Antidepressants Flashcards
What are the drugs part of antidepressants - list examples and common dosing
SSRI
- Fluoxetine 10mg - 60mg OD
Paroxetine -20mg -50 mg OD
Sertraline 50 mg OD - 200mg (100 bd)
Citalopram 20-40 mg OD
Escitalopram 10-20mg OD
SNRI - venlafaxine 75mg - 300mg
Atypical - mirtazapine 15mg nocte - 45 mg
TCA - amitriptyline 50-100mg nocte
notriptyline 25mg TDS - QID
What are the indications and contra-indications for SSRIs and which for pregnancy, parkinsons, adolescents
Indications :
o Depression – 1st line
o Anxiety – 1st line (GAD, panic disorder, OCD, PTSD)
o Eating disorders (bulimia and binge eating)
o Chronic pain
Contra-indications
o Patients with mania (as are anti-depressants and can worsen mania)
o LQTS
Pregnancy , breast feeding, post MI: sertraline
Parkinsons: fluoxetine, citalopram
Adolescents : fluoxetine
What are the dose adjustments and drug interactions for SSRI
o Need to reduce dose slowly to stop or withdrawal sx will occur
o Given in the morning (as cause insomnia)
o Monitor ECG and electrolytes (esp Na+) prior to prescribing.
LFTS before citalopram
DI
o Lithium, Phenytoin, carbamazepine
o MDMA
o Opioids - Tramadol / pethidine
o Other anti-depressants – SNRI, TCAs, MAOi
o Antiplatelets/anticoagulants
Adverse effects of SSRIs
o GI upset – N&V, diarrhoea/constipation, abdo pain, dyspepsia, changes in appetite and weight
o Dry mouth / taste disturbance
o Sexual dysfunction
o Agitation / anxiety (usually with initial treatment)
o Hyponatraemia (SIADH)
o Sedation / drowsiness
o Insomnia
o Tremor
o Dizziness
o Suicide ideation (esp in children and teenagers – try and avoid SSRI in <18yo)
Withdrawal symptoms of SSRIs and explain SSRI syndrome - presentation and treatment
Withdrawal = GI upset, headache, anxiety, dizziness, paraesthesia,
electric shock sensation in the head/neck/spine, tinnitus, sleep disturbances, fatigue, flu-like sx, sweating
o SSRI syndrome = when 2+ seratogenic drugs are used together (SSRI + MAOi) –
Presentation :
altered mental state, dilated pupils, tachy,sweating, fever, N&V, abdo pain, tremor / clonus / muscle rigidity
- Treatment: stop drugs + symptomatic treatment (benzodiazepine / cooling etc)
What are the indications and contra-indications for SNRI
Indication
o Depression – 2nd line
o Anxiety (GAD, social anxiety, OCD, PTSD)
o Fibromyalgia
o Neuropathic pain
Contra-indication
o Uncontrolled HTN
o Arrhythmias
o Within 14 days of MAO inhibitor treatment
What are the dose adjustments and drug interactions for SNRI
o BP needs to be controlled prior to starting treatment, then reviewed every 3/12 then annually
o Avoid driving or using machinery after taking this medication
discontinuation syndrome (short half life - if stopping suddenly can cause withdrawal within hours
Interactions
MAOi - eg. selegiline
Adverse effects of SNRIs, including withdrawal
o HTN
o LQTS
o GI upset – N&V, diarrhoea/constipation, anorexia,
o Sedation / Drowsiness / confusion
o Nervousness / anxiety
o Withdrawal – GI upset, headache, anxiety, dizziness, paraesthesia, tinnitus, sleep disturbances, fatigue, flu-like sx, sweating
o SSRI syndrome
MoA , indication and contraindication of Mirtazapine
MoA
o Serotonin and alpha-2 adrenergic antagonist -> increased extracellular serotonin and NA
o H1 antagonist
Indication
o Depression – especially in underweight patients or those with insomnia
o GAD
Contra-indication
o Within 14 days of MAO inhibitor treatment
o Breast-feeding
Interactions, adverse effects of Mirtazapine inc withdrawal
Interaction
o Other anti-depressants - SSRI, TCAs, MAOi
o Lithium
Adverse E
o Increased appetite and weight gain, High cholesterol and TGs
o Sedation / fatigue
o Dry mouth
o Prolonged QT
o Postural hypotension
o Tremor
o Myalgia, arthralgia
o Withdrawal – N&V, dizziness, agitation, anxiety, headaches
o SSRI syndrome
MoA , indication and contraindication of TCA
MoA:
o Inhibit reuptake of serotonin and NA in the synaptic cleft → ↑ serotonin and NA levels
o Inhibits Ach
Indication
o Depression (3rd line)
o Neuropathic pain (e.g – diabetic neuropathy)
o Chronic pain (e.g – fibromyalgia)
o Migraine prophylaxis
Contraindication
o Recovery period from MI
o Arrhythmias (esp heart block)
o Mania
o Depression in <18 yo
o Within 14 days of MAO inhibitor treatment
o Pregnancy (should be avoided if possible – congenital abnormalities + withdrawal)
- cardiotoxic with 1 week, lethal overdose
monitoring, drug interactions of TCA,
Mon
o ECG prior to prescribing
o Prescribed at night time
o Takes 4-6 weeks to work
o Need to reduce dose slowly to stop or withdrawal sx will occur
DI
- amiodarone
adverse effects of TCA
Anticholinergic – dry mouth, constipation, blurred vision
o Worsening of depression + Suicide ideation (in initial treatment)
o Anxiety / panic attacks / agitation / irritability / hostility / impulsivity / hypomania / mania
o GI - N&V, weight gain
o CVS – Tachy, arrhythmia, hypotension
o CNS – Tremor, dizziness, confusion, drowsiness
o GU / Repro - Urinary retention, breast enlargement/gynaecomastia, impotence, reduced libido
o Skin - rash, urticaria, pruritus, photosensitivity, alopecia
o Withdrawal - nausea, headache, malaise, irritability, insomnia
o Overdose – HTN, arrhythmias, altered mental status, mydriasis, fever, hyper-reflexia, seizures, absent bowel sounds
- Antidote: sodium bicarbonate
o SSRI syndrome - tachy, sweating, dilated pupils, myoclonus
steps to minimise risk from QT prolongation
May prolong QT-interval and increase risk of torsade de pointes.
- Correct hypokalaemia and hypomagnesaemia before starting treatment.
In high risk patients (those with congenital long QT-syndrome or with multiple risk factors—increasing age, female gender, family history, hypokalaemia, hypomagnesaemia, or interacting medicines) ECG monitoring should be undertaken.
Consider stopping treatment if QT interval is greater than 500 milliseconds or increased by greater than 60 milliseconds.
what is the moa of ssri and snri
SSRI Inhibit serotonin reuptake (reabsorption) in synaptic cleft leading to increased extracellular serotonin
SNRI
Inhibit serotonin and noradrenaline reuptake (reabsorption) in synaptic cleft leading to increased extracellular serotonin and NA
