Clemastine does also act as FIASMA (functional inhibitor of acid sphingomyelinase).Clemastine is rapidly absorbed from the gastrointestinal tract and peak plasma concentrations are attained in 2–4 hours. Antihistamines are thought to be metabolized in the liver, mostly by mono-/didemethylation and glucuronide conjugation. It is an inhibitor of cytochrome P450 CYP2D6 and may interfere with other drugs metabolized by this isozyme. Mechanism of action
Clemastine is a selective histamine H1 antagonist. It binds to the histamine H1 receptor, thus blocking the action of endogenous histamine, which leads to temporary relief of the negative symptoms caused by histamine. Society and culture
Clemastine is an OTC drug, and is available under many names and dosage forms worldwide. Most common brand name is Tavegyl. References
External links
NIH Medline Plus listing on Clemastine
The pharmacokinetics and bioavailability of clemastine and phenylpropanolamine in single-component and combination formulations
The third symptom would be recovery, followed by a Parkinson-like syndrome. If patients of Stern followed this course of disease, he diagnosed them with encephalitis lethargica. Stern suspected encephalitis lethargica to be close to poliomyelitis, without evidence. Nevertheless, he experimented with the convalescent serum of survivors of the first acute syndrome. He vaccinated patients with early-stage symptoms, telling them that it might be successful. Stern is author of the definitive 1920s book, Die Epidemische Encephalitis.In 2010, in a substantial Oxford University Press compendium reviewing the historic and contemporary views on EL, its editor, Joel Vilensky, of the Indiana University School of Medicine, quotes another researcher, writing in 1930, who states, "we must confess that etiology is still obscure, the causative agent still unknown, the pathological riddle still unsolved…", and goes on to offer the following conclusion, as of that publication date:

Does the present volume solve the "riddle" of EL, which… has been referred to as the greatest medical mystery of the 20th century? Unfortunately, no: but inroads are certainly made here pertaining to diagnosis, pathology, and even treatment." Subsequent to publication of this compendium, an enterovirus was discovered in encephalitis lethargica cases from the epidemic. In 2012, Oliver Sacks, the author of the book Awakenings, about institutionalized survivors, acknowledged this virus as the probable cause of the disease. Other sources have suggested Streptococcus pneumoniae as a cause. Diagnosis
There have been several proposed diagnostic criteria for encephalitis lethargica.