chemistry

Ketanserin

Ketanserin 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 Ketanserin rather than just read about it. In short: Ketanserin, sold under the brand name Sufrexal, is an antihypertensive agent which is used to treat arterial hypertension and vasospastic disorders. It is also used in scientific research as an antiserotonergic agent in the study of the serotonin system; specifically, the 5-HT2 receptor family.

Key takeaways

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

Reference excerpt

Ketanserin, sold under the brand name Sufrexal, is an antihypertensive agent which is used to treat arterial hypertension and vasospastic disorders. It is also used in scientific research as an antiserotonergic agent in the study of the serotonin system; specifically, the 5-HT2 receptor family. The drug is taken orally. Side effects of ketanserin include dizziness, tiredness, edema, dry mouth, weight gain, and QT interval prolongation. Ketanserin acts as a selective antagonist of the serotonin 5-HT2A, α1-adrenergic, and histamine H1 receptors. It also shows lower affinity for various other targets. Ketanserin was discovered at Janssen Pharmaceutica in 1980. It was the first serotonin 5-HT2A receptor antagonist to be discovered that showed selectivity over other serotonin receptors. The drug is not available in the United States and is mostly no longer marketed throughout the rest of the world.

Uses

Medical uses Ketanserin is classified as an antihypertensive by the World Health Organization and the National Institute of Health. It has been used to reverse pulmonary hypertension caused by protamine (which in turn was administered to reverse the effects of heparin overdose). The reduction in hypertension is not associated with reflex tachycardia. It has been used in cardiac surgery. A 2000 Cochrane Review found that, compared to placebo, ketanserin did not provide significant relief for people suffering from Raynaud's phenomenon attacks in the setting of progressive systemic sclerosis (an autoimmune disorder). While the frequency of the attacks was unaffected by ketanserin, there was a reduction in the duration of the individual attacks. However, due to the significant adverse effect burden, the authors concluded that ketanserin's utility for this indication is likely unbeneficial. Ketanserin is a selective 5-HT2A receptor antagonist that was initially developed as an anti-hypertensive medicine. However, now the drug is available as a topical gel formulation for treating wounds, burns, ulcers, and anal fissures. Its action is through the acceleration of epithelialization.

Research uses With tritium (3H) radioactively labeled ketanserin is used as a radioligand for serotonin 5-HT2 receptors, e.g. in receptor binding assays and autoradiography. This radio-labeling has enabled the study of serotonin 5-HT2A receptor distribution in the human brain. An autoradiography study of the human cerebellum has found an increasing binding of 3H-ketanserin with age (from below 50 femtomol per milligram tissue at around 30 years of age to over 100 above 75 years). The same research team found no significant correlation with age in their homogenate binding study. Ketanserin has also been used with carbon (11C) radioactively labeled NNC112 in order to image cortical D1 receptors without contamination by 5-HT2 receptors. Increasing research into the use of psychedelics as antidepressants has seen ketanserin used to both block the hallucinogenic experience, and to disentangle the specific cognitive effects of 5-HT2A activation. Ketanserin has been found to block the psychedelic effects of psilocybin, lysergic acid diethylamide (LSD), mescaline, and ayahuasca (dimethyltryptamine) in clinical studies.

Pharmacology

Pharmacodynamics Ketanserin is a high-affinity non-selective antagonist of 5-HT2 receptors in rodents. In addition to the 5-HT2 receptors, ketanserin is also a high affinity antagonist for the H1 receptor. It has also been found to block the vesicular monoamine transporter 2 (VMAT2). Occupancy of the serotonin 5-HT2A receptor by ketanserin in humans has been studied.

Pharmacokinetics The bioavailability of ketanserin is 50%. Its time to peak levels is 0.53 to 2.3 hours on average, with a range of 0.25 to 5.0 hours. The drug's ability to cross the blood–brain barrier varies in different species, with higher permeability in humans, monkeys, and minipigs than in mice or rats. This is probably due to ketanserin being a P-glycoprotein substrate and due to varying capacity of P-glycoprotein in limiting blood–brain barrier penetration in different species. The plasma protein binding of ketanserin is 95.0% and it is mainly bound to albumin. The elimination half-life of ketanserin is 10 to 29 hours. However, a more recent study found a half-life of 3.5 hours.

Chemistry Ketanserin is a piperidinylethylquinazoline derivative.

Synthesis

Either 3-(2-Chloroethyl)quinazoline-2,4(1H,3H)-dione [5081-87-8] (1a), or alternatively 2,3-dihydro-[1,3]oxazolo[2,3-b]quinazolin-5-one [52727-44-3] (1b) can be used as starting material. Attachment of the sidechain to 4-(4-Fluorobenzoyl)piperidine [56346-57-7] (2) completes the synthesis of Ketanserin (3).

Analogues Analogues of ketanserin include altanserin, ocaperidone, paliperidone, pelanserin, pirenperone, risperidone, ritanserin, and setoperone, among others.

History Ketanserin was first described in the scientific literature by 1980.

Society and culture

Names Ketanserin is the generic name of the drug and its INNTooltip International Nonproprietary Name, USANTooltip United States Adopted Name, and BANTooltip British Approved Name. It is also known by its major brand names Sufrexal and Serefrex and by its former developmental code names R-41468, KJK-945, and R-49945.

See also Serotonin 5-HT2A receptor antagonist List of investigational hallucinogens and entactogens Eplivanserin/volinanserin

References

External links How To Stop A Psychedelic Trip: The Promise of Ketanserin - Psychedelic Science Review (PSR)

Illustrations

Worked examples

Example 1 — a first encounter with Ketanserin

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

In research: Ketanserin 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 Ketanserin 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: Ketanserin is common in secondary-school and first-year university syllabi. It links to neighbouring topics 4-Fluorophenyl compounds, 5-HT1D antagonists, 5-HT2A antagonists, so understanding it makes those chapters shorter.
In everyday life: Look for Ketanserin 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 Ketanserin in 20 minutes

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

Frequently asked questions

What is Ketanserin in simple terms?

Why does Ketanserin 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 Ketanserin?

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 Ketanserin.