases avaliability of 5HT for neurotransmission (improves moods and stabilises associated behaviours)
Why are the SEs of SSRIs less that those of tricyclic antidepressants?
Because SSRIs do not block other receptors (dopamine, histamine, cholinergic, alpha-adrenergic), resulting in associated SEs
What are the CIs for SSRIs?
- Epileptics - lowers seizure threshold
- Young people - reduced efficacy and associated with an increased risk of suicidal thoughts and self harm
- Peptic ulcer disease - increased risk of bleeding
- Hepatic impairment - metabolised by liver
What are the SEs of SSRIs?
8 S’s
- stomach upset/bleeding
- Size (weight gain)
- Serotonin syndrome - triad of altered mental state, neuromuscular excitability, autonomic hyperactivity (hyperthermia)
- Sexual dysfunction
- Skin rash (hypersensitivity)
- Suicidal thoughts
- Stress (anxiety/worry)
- Seizure threshold reduced
What are the indications for SSRIs? Citralopram, sertraline, fluoxetine
- 1st line for treatment of moderate-severe depression
- Obsessive compulsive disorders
- Panic disorders
What are the drug interactions of SSRIs? (Citralopram, sertraline, fluoxetine)
- Do not combine with other serotonin increasing drugs e.g. MAO inhibitors, tricyclics - serotonin syndrome and potential overdose (convulsions, coma and cardiotoxicity- arrythmias)
- Avoid combination with Aspirin/NSAIDs - increased risk of gastric bleed - offer gastroprotection e.g. PPI
- Avoid combo with drugs that prolong QT duration
How long should antidepressant drugs be taken for?
6 months at least
What should be avoided wren taking anti-depressants?
- St John’s wort
- alcohol
- reduce caffeine
Name 3 benzodiazepines
Diazepam, Lorazepam, terezepam
What is the mechanism by benzodiazepines work?
Act on GABAa receptors: GABA binding results in opening of chloride channels, increasing chloride entry into cell.This results in increased resistance to depolarisation.
Benzo’s facilitate and increase GABA binding to GABAa - results in widespread depression of synaptic transmission
Results in sedation, sleepiness, anti-convulsants effects and reduced anxiety
What also acts on GABAa receptors?
Alcohol binds to same receptor - use this as means to treat alcohol withdrawal
What are the indications for benzos?
- First line management and Tx for seizures and status epilepticus
- First line Tx for alcohol withdrawal
- Common use for sedating patients prior to invasive procedures that do not warrant anaesthesia
- Short term Tx for seizure, disabling and distressing anxiety and insomnia
What are the CI for benzodiazepines?
- Elderly (increased effect)
- Respiratory impairment
- neuromuscular disorders (e.g. myaesthenia gravis)
- Liver failure - could precipitate hepatic encephalopathy
What are the SEs of benzos?
- Sedation/drowsiness
- Coma
- Loss of respiratory reflexes - result in airway obstruction/death
- Dependence
- Withdrawal (upon rapid cessation)
What are the potential interactions of benzos?
- Most are metabolised by CYP450 - increased risk of toxic doses if combined with CYP450 inhibitor
- Additive in combo with sedating drugs e.g. opioids, alcohol
Name one anti-cholinesterase inhibitor
Donepezil
What is the mechanism by which donepezil/anticholinesterase inhibitors exert their action?
Alzheimer’s - mechanism implicated is a reduction in ACh in the brain
Donepezil - reversible, non-competitive inhibitor of anticholinesterase. Centrally acting.
Inhibits the hydrolysis of ACh in the brain, increasing availability for neurotransmission
What are the indications for donepezil?
First line treatment for mild-moderate dementia in Alzheimers disease
What are the CIs for donepezil?
Cause cause unwanted cholinergic effects! Cautioned in..
- Asthma/COPD (can increase smooth muscle tone)
- Supra-ventricular conduction abnormalities (reduces HR)
- Sick sinus syndrome
- Patients susceptible to peptic ulceration
- Anti-psychotics
What are the SEs of anticholinesterase inhibitors/donepezil?
- Insomnia/weird dreams
- Hallucinations
- Agitation/aggression
- Fatigue
- Dizziness/drowsiness
- Urinary incontinence
- N/V/D
- Muscle cramps
- Rash/urticaria
