TCAs Flashcards
What are TCAs?
Tricyclic Antidepressants
What are some examples of TCAs?
- Amitryptiline
- Nortriptyline
- Lofepramine
- Dosulepin
- Trazodone
What is the mechanism of action of TCAs in depressive illness?
Not fully understood, believed to involve adaptive responses to monoaminergic neurotransmission
What are the routes of delivery of TCAs?
PO
What are the indications for TCAs?
- Depression
- Panic attacks and anxiety disorders
- Neuralgia
- Noctural enuresis
What are the contraindications for TCAs?
- Suicidal ideation
- History of psychosis or bipolar disorder
- QT interval prolongation
Why are TCAs contraindicated in patients with suicidal ideation?
More toxic in overdose compared to alternatives
Why are TCAs contraindicated when there is a history of psychosis or bipolar disorder?
May aggravate these conditions
When should TCAs be avoided?
Post MI or with other heart problems
What anti-depressant should be used in patients post-MI or with other heart problem?
Consider sertraline
When should TCAs be used with caution?
- Prostatic hypertrophy
- Urinary retention
- Chronic constipation
- Increased intraocular pressure
- Mania
- Severe liver disease
- High risk of developing acute angle-glaucoma
What might TCAs interact with?
- MAOIs
- Anti-arrhythmics
- Alcohol
What might happen if TCAs are given with MAOIs?
Severe hypertensive crisis can occur - maintain a 2 week gap between stopping a TCA and starting a MAOI
What might happen if TCAs are given with anti-arrhythmic medication?
VT
What might happen if TCAs are given with alcohol?
Increased sedation
Who is more susceptible to the side effects of TCAs?
Elderly patients (particularly hyponatraemia)
What are the common side effects of TCAs?
- Antimuscarinic effects
- Central nervous system effects
- Metabolic effects
What are the anti-muscarinic side effects of TCAs?
- Dry mouth
- Blurred vision
- Constipation
- Urinary retention
What are the CNS side effects of TCAs?
- Anxiety
- Restlessness
- Dizziness
- Agitation
- Confusion
What are the metabolic side effects of TCAs?
- Weight gain
- Altered blood glucose in diabetics
What are the less common side effects of TCAs?
- Cardiotoxic in overdose
- Neuroleptic malignant syndrome
- Hyponatraemia
What counselling is required with TCAs?
- Impairment of normal activities
- Overdose
- Increased risk of seizures in epilepsy
- Treatment cessation
What should patients be told about impairment of normal activities with TCAs?
TCA can cause drowsiness that may impair their ability to drive or operate machinery. If they drink alcohol, they may experience increased sedation
What should the patient be told about the overdose of TCAs?
Explain that the drug is very dangerous in overdose
What should be done before starting TCAs to reduce the risk of overdose?
Ascertain that the patient is not considering suicide or engaging in self-harming behaviours, as this would put them at increased risk of intentionally overdosing
What should patients with epilepsy be told before starting TCAs?
May experience more seizures as this drug lowers the seizure threshold, making it easier for a seizure to occur, as a lower level of stimuli is required
What should the patient be told about treatment cessation with TCAs?
Withdrawal symptoms may occur within 4 days of stopping drug. However such symptoms may be mild and self-limiting.
Drug should be withdrawn gradually over at least 4 weeks and this would depend on how long the patient has been taking the antidepressant and how they respond to withdrawal
