Bioavailability & Bioequivalence Studies

Done By: Hussein Talal &

Sarmad Usama

ID NO.201117011 &

201127022

Supervised by: Ashok Shakya

Bioavailability & Bioequivalence

studies

Bioavailability & Bioequivalence studiesIntroduction

• Bioequivalence is a comparison of bioavailability of two or more product i.e. Formulation containing the same active ingredient are said to be bio-equivalent if their rate & extent of absorption is same.

• One of the best way to compare two product is by clinical studies. But performing clinical studies is extremely cumbersome & expensive.

• Hence Bio-equivalence studies are generally used to compare two products so as to compare their biological equivalence.

• Bioequivalence is established if the in-vivo bioavaliability of test drug product (usually generic product) does not differ significantly in rate & extent of drug absorption, from reference listed drug (brand name product) administered at same dose, under similar experimental conditions.

Bioavailability & Bioequivalence studiesDefinitions

1. Bioavailability• Means the rate and extent to which the active substance or therapeutic

moiety is absorbed from a pharmaceutical form and becomes available at the site of action.

2. Bioequivalence: • The absence of a significant difference in the rate and extent to which the

active ingredient or active moiety in pharmaceutical equivalents or pharmaceutical alternatives becomes available at the site of drug action when administered at the same molar dose under similar conditions in an appropriately designed study.

Bioavailability & Bioequivalence studiesDefinitions

3. Pharmaceutical equivalents• Medicinal products are pharmaceutical equivalents if they contain the same

amount of the same active substance(s) in the same dosage forms that meet the same or comparable standards.

• Pharmaceutical equivalence does not necessarily imply bioequivalence as differences in the excipients and/or the manufacturing process can lead to faster or slower dissolution and/or absorption.

4. Therapeutic equivalents• A medicinal product is therapeutically equivalent with another product if it

contains the same active substance or therapeutic moiety and, clinically shows the same efficacy and safety as that product, whose efficacy and safety has been established.

Study CompoundReference Compound

Time

Conc

entr

ation

Cmax

Tmax

AUC

• AUCArea under the concentration- time curve

• CmaxMaximum concentration

• TmaxTime to maximum concentration

Bioavailability & Bioequivalence studiesNeed for Conducting BA/BE StudiesBA• To evaluate the absolute systemic availability of active drug substance from a

dosage form• To determine the linearity of the bioavailability parameters over the proposed

clinical dose range• To study the effect of food on bioavailability

BE• When the proposed marketed dosage form is different from that used in

pivotal clinical trials• When significant changes are made in the manufacture of the marketed

formulation• When a new generic formulation is tested against the innovator's marketed

product

Bioavailability & Bioequivalence studiesApproaches for Determining Bioequivalence

1. In vivo measurement of active moiety or moieties in biologic fluid

2. In vivo pharmacodynamic comparison

3. In vivo limited clinical comparison

4. In vitro comparison

Bioavailability & Bioequivalence studiesA. Pharmacokinetic StudiesDesign and conduct of studies

• The design should be based on a reasonable knowledge of the pharmacodynamics and/or the pharmacokinetics of the active substance in question.

• For the pharmacokinetic basis of these studies reference is made to the recommendation “Pharmacokinetic studies in man”.

• The design and conduct of the study should follow EC- rules for Good-Clinical Practice including reference to an Ethics Committee.

Bioavailability & Bioequivalence studiesA. Pharmacokinetic StudiesDesign

• Bioequivalence study should be designed in such away so as to identify treatment effects that are produced after administration of products.

• Two types of design1. Crossover2. Parallel

• Generally crossover is used in practice in this design both test and reference product are compared in each subject that is each subject act as his/her own control

• In this design first subjects are randomly divided in to 2 groups and sequence of drug is randomly assigned.


• If there are two formulations – test (T) and reference (R) ; in period 1 , group 1 will receive T followed by R.

• Time period between administrations of two formulations will be sufficiently long considering adequate ‘wash out period’.

• Wash out period is essential to ensure complete elimination of drug before next administration.

• 10 half lives ensures more than 99% of elimination and hence wash out period should be at least 10 half lives.


• Group II will start after completion of wash out period now in period II, group 1 will receive ‘R’ followed by ‘T’ .

• If drug require washout period of 7 days then sequence of administration of 2 formulation can be shown as:

Figure. Showing Concentrations After Two Separate Drug Administrations


• For bioequivalence study in human volunteers, a Latin square cross over design is used

• It Compares 3 different drug formulations- A,B,& C.

• In this design , each subject receives each drug product only once

SUBJECT STUDY PERIOD 1 STUDY PERIOD 2 STUDY PERIOD 3

1 A B C

2 B C A

3 C A B

4 A C B

5 C B A

6 B A C

Latin –Square Cross Over Design for bioequivalence study of 3 drug products in 6 human volunteers


• Designs used in BA/BE Trials

1. Single-dose, two-way crossover, fasted2. Single-dose, two-way crossover, fed3. Multiple-dose, two-way crossover, fed

Bioavailability & Bioequivalence studiesA. Pharmacokinetic StudiesSubjects: Selection of Volunteers

Typical Inclusion Criteria:

• 20-40 years of age• Body weight + 10% of the desirable weight for height and frame• Stable health (ECG, physical examination, blood and urine tests)

Typical Exclusion Criteria

• History of drug abuse

• A disease/condition that would contraindicate taking the investigational drug

• Conditions requiring concomitant medication



• Medication or drug use within 1 month prior to study initiation with any agent known to induce or inhibit drug-metabolizing enzymes

• Medications or drug use of any kind, including OTC medication within one week prior to study initiation

• A positive laboratory test for Hepatitis B surface antigen or urine screen for drugs of abuse

• Smokers



• Donation of blood within 60 days prior to study initiation

• Significant psychiatric disorders

• A history of hypersensitivity of intolerance.

Bioavailability & Bioequivalence studiesSubjects: Selection of Volunteers

Blinding

• If possible, the study should be conducted in such a way that the subject is not aware of which product is administered.

• Furthermore, the person checking for adverse reactions and the person conducting the analysis of samples must not know which product was administered.

Bioavailability & Bioequivalence studiesA. Pharmacokinetic StudiesStandardization of the study

• All meals and fluids taken after the treatment should be standardized in regard to composition and time of administration.

• The subjects should abstain from drugs food and drinks, which may interact with circulatory, gastro-intestinal, liver or renal function

• As the bioavailability of an active substance from a dosage form could be dependent upon gastrointestinal transit times and regional blood flows, posture and physical activity may need to be standardized.

Bioavailability & Bioequivalence studiesA. Pharmacokinetic StudiesSampling

• Blood samples in principle should be used, urine samples also can be used.

• Blood samples should be taken at a frequency sufficient for assessing Cmax, AUC, tmax and other parameters.

• The duration of blood or urine sampling in a study should be sufficient to account for at least 80 percent of the known AUC to infinity (AUCI).

• This period is usually at least three times the terminal half-life of the drug.

• To permit Calculation of the relevant pharmacokinetic parameters, from 12 to 18 samples should be collected per subject per dose.

Bioavailability & Bioequivalence studiesA. Pharmacokinetic StudiesCharacteristics to be investigated

• In most cases evaluations of bioavailability and bioequivalence will be based upon the measured concentrations of the active drug substance(s) in the biological matrix.

• In some situations, however, the measurements of an active or inactive metabolite may be necessary.

• These situations include where the concentrations of the drug(s) may be too low to accurately

measure in the biological matrix, unstable drug(s), drug(s) with a very short half-life or in the case of prodrugs.


• The plasma-time concentration curve is mostly used to assess the rate and extent of absorption of the study drug.

• These include pharmacokinetic parameters such as the Cmax, Tmax


For single-dose studies, estimates of the following pharmacokinetic parameters must be tabulated for each combination of subjects and formulations:• Cmax Maximum observed concentration.• tmax Sampling time at which Cmax occurred.• AUCT

The area under the curve to the last quantifiable concentration calculated from observed data at specific time points.• AUCI

Area to infinity = AUCT + CT/λ, where CT is the estimated concentration at LQCT.

Percent of the area measured by AUCT relative to the extrapolated AUCI.


• AUCRefTmax

Area under the curve, for a test product, to the tmax of the reference product, calculated for each study subject.• λ Terminal disposition rate constant • TLIN Time point where log-linear elimination begins.

• LQCT Lowest Quantifiable Concentration Time. Time at which the last concentration occurred that is above the lower limit of quantitation.• t½ Drug half-life = ln(2)/λ = 0.693/λ.

Parameter Definitions

Parameter Definition

Cmax Maximum observed concentration (ng/mL).

tmax Sampling time at which Cmax occurred (h).

AUCt

Area under the raw concentration versus time curve calculated using the trapezoidal rule from time 0 to LQCT (ng·h/mL).

AUCIArea to infinity = AUCT + CT/λ where CT is the estimated concentration at LQCT (ng·h/mL).

AUCT X 100AUCIPercent of the area measured by AUCT relative to the extrapolated total AUC.

λTerminal disposition rate constant calculated from the points on the log-linear end of the concentration versus time curve (h-1).

TLINTime point where log-linear elimination begins (h).

LQCTLowest Quantifiable Concentration Time. Time at which the last concentration occurred that is above the lower limit of quantitation (h).

T1/2 Drug half-life = ln2/λ = 0.693/λ (h).

Figure: Illustration of the key metrics in a comparative bioavailability trial showing, forexample, Test and Reference products. The maximum concentration (Cmax) occurs at the Tmax. The AUCt is the total area under the concentration versus time profile to the last sampling time. The area to time infinity (AUC∞) is the extrapolated area based on the AUCt and the terminal constant (λz).

randomization Scheme of the Cross-over Design for the Comparison of Test (T) Versus Reference (R) Formulations

Subject Period

Number ID Sequence May 14, 1988 May 21, 1988

001 A TR T R

002 B RT R T

003 C RT R T

004* D TR T -

005 E TR T R

006 F RT R T

007 G TR T R

008 H RT R T

009 T TR T R

010** I RT - -

Parameter Estimates for Each Subject Given the Test Formulation

ID Seq Period

TEST FORMULATIONS

Cmax(ng/mL)

tmax(h)AUC T

(ng. h/mL)

AUC I (ng. h/m

L)

AUC T (%)

λ (h- 1) TLIN (h) LQCT (h) t ½ (h)

A TR 14 May 122 1.50 365 409 89 0.3002 2.0 8.0 2.3

B RT 21 May 102 1.50 405 432 94 0.2384 3.0 12.0 2.9

C RT 21 May 202 0.66 703 774 91 0.1776 4.0 12.0 3.9

E TR 14 May 59 3.00 233 256 91 0.3680 3.0 8.0 1.9

F RT 21 May 66 1.00 247 265 93 0.3902 3.0 8.0 1.8

Parameter Estimates for Each Subject Given the Reference Formulation

ID Seq Period

REFERENCE FORMULATION

Cmax(ng/mL)

tmax(h)AUC T

(ng .h/mL)

AUC I (ng .h/m

L)

AUC I (%)

λ (h- 1 ) TLIN (h) LQCT (h) t ½ (h)A

A TR 21 May 126 1.50 375 418 90 0.2660 3.0 8.0 2.6

B RT 14 May 207 1.50 595 613 97 0.2900 3.0 12.0 2.4

C RT 14 May 123 1.50 471 492 96 0.2666 4.0 12.0 2.6

E TR 21 May 37 1.00 190 224 85 0.2653 3.0 8.0 2.6

F RT 14 May 85 2.00 257 285 90 0.3114 3.0 8.0 2.2

A. Pharmacokinetic StudiesChemical analysis

• The bioanalytical methods used to determine the active principle and/or its metabolites in plasma, serum, blood or urine or any other suitable matrix must be well characterised, fully validated and documented to yield reliable results that can be satisfactorily interpreted.

• The main objective of method validation is to demonstrate the reliability of a particular method for the quantitative determination of an analyte(s) concentration in a specific biological matrix.

Bioavailability & Bioequivalence studies

Bioavailability & Bioequivalence studiesA. Pharmacokinetic StudiesChemical analysis

• The characteristics of a bioanalytical method essential to ensure the acceptability of the performance and reliability of analytical results are

1. stability of the Drug/Metabolite in the biological matrix specificity 2. Specificity/selectivity3. Sensitivity 4. Precision and Accuracy5. response function.6. Range & Linearity

Bioavailability & Bioequivalence studiesA. Pharmacokinetic StudiesStatistical Evaluation

1. Data analysis:

• The primary concern in bio-equivalence assessment is to limit the consumer’s risk i.e., erroneously accepting bioequivalence and also at the same time minimizing the manufacture’s risk i.e., erroneously rejecting bioequivalence.

• This is done by using appropriate statistical methods for data analysis and adequate sample size.


2. Statistical analysis: • The statistical procedure should be specified in the protocol itself.

• The statistical analysis (e.g. ANOVA) should take into account sources of variation that can be reasonably assumed to have an effect on the response.


2. Statistical analysis: • To meet the assumption of normality of data underlying the statistical

analysis, the logarithmic transformation should be carried out for the pharmacokinetic parameters Cmax and AUC before performing statistical analysis.

• The analysis of Tmax is desirable if it is clinically relevant.


3. Criteria for bioequivalence: • To establish Bioequivalence, the calculated 90% confidence interval for AUC

and Cmax should fall within the bioequivalence range, usually 80-125%.

• The non-parametric 90% confidence interval for Tmax should lie within a clinically acceptable range.

Bioavailability & Bioequivalence studiesB. Pharmacodynamic Studies

• Used for establishing equivalence between two pharmaceutical products.

• These studies may become necessary if quantitative analysis of the drug and/or metabolite(s) in plasma or urine cannot be made with sufficient accuracy and sensitivity.

• Required if measurements of drug concentrations cannot be used as surrogate endpoints for the demonstration of efficacy and safety of the particular pharmaceutical product.

Bioavailability & Bioequivalence studiesC. In Vitro studies

• In vitro dissolution study may be sufficient to demonstrate equivalence between two drug products.

• The test methodology adopted should be in line with the pharmacopoeial requirements

• Dissolution studies should generally be carried out under mild agitation conditions at 37±0.5°C and at physiologically relevant pH.

• More than one batch of each formulation should be tested.

• Comparative dissolution profiles, rather than single point dissolution test data, should be generated.

Bioavailability & Bioequivalence studiesStudy report

• The report should include (as a minimum) the following information

A. Table of contents

B. Title of the study

C. Names and credentials of responsible investigators

D. Signatures of the principal and other responsible authenticating their respective sections of the report

E. Site of the study and facilities used


• The report should include (as a minimum) the following information

F. The period of dates over which the clinical and analytical steps were conducted

G. Names and batch numbers of the products compared

H. A signed declaration that this was identical to that intended for marketing.

I. Results of assays and other pharmaceutical tests

J. Full protocol for the study including a criteria for inclusion/exclusion or withdrawal of subjects


• The report should include (as a minimum) the following information K. Demographic data of subjects

L. Names and addresses of subjects

M. Details of analytical methods used, full validation data, quality control data and criteria for accepting or rejecting assay results

N. Representative chromatograms covering the whole concentration range for all, standard and quality control samples as well as specimens analysed

O. Sampling schedules and deviations of the actual times from the scheduled

P. Details of how pharmacokinetic parameters were calculated

Bioavailability & Bioequivalence studiesConclusion

• During the last few years, there is a major progress in policies and procedures concerning the determination of bioequivalence

• Presently, there ibis international harmonization of regulatory requirements for bioequivalence studies

• However, the trend in the near future appears towards achieving the appropriate choice of clinically relevant bioequivalence ranges based on therapeutic ranges, rate of absorption metrics, designs to resolve the issue of intra and inter subject variability.

Thank you

References

1-GUIDELINES FOR BIOAVAILABILITY BIOEQUIVALENCE STUDIES Central Drugs Standard Control Organization, Directorate General of Health Services,

Ministry of Health & Family Welfare, Government of India New Delhi. 2-MALAYSIAN GUIDELINES FOR THE CONDUCT OF BIOAVAILABILITY AND

BIOEQUIVALENCE STUDIES

3-Guidance for Industry Bioavailability and Bioequivalence Studies for Orally Administered Drug Products — General Considerations

U.S. Department of Health and Human Services Food and Drug Administration Center for Drug Evaluation and Research (CDER) March 2003

4-BIOAVAILABILITY & BIIOEQUIIVALENCE TRIALS Shubha Ranii, Ph.D.http://www.synchronresearch.com/pdf_files/ba-be-trials.pdf

5-Guidance Document: Conduct and Analysis of Comparative Bioavailability Studieshttp://www.hc-sc.gc.ca/dhp-mps/prodpharma/applic-demande/guide-ld/bio/gd_cbs_ebc_ld-eng.php

http://www.synchronresearch.com/pdf_files/ba-be-trials.pdf

http://www.hc-sc.gc.ca/dhp-mps/prodpharma/applic-demande/guide-ld/bio/gd_cbs_ebc_ld-eng.php

http://www.hc-sc.gc.ca/dhp-mps/prodpharma/applic-demande/guide-ld/bio/gd_cbs_ebc_ld-eng.php

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Bioavailability & Bioequivalence Studies