chemistry

Venlafaxine

Venlafaxine is a chemistry topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Venlafaxine rather than just read about it. In short: Venlafaxine, sold under the brand name Effexor among others, is an antidepressant medication of the serotonin–norepinephrine reuptake inhibitor (SNRI) class. It is used to treat major depressive disorder, generalized anxiety disorder, panic disorder, and social anxiety disorder.

Key takeaways

Venlafaxine belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Venlafaxine to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Venlafaxine from memory before moving on to harder problems.

Reference excerpt

Venlafaxine, sold under the brand name Effexor among others, is an antidepressant medication of the serotonin–norepinephrine reuptake inhibitor (SNRI) class. It is used to treat major depressive disorder, generalized anxiety disorder, panic disorder, and social anxiety disorder. Studies have shown that venlafaxine improves post-traumatic stress disorder (PTSD) as a recommended first-line treatment. It may also be used for chronic neuropathic pain. It is taken orally (swallowed by mouth). It is also available as the salt venlafaxine besylate (venlafaxine benzenesulfonate monohydrate) in an extended-release formulation (Venbysi XR). Common side effects include loss of appetite, constipation, dry mouth, dizziness, sweating, insomnia, drowsiness and sexual problems. In some patients, sexual dysfunction may persist even after the drug is discontinued, a condition known as post-SSRI sexual dysfunction. Severe side effects include an increased risk of suicide, mania, and serotonin syndrome. Antidepressant withdrawal syndrome may occur if stopped. A meta-analysis of randomized trials in depression found an increased rate of serious adverse events, particularly sexual dysfunction and anorexia, and several non-serious adverse effects, including nervousness, asthenia, and tremor. There are concerns that use during the later part of pregnancy can harm the baby. Venlafaxine's mechanism of action is not entirely clear, but it seems to be related to the potentiation of the activity of some neurotransmitters in the brain. Venlafaxine was approved for medical use in the United States in 1993. It is available as a generic medication. In 2023, it was the 51st most commonly prescribed medication in the United States, with more than 13 million prescriptions.

Medical uses Venlafaxine is used primarily for the treatment of depression, general anxiety disorder, social phobia, panic disorder, and vasomotor symptoms. Concerns that noradrenergic reuptake might precipitate anxiety have not been borne out in randomized trials: a 2016 systematic review of 52 double-blind, placebo-controlled studies (mostly with venlafaxine or duloxetine) found clinically significant improvements in anxiety symptoms and no signal for treatment-emergent anxiety attributable to SNRIs. Venlafaxine has been used off label for the treatment of diabetic neuropathy and migraine prevention. It may work on pain via effects on the opioid receptor. It has also been found to reduce the severity of 'hot flashes' in menopausal women and men on hormonal therapy for the treatment of prostate cancer. Due to its action on both the serotonergic and adrenergic systems, venlafaxine is also used as a treatment to reduce episodes of cataplexy, a form of muscle weakness, in patients with the sleep disorder narcolepsy. Some open-label and three double-blind studies have suggested the efficacy of venlafaxine in the treatment of attention deficit-hyperactivity disorder (ADHD). Clinical trials have found possible efficacy in those with post-traumatic stress disorder (PTSD). Case reports, open trials and blinded comparisons with established medications have suggested the efficacy of venlafaxine in the treatment of obsessive–compulsive disorder.

Depression A comparative meta-analysis of 21 major antidepressants found that venlafaxine, agomelatine, amitriptyline, escitalopram, mirtazapine, paroxetine, and vortioxetine were more effective than other antidepressants, although the quality of many comparisons was assessed as low or very low. Open-label evidence also suggests potential benefit in treatment-resistant cases: in a multicenter Canadian study of adults with inadequate response to prior antidepressants (n=159), 58% achieved response and 28% remission after 8 weeks of venlafaxine (mean 260 mg/day); tolerability was generally acceptable. Venlafaxine was similar in efficacy to the atypical antidepressant bupropion; however, the remission rate was lower for venlafaxine. In a double-blind study, patients who did not respond to an SSRI were switched to either venlafaxine or another SSRI (citalopram); similar improvement was observed in both groups. Studies have not established its efficacy for use in pediatric populations. In children and adolescents with depression, venlafaxine increases the risk of suicidal thoughts or attempts. Higher doses (e.g., 225 mg and 375 mg per day) of venlafaxine are more effective than lower doses (e.g., 75 mg per day) but also cause more side effects. Studies have shown that the extended-release is superior to the immediate-release form of venlafaxine. A 2017 meta-analysis has shown that the efficacy of venlafaxine is not correlated with baseline severity of depression. In other words, regardless of how severe a person's depression is at treatment initiation, the efficacy of venlafaxine remains consistent and is not influenced by the severity of depression at the start of treatment.

Contraindications Venlafaxine is not recommended in patients hypersensitive to it, nor should it be taken by anyone who is allergic to the inactive ingredients, which include gelatin, cellulose, ethylcellulose, iron oxide, titanium dioxide and hypromellose. It should not be used in conjunction with a monoamine oxidase inhibitor (MAOI), as it can cause potentially fatal serotonin syndrome. Venlafaxine might interact with tramadol or other opioids, as well as trazodone and buspirone, so caution is needed while mixing multiple serotonergic agents together.

Adverse effects

Venlafaxine can increase eye pressure, so those with glaucoma may require more frequent eye checks. A 2017 meta-analysis estimated venlafaxine discontinuation rate due to adverse effects to be 9.4%.

Suicide

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Venlafaxine

Start with the simplest possible case. Write down what Venlafaxine claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Venlafaxine before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Venlafaxine ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Venlafaxine

In research: Venlafaxine appears in chemistry research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Venlafaxine in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Venlafaxine is common in secondary-school and first-year university syllabi. It links to neighbouring topics 4-Methoxyphenyl compounds, Antidepressants, CYP2D6 inhibitors, so understanding it makes those chapters shorter.
In everyday life: Look for Venlafaxine outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Venlafaxine in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Venlafaxine means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Venlafaxine out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Venlafaxine in simple terms?

Why does Venlafaxine matter?

Because it connects several chemistry ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Venlafaxine?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Venlafaxine.