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DELIBRATED BY: UNDER THE GUIDANCE OF 
J.RAJESH Dr.SATYABRATA BHANJA M.Pharm,Ph.D 
M.PHARM(CEUTICS) DEPARTMENT OF PHARMACEUTICS 
256213886012 MALLARAEDDY COLLEGE OF PHARMACY
Bioequivalence : 
It is a relative term which denotes that the drug 
substance in 2 or more identical dosage 
form,reaches the systemic circulation at the same 
relative rate and to the same relative extent i.e. Their 
plasma concentration –time profiles will be identical 
without significant statistical differences.
Elements of Bioequivalence 
Study Protocol 
1.Title 
a.Principal investigator 
b.Project number and date 
2.Study objective 
3.Study design 
a.Design 
b.Drug Products 
i. Test products(s) 
ii.Reference product 
c.Dosage regimen 
d.Sample collection schedule
e.Housing 
f.Fasting /Meals schedule 
g.Analytical methods 
4.Study population 
a.Subjects 
b.Subject selection 
i.Medical history 
ii.Physical examination 
iii.Laboratory tests 
c.Inclusion/exclusion criteria 
i.Inclusion criteria 
ii.Exclusion criteria
d.Restrictions/prohibitions 
5.Clinical procedures 
a.Dosage and Drug Administration 
b.Biological sampling schedule 
c.Activity of subjects 
6.Ethical considerations 
a.Basic principles 
b.Institutional review board 
c.Informed consent 
d.Indication for subject withdrawl 
e.Adverse reaction and emergency procedures
7.Facilities 
8.Data Analysis 
a.Analytical validation procedure 
b.Statistical treatment of data 
9.Drug Accountability 
10.Appendix
Study Objective: 
 The objective for a bioequivalence study is 
that the drug bio availability from test and 
reference products are not statiscally 
different when administered to patients are 
subjects at same molar dose under similar 
experimental conditions.
Objectives for Bioequivalence Studies: 
Equivalence : It is a relative term that compares drug 
products with respect to a specific characteristic or 
function to a defined set of standards. 
There are several types of equivalences 
Pharmaceutical Equivalence : This term implies two 
or more drug products are identical in strength,quality 
purity ,content uniformity,and disintegration and 
dissolution characteristics. 
Chemical equivalence: It indicats that two or more 
drug products contained the same labelled chemical 
substance as an active ingrediant in the same 
amount.
Therapeutic equivalence : This term indicats that two 
or more drug products that contain the same 
therapeutically active ingrediant elicit identical 
pharmacological effects and can control the disease 
to the same extent. 
Types of Bioequivalence studies : 
Bioequivalence can be demonstrated either 
In vivo,or 
In vitro 
In vivo Bioequivalence Studies: 
1.Oral immediate – release products with systemic 
action 
2.Non oral immediate – release produts. 
3.Modified- release products with systemic action
In vitro Bioequivalence studies : 
1.The drug products differs only in strength of the 
active substances. 
2.The drug products meets of the following 
requirements. 
The product is in the form of solution 
(elixir,syrup,tincture). 
The product contains active ingrediant in the same 
concentrasation approved drug product.
Study Designs: 
 For many drug products,the FDA, division 
of bio equivalence, office of generic drugs 
provides guidances for the performances of 
in-vitro dissolution and in-vivo 
bioequivalence studies 
 Generally two bioequivalence studies 
required for solid oral dosage forms 
including
1.A fasting study 
2.A food intervention study 
1.Cross Over Study Design: 
 - Two formulations, even number of 
subjects 
 - Randomly divided into two equal groups
First Period: 
 Each number of one group receive a single 
dose of the test formulation and each 
member of the other group receive the 
standard formulations. 
Subject Period 1 Period 2 
1-8 Test Standard 
9-16 Standard Test
2.Latin Square Design: 
- More than two formulations 
Eg: A group of volunteers will receive 
formulations in the sequence. 
Volunteer 
Number 
Period 1 Period 2 Period 3 
1 A B C 
2 B C A 
3 C A B
3.Balance Incomplete Block Design: 
 - More than 3 formulations 
 - Latin square design will not be used 
because each volunteer may required 
drawing of too many many blood samples 
 If each volunteer expected to receive atleast 
2 formulations then such study can be 
carried out using BIBD.
Volunteer 
Number 
Period 1 Period 2 
1 A B 
2 A C 
3 B D 
4 B C 
5 C D 
6 B D 
7 C A 
8 D A 
9 C B 
10 D B 
11 D C 
12 A B
4.Parallel Group Design: 
- Even number of subjects in 2 
groups 
-Each receive a different 
formulation 
-No wash out necessary 
-For drugs with long half life 
Treatment A Treatment B 
1 2 
3 4 
5 6 
7 8 
9 10 
11 12
5.Replicate Cross Over Study Design: 
 For highly variable drugs 
 Allows comparisions of with in subject 
variances 
 Reduces the number of subjects needed 
 4-periods, 2-sequences, 2 formulations 
design(recommended) 
 3-sequences, 3-periods, single dose 
partially replicated
Period 1 2 3 4 
Group 1 Test Reference Test Reference 
Group 2 Reference Test Reference Test 
Peeriod 1 Period 2 Period 3 
A B C 
B C A 
C A B 
A C B 
B A C 
C B A
Difference Between Parallel Group And 
Cross Over Study Design: 
Parallel Group Cross Over 
Groups assigned different 
treatments 
Each patient receives both 
treatments 
Shorter duration Longer duration 
Larger sample size Smaller sample size 
No carry over effect Carry over effect
6.Pilot Study: 
 If the sponsor chooses in a small number of 
subjects 
 To access a variability, optimise the sampla 
collection time intervals, and provide other 
information 
 Eg:Immediate release products – careful timing 
of intial samples-avoid a sub sequent finding that 
the first samole collection, occured after the 
plasma concentration peak. 
 Modified released products: To determine 
sampling shedule- Assess log time and dose 
dumping
Analytical Methods: 
 Analytical methods used in an in-vivo bio 
availability, bio equivalence, or pharmacodynamic 
studies must be validated for accuracy and 
sufficient sensitivity. 
 The analytical method for measurement of drug 
must be validated for accuracy, precision, 
sensitivity, specificity, and robustness. The use of 
more than one analytical method during a bio 
equivalence study may not be valid because 
different methods may yield different values.
Subject Selection: 
 Healthy adult volunteers 
 age 18-45years 
 age/sex representation corresponding to 
therapeutic and safety profile 
 weight with in normal limits 
 women-pregnency test period to first and last 
dose of study 
 Selection Of Number Of Subjects: 
 Sample size estimated by 
Pilot Experiments 
Previous Studies 
Published Data
 Significance level desired usually 0.05 
 Power of study normally 80% or more 
 Minimum 16 subjects unless ethical 
justification 
 Allow for drop outs 
Exclusion Criteria: 
 H/o allergy to test drug 
 H/o liver or kidney disfunction 
 H/o jaundice in past 6 months 
 Chronic diseases Eg: asthma, arrthiritis 
 Psychiatric illness
Administration of drug products: 
 Administration of drug products to the should be 
based on randamization.After the administration 
of drug products, biood samples are withdrawn 
from the subjects at fixed time points. 
 It takes some to take a sample from each subject, 
and the total time difference between first and last 
subject ay range from 10 to 20 minutes depending 
upon the number of subjects and technicians in 
the study. 
 This 10 to 20 minutes difference would represent 
a substantial change in the drug concentrations 
observed in the blood.
 If under these conditions treatments are 
administered to the the subjects in a seqential 
manner( such as teatment A to the first 6 
volunteers,teatment B to volunteers 7 to 12, 
and teatment C to Volunteers 13 to18),the 
error between the time of administration and 
sampling will gradually increase from 
treatment group to treatment group. 
 This is because of sequential administration of 
drug products to different treatments.
Sampling: 
 The biological sample to be used in the study as to 
be decided before the commencement of a 
bioavailability study. 
 If the bioavailability of a given dosage form is to be 
evaluated by a blood level study, some estimate of 
the area under the serum concentration v/s time 
curve, peak serum concentration,time of peak 
concentration must be obtained from the study. 
 These factors can markedly influence the 
‘apparent’ results obtained in a given study.
 The sampling scheme should frequent enough 
to define the absorption phase, the peak, and 
the elimination phase during a drugs time 
course in the body. 
 The absorption rate, volume of distribution, 
elimination rate, all influence the apparent 
drug concentration one obtains in a given 
sample. 
 It is necessary to see that all these factors 
influence each dosage form equally. 
 To estimate the AUC from the data, sampling 
as to be carried out till the concentration of the 
drug reaches the linear elimination phase.
 For first-order process , the time necessary for a 
complete elimination would be infinity. 
 A rule of thumb sampling in a blood level study is 
to sample for 3-5 half lifes of the drugs. 
 If half life is not known , sampling should proceed 
untill 1/10 or 1/20 of the peak levels are reached. 
 In the case of urinary excretion studies, the same 
principles apply. 
 The advantage of urinary excretion studies are 
1.it involes non-invasive method of sampling. 
2.the drug concentration in the urine is 
greaterthan blood/serum allowing easy estimation 
of the drug.
 The amount of drug excreted in urine is 
obtained directly. In the case of a blood 
level study, the amount of drug in the body 
is estimated using pharmacokinetic 
parameters. 
 The urinary excretion method has several 
disadvantages 
1.urinary excretion studies are not useful in 
estimating the drug absorption rate. 
2.In some cases, the metabolites of the 
drug are also concentrated in the sample 
that interferes with the estimation of 
unchanged drug in the urine sample.
Evaluation of data: 
 Pharmacokinetic evaluation of the data : 
For single dose studies, including a fasting 
study or a food intervention study, the 
pharmacokinetic analyses include 
calculation for each subject of the area 
under the curve to the last quantifiable 
concentration (AUC0 ) and to infinity (AUC0), 
tmax and Cmax .Additionally ,the elimination rate 
constant,k, the elimination half-life,t1/2,
Statistical evaluation of the data: 
 Bioequivalance is generally determined 
using a comparision of population 
averages of a bioequivalance metric,such 
as AUC and Cmax. 
 This approach, termed average 
bioequivalence,involves for the ratio of 
averages of the test and reference drug 
products.
 Statistical Analysis For Average Bio 
equivalence: 
 Based on log transformed data 
 Point estimates of the mean ratios 
Test / reference for AUC and Cmax are 
between 80% -125% 
 AUC and Cmax 
 90% confident intervals must fit between 
80%-125% 
 Statistical model typically includes factors 
accounting for following sources of variations: 
Sequence, subjects, nested in sequences, 
period in treatment
Proposed And Contents Of An In vivo Bio equivalence 
Study Submission And Accompaning In vitro Data: 
Title Page 
Study Title 
Name of sponsor 
Name and Address of clinical laboratory 
Name of Principal Investigator(S) 
Name of Clinical Investigator 
Name of Analytical Laboratory 
Dates of Clinical Study 
Signature of principal investigator(and date) 
Signature of Clinical Investigator(and date)
 Table Of Contents 
1.Study Resume 
Product Information 
Summary of Bio equivalence study 
Summary of Bio equivalence data 
Plasma 
Urinary Excreation 
Figure of mean plasma concentration-time profile 
Figure of mean cumulative urinary excreation 
Figure of mean urinary excreation rates 
2.Protocol And Approvals 
Protocol 
Letter of acceptance of protocol from fda 
Informed consent form 
Letter of approval of institutional review board 
3.Clinical study 
Summary of Study 
Details of study 
Demographic characteristics of the subjects 
Subject assignement in the study
Mean physical characteristics of subjects arranged by sequence 
Details of clinical activity 
Deviation from protocol 
Vital science of subjects 
Adverse reactions report 
4.Assay Methodology And Validation 
Assay method discription 
Validation procedure 
Summary of validation 
Data on linearity of standard samples 
Data on interday precision and accuracy 
Data on intraday precision and accauracy 
Figure for standard curve for low/high ranges 
Chromatograms of standard and quality control samples 
Sample calculation
5.Pharmacokinetic Parameters and Tests 
Definitions and calculaton 
Statistical tests 
Drug levels at each sampling time and pharmacokinetic 
parameters 
Figure of mean plasma concentration-time profile 
Figure of individual subjects plasma concentrations-time 
profiles 
Figure of mean cumulative urinary excreation 
Figures of individual subject urinary excreation rates 
Tables of individual subject data arranged by drug, 
drug/period, drug/sequence
6.statistical analyses 
statistical considerations 
summary of statistical significance 
summary of statistical parameters 
analysis of variance,least squares estimates and least 
squares means 
assessment of sequence, period, and treatment effects 
90% confidence intervals for the differences between 
test and reference products for the log-normal-transformed 
parameters of AUC0-t, AUC0-infinty, CMAX should be 80%-125%.
 7. appendices 
Randamization schedulule 
sample identification codes 
analytical raw data 
chromatograms of at least 20% of subjects 
medical records and clinical reports 
clinical facilities discription 
analytical facilities discription 
curricula vitae of investigators 
8. invitro testing 
dissolution testing 
dissolution assay methadology 
content uniformity testing 
potency determination 

 9. batch size and formulations 
batch record 
quantitative formulations
Applications of pharmacokinetics in drug 
development,NDDS: 
Drug research: 
 New Drug 
 i.Discovery 
 ii.Development 
 Drug Discovery :- Hypothesis of target enzyme on receptor for 
particular disease 
 Suitable models 
 Screening of new drug 
 Screening of in vitro/in vivo biological activity 
 Drug development : 
 Empirical Dosage regimen 
 Semi empirical Dosage regimen 
 Structaral activity 
 These are development of chemical structures.
 Emprical Dosage Regimen :- 
 It is designated by the physician based on emprical 
clinical data,personal experience and clinical 
observations.This approach is however,not very 
accurate 
 Semi emprical Dosage regimen : 
 It is most accurate approach and is based on the 
pharmacokinetics of drug in the individual patient.The 
approch is suitable for hospitalised patients but is 
quite expensive. 
 Pharmacokinetics-AUC,CMAX,TMAX. 
 Pharmacodynamics-On set of action, On set of 
time,MSC,MEC,MTC.
 Applications: 
 Design of new drug development: 
 Design a level of optimum formalation for better use of drug 
 Design a level of control and sustained released 
formulation. 
 Selection of appropriate new drug administration then the 
selection of right drug for the particular disease 
 Design and development of drug design,processing dosage 
regimen 
 Study of in vitro, in vivo studies 
 Study of bioequivalant studies. 
 The study of pharmacokinetics and pharmacodynamic 
relationship 
 Development of rational drug design,development rational 
dose frequency and duration.
 Determaine the drug drug interactions 
 Design of appropriate multiple dosage regimen 
 Therapeutic dose of indiviual drug 
 Pharmacokinetics charactarization of drug selection of the suitable novel 
drug delivary system. 
 NDDS parameters are the 
 i.T1/2 
 ii.T90 
 iii.Elimination rate constant 
 iv. Area under curve 
 v.Volume of distibution 
 vi.Steady state concentration 
 vii.Mean residance time 
 ix.Dosage form index 
 x.Relative area 
 xi.Absorption rate
 References: 
 BIOPHARMACEUTICS AND 
PHARMACOKINETICS 
 second edition 
o V.Venkateswarlu 
o APPLIED BIOPHARMACEUTICS & 
PHARMACOKINETICS 
o sixth edition 
o Leon Shargel 
o Susanna wu-Pong 
o Andrew yu
Bioequivalence  protocol 46