Desvenlafaxine (US brand name Pristiq®, Khedezla®, and generic) is a serotonin and norepinephrine reuptake inhibitor (SNRI). Here is basic information about this medication.
Desvenlafaxine is a metabolite of venlafaxine. Venlafaxine is metabolized by P450 2D6 and is, therefore, subject to clinically significant effects of 2D6 pharmacogenetic status (e.g., poor metabolizer) and to drug-drug interactions when given with a significant 2D6 inhibitor (e.g., bupropion).
On the other hand, 45% of the desvenlafaxine dose is excreted unchanged and most of the rest is metabolized, not by the P450 system but by another metabolic system called the UGT system (UGT stands for uridine 5′-diphosphate glucuronosyltransferases, but who can — or needs to — remember that?)
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Desvenlafaxine is not metabolized to any great extent through the cytochrome P450 system.
1. About 45% is excreted unchanged in the urine.
2. About 20% is glucuronidated and then excreted in the urine.
3. Only about 5% is metabolized by CYP 3A4.
50 mg once daily, with or without food according to the Prescribing Information), but SPMHE disagrees and recommends that it should be taken after food (at least initially) since nausea is its commonest potential side effect.
Note: Desvenlafaxine is available in tablets rather than capsules but the tablets are extended-release tablets; they should not be split.
The 50 mg dose is both a starting dose and the therapeutic dose. There is no evidence that doses greater than 50 mg/day confer any additional benefit.
Dosage forms and strengths (USA)
Extended-release tablets (Pristiq®, Khedezla®, and generic): 25 mg (Pristiq® only), 50 mg, and 100 mg
Potential side effects
Please see THIS PAGE for a handout listing the common and less common side effects of desvenlafaxine along with the percentages of patients who report them.
Important! Please refer to the full Prescribing Information (see links below) before prescribing this medication.
Copyright 2016, Rajnish Mago, MD. All rights reserved. May not be reproduced in any form without express written permission.
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