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

Peeriod 1 Period 2 Period 3

A B C

B C A

C A B

A C B

B A C

C B A

Period 1 2 3 4

Group 1 Test Reference Test Reference

Group 2 Reference Test Reference Test

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 (AUC 0 ) 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 Contents1.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