Introduction
Sertraline is a popular antidepressant medication commonly known as a selective serotonin reuptake inhibitor (SSRI), and is similar to drugs such as Citalopram and Fluoxetine. Despite marked structural differences between compounds in this drug class, SSRIs exert similar pharmacological effects.
Several weeks of therapy with sertraline may be required before beneficial effects are noticed. Sertraline displays enhanced safety or tolerability than other classes of antidepressants, which frequently cause high levels of drowsiness, dizziness, blurred vision, and other undesirable effects.
Uses
Sertraline is a selective serotonin reuptake inhibitor (SSRI) indicated to treat major depressive disorder, social anxiety disorder and many other psychiatric conditions.
Sertraline is indicated for the management of major depressive disorder (MDD), post-traumatic stress disorder (PTSD), obsessive-compulsive disorder (OCD), panic disorder (PD), premenstrual dysphoric disorder (PMDD), and social anxiety disorder (SAD). Common off-label uses for sertraline include the prevention of post stroke depression, generalized anxiety disorder (GAD), fibromyalgia, premature ejaculation, migraine prophylaxis, diabetic neuropathy, and neurocardiogenic syncope.
Associated Conditions
Pharmacodynamics
Sertraline improves or relieves the symptoms of depression, OCD, post-traumatic stress disorder, obsessive-compulsive disorder, panic disorder, and premenstrual dysphoric disorder via the inhibition of serotonin reuptake. Clinical studies have shown that it improves cognition in depressed patients. It has less sedative, anticholinergic, and cardiovascular effects than the tricyclic antidepressant drugs because it does not exert significant anticholinergic, antihistamine, or adrenergic (alpha1, alpha2, beta) blocking activity. The onset of action and beneficial effects are usually noticed after 4-6 weeks, for reasons that are not fully understood and currently under investigation.
Mechanism of Action
Sertraline selectively inhibits the reuptake of serotonin (5-HT) at the presynaptic neuronal membrane, thereby increasing serotonergic activity. This results in an increased synaptic concentration of serotonin in the CNS, which leads to numerous functional changes associated with enhanced serotonergic neurotransmission. These changes are believed to be responsible for the antidepressant action and beneficial effects in obsessive-compulsive (and other anxiety related disorders). It has been hypothesized that obsessive-compulsive disorder, like depression, is also caused by the disregulation of serotonin.
In animal studies, chronic administration of sertraline results in down-regulation of brain norepinephrine receptors. Sertraline displays affinity for sigma-1 and 2 receptor binding sites, but binds with stronger affinity to sigma-1 binding sites. In vitro, sertraline shows little to no affinity for GABA, dopaminergic, serotonergic (5HT1A, 5HT1B, 5HT2), or benzodiazepine receptors. It exerts weak inhibitory actions on the neuronal uptake of norepinephrine and dopamine and exhibits no inhibitory effects on the monoamine oxidase enzyme.
Absorption
Following once-daily administration of 50 to 200 mg for two weeks, the mean peak plasma concentrations (Cmax) of sertraline occurred between 4.5 to 8.4 hours after administration, and measured at 20 to 55 μg/L. Steady-state concentrations are reached after 1 week following once-daily administration, and vary greatly depending on the patient. Bioavailability has been estimated to be above 44%. The area under the curve in healthy volunteers after a 100mg dose of sertraline was 456 μg × h/mL in one study.
Effects of food on absorption
The effects of food on the bioavailability of the sertraline tablet and oral concentrate were studied in subjects given a single dose with and without food. For the tablet, AUC was slightly increased when sertraline was administered with food, the Cmax was 25% greater, and the time to peak plasma concentration was shortened by about 2.5 hours. For the oral concentrate preparation of sertraline, peak concentration was prolonged by approximately 1 hour with the ingestion of food.
Volume of Distribution
Sertraline is widely distributed, and its volume of distribution is estimated to be more than 20L/kg. Post-mortem studies in humans have measured liver tissue concentrations of 3.9–20 mg/kg for sertraline and between 1.4 to 11 mg/kg for its active metabolite, N-desmethyl-sertraline (DMS). Studies have also determined sertraline distributes into the brain, plasma, and serum.
Protein Binding
Sertraline is highly bound to serum proteins, at about 98%-99%.
Route of Elimination
Since sertraline is extensively metabolized, excretion of unchanged drug in the urine is a minor route of elimination, with 12-14% of unchanged sertraline excreted in the feces.
Half Life
The elimination half-life of sertraline is approximately 26 hours. One reference mentions an elimination half-life ranging from 22-36 hours.
Clearance
In pharmacokinetic studies, the clearance of a 200mg dose of sertraline in studies of both young and elderly patients ranged between 1.09 ± 0.38 L/h/kg - 1.35 ± 0.67 L/h/kg.
Toxicity
The LD50 of sertraline is >2000 mg/kg in rats according to the FDA label. One other references indicates an oral LD50 of in mice and rats of 419 - 548 mg/kg and 1327 - 1591mg/kg, respectively.
The most common signs and symptoms associated with a non-fatal sertraline overdose are somnolence, vomiting, tachycardia, nausea, dizziness, agitation, and tremor. No cases of fatal overdose with only sertraline have been reported. Most fatal cases are associated with the ingestion of sertraline with other drugs. Consequences of a sertraline overdose may include serotonin syndrome, hypertension, hypotension, syncope, stupor, coma, bradycardia, bundle branch block, QT-prolongation, torsade de pointes, delirium, hallucinations, and pancreatitis.
Food Interactions
- Avoid St. John's Wort.
- Take with or without food.
Dosage
Major depressive disorder:
- Starting Dose: 50 mg
- Therapeutic Range: 50-200 mg
- Starting Dose: 50 mg
- Therapeutic Range: 50-200 mg
- Starting Dose: 25 mg
- Therapeutic Range: 50-200 mg
Obsessive-compulsive disorder:
- Starting Dose: 25 mg
- Therapeutic Range: 50-200 mg
Premenstrual dysphoric disorder (PMDD): Starting dosage for PMDD is 50 mg/day. Sertraline may be administered either continuously (every day throughout the menstrual cycle) or intermittently (starting the daily dosage 14 days prior to the anticipated onset of menstruation and continuing through the onset of menses). Intermittent dosing would be repeated with each new cycle.
- Continuous: Patients not responding to a 50 mg dosage may benefit from dosage increases at 50 mg increments per menstrual cycle up to 150 mg per day.
- Intermittent: Patients not responding to a 50 mg dosage may benefit from increasing the dosage up to a maximum of 100 mg per day during the next menstrual cycle (and subsequent cycles).
