Escitalopram oxalate - How It Works
Clinical pharmacology details from the US FDA-approved label: how Escitalopram oxalate works in your body, how it's absorbed, how long it stays active, and how it's eliminated.
Mechanism of Action
12.1 Mechanism of Action The mechanism of antidepressant action of escitalopram, the S-enantiomer of racemic citalopram, is presumed to be linked to potentiation of serotonergic activity in the central nervous system (CNS) resulting from its inhibition of CNS neuronal reuptake of serotonin (5-HT).
12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action The mechanism of antidepressant action of escitalopram, the S-enantiomer of racemic citalopram, is presumed to be linked to potentiation of serotonergic activity in the central nervous system (CNS) resulting from its inhibition of CNS neuronal reuptake of serotonin (5-HT).
12.2 Pharmacodynamics In vitro and in vivo studies in animals suggest that escitalopram is a highly selective serotonin reuptake inhibitor (SSRI) with minimal effects on norepinephrine and dopamine neuronal reuptake.
Escitalopram is at least 100-fold more potent than the R-enantiomer with respect to inhibition of 5-HT reuptake and inhibition of 5-HT neuronal firing rate.
Tolerance to a model of antidepressant effect in rats was not induced by long-term (up to 5 weeks) treatment with escitalopram.
Escitalopram has no or very low affinity for serotonergic (5-HT 1-7 ) or other receptors including alpha- and beta-adrenergic, dopamine (D 1-5 ), histamine (H 1-3 ), muscarinic (M 1-5 ), and benzodiazepine receptors.
Escitalopram also does not bind to, or has low affinity for, various ion channels including Na + , K + , Cl - , and Ca ++ channels.
Antagonism of muscarinic, histaminergic, and adrenergic receptors has been hypothesized to be associated with various anticholinergic, sedative, and cardiovascular side effects of other psychotropic drugs.
12.3 Pharmacokinetics The single- and multiple-dose pharmacokinetics of escitalopram are linear and dose-proportional in a dose range of 10 to 30 mg/day.
Biotransformation of escitalopram is mainly hepatic, with a mean terminal half-life of about 27 to 32 hours.
With once-daily dosing, steady state plasma concentrations are achieved within approximately one week.
At steady state, the extent of accumulation of escitalopram in plasma in young healthy subjects was 2.2 to 2.5 times the plasma concentrations observed after a single dose.
The tablet and the oral solution dosage forms of escitalopram oxalate are bioequivalent.
Absorption and Distribution Following a single oral dose (20 mg tablet or solution) of escitalopram, peak blood levels occur at about 5 hours.
Absorption of escitalopram is not affected by food.
The absolute bioavailability of citalopram is about 80% relative to an intravenous dose, and the volume of distribution of citalopram is about 12 L/kg.
Data specific on escitalopram are unavailable.
The binding of escitalopram to human plasma proteins is approximately 56%.
Metabolism and Elimination Following oral administrations of escitalopram, the fraction of drug recovered in the urine as escitalopram and S-demethylcitalopram (S-DCT) is about 8% and 10%, respectively.
The oral clearance of escitalopram is 600 mL/min, with approximately 7% of that due to renal clearance.
Escitalopram is metabolized to S-DCT and S-didemethylcitalopram (S-DDCT).
Pharmacokinetics
12.3 Pharmacokinetics The single- and multiple-dose pharmacokinetics of escitalopram are linear and dose-proportional in a dose range of 10 to 30 mg/day. Biotransformation of escitalopram is mainly hepatic, with a mean terminal half-life of about 27 to 32 hours. With once-daily dosing, steady state plasma concentrations are achieved within approximately one week. At steady state, the extent of accumulation of escitalopram in plasma in young healthy subjects was 2.2 to 2.5 times the plasma concentrations observed after a single dose. The tablet and the oral solution dosage forms of escitalopram oxalate are bioequivalent. Absorption and Distribution Following a single oral dose (20 mg tablet or solution) of escitalopram, peak blood levels occur at about 5 hours. Absorption of escitalopram is not affected by food. The absolute bioavailability of citalopram is about 80% relative to an intravenous dose, and the volume of distribution of citalopram is about 12 L/kg. Data specific on escitalopram are unavailable. The binding of escitalopram to human plasma proteins is approximately 56%. Metabolism and Elimination Following oral administrations of escitalopram, the fraction of drug recovered in the urine as escitalopram and S-demethylcitalopram (S-DCT) is about 8% and 10%, respectively. The oral clearance of escitalopram is 600 mL/min, with approximately 7% of that due to renal clearance. Escitalopram is metabolized to S-DCT and S-didemethylcitalopram (S-DDCT). In humans, unchanged e