WHO Workshop on Assessment of
Bioequivalence Data
Addis Ababa, August 2010
BE Study Assessment – Practical Issues
Dr. Henrike Potthast (henrike.potthast@bfarm.de)
WHO workshop on Assessment of Bioequivalence Data, Addis Ababa, 31. August-3. September 2010
Guidance Documents
 WHO Technical Report Series No. 937 May 2006:
Annex 7: Multisource (generic pharmaceutical products: Guidelines on
Registration Requirements to Establish Interchangeability)
 EU “Note for Guidance on the Investigation of Bioavailability and
Bioequivalence”
CPMP/EWP/QWP/1401/98 Rev.1 and related guidances and documents
(www.emea.eu.int/pdfs/human/ewp )
 FDA - Guidance for Industry: “Bioavailability and Bioequivalence Studies
for Orally Administered Drug Products – General Considerations” (Oct.
2000)
 Canadian Guidance for Industry: “Conduct and Analysis of Bioavailability
and Bioequivalence Studies – Part A: Oral Dosage Formulations used for
systemic effects.” (1992)……………………….and related/others
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
Some Background Information
1. drugs are usually administered as dosage forms
2. the dosage form can affect drug bioavailability
3. differences in the pharmaceutical formulation can lead to different
bioavailabilities
4. effects of formulation differences apply particularly to oral dosage
forms and may be manifest at all stages of the absorption process
5. in vitro tests provide valuable information but are not necessarily a
reliable guide to the bioavailability or therapeutic performance of the
product
6. therapeutic equivalence between like formulations should not be
assumed, unless therapeutic equivalence (bioequivalence) has been
demonstrated in man; nor should therapeutic equivalence be assumed
simply because therapeutic non-equivalence has not been reported
(nach D.N. Wade aus ‚Drug Treatment‘, Graeme S. Avery, 1980, Adis Press, Sydney))
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
Definitions
 Bioavailability – rate and extent at which a drug
substance... becomes available in the general system
(product characteristic!)
 Bioequivalence – equivalent bioavailability within pre-set
acceptance ranges
 Pharmaceutical equivalence  Bioequivalence
 Bioequivalence  Therapeutic equivalence
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
Definitions
♦ „Two medicinal products containing the same active
substance are considered bioequivalent if they are
pharmaceutically equivalent or pharmaceutical alternatives
and their bioavailabilities (rate and extent) after
administration in the same molar dose lie within acceptable
predefined limits. These limits are set to ensure
comparable in vivo performance, i.e. similarity in terms of
safety and efficacy .“
[section 1.1 of the revised EU guidance on BE]
 possible surrogate for full clinical/toxicological documentation
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
Definitions
♦ „…Bioequivalence focuses on the equivalence of
release of the active pharmaceutical ingredient from
the pharmaceutical product and its subsequent
absorption into the systemic circulation.“
[WHO Technical Report Series, No. 937, Annex 7]
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
Definitions
♦ „….if the fraction of the dose absorbed is the same, the
human body should always do the same with the
absorbed compound …Even in a disease state, this
argument is still a valid statement.“
[Faassen et al. Clin Pharmacokinet 43 (2004)1117]
 what does the product do to the drug substance?
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
 Bioequivalence Studies
 in vivo comparison by means of volunteers serving
as “in vivo dissolution model”
 ‘biological quality control’
 comparison of product characteristics in order to ensure
therapeutic equivalence
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Ethical Considerations
IEC / IRB: ICH Definition
 An independent body of medical, scientific and nonscientific members
 Responsibility is to ensure the protection of the rights,
safety and well-being of human subjects involved in a trial
 Among other things, reviewing, approving, and providing
continuing review of trial protocol and amendments and of
the methods and material to be used in obtaining and
documenting informed consent of the trial subjects;
 Independent “Risk-benefit” evaluation
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Ethical Considerations
Composition requirements ICH GCP
 At least 5 members
 At least one member whose primary area of interest is a nonscientific area
 At least one member who is independent of the trial site
 Members without conflicting interest
 Only those members independent of the investigator and the sponsor
should review on a trial-related matter
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Ethical considerations
e.g. additional US FDA requirement for IRB composition:
 Diverse backgrounds (race, gender, cultural, qualification)
 Not entirely one gender
 Special expertise may be invited but without voting rights
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Ethical Considerations
Documents that should be available for the IRB
 Protocol (signed at least by the principal investigator)
 Patient Information Sheet/Consent Form
 Investigator´s Brochure
 Subject recruitement procedures (e. g. advertisements)
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Ethical Considerations
Approval notification to be available in the study report
 Timely written approval
-
Identification of study (title, protocol number, version, investigator, site)
Specifification of all items reviewed
Date & place of review
Trial/study related decisions
Reasons for modifications & disapprovals
Minimum information required by ICH-GCP:
 Date of the meeting
 Documents reviewed (versions & dates)
 List of members
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Study Protocol/Report
♦ „A document that describes the objective(s), design,
methodology, statistical consideration and organisation
of a trial. It usually gives the background and rationale
of the trial …“
Ref.: ICH GCP Guidance
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Study Protocol/Report
General Information/Title Page
♦ Title
♦ Protocol Number
♦ Version Number/Date
♦ Sponsor Details
♦ Name, Address, Telephone
♦ Monitor/Medical Personnel
 Responsibilities!
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Study Protocol/Report
General Information/Title Page contd.
♦ Investigator Details
♦ Principal Investigator, Medical Doctor
♦ Other Laboratory/Institution Details
 Responsibilities!
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Study Protocol/Report
Protocol Development
Definition of Responsibilities
 Organisation, premises, personnel & QMS
 Clinical phase (timely data transfer ensured?)
 Bioanalytical phase (timely data transfer ensured?)
 Statistics and reporting (timely data transfer ensured?)
 Archival
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Objectives
Drug substance / Drug products
basic knowledge about particularities e.g.
 pharmacokinetics (t1/2, peak concentration, time of peak concentration,
metabolism, variability?…)
 practicability of roughly anticipated measurement period
and/or wash-out period (crossover study possible?)
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Drug substance / Drug products
basic knowledge about particularities e.g.
 important side effects (acceptable for healthy volunteers or is there a
need for a study in patients?, concomitant medication necessary, acceptable
regarding evaluation (e.g. vomiting); acceptable for women with childbearing
potential?)
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Drug substance / Drug products
basic knowledge about particularities e.g.
 concept of bioanalytical method available?
 plasma concentrations sufficiently quantifiable (LOQ) – e.g.
administration of more than one dosage form
acceptable/necessary/possible?
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Drug Products
 Availability
 Certification
 Content/Potency
 (comparative) in-vitro dissolution
 Preparation of investigative products per volunteer acc. to GMP
 Protocol amendment for product details frequently necessary (e. g. labeling)
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Drug Products
 batch size
 pilot batch?
 commercial batch?
 not smaller than 100 000 units or 10 % of industrial
batch size (whichever is higher)
- this is of particular importance 23 |
WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Drug Products (WHOTechn. Rep. Series No. 937 May 2006 Annex 7, sect. 6.5.1)
 “…Batch-control results of the multisource product, and the lot
numbers and expiry dates of both multisource and comparator
products should be stated….
 It is recommended that potency and in vitro dissolution
characteristics of the multisource and the comparator
pharmaceutical products be ascertained prior to performance of
an equivalence study….”
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Drug Products
 assay
 close to label claim
 difference regarding the content of the investigative
products (T and R) should preferably be not more
than 5 % - (“dose correction”?!)
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Drug Products
 Dose to be investigated (WHOTechn. Rep. Series No. 937 May
2006 Annex 7, sect. 6.6.1)
“In bioequivalence studies the molar equivalent dose of
multisource and comparator product must be used.”
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Drug Products
 Dose to be investigated ctd. (WHOTechn. Rep. Series No. 937 May 2006 Annex
7, sect. 6.6.1) – product series
 “Generally the marketed strength with the greatest sensitivity to
bioequivalence assessment should be administered as a single unit.
This will usually be the highest marketed strength. A higher dose
(i.e. more than one dosage unit) may be employed when analytical
difficulties exist. In this case the total single dose should not exceed
the maximal daily dose of the dosage regimen. Alternatively, the
application of area under the curve (AUC) truncated to 3 × median
tmax of the comparator formulation would avoid problems of lack of
assay sensitivity in many cases. In certain cases a study performed
with a lower strength can be considered acceptable if this lower
strength is chosen for reasons of safety.”
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Drug Products
 Dose to be investigated ctd.– product series
 Cave: – if AUC increases less than proportional with dose
then the lower dose may be most sensitive -
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Study Subjects
 Selection of subjects
 participation of healthy volunteers (“in vivo model”)
 reasonable inclusion and exclusion criteria (protocol
and CRFs)
 comprehensive verbal and written information and
informed consent
 volunteers´ insurance
 reimbursement
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Study Subjects
 Selection of subjects
males or females or both gender?
“…the sponsor may wish to include
both…”(WHO)
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Study Subjects
 Selection of subjects
 Safe contraception for women (cave: interferences of
contraceptives with investigative drug excluded?)
 Phenotyping of volunteers (cave: possible side effects with e.g.
“poor metabolisers” may cause drop-outs; variability
reduction/explanation; fast and slow metabolizers evenly
distributed in parallel group designs)
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Study Subjects
 Selection of subjects ctd. (WHOTechn. Rep. Series No. 937, sect. 6.3.5)
 “Phenotyping for metabolizing activity can be of importance for
studies with high-clearance drugs that are metabolized by
enzymes that are subject to genetic polymorphism, e.g.
propranolol. In such cases, slow metabolizers will have a
higher bioavailability of the parent drug, while the
bioavailability of possible active metabolites will be lower.
Phenotyping of subjects can be considered for studies of
drugs that show phenotype-linked metabolism and for which a
parallel group design is to be used… Phenotyping could also
be important for safety reasons, determination of sampling
times and wash-out periods in cross-over design studies.”
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Study Subjects
 Selection of subjects
♦ description of volunteers; smoker, vegetarian, phenotyping….
EU: healthy, BMI; FDA: both sexes, > 18y; WHO: 18-55y)
♦ verifying health of volunteers ( e. g. ECG, clinical blood
chemistry, blood pressure…)
♦ number of volunteers depending on variability (at least 12)
♦ randomisation
objective: minimising interindividual variability in order to
detect possible product differences!
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Study Subjects
 Number of subjects
 Required sample size depends on intra-individual
variability either known through reasonable literature
or by means of a pilot study
“low” variability: ~ 12 – 20 volunteers
“high” variability: ~ 24 – 26 (plus) volunteers
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Study Subjects
 Number of subjects ctd.
 Required sample size depends on the expected mean
difference between the test and reference formulation
 Required sample size depends on the desired
significance and power level
 For sample size calculation see also literature data (e.g. Eur J Drug Metab
Pharmacokinet 30 (2005) 41; J Biopharm Stat 13 (2003) 529; Stat Med 18
(1999) 93 …)
 Consideration of possible withdrawals
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Study Subjects
 Number of subjects ctd
 “The number of subjects to be used in the study
should be estimated by considering the standards
that must be passed. It should be calculated by
appropriate methods (…). The number of
recruited subjects should always be justified with
the sample size calculation provided in the study
protocol. A minimum of 12 subjects is required.”
[WHO Technical Report Series, No. 937, Annex 7]
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Study Subjects
 Subject withdrawals
 subject must adhere to study requirements…
…however …
 they are free to break off at any time!
 definition of “drop-outs” in the protocol (reason,
reimbursement policy, handling of data, follow-up…)
 concomitant medication
 comprehensive reporting in the study report
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Study Subjects
 Subject withdrawals contd…
 subject must adhere to study requirements but …
 define a time frame regarding vomiting depending also on
pharmacokinetics of the drug substance, e.g. volunteers
must be withdrawn in case vomiting occurs within 4 h
postdose
“pre-specify!!”
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Standardisation
 Procedure of drug intake
 time of administration (fasted or fed state)
 liquid volume
 traceability of administrations
 cave: e.g. granules, suspensions liquid formulations!
(require ‘method sheet’)
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Standardisation
 Fasted state e.g.
 Confinement of subjects at least 10 h prior to drug
administration
 Last food intake ~10 h prior to drug intake
 No food or fluids ~2 h prior to drug intake
 Drug administration with ~150-200 ml (e.g.) water
 Light standardized meal not before ~4 h post-dose
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Standardisation
 Standardized fluid and food intake (time, composition, amount)
 Prohibition of alcohol
 Restriction of xanthins (coffee*, tea, coke, chocolate, chewing
gum, grapefruit….)
 Standardized posture
 Restriction of physical activities
…
*cave: withdrawal may cause headache
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Standardisation
 Fed state
 Define time of drug administration and food intake, (e. g. drug
intake within 30 min. before, immediately before or after the
standardised meal)
 High fat meal may serve to investigate the „worst case“ scenario
and formulation robustness
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Standardisation
 Fed state ctd: (WHO Technical Report Series, No. 937, Annex 7, sect. 6.4)
„Some medicines are normally given with food to reduce gastrointestinal
side-effects; in certain cases coadministration with food increases
bioavailability of orally administered preparations. If the labelling
states that the pharmaceutical product should be taken with food then
a fed study should be used to assess bioequivalence. Fed state
studies are also required in bioequivalence studies of modified release
formulations. In these cases the objective is to select a meal that will
challenge the robustness of the new multisource formulation to
prandial effects on bioavailability (see 6.2.4). The test meal selected
should take account of local custom and diet and should be consumed
within 20 minutes. The product should be administered according to
the protocol and within 30 minutes after the meal has been eaten.“
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Study Samples
♦ Sampling
♦ number of samples
♦ sampling times (Cmax!)
♦ time of sampling (extrapolated AUC max. 20 %)
♦ wash-out-phase (not less than 5 half-lives)
 knowledge of basic pharmacokinetics of the particular
drug substance is inevitable!
objective: characterisation of ‚drug input‘!
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Study Samples
 Sampling times
 appr. 3 – 4 to describe drug “input”
 appr. 3 sampling times around peak concentration
 appr. 3 – 4 to describe elimination
 Minimum!
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Study Samples
 Number of samples
 sufficient to “describe” at least 80 % of total AUC
 usually ~12– 18 samples (minimum)
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Study Samples
 WHO Technical Report Series 937 Annex 7 sect. 6.6.2
“Blood samples should be taken at a frequency sufficient for
assessing Cmax, AUC and other parameters. Sampling points
should include a pre-dose sample, at least 1–2 points before Cmax,
2 points around Cmax and 3–4 points during the elimination phase.
Consequently at least seven sampling points will be necessary for
estimation of the required pharmacokinetic parameters. For most
medicines the number of samples necessary will be higher to
compensate for between-subject differences in absorption and
elimination rate and thus enable accurate determination of the
maximum concentration of the API in the blood (Cmax) and terminal
elimination rate constant in all subjects..”
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Study Samples
 WHO Technical Report Series 937 Annex 7 sect. 6.6.2
“Generally, sampling should continue for long enough to
ensure that 80% of the AUC (0→ infinity) can be accrued,
but it is not necessary to sample for more than 72
hours. The exact duration of sample collection depends
on the nature of the API and the input function from the
administered dosage form (see also 6.11.4).”
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Study Samples
 WHO Technical Report Series 937 Annex 7 sect. 6.2.2
“For both cross-over and parallel-design studies, sample
collection time should be adequate to ensure completion
of gastrointestinal transit (approximately 2–3 days) of the
pharmaceutical product and absorption of the API. Blood
sampling up to 72 hours following administration should
be carried out, unless shorter periods can be justified.”
49 |
WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Study Samples
50 |
WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Verapamil; BE
study; GoviVerlag 1989
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Exceptional Cases!
„…Cmax is affected by the sampling points of
truncated screening protocol. As isoniazid and
pyrazinamide are highly soluble and highly permeable
molecules resulting in rapid absorption….Cmax should
be carefully evaluated…..AUC was found to be a
robust parameter unaffected by sampling points….“
[Panchagnula et al., Pharmacol Res 48 (2003) 383]
53 |
WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Exceptional Cases!
„The comparative Spearman‘s correlation analysis on
the pharmacokinetic parameters Cmax, AUCt and
AUCinf … showed that the 11 time points, namely 0,
0.25, 0.5, 1, 1.5, 2, 2.5, 3, 4, 6, and 8 h, were sufficient
for demonstration of comparative bioavailability and
bioequivalence of INH, RMP, PZA, and EMB, and that
a schedule of six time points…..is not adequately
reliable for determining the bioavailability and
bioequivalence of anti-tuberculosis FDCs.“
[Gabriels et al., Int J Tuberc Lung Dis 11 (2007) 181]
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Sample Fluids and Collection!
„Blood samples should be processed and stored under
conditions that have been shown not to cause degradation of
the analytes. This can be proven by analysing duplicate quality
control samples during the analytical period. Quality control
samples must be prepared in the fluid of interest (e.g. plasma),
including concentrations at least at the low, middle and high
segments of the calibration range. The quality control samples
must be stored with the study samples and analysed with
each set of study samples for each analytical run.
The sample collection methodology must be specified in the
study protocol.“
[WHO Technical Report Series 937 Annex 7 sect. 6.6.3]
55 |
WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Sampling
 Blood withdrawal equipment (consider bioanalytical method)
 Preparation of plasma or serum








56 |
volume
cooling
anticoagulant
centrifugation
aliquotation
labeling
freezing
transport…
WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Bioanalytical Method
 It should be reported what is/has been …
 the bioanalytical method/detection
 the limit of quantitation (1/20 of the expected peak concentration
should be measurable)
 the validation concept
 whether metabolites are to be considered
 enantioselective method necessary?
57 |
WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Bioanalytical Method!
„Generally, evaluation of pharmacokinetic bioequivalence will be
based upon the measured concentrations of the parent drug
released from the dosage form rather than the metabolite. The
concentration–time profile of the parent drug is more sensitive to
changes in formulation performance than a metabolite, which is
more reflective of metabolite formation, distribution and
elimination. It is important to state a priori in the study protocol
which chemical entities (pro-drug, drug (API) or metabolite) will
be analysed in the samples.„
[WHO Technical Report Series 937 Annex 7 sect. 6.6.5]
58 |
WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Bioanalytical Method!
„A non-stereoselective assay is currently acceptable
for most pharmacokinetic bioequivalence studies.
When the enantiomers have very different
pharmacological or metabolic profiles, assays that
distinguish between the enantiomers of a chiral API
may be appropriate. Stereoselective assay is also
preferred when systemic availability of different
enantiomers is demonstrated to be non-linear.„
[WHO Technical Report Series 937 Annex 7 sect. 6.6.6]
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Bioanalytical Method!
„All analytical test methods used to determine the
active compound and/or its biotransformation product
in the biological fluid must be well characterized, fully
validated and documented. The objective of the
validation is to demonstrate that a particular method
used for quantitative measurement of analytes in a
given biological matrix, such as blood, plasma, serum
or urine, is reliable and reproducible for the intended
use…“
[WHO Technical Report Series 937 Annex 7 sect. 6.7]
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Calculations
 The protocol should state (-among others-)
 the transfer of bioanalytical results for biostatistical
calculations
 the handling of missing data
 the handling of digits
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Calculations
 The protocol should state (-among others-)
 calculation procedure/methods
 characteristics (e.g. AUC, Cmax…)
 possible consideration of differences of drug content
 acceptance ranges – widening acceptable or even
tighter accepance limits needed?!
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Calculations
 single dose studies
 reg. characteristics
 AUC – extent of bioavailability (calculated by means of
‚trapezoidal rule‘)
 AUCt – for single dose studies (t = last quantifiable
concentration)
 AUCinf – AUCt extrapolated to infinity (‚total exposure‘)
‚exposure‘
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Calculations
 single dose studies
 ‚rate‘ of bioavailability
 Cmax – observed maximum concentration (peak
exposure)
 tmax – time at which maximum concentration occurs
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Calculations
 multiple dose studies (exceptional cases)
„Single dose studies are preferred to multiple-dose
studies as single-dose studies are considered to
provide more sensitive measurements of the release
of API from the pharmaceutical product into the
systemic circulation. Multiple-dose studies may need
to be considered (in addition to a single dose study) for
extended-release dosage forms with a tendency to
accumulate.“ (WHO TRS937 Annex 7; 6.2.4)
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Calculations
 multiple dose studies (exceptional cases)
 direct switching vs. wash-out
 primary characteristics (e.g. AUCtau, Cmax, Cmin…)
 consideration of fluctuation (e.g. Ptf…)
 compare Cmin to ensure steady-state
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Safety/Adverse Events
 Definitions, handling/information/report
 Evaluation of seriousness
 Evaluation of relation to investigative drugs
 Treatment (cave: concomitant drug intake should be tested ‘a priori’ for
possible analytical interferences)
serious but not study drug related 
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Proportionality Biowaiver
 Biowaiver based on dose-proportionality of
formulations
„A prerequisite for qualification for a biowaiver based on doseproportionality of formulations is that the multisource product at one
strength has been shown in in vivo studies to be bioequivalent to
the corresponding strength of the comparator product. The second
requirement is that the further strengths of the multisource product are
proportionally similar in formulation to that of the strength
studied. When both of these criteria are met and the dissolution
profiles of the further dosage strengths are shown to be similar to
that of the strength studied on a percentage released against time
basis, the biowaiver procedure can be considered for the further
strengths…“
(WHO TRS 937 Annex 7; sect. 9.3)
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Proportionality Biowaiver
 Biowaiver based on dose-proportionality of
formulations ctd.
„For the purpose of this guidance proportionally similar
formulations can be defined in two ways, based on the
strength of dosage forms.
(i) All active and inactive ingredients are exactly in the same
proportions in the different strengths (e.g. a tablet of 50 mg
strength has all the active and inactive ingredients exactly
half that of a tablet of 100 mg strength, and twice that of a
tablet of 25 mg strength)….“
(WHO TRS 937 Annex 7; sect. 9.3)
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
Proportionality Biowaiver
 Biowaiver based on dose-proportionality of
formulations ctd.
(ii) For a high potency API, where the amount of the API in the
dosage form is relatively low (up to 10 mg per dosage unit),
the total weight of the dosage form remains nearly the
same for all strengths (within ± 10% of the total weight), the
same inactive ingredients are used for all strengths, and
the change in strength is obtained by altering essentially
only the amount of the API(s).
(WHO TRS 937 Annex 7; sect. 9.3)
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
Remember
 Bioequivalence – equivalent bioavailability within
pre-set acceptance ranges
 Pharmaceutical equivalence  Bioequivalence
 Bioequivalence  Therapeutic equivalence
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa
BE Study Assessment – Practical Issues
THANK YOU FOR YOUR
ATTENTION
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WHO Workshop on Assessment of Bioequivalence Data
31. August – 3. September 2010, Addis Ababa