Duloxetine Delayed-Release (Page 9 of 15)

9.3 Dependence

In drug dependence studies, duloxetine did not demonstrate dependence-producing potential in rats.


10.1 Signs and Symptoms

In postmarketing experience, fatal outcomes have been reported for acute duloxetine overdoses, primarily with mixed overdoses, but also with duloxetine only, including 1000 mg of duloxetine (approximately 8.3 times the maximum recommended dosage). Signs and symptoms of overdose (duloxetine alone or with mixed drugs) included somnolence, coma, serotonin syndrome, seizures, syncope, tachycardia, hypotension, hypertension, and vomiting.

10.2 Management of Overdose

There is no specific antidote to a Duloxetine delayed-release capsules overdosage, but if serotonin syndrome ensues, specific treatment (such as with cyproheptadine and/or temperature control) may be considered.

In case of acute overdose with Duloxetine delayed-release capsules, treatment should consist of those general measures employed in the management of overdose with any drug, such as assuring an adequate airway, oxygenation, and ventilation and monitoring cardiac rhythm and vital signs. Gastric lavage with a large-bore orogastric tube with appropriate airway protection, if needed, may be indicated if performed soon after ingestion or in symptomatic patients. Induction of emesis is not recommended.

Activated charcoal may be useful in limiting absorption of duloxetine from the gastrointestinal tract. Administration of activated charcoal has been shown to decrease duloxetine AUC and C max by an average of one-third, although some patients had a limited effect of activated charcoal. Due to the large volume of distribution of duloxetine, forced diuresis, dialysis, hemoperfusion, and exchange transfusion are unlikely to be beneficial.

In managing overdose, the possibility of multiple drug involvement should be considered. A specific caution involves patients who overdose with Duloxetine delayed-release capsules, and tricyclic antidepressants. In such a case, decreased clearance of the parent tricyclic and/or its active metabolite may increase the possibility of clinically significant sequelae and extend the time needed for close medical observation [see Warnings and Precautions (5.4) and Drug Interactions (7)].

Consider contacting a poison control center (1-800-222-1222 or www.poison.org) for additional information on the treatment of overdosage.


Duloxetine delayed-release capsules, USP are a selective serotonin and norepinephrine reuptake inhibitor (SNRI) for oral administration. Its chemical designation is (+)-( S )- N -methyl-γ-(1-naphthyloxy)-2-thiophenepropylamine hydrochloride. The empirical formula is C 18 H 19 NOS∙HCl, which corresponds to a molecular weight of 333.88. The structural formula is:

Chemical Structure

Duloxetine hydrochloride is a white to slightly brownish white solid, which is slightly soluble in water.

Each capsule contains enteric-coated pellets of 22.4, 33.7, 44.9 or 67.3 mg of duloxetine hydrochloride equivalent to 20, 30, 40 or 60 mg of duloxetine, respectively. These enteric-coated pellets are designed to prevent degradation of the drug in the acidic environment of the stomach. Inactive ingredients include ammonium hydroxide, black iron oxide, hypromellose, methacrylic acid copolymer dispersion (methacrylic acid-ethyl acrylate copolymer, polysorbate 80, sodium lauryl sulfate), potassium hydroxide, propylene glycol, shellac, sucrose, sugar spheres (maize starch, sucrose), talc, titanium dioxide, triethylcitrate, and hard gelatin capsules (gelatin, titanium dioxide). The 20 mg hard gelatin capsule colorant is yellow iron oxide. The 30 mg hard gelatin capsule colorants are FD&C Blue No. 1, FD&C Yellow No. 6, and FD&C Yellow No. 10. The 40 mg hard gelatin capsule colorants are FD&C Blue No. 2, red iron oxide, and yellow iron oxide. The 60 mg hard gelatin capsule colorants are FD&C Blue No. 1, FD&C Yellow No. 6, FD&C Yellow No.10, and yellow iron oxide.


12.1 Mechanism of Action

Although the exact mechanisms of the antidepressant, central pain inhibitory and anxiolytic actions of duloxetine in humans are unknown, these actions are believed to be related to its potentiation of serotonergic and noradrenergic activity in the CNS.

12.2 Pharmacodynamics

Preclinical studies have shown that duloxetine is a potent inhibitor of neuronal serotonin and norepinephrine reuptake and a less potent inhibitor of dopamine reuptake. Duloxetine has no significant affinity for dopaminergic, adrenergic, cholinergic, histaminergic, opioid, glutamate, and GABA receptors in vitro. Duloxetine does not inhibit monoamine oxidase (MAO).

Duloxetine delayed-release capsules are in a class of drugs known to affect urethral resistance [see Warnings and Precautions (5.15)].

Cardiac Electrophysiology

The effect of Duloxetine delayed-release capsules, 160 mg and 200 mg administered twice daily (2.7 and 3.3 times the maximum recommended dosage, respectively) to steady state was evaluated in a randomized, double-blinded, two-way crossover study in 117 healthy female adult subjects. No QT interval prolongation was detected. Duloxetine delayed-release capsules appears to be associated with concentration-dependent but not clinically meaningful QT shortening.

12.3 Pharmacokinetics

Duloxetine has an elimination half-life of about 12 hours (range 8 to 17 hours) and its pharmacokinetics are dose proportional over the therapeutic range. Steady-state plasma concentrations are typically achieved after 3 days of dosing. Elimination of duloxetine is mainly through hepatic metabolism involving two P450 isozymes, CYP1A2 and CYP2D6.


After oral Duloxetine delayed-release capsules administration, duloxetine hydrochloride is well absorbed. There is a median 2 hour lag until absorption begins (T lag ), with maximal plasma concentrations (C max ) of duloxetine occurring 6 hours post dose. There is a 3 hour delay in absorption and a one-third increase in apparent clearance of duloxetine after an evening dose as compared to a morning dose.

Effect of Food: Food does not affect the C max of duloxetine, but delays the time to reach peak concentration from 6 to 10 hours and it marginally decreases the extent of absorption (AUC) by about 10%.


The apparent volume of distribution averages about 1640 L. Duloxetine is highly bound (>90%) to proteins in human plasma, binding primarily to albumin and α 1 -acid glycoprotein. The interaction between duloxetine and other highly protein bound drugs has not been fully evaluated. Plasma protein binding of duloxetine is not affected by renal or hepatic impairment.



Biotransformation and disposition of duloxetine in humans have been determined following oral administration of 14 C-labeled duloxetine. Duloxetine comprises about 3% of the total radiolabeled material in the plasma, indicating that it undergoes extensive metabolism to numerous metabolites. The major biotransformation pathways for duloxetine involve oxidation of the naphthyl ring followed by conjugation and further oxidation. Both CYP1A2 and CYP2D6 catalyze the oxidation of the naphthyl ring in vitro. Metabolites found in plasma include 4-hydroxy duloxetine glucuronide and 5-hydroxy, 6-methoxy duloxetine sulfate.


Many additional metabolites have been identified in urine, some representing only minor pathways of elimination. Only trace (<1% of the dose) amounts of unchanged duloxetine are present in the urine. Most (about 70%) of the duloxetine dose appears in the urine as metabolites of duloxetine; about 20% is excreted in the feces. Duloxetine undergoes extensive metabolism, but the major circulating metabolites have not been shown to contribute significantly to the pharmacologic activity of duloxetine.

Specific Populations

Pediatric Patients

Duloxetine steady-state plasma concentration was comparable in pediatric patients 7 to 17 years of age and adult patients. The average steady-state duloxetine concentration was approximately 30% lower in this pediatric population relative to adult patients. The model-predicted duloxetine steady state plasma concentrations in pediatric patients 7 to 17 years of age were mostly within the concentration range observed in adult patients and did not exceed the concentration range in adults.

All MedLibrary.org resources are included in as near-original form as possible, meaning that the information from the original provider has been rendered here with only typographical or stylistic modifications and not with any substantive alterations of content, meaning or intent.

This site is provided for educational and informational purposes only, in accordance with our Terms of Use, and is not intended as a substitute for the advice of a medical doctor, nurse, nurse practitioner or other qualified health professional.

Privacy Policy | Copyright © 2023. All Rights Reserved.