Antidepressants are medication with the intent to improve mood and relieve depression.
SSRIs: Escitalopram (first line treatment for unipolar depression)
These block serotonin from being uptaken, which leads to higher signalling of the 5ht1a axon receptor which inhibits serotonin release. This then causes less 5-ht1a receptor production and greater serotonin release net.
Side effects can be
- Acute increased anxiety
- Sleep dysfunction
- Sexual dysfunction
- Emotional blunting
- Cognitive impariment
- Withdrawal symptoms
Drug interactions are
- MAOIs
- This is due to the fact that if you remove the 2 exit routes for serotonin it will build up to very high levels.
- NSAIDs
- as ssris block serotonin uptake this block platelet serotonin intake leading to reduced platelet aggregation
- Codeine
- SSRIS can block CYP450 which decreases rate of codeine → morphine
SNRIs: Venlafaxine (second line)
This works the same but also decreases noradrenaline reuptake at the same time. There is slightly higher efficacy than ssris and higher overdose effects too. Increased blood pressure at higher doses due to noradrenergic effects.
Side effects can be
- Acute increased anxiety
- Sleep dysfunction
- Sexual dysfunction
- Emotional blunting
- Cognitive impariment
- Withdrawal symptoms
- high BP from noradrenaline
Drug interactions are saem as SSRIs
- MAOIs
- This is due to the fact that if you remove the 2 exit routes for serotonin it will build up to very high levels.
- NSAIDs
- as ssris block serotonin uptake this block platelet serotonin intake leading to reduced platelet aggregation
- Codeine
- SSRIS can block CYP450 which decreases rate of codeine → morphine
TCAs: Amitriptyline (second to third line)
These are like superpowered SNRIs, they can also be more toxic. this is because of promiscuous activity. also blocks voltage gated sodium channels.
Side effects
- dizziness
- sedation and drowsiness
- weight gain
- reduced parasympathetic action
- cardiotoxicity
MAOIs
These inhibit the monoamine oxidase enzymes, and are less preferred due to side effects on other enzymes in the body
side effects:
- more than TCAs
- risk of serotonin syndrome
Ketamine
This is thought to improve depression through disinhibition, inhibition of gabaergic neurons, leading to a net positive signalling and neuroplasticity