What are Antidepressants?

These are molecules which help in improving symptoms of depression. There are different classes of antidepressants which are available for treatment.  Different clients respond to different antidepressants and it is difficult to predict which client will respond to which drug.  However, there are some laboratory tests which can predict this but those test are very expensive and cannot be employed in routine practice.  Perhaps in future these tests will become a routine psychiatric practice.  For now we have to try one drug first and if that doesn’t bring about a satisfactory improvement we try the second one and then the third one.

The choice of a particular drug in a given client also depends upon their symptom profile.  It has also been seen that if a family member has responded well to a particular drug the chances that the client will respond to that particular drug would be higher.

These various antidepressant drugs are:-

1. Selective Serotonin Reuptake Inhibitors (SSRIs) e.g. escitalopram, sertraline, fluoxetine, etc.

2. Serotonin and Norepinephrine Reuptake Inhibitors (SNRIs) e.g. venlafaxine, duloxetine, etc.

3. Noradrenergic and specific serotonergic antidepressant (NaSSA) e.g. Mirtazapine

4. Noradrenergic-dopamine reuptake inhibitors (e.g. bupropion),

5. Tricyclic antidepressants (e.g. imipramine, nortriptyline, amitriptyline, etc.),

6. Mono-amine oxidase inhibitor (e.g. tranylcypromine), etc.

7. Some newer agents have been introduced in the few years as well, e.g. serotonin partial agonist reuptake inhibitor like vilazodone. Recently intranasal ketamine has also been approved for resistant cases of depression. One should, however, ensure to take these medications only on prescription from a trained psychiatrist and under supervision.

When are antidepressants given?

They are usually employed in moderate and severe cases of depression. Mild depression may respond better to non-pharmacological (psychological) interventions like CBT. Severe depression (particularly with suicidal ideations, or psychotic symptoms), on the other hand, may certainly require the use of antidepressants for certain period. In addition to depression antidepressants have also been used in certain other conditions such as obsessive compulsive disorders, anxiety, phobic disorders, eating disorders etc.

How do they work?

Antidepressants work by acting on certain chemical pathways in the brain. The common mechanisms include increasing the levels of brain chemicals like serotonin, norepinephrine, dopamine, etc in the areas regulating emotions. The efficacy of various antidepressants is almost similar. Thus, the choice of the antidepressant in a given individual is based on history past response to a particular molecule (in case of recurrent depressive disorder), the side effect profile (e.g. certain antidepressants may be avoided in elderly individuals due to risk of falls because of postural hypotension), family history of response to a particular molecule, patient’s preference, or clinician’s preference (e.g. more experience with certain molecules).

Are they addictive?

Antidepressants are not addictive according to the strict definition of addictions. An addictive substance is said to be addictive when it causes cravings, it requires gradually increasing doses to have the same effect (tolerance), there is a loss of control over the intake, there are withdrawal symptoms on sudden stoppage and one experiences physical/ psychological harm as a result of their use.

Sudden stoppage of some antidepressants has been shown to lead to emergence of some withdrawal symptoms, but this is usually managed by gradual reduction in dose while planning to stop the antidepressant. No other symptoms suggestive of dependence on antidepressants is seen.

Withdrawal symptoms, if antidepressant is stopped abruptly, include flu-like symptoms, sleep disturbance, nausea, imbalance, sensory disturbances, etc. The withdrawal of antidepressants should thus be done as per the doctor’s advice.

Antidepressants are not required life-long in all cases of depression. The duration of antidepressant intake is based on various criteria, like duration of depression, severity of depression, family history, recurrence of depressive episodes, co-morbidities (personality disorder, anxiety disorder, substance use disorder) to name a few. Life-long use of antidepressant may be required only in a few cases.

What are common side effects?

Antidepressants are commonly associated with emergence of, or exacerbation of on-going anxiety symptoms, gastrointestinal disturbances (most commonly gastritis), sleep disturbances (insomnia, or increased sedation), sexual dysfunction (most commonly delayed ejaculation, or anorgasmia), headache, etc. The side-effect profile of each molecule is different, based on the type of receptor they act on.

Fortunately, majority of the side-effects are transient present only initially while initiating and building up the dose of antidepressants. Not all patients may experience all side-effects. In order to reduce the initial side-effects, the antidepressants are usually started from a low dose, and gradually built up to the therapeutic dose (“start low go slow”).

Can the antidepressants be taken on “as and when required” basis?

No, antidepressants should not be taken on “as and when required” basis as they usually show their therapeutic effect in at least 7-10 days. The therapeutic effect practically starts as the initial side effects begin to subside. Taking the antidepressants on “as and when required” basis may in fact prove counterproductive as they may cause only side effects without leading to any therapeutic benefit.

Who should not take antidepressants?

There are no absolute contraindications for antidepressants. However, certain molecules may be cautiously given in children/ adolescents, elderly, individuals with associated medical illnesses, and pregnant females. Safer agents are available for each such category and they may be used.

Alternate treatments to antidepressants include psychotherapy like CBT/ mindfulness-based training, behavioural activation, electroconvulsive therapy, transcranial magnetic stimulation, etc.

What should I do if I have a serious side effect to these medications?

One should report to their treating psychiatrist on emergence of any side-effects. The common initial side effects may be manged symptomatically for short-term till they subside, e.g. antacid medication for gastritis, analgesics for headache, or sedatives for sleep disturbances. While majority side effects subside on their own in a few days, some side-effects may persist. In such cases, based on the clinical situation the psychiatrist and patient may take a collaborative decision to alter the dose, use an alternate agent, or provide an antidote to the side-effect.