Thursday, August 28, 2008

DRUG HEPATITIS

DRUG HEPATITIS
From professeur Yves Horsmans, service de Gastroentérologie des Cliniques Universitaires Saint-Luc, 1200 Bruxelles.

MEDICINAL HEPATITIS
INTRODUCTION
Hepatitis owing to medicines is an inflammation of the liver provoked by taking medicaments.
Actually, before tackling the problem of medicinal hepatitis, it is fitting to emphasize the fact that a medicine may provoke the appearance of all forms of liver diseases: not only a hepatitis but also a cholestasis, a liver tumour, a steatosis (fat accumulation in the liver), a phospholipidosis (phospholipides accumulation in the liver), a sclerosed cholangitis, a vascular affection, …All these diseases may be provoked by taking a medicine.
This problem remains important even now, because we often consume medicaments. Besides, hepatic toxicity still is the first cause of death owing to medicaments and the most important reason for the withdrawal of a medicament from the market.
Finally, in spite of the progress in the toxicological field and the scope of the clinical studies made before commercialising, the frequency of hepatic diseases owing to medicaments has not diminished over the years.
.
Top
FREQUENCY
At the moment about 1 000 medicaments have been recognized as potential hepatotoxic.
However, they very rarely provoke a hepatic affection: the fact is that when a medicine is held responsible for a toxic hepatitis with one patient in every hundred, it is withdrawn from the market.
For the most part of the medicaments the frequency of hepatotoxicity is situated between one patient in every 10 000 to 100 000 patients.
This frequency number explains why the risk of hepatotoxicity usually is only recognized after it has been thrown on the market: the number of patients included in clinical studies before putting a medicine on the market is almost always less than 10 000.
The difficulties to establish the hepatic toxicity of a medicine also result from the fact that the toxicity mechanisms are not very well known yet. A lot of factors have already been mentioned: genetics, alimentation, age, sex, … but none of them is common to all those different form of medicinal toxicity.Finally, and that may be the most important factor, remains the problem of diagnosing the liver disease owing to medicine.
Returning to the subject, medicinal hepatitis, we mustn't forget that it is necessary to distinguish between acute and chronic hepatitis: acute hepatitis last less whereas chronic hepatitis last more than 6 months.

Top

DIAGNOSTIC
Diagnosing the hepatitis requires the following elements:
1. taking the medicine (patient may have forgotten).
2. there must be a chronic relation between the first taking of the medicine and the appearance of the hepatitis. In most cases the delay is less than 6 months.
3. the other causes of hepatitis must be excluded: viral forms, metabolic …
4. the end of the taking of the medicine must be associated with an amelioration of the hepatic affection.
5. and finally, even though it is not necessary to have recourse to that remedy, re-administering the medicine concerned must be associated with a re-appearance of the hepatitis.
In practice, it is of course quite clear that these 5 elements must be taken into account but it also is necessary to emphasize the fact that a medicinal hepatic affection for the most part is observed among patients more than 50 years of age and taking several medicines.
Finally, as far as allopathic medicines are concerned it is necessary to notice that phytotherapeutic medications as well as excipientia and chemical agents can bring about the appearance of hepatic diseases

No comments: