chemistry

Guanfacine

Guanfacine 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 Guanfacine rather than just read about it. In short: Guanfacine, sold under the brand name Tenex (immediate-release) and Intuniv (extended-release) among others, is an oral alpha-2a agonist medication used to treat attention deficit hyperactivity disorder (ADHD) and high blood pressure. Common side effects include sleepiness, constipation, and dry mouth.

Key takeaways

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

Reference excerpt

Guanfacine, sold under the brand name Tenex (immediate-release) and Intuniv (extended-release) among others, is an oral alpha-2a agonist medication used to treat attention deficit hyperactivity disorder (ADHD) and high blood pressure. Common side effects include sleepiness, constipation, and dry mouth. Other side effects may include low blood pressure and urinary problems. It appears to work by activating α2A-adrenergic receptors in the brain, thereby decreasing sympathetic nervous system activity. Guanfacine was first described in 1974 and was approved for medical use in the United States in 1986. It is available as a generic medication. In 2023, it was the 263rd most commonly prescribed medication in the United States, with more than 1 million prescriptions. Guanfacine is approved in the US for monotherapy treatment of attention deficit hyperactivity disorder, as well as being used for augmentation of stimulant medications. Guanfacine is also used off-label to treat tic disorders, anxiety disorders, and post-traumatic stress disorder (PTSD).

Medical uses

Guanfacine IR (as the brand name Tenex) is FDA-approved for the management of hypertension. Guanfacine XR (as brand name Intuniv) is indicated for the treatment of attention deficit hyperactivity disorder (ADHD), primarily for hyperactive symptoms. It is used both as monotherapy and as adjunctive therapy to stimulant medications. In some cases, it can also help control the side effect profile of stimulant medications. Unlike stimulant medications, guanfacine is regarded as having no abuse potential. However, stimulant medications still remain the first-line treatment for ADHD, and guanfacine is typically only prescribed by itself in patients who cannot take stimulant medications (due to mental or physical side effects). For attention deficit hyperactivity disorder (ADHD), it is claimed that guanfacine helps individuals better control behavior, inhibit inappropriate distractions and impulses, and inhibit inappropriate aggressive impulses. Systematic reviews and meta-analyses have found guanfacine to be effective in the treatment of ADHD in both children and adults, with a moderate effect size found in adults (Hedges' g = -0.66). A systematic review and meta-analysis also found that guanfacine reduced oppositional behavior in children and adolescents with ADHD who also had or did not also have oppositional defiant disorder, with a small-to-moderate effect size. In any case, guanfacine and other α2-adrenergic receptor agonists are considered to be less effective than stimulants in the treatment of ADHD, at least when compared on rating scales developed to assess stimulant efficacy. Guanfacine is also used off-label to treat tic disorders, anxiety disorders such as generalized anxiety disorder, and PTSD. Guanfacine and other α2A-adrenergic receptor agonists have anxiolytic-like action, thereby reducing the emotional responses of the amygdala, and strengthening prefrontal cortical regulation of emotion, action, and thought. These actions arise from both inhibition of stress-induced catecholamine release, and from prominent, post-synaptic actions in the prefrontal cortex. Due to its prolonged elimination half-life, it also has been seen to improve sleep interrupted by nightmares in PTSD patients. All of these actions likely contribute to the relief of the hyperarousal, re-experiencing of memory, and impulsivity associated with PTSD. Guanfacine appears to be especially helpful in treating children who have been traumatized or abused. Other indications for guanfacine are drug (opioid, nicotine, cocaine) withdrawals, migraine prophylaxis, and Fragile X Syndrome, among others.

Adverse effects Side effects of guanfacine are dose-dependent. Very common (>10% incidence) adverse effects include somnolence (drowsiness), fatigue, headache, and stomach ache. Common (1–10% incidence) adverse effects include decreased appetite, nausea, dry mouth, urinary incontinence, and rashes. Guanfacine has been reported to cause high rates of somnolence in children with attention deficit hyperactivity disorder, for instance 73% with guanfacine versus 6% with placebo in one trial. Guanfacine may worsen sleep in children with attention deficit hyperactivity disorder, including reduced total sleep time. A 2020 systematic review found side effects of guanfacine including abdominal pain, sedation, and QT prolongation.

Interactions Guanfacine availability is significantly affected by the CYP3A4 and CYP3A5 enzymes. Medications that inhibit or induce those enzymes change the amount of guanfacine in circulation and thus its efficacy and rate of adverse effects. Because of its impact on the heart, it should be used with caution with other cardioactive drugs. A similar concern is appropriate when it is used with sedating medications.

Pharmacology

Pharmacodynamics

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Guanfacine

Start with the simplest possible case. Write down what Guanfacine 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 Guanfacine 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 Guanfacine 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 Guanfacine

In research: Guanfacine 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 Guanfacine 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: Guanfacine is common in secondary-school and first-year university syllabi. It links to neighbouring topics 5-HT2B agonists, Acylguanidines, Alpha2-adrenergic agonists, so understanding it makes those chapters shorter.
In everyday life: Look for Guanfacine 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 Guanfacine in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Guanfacine 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 Guanfacine out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Guanfacine in simple terms?

Why does Guanfacine 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 Guanfacine?

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 Guanfacine.