Clemastine, also known as meclastin, is a first-generation H1 histamine antagonist (antihistamine) with anticholinergic properties (drying) and sedative side effects. Like all first-generation antihistamines, it is sedating.Patented in 1960, it came into medical use in 1967. Medical uses
Clemastine is used to relieve hay fever and allergy symptoms, including sneezing; runny nose; and red, itchy, tearing eyes. Prescription strength clemastine is also used to relieve the itching and swelling of hives. Side effects
Overdosage symptoms are paradoxical, ranging from CNS depression to stimulation. Stimulation is most common in children, and is usually followed by excitement, hallucinations, ataxia, loss of coordination, muscle twitching, athetosis, hyperthermia, cyanosis, convulsions, tremors, and hyperreflexia. This may be followed by postictal depression and cardiovascular/respiratory arrest. Other common overdose symptoms include dry mouth, fixed dilated pupils, flushing of the face, and pyrexia. In adults, overdose usually leads to CNS depression, ranging from drowsiness to coma. Pharmacology
Clemastine is an antihistamine with anticholinergic and sedative effects. Antihistamines competitively bind to histamine receptor sites, thus reducing the neurotransmitters effects. Effects of histamine (which are countered by antihistamines) include:

Increased capillary permeability
Increased capillary dilatation
Edema (i.e., swelling)
Pruritus (Itch)
Gastrointestinal/respiratory smooth muscle constrictionClemastine inhibits both the vasoconstrictor and vasodilator effects of histamine. Depending on the dose, the drug can produce paradoxical effects, including CNS stimulation or depression. Most antihistamines exhibit some type of anticholinergic activity. Antihistamines act by competitively binding to H1-receptor sites, thus blocking the binding of endogenous histamine. Antihistamines do not chemically inactivate or prevent the normal release of histamine.
Treatment
Treatment for rheumatoid nodules may be tricky as some treatments for rheumatoid arthritis can act against the nodules. Common drug therapies for rheumatoid arthritis may show no benefits towards the treatment for rheumatoid nodules. Common drug therapies, such as anti TNF treatment or other immunosuppressive drugs, for rheumatoid arthritis has shown little effect on the nodules. In fact, it has been shown that Methotrexate, a drug often used in rheumatoid arthritis, is actually correlated with the increased risk of nodule formation. Because rheumatoid nodules also cause pain or nerve entrapment, treatment for these symptoms with nonsteroidal anti-inflammatory drugs may be sufficient. Other drug therapies, such as corticosteroids, have shown to decrease nodular size, however, it can increase the risk of infection as well. Local corticosteroid injections seems to be the most studied treatment for rheumatoid nodules as of now. Surgery to have the nodule removed is another option that can be done to treat rheumatoid nodules. However, usually these are usually only indicated in the case of eroding/ necrotising skin. See also
Rheumatoid nodulosis
Rheumatoid arthritis

References


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