Desvenlafaxine ER 100mg

Route: Oral extended-release tablet.

• Swallow whole; do not crush, chew, or split the tablet—the extended-release mechanism requires an intact matrix.
• May be taken with or without food; consistency is preferred.
• Take at approximately the same time each day.
• Do not abruptly discontinue; taper per prescriber guidance to minimize discontinuation syndrome.

Prescriber-determined based on indication and patient-specific factors. Reference dosing from the FDA-approved labeling context:

• MDD: Starting and target therapeutic dose is 50 mg once daily. The compounded 100 mg tablet may be used when dose escalation beyond 50 mg is clinically indicated; doses above 50 mg have not demonstrated additional efficacy for MDD in most patients but may be appropriate for individual cases.
• Off-label vasomotor symptoms (menopause): 100 mg daily has been evaluated in clinical trials for hot flash reduction.
• Maximum dose: up to 400 mg/day (though higher doses increase side effect burden without proportional efficacy gain).
• Taper dose gradually on discontinuation; abrupt cessation causes discontinuation syndrome (irritability, nausea, headache, dizziness).
• Final dose and titration are prescriber-determined.

Desvenlafaxine is the primary active metabolite of venlafaxine and exerts its pharmacological effects through potent inhibition of neuronal serotonin (SERT) and norepinephrine (NET) reuptake transporters in presynaptic neurons. Blockade of SERT increases synaptic serotonin availability; NET blockade increases synaptic norepinephrine. In vitro studies show approximately 10-fold greater selectivity for serotonin over norepinephrine. Unlike many SNRIs and TCAs, desvenlafaxine has minimal affinity for muscarinic, histaminergic, or α1-adrenergic receptors—resulting in a cleaner tolerability profile. Weak dopamine reuptake inhibition also occurs. In vasomotor symptom management, upregulation of noradrenergic and serotonergic tone in the hypothalamic thermoregulatory center is hypothesized to reduce the frequency and severity of hot flashes by narrowing the thermoneutral zone.

Desvenlafaxine ER 100 mg is used for:

• Major depressive disorder (FDA-approved): Treatment of MDD in adults; the extended-release formulation provides once-daily dosing with stable plasma levels. Onset of antidepressant effect typically occurs over 2–4 weeks; full effect may require 4–8 weeks.
• Menopausal vasomotor symptoms (off-label): Particularly valuable in women with contraindications to hormone therapy (e.g., history of breast cancer, estrogen-sensitive malignancy, thromboembolic risk). Reduces hot flash frequency and severity.

Prescriber monitoring:

• Suicide risk assessment at initiation and during dose changes (FDA Boxed Warning).
• Blood pressure monitoring (noradrenergic effect can raise BP).
• Assess for hyponatremia (SIADH) in elderly or at-risk patients.
• Monitor for activation of mania in patients with unrecognized bipolar disorder.
• Serum sodium at baseline in at-risk patients.
• Evaluate for serotonin syndrome if combining with other serotonergic agents.

Contraindications:

• Hypersensitivity to desvenlafaxine, venlafaxine, or any formulation component
• Concomitant or within 14 days of MAO inhibitor use (serotonin syndrome risk)
• Concomitant use with linezolid or IV methylene blue

Warnings & Precautions:

• Boxed Warning: Antidepressants increase risk of suicidal thinking and behavior in children, adolescents, and young adults (up to age 24) during initial treatment; monitor closely and advise patients/families accordingly.
• Serotonin syndrome: life-threatening risk with concurrent serotonergic agents, MAOIs, triptans, TCAs, fentanyl, tramadol, St. John's Wort; discontinue promptly if suspected.
• Elevated blood pressure: dose-dependent noradrenergic effect; monitor BP.
• Hyponatremia/SIADH: risk in elderly or volume-depleted patients; obtain baseline sodium.
• Activation of mania/hypomania in undiagnosed bipolar disorder.
• Bleeding risk: SNRIs inhibit platelet serotonin uptake; additive with NSAIDs, aspirin, anticoagulants.
• Angle-closure glaucoma risk: mydriasis possible.
• Neonatal discontinuation syndrome if used in late pregnancy.

Drug Interactions:

• MAO inhibitors: serotonin syndrome—absolutely contraindicated; 14-day washout required.
• Other serotonergic agents (SSRIs, other SNRIs, triptans, tramadol, linezolid, St. John's Wort): additive serotonin syndrome risk.
• NSAIDs, aspirin, anticoagulants: increased bleeding risk via platelet serotonin depletion.
• CYP3A4 inhibitors: desvenlafaxine is less CYP-dependent than venlafaxine; interactions are less clinically prominent but monitor.

Common Side Effects: Nausea (most common, especially early in treatment), dry mouth, hyperhidrosis, dizziness, insomnia, constipation, decreased appetite, sexual dysfunction (decreased libido, orgasmic dysfunction); elevated blood pressure; headache.

Store at controlled room temperature (20–25°C / 68–77°F). Protect from moisture and humidity—keep in a dry location. Protect from light. Do not freeze. Keep tightly sealed. Use before the beyond-use date assigned by Genesis Compounding. Keep out of reach of children. If a dose-dispensing pill organizer is used, transfer only daily amounts and keep the remainder in the sealed original container.

What is the difference between desvenlafaxine and venlafaxine?

Desvenlafaxine is the active metabolite of venlafaxine—it is what venlafaxine is converted to in the body. Desvenlafaxine has more predictable pharmacokinetics (less CYP2D6 variability), requires no hepatic conversion step, and has a cleaner receptor profile with minimal histaminergic, muscarinic, or alpha-adrenergic binding compared to venlafaxine.

How long before I feel the antidepressant effect?

Most patients notice partial improvement in mood, energy, and sleep within 2–4 weeks. Full antidepressant effect typically requires 4–8 weeks of consistent dosing. Symptomatic relief of vasomotor symptoms with off-label use may begin sooner. Do not discontinue treatment early because of a perceived lack of effect without consulting your prescriber.

Can I stop taking this medication abruptly?

No. Abrupt discontinuation of desvenlafaxine causes discontinuation syndrome: irritability, nausea, headache, dizziness, and "electric shock" sensations. The dose should be tapered gradually per your prescriber's instructions when discontinuing treatment.

Is this product FDA-approved?

Desvenlafaxine ER is FDA-approved (as Pristiq®) at 50 mg and 100 mg doses for major depressive disorder. This compounded preparation is a 503A prescription product from Genesis Compounding for a specific patient and is not an FDA-approved branded product, but uses the same active ingredient at an established FDA-approved dose.

What serotonin syndrome symptoms should I watch for?

Serotonin syndrome is a medical emergency. Symptoms include agitation, rapid heart rate, sweating, dilated pupils, muscle twitching or rigidity, diarrhea, and high body temperature. If you experience these symptoms—especially after adding a new medication—seek emergency care immediately and inform providers you are on an SNRI.