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mild. A full recovery is normally recorded. Hepatitis B is transmitted via infected blood. Symp-
toms of acute hepatitis B include fever, chill, weakness and jaundice. Most suffers recover from
such infection, although acute liver failure and death sometimes occur. Some 5-10 per cent of
suffers go on to develop chronic hepatitis B. Acute hepatitis C is usually mild and asymptomatic.
However, up to 90 per cent of infected persons go on to develop a chronic form of the condition.
Hepatitis D is unusual in that it requires the presence of hepatitis B in order to replicate. It thus
occurs in some persons concomitantly infected with hepatitis B virus. Its clinical symptoms are
usually severe, and can occur in acute or chronic form.
Chronic forms of hepatitis (in particular B, C and D) can result in liver cirrhosis and/or
hepatocellular carcinoma. This occurs in up to 20 per cent of chronic hepatitis B sufferers and
in up to 30 per cent of chronic hepatitis C sufferers. The scale of human suffering caused by
hepatitis on a worldwide basis is enormous. Approximately 5 per cent of the global population
suffer from chronic hepatitis B. An estimated 50 million new infections occur each year. Over
1.5 million of the 300 million carriers worldwide die annually from liver cirrhosis and hepato-
cellular carcinoma.
IFN-α2b is now approved in the USA for the treatment of hepatitis B and C. Clinical studies
undertaken with additional IFN-
preparations indicate their effectiveness in managing such con-
ditions, and several such products are also likely to gain regulatory approval.
IFN-
α
2a, when administered three times weekly for several weeks/months, was found effective
in treating several forms of hepatitis. Remission is observed in 30-45 per cent of patients suffering
from chronic hepatitis B, and a complete recovery is noted in up to 20 per cent of cases. The drug
induces sustained remission in up to 30 per cent of patients suffering from chronic hepatitis C,
but can ease clinical symptoms of this disease in up to 75 per cent of such patients. Ongoing stud-
ies also indicate its effi cacy in treating chronic hepatitis D, though relapse is frequently observed
upon cessation of therapy. The drug is normally administered by i.m. or s.c. (directly beneath the
skin) injection. Peak plasma concentrations of the interferon are observed more quickly upon i.m.
injection (4 h versus 7.5 h). The elimination half-life of the drug ranges from 2.5 to 3.5 h.
IFN-α preparations have also proven effi cacious in the treatment of additional viral-induced
medical conditions. rhIFN-
α
n3 are already approved for the treatment of sexually
transmitted genital warts, caused by a human papilloma virus. Although this condition is often un-
responsive to various additional therapies, direct injection of the interferon into the wart causes its
destruction in up to 70 per cent of patients. Another member of the papilloma family is associated
with the development of benign growths in the larynx (laryngeal papillomatosis). This condition
can be successfully treated with IFN-α preparations, as can certain papilloma-related epithelial
cell cancers, such as cervical intraepithelial neoplasm (epithelial cells are those that cover all ex-
ternal surfaces of the body and line hollow structures, with the exception of blood and lymph ves-
sels). IFN-
α
2b and IFN-
α
's ability to combat a range of additional virally induced diseases, including acquired
immune defi ciency syndrome (AIDS), is currently being appraised in clinical trials.
α
8.3.2 Medical uses of interferon-
β
rhIFN-β has found medical application in the treatment of relapsing-remitting multiple scle-
rosis (MS), a chronic disease of the nervous system. This disease normally presents in young
adults (more commonly women) aged 20-40 years. It is characterized by damage to the
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