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Bristol-Myers
Squibb Issues Warning Letter Re Coadministration of Atazanavir and
Ritonavir with Acid Inhibitor Omeprazole (Prilosec) and Other Acid-control
Agents
Bristol-Meyers
Squibb has issued a “Dear Healthcare Provider” letter regarding
important new pharmacokinetic
data concerning the coadministration of Reyataz
(atazanavir)
and Norvir (ritonavir) with Prilosec (omeprazole). Omeprazole
is a proton-pump inhibitor (PPI) for the treatment of acid-related
diseases that works by suppressing gastric acid secretion.
The
following observations were made from a randomized, open-label,
multiple-dose drug interaction study.
A
76% reduction in atazanavir area under the concentration-time curve
(AUC) and a 78% reduction in atazanavir trough plasma concentration
(Cmin) were observed when REYATAZ/ritonavir 300/100 mg was coadministered
with omeprazole 40 mg.
Based
on the study results:
* DO NOT COADMINISTER REYATAZ OR REYATAZ/RITONAVIR WITH OMEPRAZOLE
due to the reduction in atazanavir exposure levels. This recommendation
is consistent with the current REYATAZ U.S. Package Insert.
*
It is not known whether the over-the-counter dose of omeprazole
(20 mg once daily) would produce similar results; therefore, coadministration
is not recommended.
* Increasing the REYATAZ/ritonavir dose to 400/100 mg in combination
with omeprazole DID NOT result in REYATAZ exposures comparable to
those observed with a regimen of REYATAZ/ritonavir 300/100 mg without
omeprazole.
*
Simultaneous administration of 8 ounces of cola given in an effort
to decrease (acidify) gastric pH did not appear to affect this reduction.
Investigations
regarding the potential drug interaction between Reyataz (atazanavir
sulfate) and H2-Receptor antagonists (another type of gastric medication)
when coadministered are ongoing. Until data are available, clinicians
should note the following statements from the Reyataz Package Insert:
"Reduced plasma concentrations of atazanavir are expected if
H2-receptor antagonists are administered with Reyataz (atazanavir
sulfate). This may result in loss of therapeutic effect and development
of resistance. To lessen the effect of H2 -receptor antagonists
on atazanavir exposure, it is recommended that an H2-receptor antagonist
and Reyataz be administered as far apart as possible, preferably
12 hours apart."
Articles on Reyataz
on HIV and Hepatitis.com
01/03/05
Source
R
Klein and K Struble. Office of Special Health Issues. US Food and
Drug Administration
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