Antidepressant medications Flashcards
What class of drug is Citalopram?
SSRI
++ doses over 600mg can cause QT prolongation
What class of drug is Dapoxetine?
SSRI (used for premature ejaculation, not depression)
What class of drug is Escitalopram (Lexapro, lexam, esipram, cilopam)?
SSRI
++ Doses over 300mg can cause QT prolongation
What class of drug is Fluoxetine (prosac, lovan, zactin, fluotex)?
SSRI
What class of drug is Fluvoxamine?
SSRI
What class of drug is Paroxetine?
SSRI
What class of drug is Sertraline?
SSRI
What class of drug is Vortioxetine?
SSRI (acts in the CNS only)
What is the basic MOA of SSRIs?
Decrease serotonin reuptake
What is the clinical presentation of someone with acute serotonergic syndrome from SSRI or MAOI poisoning?
Acute serotonergic syndrome (when taken with other serotonergic drugs). Neuromuscular excitation, hyperthermia, altered conscious state.
Neuromuscular excitation = hyperreflexia, clonus, ocular clonus, myoclonus, shivering, hypertonia, rigidity.
++ (600mg) Citalopram and (300mg) Escitalopram can cause QT prolongation and torsades de pointes
++ Citalopram, escitalopram, and fluoxetine can cause mild bradycardia
What are the investigations required in SSRI poisoning?
ECG where the patient is taking Citalopram or Escitalopram.
Management of SSRI poisoning.
Activated charcoal within two hours where dose is greater than 50x the defined daily dose,
or Activated charcoal within 4 hours where dose is over 600mg and 300mg for Citalopram and Escitalopram respectively.
IV fluids for hypotension
Diazepam and cyproheptadine (oral)
Diazepam and Midazolam (IV)
Continuous ECG monitoring for Citralopram (>800 with charcoal, >600 without charcoal.) and Escitalopram (>400 with charcoal, >300 without charcoal).
Management of QT interval prolongation
Correct magnesium deficiency:
Magnesium sulfate 50% 5-10ml IV over 30-60mins)
If deficient, fix potassium
If deficient, fix calcium
What is the dosage of potassium in QT prolongation with potassium deficiency?
ORAL: Potassium chloride 14-16mmol orally every 2-4 hours
IV: 10-20mmol potassium chloride IV over 1-2 hours (premixed infusion bag)
What is the dosage of calcium in QT prolongation with calcium deficiency?
Calcium gluconate 10% 10-20ml IV over 10-30 mins
repeat until levels normalised
Management of torsades de pointes
Magnesium sulfate 50% (8mmol) 4ml IV over 10-15 mins.
Isoprenaline 20micrograms IV every 2-3 minutes to maintain heart rate above 90BPM
What is the primary MOA of tricyclic antidepressants
TCAs inhibit reuptake of noradrenaline and serotonin into presynaptic terminals. Although unrelated to the therapeutic effects of the TCAs, they also block cholinergic, histaminergic, alpha1-adrenergic and serotonergic receptors. Clomipramine has a greater effect on serotonin transport than other TCAs.
What class of drug is Amitriptyline?
TCA
What class of drug is Clomipramine?
TCA
What class of drug is Dosulepin (Dothiepin)?
TCA
What class of drug is Doxepin?
TCA
What class of drug is Imipramine?
TCA
What class of drug is Nortriptyline?
TCA
What is the dose toxicity of TCAs
Less than 5mg/kg - usually non-toxic
Between 5-20mg/kg - sedation and anticholinergic effects
Over 20mg/kg - severe toxicity (coma, seizures, major cardiovascular toxicity)
What is the clinical presentation of TCA poisoning?
Symptoms start at 2h. Severe complications at 6h.
- CNS effects:
Decreased consciousness, respiratory depression and coma.
seizures - CV effects:
Hypotension (alpha-adrenoreceptor blockade)
Sinus tachycardia (Alpha-adrenoreceptor blockade and anti-cholinergic effects)
QRS widening and arrhythmia (Sodium channel blockade) - Anticholinergic toxidrome:
Mydriasis, warm dry skin, sinus tachy, dry mouth.
Urinary retention and reduced bowel sounds.
Delirium that can persist for 24-48 hours
What are the ECG changes in TCA poisoning
QRS widening (<200ms)
Broad complex tachycardia
Dominant R wave in aVR (more than 3mm in height and an R:S ratio of 2:1)
What investigations are required in TCA poisoning?
ECG
Blood gas
Serum potassium (patients treated with alkalinisation)
What is the treatment for TCA poisoning?
Activated charcoal
If seizures - intubate + IV benzodiazepine
Sodium bicarbonate for wide QRS
+++Quinidine and Procainamide are strictly contraindicated
What class of drug Phenelzine?
MOAI (irreversible non-selective)
What class of drug Tranylcypromine (parnate)?
MAOI (irreversible non-selective)
What class of drug Moclobemide?
MOAI (reversible selective)
Why do you have to be cautious when prescribing Phenelzine and tranylcypromine MOAI?
Because they have a narrow therapeutic index and doses marginally above the therapeutic dose can be toxic.
What is the dose toxicity of Phenelzine and Tranylcypromine?
1-2mg/kg - mild to moderate toxicity
2-4mg/kg - severe toxicity
> 4mg/kg - death
+++Measurement of serum MAOI concentration is not useful as it does not correlate with toxicity