Prescription Drug Information: Desvenlafaxine (Page 4 of 7)

8.2 Lactation

Risk Summary

Available limited data from published literature show low levels of desvenlafaxine in human milk, and have not shown adverse reactions in breastfed infants ( see Data). There are no data on the effects of desvenlafaxine on milk production.

The developmental and health benefits of breastfeeding should be considered along with the mother’s clinical need for desvenlafaxine extended-release tablets and any potential adverse effects on the breastfed child from desvenlafaxine extended-release tablets or from the underlying maternal condition.

Data

A lactation study was conducted in 10 breastfeeding women (at a mean of 4.3 months postpartum) who were being treated with a 50 to 150 mg daily dose of desvenlafaxine for postpartum depression. Sampling was performed at steady state (up to 8 samples) over a 24 hour dosing period, and included foremilk and hindmilk. The mean relative infant dose was calculated to be 6.8% (range of 5.5 to 8.1%). No adverse reactions were seen in the infants.

8.4 Pediatric Use

The safety and effectiveness of desvenlafaxine extended-release tablets have not been established in pediatric patients for the treatment of MDD.

Antidepressants, such as desvenlafaxine extended-release tablets, increase the risk of suicidal thoughts and behaviors in pediatric patients [see the Boxed Warning and Warnings and Precautions ( 5.1)] .

Additional information describing clinical studies in which efficacy was not demonstrated in pediatric patients is approved for Wyeth Pharmaceuticals Inc. a subsidiary of Pfizer Inc.’s PRISTIQ® (desvenlafaxine) Extended-Release Tablets. However, due to Wyeth Pharmaceuticals Inc., a subsidiary of Pfizer Inc.’s marketing exclusivity rights, this product is not labeled with that pediatric information.

Juvenile Animal Studies

In a juvenile animal study, male and female rats were treated with desvenlafaxine (75, 225 and 675 mg/kg/day) starting on postnatal day (PND) 22 through 112. Behavioral deficits (longer time immobile in a motor activity test, longer time swimming in a straight channel test, and lack of habituation in an acoustic startle test) were observed in males and females but were reversed after a recovery period. A No Adverse Effect Level (NOAEL) was not identified for these deficits. The Low Adverse Effect Level (LOAEL) was 75 mg/kg/day which was associated with plasma exposure (AUC) twice the levels measured with a pediatric dose of 100 mg/day.

In a second juvenile animal study, male and female rats were administered desvenlafaxine (75, 225 or 675 mg/kg/day) for 8-9 weeks starting on PND 22 and were mated with naïve counterparts. Delays in sexual maturation and decreased fertility, number of implantation sites and total live embryos were observed in treated females at all doses. The LOAEL for these findings is 75 mg/kg/day which was associated with an AUC twice the levels measured with a pediatric dose of 100 mg/day. These findings were reversed at the end of a 4-week recovery period.The relevance of these findings to humans is not known.

8.5 Geriatric Use

Of the 4,158 patients in pre-marketing clinical studies with desvenlafaxine extended-release tablets, 6% were 65 years of age or older. No overall differences in safety or efficacy were observed between these patients and younger patients; however, in the short-term placebo-controlled studies, there was a higher incidence of systolic orthostatic hypotension in patients ≥ 65 years of age compared to patients <65 years of age treated with desvenlafaxine extended-release tablets [see Adverse Reactions (6.1 )]. For elderly patients, possible reduced renal clearance of desvenlafaxine extended-release tablets should be considered when determining dose [see Dosage and Administration ( 2.2) and Clinical Pharmacology ( 12.3)].

SSRIs and SNRIs, including desvenlafaxine extended-release tablets, have been associated with cases of clinically significant hyponatremia in elderly patients, who may be at greater risk for this adverse event [see Warnings and Precautions ( 5.9)].

8.6 Renal Impairment

Adjust the maximum recommended dosage in patients with moderate or severe renal impairment (CLcr 15 to 50 mL/min, C-G), or end-stage renal disease (CLcr < 15 mL/min, C-G) [see Dosage and Administration ( 2.2) and Clinical Pharmacology ( 12.3)] .

8.7 Hepatic Impairment

Adjust the maximum recommended dosage in patients with moderate to severe hepatic impairment (Child-Pugh score 7 to 15) [see Dosage and Administration ( 2.3) and Clinical Pharmacology ( 12.3)] .

9 DRUG ABUSE AND DEPENDENCE

9.1 Controlled Substance

Desvenlafaxine extended-release tablets are not a controlled substance.

10 OVERDOSAGE

10.1 Human Experience with Overdosage

There is limited clinical trial experience with desvenlafaxine succinate overdosage in humans. However, desvenlafaxine (desvenlafaxine extended-release tablets) is the major active metabolite of venlafaxine. Overdose experience reported with venlafaxine (the parent drug of desvenlafaxine extended-release tablets) is presented below; the identical information can be found in the Overdosage section of the venlafaxine package insert.

In postmarketing experience, overdose with venlafaxine (the parent drug of desvenlafaxine extended-release tablets) has occurred predominantly in combination with alcohol and/or other drugs. The most commonly reported events in overdosage include tachycardia, changes in level of consciousness (ranging from somnolence to coma), mydriasis, seizures, and vomiting. Electrocardiogram changes (e.g., prolongation of QT interval, bundle branch block, QRS prolongation), sinus and ventricular tachycardia, bradycardia, hypotension, rhabdomyolysis, vertigo, liver necrosis, serotonin syndrome, and death have been reported.

Published retrospective studies report that venlafaxine overdosage may be associated with an increased risk of fatal outcomes compared to that observed with SSRI antidepressant products, but lower than that for tricyclic antidepressants. Epidemiological studies have shown that venlafaxine-treated patients have a higher pre-existing burden of suicide risk factors than SSRI-treated patients. The extent to which the finding of an increased risk of fatal outcomes can be attributed to the toxicity of venlafaxine in overdosage, as opposed to some characteristic(s) of venlafaxine-treated patients, is not clear.

10.2 Management of Overdosage

No specific antidotes for desvenlafaxine extended-release tablets are known. In managing over dosage, consider the possibility of multiple drug involvement. In case of overdose, call Poison Control Center at 1-800-222-1222 for latest recommendations.

11 DESCRIPTION

Desvenlafaxine extended-release tablets are an extended-release tablet for oral administration that contains desvenlafaxine succinate, a structurally novel SNRI for the treatment of MDD. Desvenlafaxine (O-desmethylvenlafaxine) is the major active metabolite of the antidepressant venlafaxine, a medication used to treat major depressive disorder.

Desvenlafaxine is designated RS -4-[2-dimethylamino-1-(1-hydroxycyclohexyl)ethyl]phenol and has the empirical formula of C 16 H 25 NO 2 (free base) and C 16 H 25 NO 2 •C 4 H 6 O 4 •H 2 O (succinate monohydrate). Desvenlafaxine succinate monohydrate has a molecular weight of 399.48. The structural formula is shown below.

structure
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Desvenlafaxine succinate is a white to off-white powder that is soluble in water. The solubility of desvenlafaxine succinate is pH dependent. Its octanol:aqueous system (at pH 7.0) partition coefficient is 0.21.

Desvenlafaxine extended-release tablets are formulated as an extended-release tablet for once-a-day oral administration.

Each tablet contains 38 mg, 76 mg or 152 mg of desvenlafaxine succinate equivalent to 25 mg, 50 mg or 100 mg of desvenlafaxine, respectively.

Inactive ingredients for the 25 mg, 50 mg and 100 mg tablet consist of hypromellose, microcrystalline cellulose, talc, magnesium stearate, polyethylene oxide and colloidal silicon dioxide and film coating, which consists of polyvinyl alcohol, polyethylene glycol, talc, titanium dioxide, and iron oxide yellow and iron oxide red. The imprinting ink contains hypromellose, propylene glycol and iron oxide black.

12 CLINICAL PHARMACOLOGY

12.1 Mechanism of Action

The exact mechanism of the antidepressant action of desvenlafaxine is unknown, but is thought to be related to the potentiation of serotonin and norepinephrine in the central nervous system, through inhibition of their reuptake. Non-clinical studies have shown that desvenlafaxine is a potent and selective serotonin and norepinephrine reuptake inhibitor (SNRI).

​12.2 Pharmacodynamics

Desvenlafaxine lacked significant affinity for numerous receptors, including muscarinic-cholinergic, H 1 -histaminergic, or α 1 -adrenergic receptors in vitro. Desvenlafaxine also lacked monoamine oxidase (MAO) inhibitory activity.

ECG changes

Electrocardiograms were obtained from 1,492 desvenlafaxine treated patients with major depressive disorder and 984 placebo-treated patients in clinical studies lasting up to 8 weeks. No clinically relevant differences were observed between desvenlafaxine treated and placebo-treated patients for QT, QTc, PR, and QRS intervals. In a thorough QTc study with prospectively determined criteria, desvenlafaxine did not cause QT prolongation. No difference was observed between placebo and desvenlafaxine treatments for the QRS interval.

12.3 Pharmacokinetics

The single-dose pharmacokinetics of desvenlafaxine are linear and dose-proportional in a dose range of 50 to 600 mg (1 to 12 times the recommended approved dosage) per day. With once-daily dosing, steady-state plasma concentrations are achieved within approximately 4 to 5 days. At steady-state, multiple-dose accumulation of desvenlafaxine is linear and predictable from the single-dose pharmacokinetic profile.

Absorption

The absolute oral bioavailability of desvenlafaxine extended-release tablets after oral administration is about 80%.

Effect of Food

Ingestion of a high-fat meal (800 to 1000 calories) increased desvenlafaxine C max about 16% and had no effect on AUC.

Distribution

Steady-state volume of distribution of desvenlafaxine is 3.4 L/kg. Plasma protein binding of desvenlafaxine is 30% and is independent of drug concentration.

Elimination

Metabolism

Desvenlafaxine is primarily metabolized by conjugation (mediated by UGT isoforms) and, to a minor extent, through oxidative metabolism. CYP3A4 mediates the oxidative metabolism (N-demethylation) of desvenlafaxine. The CYP2D6 metabolic pathway is not involved. The pharmacokinetics of desvenlafaxine was similar in subjects with CYP2D6 poor and extensive metabolizer phenotype.

Excretion

Approximately 45% of desvenlafaxine is excreted unchanged in urine at 72 hours after oral administration. Approximately 19% of the administered dose is excreted as the glucuronide metabolite and <5% as the oxidative metabolite (N,O-didesmethylvenlafaxine) in urine.

Specific Populations

No clinically significant differences in the exposures of desvenlafaxine were observed based on ethnicity (White, Black, Hispanic).

The effect of intrinsic patient factors on the pharmacokinetics of desvenlafaxine is presented in Figure 1.

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Drug Interaction Studies

Clinical Studies

Other Drugs on desvenlafaxine extended-release tablets

The effect of ketoconazole on the exposures of desvenlafaxine is summarized in Figure 2.

Figure 2. Effect of Other Drugs on Desvenlafaxine Pharmacokinetics

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Desvenlafaxine extended-release tablets on Other Drugs

The effects of desvenlafaxine extended-release tablets on the exposures of other drugs are summarized in Figure 3.

Figure 3. Effects of Desvenlafaxine Extended-Release Tablets on Pharmacokinetics of Other Drugs

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In Vitro Studies

Based on in vitro data, drugs that inhibit CYP isozymes 1A1, 1A2, 2A6, 2D6, 2C8, 2C9, 2C19, and 2E1 are not expected to have significant impact on the pharmacokinetic profile of desvenlafaxine.

Desvenlafaxine does not inhibit CYP1A2, 2A6, 2C8, 2C9, 2C19, CYP2D6, or CYP3A4 isozymes. Desvenlafaxine does not induce CYP3A4 either.

Desvenlafaxine is not a substrate or an inhibitor for the P-glycoprotein (P-gp) transporter.

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