Clemastine review

Clemastine is one effective antihistamine that can quickly reduce allergic symptoms within 24 hours. There are a number of precautions and side effects to watch out for so that patients stay safe.

Clemastine is the generic name of the antihistamine drug having sedative and anticholinergic effects. It is used for the treatment of allergic symptoms like runny nose, swelling, itchy skin, hives, rash, sneezing, red and teary eyes and pruritus. It is also known as meclastin and classified as an antipruritic. Clemastine is able to increase capillary dilatation and permeability as well as improve gastrointestinal and respiratory smooth muscle contraction.

Depending on the amount used, Clemastine can cause paradoxical effects like CNS depression and stimulation. By blocking the effects of natural-occurring histamine chemical, it inhibits histamine’s vasodilator and vasoconstrictor effects. The drug comes in the form of tablets and extended-release tablets which should be taken orally. It is also available in syrup form under the brand name Tavist.

Just like all other drugs, Clemastine can cause many side effects like drowsiness, dry mouth, nose or throat, dizziness, chest congestion, headache, upset stomach, excitability, nervousness, pupil dilation, extra sunlight sensitivity, heart palpitation, sleepiness, enlarged prostate and difficulty urinating. These symptoms should be reported to the doctor especially if they become severe. Other adverse reactions include loss of appetite, vision changes and irritability. Some symptoms are mild and will only be present as the body adjusts to the medication. Serious ones like breathing difficulty, arrhythmia and ear ringing should be taken care of immediately.

Individuals with known hypersensitivity reactions to the drug should never take it. Those with a history of lung disease, asthma, glaucoma, ulcers, difficulty urinating, enlarged prostate, overactive thyroid, hypertension, seizure and heart disease should consult their doctor first before consumption. Breastfeeding mothers and pregnant women should ask their doctor first and elderly patients may require lower dosages since they are more sensitive to the drug. Clemastine can also interact with drugs like MAOIs or monoamine oxidase inihibitors, sedatives, tranquilizers, narcotics and antipsychotics.

Clemastine acts by aggressively binding to H1-receptor sites making it a selective histamine H1 antagonist. The sites are then blocked, stopping endogenous histamine from attaching. When endogenous histamine is blocked, it cannot act and cause symptoms and reactions. As a result, the person experiences temporary relief. The drug is thought to be metabolized in the liver by mono-didemethylation and glucuronide conjugation.

12 patients suffering from anaphylactic reactions were given 1 mg of clemastine 4 times a day for 3 days. Within the first 24 hours, all patients had reduced symptoms and were completely free of symptoms by the second day. The only drawback was that 10 of the patients reported sleepiness that lasted up to 1 week after treatment was over.

Clemastine is an over-the-counter or OTC drug so a prescription is no longer needed. It is available in almost all pharmacies and doctors’ clinics. Check the expiry date and manufacturing upon purchase to ensure quality and freshness. The drug may also be ordered online at certified pharmacies.

Drowsiness is one of the most common side effects of Clemastine so patients should not drive or operate heavy machinery until full effects are realized. Children younger than 12 years old should ask a doctor first to ensure safety. The drug should be stored at room temperature away from sunlight and moisture. Dosage should also be followed religiously and patients should never take more or less than recommended.

Clemastine has the following structural formula:

Chemical structure of clemastine

• Molecular formula of clemastine is C21H26ClNO
• Chemical IUPAC Name is 2-[2-[1-(4-chlorophenyl)-1-phenyl-ethoxy]ethyl]-1-methyl-pyrrolidine
• Molecular weight is 343.89 g/mol
Clemastine available : 1mg tablets

Brand name(s): Clemastina, Clemastinum, Meclastin, Mecloprodin, Tavegil, Tavist

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