Desvenlafaxine ER Tablets

Desvenlafaxine, a serotonin and norepinephrine reuptake inhibitor (SNRI), is indicated for the treatment of major depressive disorder (MDD) [see Clinical Studies (14)and Dosage and Administration (2.1)]. The efficacy of desvenlafaxine has been established in four short-term (8-week, placebo-controlled studies) and two maintenance studies in adult outpatients who met DSM-IV criteria for major depressive disorder.

• Hypersensitivity to desvenlafaxine succinate, venlafaxine hydrochloride or to any excipients in the desvenlafaxine formulation. Angioedema has been reported in patients treated with desvenlafaxine [see Adverse Reactions (6.1)]. • The use of MAOIs intended to treat psychiatric disorders with desvenlafaxine or within 7 days of stopping treatment with desvenlafaxine is contraindicated because of an increased risk of serotonin syndrome. The use of desvenlafaxine within 14 days of stopping an MAOI intended to treat psychiatric disorders is also contraindicated [see Dosage and Administration (2.6)and Warnings and Precautions (5.2)]. • Starting desvenlafaxine in a patient who is being treated with MAOIs such as linezolid or intravenous methylene blue is also contraindicated because of an increased risk of serotonin syndrome [see Dosage and Administration (2.6)and Warnings and Precautions (5.2)].

Desvenlafaxine is 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 molecular formula of C16H25NO2 (free base) and C16H25NO2•C4H6O4•H2O (succinate monohydrate). Desvenlafaxine succinate monohydrate has a molecular weight of 399.48. The structural formula is shown below.

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 is formulated as an extended-release tablet for once-a-day oral administration containing 38 mg, 76 mg or 152 mg of desvenlafaxine succinate equivalent to 25 mg, 50 mg or 100 mg of desvenlafaxine.

Each tablet contains the following inactive ingredients: colloidal silicon dioxide, hypromellose, magnesium stearate, microcrystalline cellulose, povidone and sodium stearyl fumarate. In addition to the ingredients listed above, the 25 mg tablets are film-coated with Opadry II Beige film-coating which contains FD&C Red No. 40, FD&C Yellow No. 6, FD&C Blue No. 1, polyvinyl alcohol, polyethylene glycol, talc and titanium dioxide. The 50 mg and 100 mg tablets are film-coated with Opadry II Orange film-coating which contains: FD&C Red No. 40, FD&C Yellow No. 6, polyvinyl alcohol, polyethylene glycol, talc and titanium dioxide.

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).

Pharmacodynamics

Desvenlafaxine lacked significant affinity for numerous receptors, including muscarinic-cholinergic, H1-histaminergic, or α1-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.

Pharmacokinetics

The single-dose pharmacokinetics of desvenlafaxine are linear and dose-proportional in a dose range of 50 mg to 600 mg 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 and Distribution

The absolute oral bioavailability of desvenlafaxine after oral administration is about 80%.

A food-effect study involving administration of desvenlafaxine to healthy subjects under fasting and fed conditions (high-fat meal, 800 to 1000 calories) indicated that desvenlafaxine Cmax was increased about 16% in the fed state, while the AUCs were similar. This difference is not expected to be clinically significant; therefore, desvenlafaxine can be taken without regard to meals [see Dosage and Administration (2.1)].

The plasma protein binding of desvenlafaxine is low (30%) and is independent of drug concentration. The desvenlafaxine volume of distribution at steady-state following intravenous administration is 3.4 L/kg, indicating distribution into nonvascular compartments.

Metabolism and Elimination

Desvenlafaxine is primarily metabolized by conjugation (mediated by UGT isoforms) and, to a minor extent, through oxidative metabolism. CYP3A4 is the cytochrome P450 isozyme mediating the oxidative metabolism (N-demethylation) of desvenlafaxine. The CYP2D6 metabolic pathway is not involved, and after administration of 100 mg, the pharmacokinetics of desvenlafaxine was similar in subjects with CYP2D6 poor and extensive metabolizer phenotype. 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.

Drug Interaction Studies

Inhibitors of CYP3A4 (Ketoconazole): CYP3A4 is a minor pathway for the metabolism of desvenlafaxine. In a clinical study, ketoconazole (200 mg BID) increased the area under the concentration vs. time curve (AUC) of desvenlafaxine (400 mg single dose) by about 43% and Cmax by about 8%. Concomitant use of desvenlafaxine with potent inhibitors of CYP3A4 may result in higher concentrations of desvenlafaxine.

Inhibitors of Other CYP Enzymes: 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.

Drugs Metabolized by CYP2D6 (e.g. Desipramine, Dextromethorphan, Metoprolol, Atomoxetine): In vitro studies showed minimal inhibitory effect of desvenlafaxine on CYP2D6. Clinical studies have shown that desvenlafaxine does not have a clinically relevant effect on CYP2D6 metabolism at the dose of 100 mg daily. When desvenlafaxine succinate was administered at a dose of 100 mg daily in conjunction with a single 50 mg dose of desipramine, a CYP2D6 substrate, the Cmax and AUC of desipramine increased approximately 25% and 17%, respectively. When 400 mg (8 times the recommended 50 mg dose) was administered, the Cmax and AUC of desipramine increased approximately 50% and 90%, respectively. Concomitant use of desvenlafaxine with a drug metabolized by CYP2D6 can result in higher concentrations of that drug [see Drug Interactions (7.5)].

Drugs Metabolized by CYP3A4 (Midazolam): In vitro, desvenlafaxine does not inhibit or induce the CYP3A4 isozyme. In a clinical study, desvenlafaxine 400 mg daily (8 times the recommended 50 mg dose) was co-administered with a single 4 mg dose of midazolam (a CYP3A4 substrate). The AUC and Cmax of midazolam decreased by approximately 31% and 16%, respectively. Concomitant use of desvenlafaxine with a drug metabolized by CYP3A4 can result in lower exposures to that drug.

Drugs Metabolized by CYP1A2, 2A6, 2C8, 2C9 and 2C19: In vitro, desvenlafaxine does not inhibit CYP1A2, 2A6, 2C8, 2C9, and 2C19 isozymes and would not be expected to affect the pharmacokinetics of drugs that are metabolized by these CYP isozymes.

In vitro, desvenlafaxine is not a substrate or an inhibitor for the P-glycoprotein transporter. The pharmacokinetics of desvenlafaxine are unlikely to be affected by drugs that inhibit the P-glycoprotein transporter, and desvenlafaxine is not likely to affect the pharmacokinetics of drugs that are substrates of the P-glycoprotein transporter.

Special Populations

Age: In a study of healthy subjects administered doses of up to 300 mg, there was an approximate 32% increase in Cmax and a 55% increase in AUC in subjects older than 75 years of age (n = 17), compared with subjects 18 to 45 years of age (n = 16). Subjects 65 to 75 years of age (n = 15) had no change in Cmax, but an approximately 32% increase in AUC, compared to subjects 18 to 45 years of age [see Dosage and Administration (2.2)].

Gender: In a study of healthy subjects administered doses of up to 300 mg, women had an approximately 25% higher Cmax and an approximately 10% higher AUC than age-matched men. No adjustment of dosage on the basis of gender is needed.

Race: Pharmacokinetic analysis showed that race (White, n = 466; Black, n = 97; Hispanic, n = 39; Other, n = 33) had no apparent effect on the pharmacokinetics of desvenlafaxine. No adjustment of dosage on the basis of race is needed.

Hepatic Insufficiency: The disposition of desvenlafaxine succinate after administration of 100 mg was studied in subjects with mild (Child-Pugh A, n = 8), moderate (Child-Pugh B, n = 8), and severe (Child-Pugh C, n = 8) hepatic impairment and to healthy subjects (n = 12).

Average AUC was increased by approximately 31% and 35% in patients with moderate and severe hepatic impairment, respectively, as compared to healthy subjects. Average AUC values were similar in subjects with mild hepatic impairment and healthy subjects (< 5% difference).

Systemic clearance (CL/F) was decreased by approximately 20% and 36% in patients with moderate and severe hepatic impairment, respectively, as compared to healthy subjects. CL/F values were comparable in mild hepatic impairment and healthy subjects (< 5% difference).

The mean t1/2 changed from approximately 10 hours in healthy subjects and subjects with mild hepatic impairment to 13 and 14 hours in moderate and severe hepatic impairment, respectively. The recommended dose in patients with hepatic impairment is 50 mg per day. Dose escalation above 100 mg per day is not recommended [see Use in Specific Populations (8.6)].

Renal Insufficiency: The disposition of desvenlafaxine after administration of 100 mg was studied in subjects with mild (n = 9), moderate (n = 8), severe (n = 7) and end-stage renal disease (ESRD) (n = 9) requiring dialysis and in healthy, age-matched control subjects (n = 8). Elimination was significantly correlated with creatinine clearance. Increases in AUCs of about 42% in mild renal impairment (24-hr CrCl = 50 to 80 mL/min, Cockcroft-Gault [C-G]), about 56% in moderate renal impairment (24-hr CrCl = 30 to 50 mL/min, C-G), about 108% in severe renal impairment (24-hr CrCl ≤30 mL/min, C-G), and about 116% in ESRD subjects were observed, compared with healthy, age-matched control subjects.

The mean terminal half-life (t1/2) was prolonged from 11.1 hours in the control subjects to approximately 13.5, 15.5, 17.6, and 22.8 hours in mild, moderate, severe renal impairment and ESRD subjects, respectively. Less than 5% of the drug in the body was cleared during a standard 4-hour hemodialysis procedure.

The maximum recommended dose in patients with moderate renal impairment is 50 mg per day. Dosage adjustment of 50 mg every other day is recommended in patients with severe renal impairment or ESRD [see Dosage and Administration (2.2)and Use in Specific Populations (8.6)].

Carcinogenesis, Mutagenesis, Impairment of Fertility

Carcinogenesis

Desvenlafaxine succinate administered by oral gavage to mice and rats for 2 years did not increase the incidence of tumors in either study.

Mice received desvenlafaxine succinate at dosages up to 500/300 mg/kg/day (dosage lowered after 45 weeks of dosing). The 300 mg/kg/day dose is 15 times a human dose of 100 mg per day on a mg/m2 basis.

Rats received desvenlafaxine succinate at dosages up to 300 mg/kg/day (males) or 500 mg/kg/day (females). The highest dose is 29 (males) or 48 (females) times a human dose of 100 mg per day on a mg/m2 basis.

Mutagenesis

Desvenlafaxine was not mutagenic in the in vitro bacterial mutation assay (Ames test) and was not clastogenic in an in vitro chromosome aberration assay in cultured CHO cells, an in vivo mouse micronucleus assay, or an in vivo chromosome aberration assay in rats. Additionally, desvenlafaxine was not genotoxic in the in vitro CHO mammalian cell forward mutation assay and was negative in the in vitro BALB/c-3T3 mouse embryo cell transformation assay.

Impairment of Fertility

When desvenlafaxine succinate was administered orally to male and female rats, fertility was reduced at the high dose of 300 mg/kg/day, which is 30 times a human dose of 100 mg per day (on a mg/m2 basis). There was no effect on fertility at 100 mg/kg/day, approximately 10 times a human dose of 100 mg per day (on a mg/m2 basis).

The efficacy of desvenlafaxine as a treatment for depression was established in four 8-week, randomized, double-blind, placebo-controlled, fixed-dose studies (at doses of 50 mg per day to 400 mg per day) in adult outpatients who met the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria for major depressive disorder. In the first study, patients received 100 mg (n = 114), 200 mg (n = 116), or 400 mg (n = 113) of desvenlafaxine once daily, or placebo (n = 118). In a second study, patients received either 200 mg (n = 121) or 400 mg (n = 124) of desvenlafaxine once daily, or placebo (n = 124). In two additional studies, patients received 50 mg (n = 150 and n = 164) or 100 mg (n = 147 and n = 158) of desvenlafaxine once daily, or placebo (n = 150 and n = 161).

Desvenlafaxine showed superiority over placebo as measured by improvement in the 17-item Hamilton Rating Scale for Depression (HAM-D17) total score in four studies and overall improvement, as measured by the Clinical Global Impressions Scale - Improvement (CGI-I), in three of the four studies. In studies directly comparing 50 mg per day and 100 mg per day there was no suggestion of a greater effect with the higher dose and adverse reactions and discontinuations were more frequent at higher doses [see Dosage and Administration (2.1)].

Table 8: Primary Efficacy (HAM-D17) Results for Short-term Studies

* Standard deviation; † Difference between least square means at final evaluation, calculated as drug response minus placebo response; unadjusted 95% confidence intervals. ‡ Adjusted p-value < 0.05;
			Desvenlafaxine
Study No.	Primary Endpoint: HAM-D17	Placebo	50 mg per day	100 mg per day	200 mg per day	400 mg per day
1	Baseline Score (SD*)	23.1 (2.5)		23.2 (2.5)	22.9 (2.4)	23 (2.2)
	Difference from Placebo (95% CI†)			-2.9‡ (-5.1, -0.8)	-2	-3.1‡ (-5.2, -0.9)
2	Baseline Score (SD*)	25.3 (3.3)			24.8 (2.9)	25.2 (3.2)
	Difference from Placebo (95% CI†)				-3.3‡ (-5.3, -1.2)	-2.8‡ (-4.8, -0.7)
3	Baseline Score (SD*)	23 (2.6)	23.4 (2.6)	23.4 (2.6)
	Difference from Placebo (95% CI†)		-1.9‡ (-3.5, -0.3)	-1.5
4	Baseline Score (SD*)	24.3 (2.6)	24.3 (2.4)	24.4 (2.7)
	Difference from Placebo (95% CI†)		-2.5‡ (-4.1, -0.9)	-3‡ (-4.7, -1.4)

Analyses of the relationships between treatment outcome and age and treatment outcome and gender did not suggest any differential responsiveness on the basis of these patient characteristics. There was insufficient information to determine the effect of race on outcome in these studies.

In a longer-term trial (Study 5), adult outpatients meeting DSM-IV criteria for major depressive disorder, who responded to 8 weeks of open-label acute treatment with 50 mg per day desvenlafaxine and subsequently remained stable for 12 weeks on desvenlafaxine, were assigned randomly in a double-blind manner to remain on active treatment or switch to placebo for up to 26 weeks of observation for relapse. Response during the open-label phase was defined as a HAM-D17 total score of ≤ 11 and CGI-I ≤ 2 at the day 56 evaluation; stability was defined as HAM-D17 total score of ≤ 11 and CGI-I ≤ 2 at week 20 and not having a HAM-D17 total score of ≥ 16 or a CGI-I score ≥ 4 at any office visit. Relapse during the double-blind phase was defined as follows: (1) a HAM-D17 total score of ≥ 16 at any office visit, (2) discontinuation for unsatisfactory efficacy response, (3) hospitalized for depression, (4) suicide attempt, or (5) suicide. Patients receiving continued desvenlafaxine treatment experienced statistically significantly longer time to relapse compared with placebo. At 26 weeks, the Kaplan-Meier estimated proportion of relapse was 14% with desvenlafaxine treatment versus 30% with placebo.

Figure 4: Estimated Proportion of Relapses vs. Number of Days Since Randomization (Study 5)

In another longer-term trial (Study 6), adult outpatients meeting DSM-IV criteria for major depressive disorder and who responded to 12 weeks of acute treatment with desvenlafaxine were assigned randomly to the same dose (200 mg or 400 mg per day) they had received during acute treatment or to placebo for up to 26 weeks of observation for relapse. Response during the open-label phase was defined as a HAM-D17 total score of ≤ 11 at the day 84 evaluation. Relapse during the double-blind phase was defined as follows: (1) a HAM-D17 total score of > 16 at any office visit, (2) a CGI-I score of ≥ 6 (versus day 84) at any office visit, or (3) discontinuation from the trial due to unsatisfactory response. Patients receiving continued desvenlafaxine treatment experienced statistically significantly longer time to relapse over the subsequent 26 weeks compared with those receiving placebo. At 26 weeks, the Kaplan-Meier estimated proportion of relapse was 29% with desvenlafaxine treatment versus 49% with placebo.

Figure 5: Estimated Proportion of Relapses vs. Number of Days Since Randomization (Study 6)

In a postmarketing study, the efficacy of desvenlafaxine at a dose lower than 50 mg per day was evaluated in an 8-week, multicenter, randomized, double-blind, placebo-controlled, fixed-dose study in adult outpatients with Major Depressive Disorder. The treatment arms were 25 mg (n=232), 50 mg (n=236), and placebo (n=231). The 50 mg dose was superior to placebo, as measured by the mean change from baseline on the HAMD17. The 25 mg dose was not superior to placebo.