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Mechanism Of Action
The exact mechanism of the antidepressant action of KHEDEZLA 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).
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.
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.
The single-dose pharmacokinetics of desvenlafaxine are linear and dose-proportional in a dose range of 100 to 600 mg/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.
The mean ± SD terminal half-life, t½, after administration of KHEDEZLA is about 9.5 ± 1.5 hours. The median (range) time to peak concentration (Tmax) is 6 (3 – 14) hours after administration of 50 mg KHEDEZLA .
Absorption and Distribution
KHEDEZLA 50 mg and 100 mg demonstrated similar exposures (Cmax, AUC) to a 50 mg and 100 mg extended-release desvenlafaxine succinate product, respectively.
The absolute oral bioavailability after the administration of desvenlafaxine succinate is about 80%. There was no clinically significant food effect seen when KHEDEZLA was administered with a high fat meal. Therefore, KHEDEZLA can be taken without regard to meals [see DOSAGE AND ADMINISTRATION].
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 KHEDEZLA 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 KHEDEZLA.
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].
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 KHEDEZLA 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, desevenlafaxine 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 KHEDEZLA are unlikely to be affected by drugs that inhibit the P-glycoprotein transporter, and KHEDEZLA is not likely to affect the pharmacokinetics of drugs that are substrates of the P-glycoprotein transporter.
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].
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.
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.
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 t½ 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/day. Dose escalation above 100 mg/day is not recommended [see Use In Specific Populations].
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 (t½) 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 and Use In Specific Populations].
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/day to 400 mg/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/day and 100 mg/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].
Table 8: Primary Efficacy (HAM-D17) Results for
|Study No.||Primary Endpoint: HAM-D17||Placebo||Desvenlafaxine|
|50 mg/day||100 mg/day||200 mg/day||400 mg/day|
|1||Baseline Score (SDa)||23.1 (2.5)||23.2 (2.5)||22.9 (2.4)||23.0 (2.2)|
|Difference from Placebo (95% CIc)||-2.9b (-5.1, -0.8)||-2.0||-3.1b ( -5.2, -0.9)|
|2||Baseline Score (SDa)||25.3 (2.3)||24.8 (2.9)||25.2 (3.2)|
|Difference from Placebo (95% CIc)||-3.3b (-5.3, -1.2)||-2.8b (-4.8, -0.7)|
|3||Baseline Score (SDa)||23.4 (2.6)||23.4 (2.6)|
|Difference from Placebo (95% CIc)||23.0 (2.6)||-1.9b (-3.5, -0.3)||-1.5|
|4||Baseline Score (SDa)||24.3 (2.6)||24.3 (2.4)||24.4 (2.7)|
|Difference from Placebo (95% CIc)||-2.5b (-4.1, -0.9)||-3.0b (-4.7, -1.4)|
|a Standard deviation
b Adjusted p-value < 0.05;
c Difference between least squares means at final evaluation, calculated as drug response minus placebo response; unadjusted 95% confidence intervals
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.
Last reviewed on RxList: 1/23/2017
This monograph has been modified to include the generic and brand name in many instances.
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