This document discusses guidelines for bioavailability and bioequivalence studies. It defines key terms like bioavailability, bioequivalence, pharmaceutical equivalents and alternatives. It outlines when bioequivalence studies are necessary, such as for modified release drugs, and when they are not required, such as for parenteral solutions. It also describes the different types of studies including pharmacokinetic, pharmacodynamic and clinical endpoint studies. Finally, it provides details on study design, population, conditions and statistical evaluation for pharmacokinetic bioequivalence studies.

1. Presented By-
ROHIT
R.K.S.D college of
pharmacy, Kaithal (Hry)
M.Pharma 1st year
(Pharmaceutics)
Bioavailability and
bioequivalence studies

2. • INTRODUCTION
•DEFINATION
•SCOPE OF GUIDELINES
•DESIGN AND CONDUCT OFSTUDIES
•DOCUMENTATION
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3. •Ensuring uniformity in standard of quality safety and efficacy of
pharmaceutical product is a matter of concern.
•Bioavailability of a pharmaceutical product should be known and
reproducible.
•BE/BA data is required to be furnished during new drugapplication
as per schedule Y.
•Both bioavailability and bioequivalence focus on the release of a
drug substance from its dosage form and subsequent absorption
into the systemiccirculation.
•For this reason, similar approaches to measuring bioavailability
should generally be followed in demonstrating bioequivalence.
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4. •Bioavailability can be generally documented by a systemic exposure
profileobtained by measuring drug and/or metaboliteconcentration
in thesystemic circulation overtime.
•Bioequivalencestudies should be conducted forthecomparison of
two medicinal products containing the sameactivesubstance.
• Several test methodsareavailable toassessequivalence, including :
comparative bioavailability (bioequivalence) studies, in whichthe
active drug substance or one or more metabolites is measured in an
accessible biological fluid such as plasma, blood orurine
comparative pharmacodynamic studies inhumans
 comparative clinical trials
 in-vitro dissolutiontests
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5. •In vivo bioequivalence/bioavailability studies recommended for
approval of modified release products should be designed to ensure
that –
The product meets the modified release label claims.
The product does not release the active drug substance at a rate
and extent leading to dosedumping.
There is no significant difference between the performance of the
modified release product and the reference product, when given in
dosageregimes toarriveat the steadystate.
There must be a significant difference between the performance of
modified release product and the conventional release product when
used as referenceproduct.
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6. •BIOAVAILABILITY
Bioavailability refers to the relative amount of drug from an
administered dosage form which enters the systemic circulation
and the rate at which the drug appears in the systemiccirculation.
•BIOEQUIVALENCE
Bioequivalence of a drug product is achieved if its extent and rate
of absorption are not statistically significantly different from those
of the reference product when administered at the same molar
dose.
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7. PHARMACEUTICAL EQUIVALENTS
Pharmaceutical equivalents are drug products that contain identical
amounts of the identical active drug ingredient, i.e., the same salt or
ester of the same therapeutic moiety, in identical dosage forms, but not
necessarily containing the same inactiveingredients.
PHARMACEUTICAL ALTERNATIVES
Pharmaceutical alternatives are drug products that contain the identical
therapeutic moiety, or its precursor, but not necessarily in the same
amountordosage formoras the samesaltorester.
SUPRA-BIOAVAILABILITY
This is a term used when a test product displays an appreciably larger
bioavailability than the referenceproduct.
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8. THERAPEUTIC EQUIVALENTS
Therapeutic equivalents are drug products that contain the same
active substance or therapeutic moiety and, clinically show the
same efficacy andsafety.
SCOPE OF THE GUIDELINES
Bioavailability and Bioequivalence studies are required by
regulations to ensure therapeutic equivalence between a
pharmaceutically equivalent test product and a reference
product.
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9. 1. When bioequivalence studies are necessary and types of studies required –
a) In vivo studies :
For . Oral immediate release drug formulations with systemic action when one or
more of the following criteria apply:-
1. Indicated for serious conditions;
2. Narrow therapeutic window/safety margin;
3.Pharmacokinetics complicated by variable or incomplete absorption
or absorption window,
4. Unfavorable physicochemical properties,
5.Documented evidence for bioavailability problems related to the
drug or
drugs of similar chemical structure or formulations;
6. Where a high ratio of excipients to active ingredients exists.
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10. For Non-oral and non-parenteral drug formulations designed to act by
systemic absorption (such as transdermal patches, suppositories, etc.).
ForSustained orotherwise modified releasedrug formulations
designed to act by systemicabsorption.
ForFixed-dose combination products with systemicaction.
For Non-solution pharmaceutical products which are for non-systemic
use (oral, nasal, ocular, dermal, rectal, vaginal, etc. application) and are
intended toactwithout systemicabsorption.
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11. B. In vitro studies:
ForDrugs forwhich theapplicant providesdata to substantiateall of
the following :
a.Highestdose strength is soluble in 250 ml of an aqueous mediaover
the pH range of 1-7.5 at37°C.
b.At least 90% of the administered oral dose is absorbed on mass
balancedeterminationor in comparison toan intravenousreference
dose.
c.Speed of dissolution asdemonstrated by more than 80% dissolution
within 15 minutes at 37°C using IP apparatus 1, at 50 rpm or IP
apparatus 2, at 100rpm.
For. Differentstrengthsof thedrug manufactured by the same
manufacturer,whereall of the following criteriaare fulfilled:
a. the qualitativecomposition between the strengths is essentially the
same.
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12. B.The ratioof active ingredientsand excipients between the strengths is
essentially thesame,
C. The method of manufacture is essentially the same
D. An appropriateequivalencestudy has been performed on at leastone
of the strengths of theformulation
E.In caseof systemicavailability - pharmacokinetics have been shown
to be linearoverthe therapeuticdose range.
NOTE :
In each comparison, the new formulation or new method of
manufactureshall be the test product and the prior formulation (or
respective method of manufacture) shall be the referenceproduct.
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13. When bioequivalence studies are not necessary:
A.When new drugs are tobeadministered parent rally (e.g.,
intravenous, intramuscular, subcutaneous, intrathecal
administrationetc.) as aqueous solutionsand contain the sameactive
substance(s) in the same concentration and the same excipients in
comparableconcentrations;
B.When the new drug is a solution for oral use, and contains the active
substance in the same concentration, and does not contain an
excipients that is known orsuspected toaffectgastro-intestinal transit
or absorption of theactive substance;
C. When the newdrug is agas;
D.When the newdrug is an opticorophthalmicor topical product
prepared as aqueous solution and contains the same active
substance(s) in the sameconcentration
E.When the newdrug is a powder forreconstitution asa solutionand
thesolution meetseithercriterion (a) orcriterion (b) above.
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14. BE /BA studiesare generally classified as
Pharmacokinetic endpointstudies.
Pharmacodynamic endpointstudies.
Clinical endpoint studies.
In vitro endpointstudies .
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16. 1. PHARMACOKINETIC STUDIES
c) SELECTION d) STUDY e) STASTICALa)STUDY
DESIGN
b) STUDY
POPULATION CRITERIA CONDITION EVALUVA
- TION
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17. 1. Pharmacokinetic Studies:
1. A ) Study Design :
The basic design of an in-vivo bioavailability study is determined by the
following:
• What is the scientificquestion(s) to beanswered.
• The natureof the reference material and thedosage form to be tested.
• The availability of analyticalmethods.
• Benefit-risk ratioconsiderations in regard to testing in humans.
1. B ) Study Population :
•The numberof subjects recruited should be sufficient toallow for
possiblewithdrawalsorremovals (dropouts) from the study.
• The minimum numberof subjectsshould not be less than 16 unless
justified for ethicalreasons.
•The significance level desired: usually0.05.
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18. 1.C ) Selection Criteria for Subjects:
•To minimize intraand inter individual variation subjects should be
standardized as much as possible andacceptable.
•The studies should be normally performed on healthy adult volunteers
with the aim to minimize variability and permit detection of differences
between the studydrugs.
•Womenshould be required togiveassurancethat theyare neither
pregnant, nor likely to become pregnantuntil afterthe study.
•Studies on teratogenic drugs should be conducted only on males.
Fordrugs where the risk of toxicity orside effects is significant, studies
may have to becarried out in patientswith theconcerned disease, but
whose disease state isstable.
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19. 1.D ) Study Conditions :
A. . Selection of Blood Sampling Points/Schedules
The blood-sampling period in single-dose trialsof an immediate release
product should extend to at least three-elimination half-lives.
•There should be at least three sampling points during the absorption
phase, three to four at the projected Tmax, and four points during the
elimination phase.
Where urinaryexcretion is measured in a single-dosestudy it is
necessary tocollect urine forsevenor more half-lives.
•Theareaextrapolated from the timeof the last measured concentration
to infinite time is only a small percentage (normally less than 20%) of
the total AUC .
B. Fasting and Fed State Considerations
•A singledose study should beconducted afteran overnight fast (at
least 10 hours), with subsequent fastof 4 hours following dosing.
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20. •For multipledose fasting statestudies, when an evening dose must be
given, two hours of fasting before and after the dose is considered
acceptable.
•When it is recommended that the study drug be given with food or
where thedosage form isa modified release product, fed statestudies
need to becarried out in addition to the fasting statestudies.
•Studies in the fed state require theconsumption of a high-fat
breakfast 15 min beforedosing.
C. Steady State Studies
•Where the drug has a long terminal elimination half-life and blood
concentrations after a single dose cannot be followed for a sufficient
time.
•Where thedrug is likely toaccumulate in the body.
•For drugs that exhibit non-linear pharmacokinetics.
The dosing schedule should follow the clinically recommended
dosageregimen.
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21. 1.E ) Characteristics to be investigated during BE/BA study
•Evaluations of BA/BE will be based upon the measured concentrationsof the
active drug substance(s) in the biologicalmatrix.
•The measurements of an active or inactive metabolite may be necessary:
a)where the concentrations of the drug(s) may be too low to accurately
measure in the biological matrix, (b) limitationsof theanalytical method, (c)
unstabledrug(s), (d) drug(s) with averyshort half-life or (e) in thecase of
prodrugs.
•Racemates should be measured using an achiral assay method.
•The plasma-time concentration curve is mostly used to assess the rate and
extentof absorptionof thestudydrug. This include Cmax, Tmax, AUC0-tand
AUC0-∞.
1.F ) Statistical Evaluation
•The statistical analysis (e.g. ANOVA) should take into account sources of
variation thatcan be reasonablyassumed to havean effecton the response.
•The logarithmic transformation should be carried out for the
pharmacokinetic parameters Cmax and AUC before performing statistical
analysis.
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22. •The parameterTmax should beanalyzed using non-parametric
methods.
1.G) Criteria forbioequivalence
•Toestablish Bioequivalence, the calculated 90% confidence interval
for AUC and Cmax should fall within the bioequivalence range,usually
80-125%.
•Tighter limits forpermissibledifferences in bioavailability may be
required for drugs thathave:
I. A narrow therapeutic index.
II.A serious, dose-relatedtoxicity.
IIIA steep dose/effect curve,or
IV A non-linearpharmacokinetics within the therapeuticdose range.
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23. 1.H) Immediate-release formulations
• Generallya single-dose, non replicate, fasting study is done.
• Food-effect studies arerequired:
1)when it is recommended that the study drug should be taken with
food (as would be in routine clinicalpractice);
2)when fasting state studies makeassessmentof Cmax and Tmax is
difficult.
1 I) Modified-release formulations
• Should conduct fasting aswell as food-effectstudies.
•If multiple-study design is important, appropriate dosage
administered and sampling carried out todocumentattainmentof
steadystate.
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24. Thevarious typesof testdesign thatareemployed are :
1. COMPLETELY RANDOMISED DESIGNS ;
• All treatments are randomly allocated among all experimental
subjects.
• Label all subjects with the same no. of digits, for e.g. 1 to 20.
for firstrandomly select non repeating numbers from these labels
treatment, and then repeat forall othertreatment.
2. RANDOMIZED BLOCK DESIGN ;
• First the subjects are sorted into homogenous groups, called blocks
and the treatmentsare then assigned at random within the block.
3. CROSSOVER & CARRYOVER DESIGN;
• The administration of two or more treatment one after other in a
specific or random order to the same group of patients .
• Its drawback is carryover effect i.e. residual effect from preceding
treatments.
• Toprevent this wash out period is always allowed to eliminate most
of the drug from body.
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25. 4. LATIN SQUARE DESIGN;
•It is a two factordesignwith oneobservation in each cell.
•Here, the rows representsubjectand column represent treatment.
Fig ; Latin squaredesign for12 subject tocompare 3 formulation A,B,C
Subject Study Wash Study Wash Study
no. period out period out period
I period II period III
1,7 A B C
2,8 B C A
3,9 C A B
4,10 A B B
5,11 C C A
6,12 B A C
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26. BIOWAIVERS ( exemptions) –
In vitro studies ,i.e. dissolution studiescan be used in placeof in vivo
bioequivalence under certain conditions ,calledBIOWAVIERS.
1. Thedrug product differsonly in strength of activesubstance,
provided the following condition hold ;
a) Pharmacokinetics arelinear.
b) The qualitative composition issame.
c) The ratio betweenactivesubstanceand exepient is same.
d) Both product are produced by same manufactureratsamesite.
e) A BA/BE study is performed with originalproduct.
2. The drug has been slightly reformulated or manufacturing method
has been slightly modifies by same manufacturerin ways thatcan
beargues irrelevantforBA.
3. The product meets following requirement;
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27. a) The product is in form of solution or solublised form ( elixir, syrup)
etc.
b) The product contain active ingredient in samecon asapproved drug.
affectc) The product contain no exepient known to significantly
absorption of activeingredient.
d) The product is administered by inhalation as gas orvapor.
e) The product is for oral administration but not intended for
( ointment,
absorption ( antacid orradioopaque medium ).
f) The product is intended for topical administration
creams, gels etc,) for localeffect.
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28. 2. . Pharmacodynamic Studies
•Studies in healthy volunteers or patients using pharmacodynamic
parameters may be used for establishing equivalence between two
pharmaceutical products;
•These studies may become necessary:
If quantitativeanalysis of the drug and/or metabolite(s) in plasmaor
urinecannot be madewith sufficientaccuracyand sensitivity;
If drug concentration measurement cannot be used as surrogate
endpoints forthedemonstrationof efficacy and safetyof the particular
pharmaceutical product.
•Importantspecifications forpharmacodynamic studies include :
I ) A dose-response relationshipshould bedemonstrated;
II) Sufficient measurementsshould be taken to provide an appropriate
pharmacodynamic responseprofile;
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29. III)The completedose-effectcurve should remain below the maximum
physiological response;
IV)All pharmacodynamic measurements/methods should bevalidated
for specificity, accuracy, andreproducibility.
•The responseshould be measured quantitatively underdouble-blind
conditions and be recorded in a instrument-produced or instrument-
recorded fashion on a repetitive basis to provide a record of
pharmacodynamiceventswhich area substitute forplasma
concentrations.
• A crossoverorparallel study design should be used, asappropriate.
•When pharmacodynamic studies are to becarried outon patients, the
underlying pathology and natural history of the condition should be
considered in the studydesign.
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30. 3. Clinical endpointstudiesorcomparativeclinical trials
•In the absence of pharmacokinetic and pharmacodynamic approaches,
adequateand well-controlled clinical trials may be used toestablish BA/BE.
•The numberof patients to be included in the studywill depend
on the variability of the target parameters and the acceptance range, and is
usually much higherthan the numberof subjects in bioequivalence studies.
•The following items are important and need to be defined in the protocol in
advance:
a.The targetparameters which usually representrelevantclinical end-points
from which the intensity and the onset, if applicable and relevant, of the
response are to bederived.
b.The sizeof theacceptance range has to bedefined case-to- case taking into
consideration the specific clinicalconditions.
C . The presentlyused statistical method is theconfidence interval approach.
d. Whereappropriate, a placebo leg should be included in thedesign.
e.In somecases, it is relevantto includesafetyend-points in the final
comparativeassessments.
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31. 4. In Vitrostudies
•In certain situations a comparative in vitro dissolution study may be sufficient
todemonstrateequivalence between twodrug products (biowaviers).
•Dissolution studies should generally be carried out under mild agitation
conditionsat 37±0.5°Cand at physiologically relevantpH.
•More than one batch of each formulation should be test. Comparative
dissolution profiles, rather than single point dissolution test data, should be
generated .
• The design shouldinclude:
Individually testing of at least twelve dosage units of each batch.
Suitably spaced time points to provide a profile for each batch, e.g. at 10, 20
and 30 minutesoras appropriate toachievevirtuallycompletedissolution.
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32. Determining thedissolution profile in at least threeaqueous media
covering the pH range of 1.0 to 6.8 or in cases where considered
necessary, Ph range of 1.0 to8.0.
Conducting the tests on each batch using the sameapparatusand,
if possible, on the sameorconsecutivedays.
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33. •With respect to theconductof bioequivalence/bioavailability studies
following important documents must bemaintained:
A) Clinical Data :
•All relevantdocumentsas required to be maintained forcompliance
with GCP Guidelines.
B) Details of the analytical method validation including thefollowing:
a. System suitabilitytest
b. Linearityrange
c. Lowest limit of quantization
d. QC sampleanalysis
e. Stability sampleanalysis
f. Recovery experimentresult
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34. C) Analytical dataof volunteerplasmasampleswhich should include
the following:
a. Validation data of analytical methodsused,
b. Chromatograms of allvolunteers,
c. Inter-dayand intra-dayvariationof assay results,
d. Details including chromatogramsof any repeatanalysis performed,
e. Calibration status of the instruments.
D) Raw data
E)All commentsof thechief investigatorregarding the dataof the
study submitted forreview.
F) A copy of the finalreport
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