Sertraline (Generic Zoloft): Pharmacokinetics, Indications, Adverse Effects

Today, depression is one of the most common illnesses. Drugs that help fight depression are called antidepressants. One of the best modern drugs recommended to treat depression is Zoloft, which pertains to the group of selective serotonin reuptake inhibitors (SSRIs). Canadian Pharmacy Zoloft has a high efficacy comparable to that of tricyclic antidepressants, but it has a significantly better tolerance and much safer than other antidepressants. Specialists of My Canadian Pharmacy prepared a detailed guide on Zoloft that offers useful information on the drug.

Zoloft is an antidepressant that has a very weak effect on the norepinephrine and dopamine reuptake. The main component of Zoloft is sertraline. In therapeutic doses, it blocks the serotonin seizure in platelets. It has no anticholinergic, sedative, or stimulating action. It does not lead to an increase in the adrenergic activity. Sertraline does not have similarity with muscarinic cholinergic receptors, serotonin, dopamine, histamine, GABA-, benzodiazepine, and adrenoreceptors. It does not lead to drug dependence or an increase in body weight with long admission.

Ingredients of Zoloft

Zoloft’s active ingredient is sertraline hydrochloride in a dose corresponding to 50 mg or 100 mg of sertraline.

Additional ingredients include:

  • Calcium phosphoric acid
  • Microcrystalline cellulose
  • Hydroxypropyl cellulose
  • Magnesium stearate
  • Sodium starch glycolate
  • Hydroxypropyl methylcellulose
  • Hydroxypropyl cellulose
  • Polyethylene glycol
  • Polysorbates
  • Titanium dioxide

How Does It Works?

Sertraline inhibits the reuptake of serotonin in neurons of the central nervous system. In this respect, it exceeds amitriptyline in 100–200 times, fluvoxamine – in 9 times, fluoxetine – in 5 times, and clomipramine – in 2 times. Thus, the serotonin content in the synapses increases, which is associated with the antidepressant and anti-anxiety effect of sertraline. Concurrently, sertraline has a very weak effect on the reuptake of norepinephrine and dopamine.


Some of the sertraline’s positive properties are related to the characteristics of its pharmacokinetics. With a 14-day application of sertraline at a dosage of 50–200 mg one time a day, the maximum drug concentrations in the plasma are reached within 4.5–8.5 hours. The half-life of the plasma is 26 hours, which is enough to get a single daily dosage while excluding the risk of cumulation of the drug and the development of dose-dependent side effects. With regular admission in dosages of 50–200 mg one time a day, the equilibrium state is attained within about 1 week. In the equilibrium state, the sertraline absorption rate is equal to the rate of its removal, so the drug levels remain practically constant.

Sertraline is subject to metabolism when it passes the liver for the first time. After discontinuation of therapy, sertraline is secreted from the body by 95% within 1 week.

Comparative Studies of SSRIs and Other Antidepressants

There are many meta-analyzes devoted to comparing antidepressants. According to these studies, SSRIs are generally not inferior in effectiveness to tricyclic antidepressants. Concurrently, the tolerability of SSRIs is significantly better than the tolerance of tricyclic antidepressants. Side effects also differ significantly in SSRIs. The use of SSRIs is accompanied by significantly less antimuscarinic effects, with more frequent gastrointestinal and psychostimulatory effects.

When comparing drugs from the SSRI group, their comparative efficacy was shown to be comparable, with the application of sertraline better tolerated than other SSRIs.

When comparing tricyclic antidepressants and SSRIs in elderly patients, better tolerability of SSRIs and a faster amelioration in quality of life were demonstrated.

Indications for Use

Zoloft is prescribed to treat and prevent relapses in the following cases:

  • Depressive states
  • Social phobia
  • Depression with manic conditions
  • Obsessive-compulsive disorder (ROC)
  • Panic disorders
  • Depression with a sense of anxiety
  • Panic disorders with agoraphobia
  • Post-traumatic depressive disorders


Zoloft is not assigned in the following cases:

  • Therapy with MAO inhibitors
  • Pregnancy
  • Hypersensitivity to sertraline
  • Lactation

Zoloft is not used in children up to 6 years old. Extreme caution is necessary in the following cases:

  • Organic pathologies of the brain
  • Epilepsy
  • Exhaustion
  • Delay in mental development

Dosing and Administration

Zoloft is prescribed once a day in the dosage of 50 mg. Pills can be taken regardless of meals.

If there is no a positive effect, a gradual (several weeks) augment to 200 mg/day (50 mg/week) is possible.

To treat panic disorders, the incipient dosage is 25 mg/day. It can be augmented to 50 mg within 1 week.

During prolonged maintenance therapy, a minimum effective dosage is prescribed, which is subsequently altered depending on the effect.

With obsessive-compulsive disorders in children and adolescents aged 13–17, the incipient dosage is 50 mg/day. If the positive effect is insufficient, it can be augmented stepwise by 50 mg/day to 200 mg, with an interval of at least a week. In elderly patients, the incipient dosage is 25 mg/day (morning or evening) followed by a step-by-step augment.

Special Instructions

During the treatment period, it is important to strictly control the behavior of patients (the risk of suicide attempts) until there is a significant amelioration because of the treatment.

Zoloft is appointed no earlier than 2 weeks after the abolition of MAO inhibitors.

During the treatment period, caution must be taken when driving and engaging in potentially dangerous activities that require attention and fast psychomotor reactions.

Adverse Effects

As mentioned above, Zoloft has few adverse effects. Nevertheless, it is necessary to know the possible side effect that may occur when using Zoloft to warn about the possibility of their occurrence and take measures to overcome them.

Undesirable effects may include:

  • Drowsiness and tremor
  • Ejaculatory disorders, dry mouth, and sweating
  • Fatigue
  • Anorexia, diarrhea, constipation, dyspepsia, and nausea
  • Agitation, anxiety, insomnia, and decreased libido

In addition, when applying Zoloft in children, there may be hyperkinesia, fever, weight loss, malaise, impaired concentration, monic reactions, emotional lability, impaired thinking, and nosebleeds.


Toxicity. Sertraline has a range of safety that depends on the patient population and/or the concomitant use of medicines. Lethal cases have been reported both with the separate use of sertraline (without concomitant medications) and in combination with other drugs and/or alcohol. In this regard, every case of overdose requires intensive therapy.

Symptoms of overdose include:

  • Drowsiness
  • Gastrointestinal disturbances such as nausea and vomiting
  • Tachycardia
  • Tremors
  • Agitation
  • Dizziness

The cases of coma are rare.

It is necessary to provide and maintain patency of the airways and a sufficient level of oxygenation and ventilation. The intake of activated carbon, which can be used together with a laxative, can be no less effective than gastric lavage, which should be taken into account in case of overdose therapy. Vomiting is not advisable. It is recommended to monitor cardiac activity and other basic vital signs along with symptomatic and supportive therapy. Given the significant volume of sertraline distribution, activities such as forced diuresis, hemoperfusion, dialysis, or replacement blood transfusion are unlikely to be helpful.

An overdose of sertraline may lead to an elongation of the Q-T interval and therefore it is recommended to perform ECG monitoring in all cases of drug overdose.

What Should Your Doctor Tell You About Using Zoloft?

Do not expect a quick positive effect of taking the medication. Symptoms of depression usually disappear within 4–6 weeks after beginning to apply the drug. Reduce in somatic symptoms and normalization of sleep can happen 1–2 weeks after the beginning of using the drug, before there is a significant amelioration in mood of a patient. Nevertheless, after the appearance of a noticeable amelioration, therapy must be continued.

Before there is the effectiveness of the medication for depression, Zoloft should be applied at least for 2 months. You cannot stop taking the medication yourself or change its dosage. A sudden stop of the medication may lead to one and/or few of the following withdrawal symptoms:

  • Nausea
  • Irritability
  • Dizziness
  • Nightmares
  • Vomiting
  • Headaches
  • Paresthesia

At the beginning of using the medication, there may be some side effects. They are usually mild or moderate and pass in 1–2 weeks. There may be a deterioration in sexual function when taking Zoloft.

Thus, with the advent of a new class of antidepressants – SSRIs – it became possible to use antidepressants more widely – not only in psychiatric but also in general medical practice. Zoloft is highly effective in a wide range of depressive disorders, characteristic of many patients who seek medical advice about somatic complaints. Due to its high safety profile and ease of use, Zoloft is an effective medication that is convenient for use in general medical practice.

Note: As a disclaimer, we should mention that this article was created with the intention of providing educational materials. It cannot be viewed or used as a substitute for professional medical advice. We are not responsible for any health concerns.