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Dear all,
I am interested in an issue regarding of extrapolating BE study
conclusion from healthy patients to cancer patients. the point of
interest is some oncologists refuse the use of generics based on BE
studies on healthy stating that it does not reflect the behavior of the
product in the patient. The drug I am refering to is imatinib for this
case. Although the answer and the justifications for healthy use in the
study are there, we still cannot convince them that the clinical impact
should be the same.
I rephrase this questions as follows: can we assume BE in healthy is
definetly a measure for the behavior for the dosage form in the cancer
patient setting or there are requirements for any such conclusion?
Raja Sammour
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Dear all,
I am interested in an issue regarding of extrapolating BE study
conclusion from healthy patients to cancer patients. the point of
interest is some oncologists refuse the use of generics based on BE
studies on healthy stating that it does not reflect the behavior of the
product in the patient. The drug I am refering to is imatinib for this
case. Although the answer and the justifications for healthy use in the
study are there, we still cannot convince them that the clinical impact
should be the same.
I rephrase this questions as follows: can we assume BE in healthy is
definetly a measure for the behavior for the dosage form in the cancer
patient setting or there are requirements for any such conclusion?
Raja Sammour
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The following message was posted to: PharmPK
Dear Raja
Not sure if this is a situation in US or not. I am further unsure if
generics of imatinib are approved in US yet. But the following comments
might be helpful in general.
I think what is needed is educating them on how generic drugs are
approved. I provide below a link to information about generic drugs from
FDA and a FAQ.
1. On a technical matter, BE is approved based on ratio of PK parameters
of test and reference products. So, even if the PK are different between
patients and healthies - a ratio of about one ensures similar PK of both
products in both populations.
2. For imatinib, dosing instructions for use with concomitant metabolic
inhibitors was derived from healthies. So were several parts of the
labeling instructions. The PK in healthies and patients are similar (but
that is not a requirement for the generic to behave similarly to the
innovator product).
======
http://www.fda.gov/Drugs/ResourcesForYou/Consumers/QuestionsAnswers/ucm100100.htm
Are generic drugs as effective as brand-name drugs?
Yes. A generic drug is the same as a brand-name drug in dosage, safety,
strength, quality, the way it works, the way it is taken and the way it
should be used.
FDA requires generic drugs have the same high quality, strength, purity
and stability as brand-name drugs.
Not every brand-name drug has a generic drug. When new drugs are first
made they have drug patents. Most drug patents are protected for 20
years. The patent, which protects the company that made the drug first,
doesn't allow anyone else to make and sell the drug. When the patent
expires, other drug companies can start selling a generic version of the
drug. But, first, they must test the drug and the FDA must approve it.
Creating a drug costs lots of money. Since generic drug makers do not
develop a drug from scratch, the costs to bring the drug to market are
less; therefore, generic drugs are usually less expensive than
brand-name drugs. But, generic drug makers must show that their product
performs in the same way as the brand-name drug.
--
Joga Gobburu, PhD, FCP, MBA | Professor
School of Pharmacy | School of Medicine
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Dear Mr.Raja,
FDA's Individual Product Bioequivalence for Imatinib mesylate recommends to do a Steady
State FED BE study in Patients already receiving stable dose of Imatinib 400 mg
tablets.Recruitment efforts should be targeted at patients for whom a titration away from
the 400 mg dose is unlikely, such as patients with gastrointestinal stromal tumors and
patients in their first three months of treatment for chronic myeloid leukemia (CML)
Quote from FDA Recommendations:
Type of study: Fed
Design: Steady state, two-way crossover in-vivo
Strength: 400 mg
Subjects: Patients already receiving a stable dose of imatinib tablets, 400 mg.
Additional Comments: Recruitment efforts should be targeted at patients for whom a
titration away from the 400 mg dose is unlikely, such as patients with gastrointestinal
stromal tumors and patients in their first three months of treatment for chronic myeloid
leukemia (CML). Patients should be screened for hepatotoxicity prior to enrollment and the
protocol should include procedures to monitor for hepatotoxicity during the course of the
study. Concomitant medication with drugs known to be inhibitors and/or inducers of CYP3A4
family should be a protocol exclusion criterion.
Unquote.
Regards,
Dr.S.Gunasakaran, MD,
Head - Clinical Research & Medical Affairs
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