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Effects of interferon-alpha on cytochrome P-450 isoforms 1A2 and 3A activities in patients with chronic hepatitis C
G P Pageaux1, Y le Bricquir, F Berthou
1Service d'Hépatogastroentérologie, Hôpital Saint-Eloi, Montpellier, France.
Background/Aim:
The risk of adverse drug interactions with interferon-alpha has been poorly assessed. The aim of our study was to establish whether administration of interferon-alpha at therapeutic doses in patients with chronic hepatitis C may have significant inhibitory effects on other drug metabolism. The study was focused on cytochromes P-450 1A2 and 3A, two major isoforms involved in the metabolism of numerous substrates.
Methods:
Eighteen patients with chronic active hepatitis C requiring an interferon-alpha treatment were studied. Cytochrome P-450 1A2 activity was determined on the basis of an in vivo caffeine metabolism study. Cytochrome P-450 3A activity was determined according to in vivo cortisol metabolism into 6-beta-hydroxycortisol. Both activities were determined 1 month before, at initiation and 1 month after interferon-alpha therapy (3 x 10(6) units, three times a week).
Results:
There were no significant differences in the caffeine index (CYP 1A2) and in the 6-beta-hydroxycortisol/free cortisol urinary ratio (CYP 3A) before and after alpha interferon treatment
Conclusion:
Chronic administration of interferon-alpha at therapeutic doses does not change in vivo cytochrome P-450 1A2 and 3A activities. These results support the suggestion that drugs metabolized by these isoenzymes may be used together with interferon-alpha in patients with chronic hepatitis C without significant risks of drug interactions.
Insights
Interferon-alpha treatment for chronic hepatitis C does not significantly affect drug metabolism by cytochrome P-450 1A2 and 3A enzymes. This suggests co-administration with drugs metabolized by these pathways is safe.
Area of Science:
- Pharmacology
- Hepatology
- Drug Metabolism
Background:
- Adverse drug interactions with interferon-alpha are not well understood.
- Interferon-alpha is used to treat chronic hepatitis C.
- Cytochrome P-450 1A2 and 3A are key enzymes in drug metabolism.
Purpose of the Study:
- To assess if interferon-alpha impacts drug metabolism.
- To investigate effects on cytochrome P-450 1A2 and 3A activity.
- To evaluate drug interaction risks in chronic hepatitis C patients.
Main Methods:
- Studied 18 chronic hepatitis C patients receiving interferon-alpha.
- Assessed cytochrome P-450 1A2 activity via in vivo caffeine metabolism.
- Measured cytochrome P-450 3A activity through cortisol metabolism to 6-beta-hydroxycortisol.
Main Results:
- No significant changes in caffeine metabolism (CYP 1A2 activity) were observed.
- No significant alterations in the 6-beta-hydroxycortisol/free cortisol ratio (CYP 3A activity) were found.
- Interferon-alpha therapy did not alter the activity of these key drug-metabolizing enzymes.
Conclusions:
- Therapeutic doses of interferon-alpha do not inhibit CYP 1A2 or CYP 3A activity in vivo.
- Patients with chronic hepatitis C can likely use drugs metabolized by these enzymes alongside interferon-alpha.
- The risk of significant drug interactions appears low when co-administering interferon-alpha with CYP 1A2 or CYP 3A substrates.