introduction of bioequivalance, significance, history of bioequivalance

1. Prepared by
P. NAGA CHANDRIKA, M. Pharm, Ph.d
.Scholar,
ASSIST. PROFESSOR
DEPATMENT OF PHARMACEUTICS,
GEETHANLI COLLEGE OF PHARMACY,
CHEERYAL, KEESARA, TELANGANA, HYD.
BIOEQUIVALANCE

2. CONTENTS
 DEFINITIONS
 HISTORY
 OBJECTIVES
 SIGNIFICANCE
 REFERENCES

3. DEFINITION
 BIOAVAILABILITY is defend as a measure of the rate and extent
of drug, which reaches the systematic circulation in contrast to
that stated on the label.
 (FDA revised definition), BIOAVAILABILITY means the rate and
extent to which the active drug ingredient or therapeutic moiety
from a drug product becomes available at the site of drug action or
in a biological medium believed to reflect accessibility to a site of
action
 BIOEQUIVALENCE: It refers to the drug substance in two or
more identical dosage forms, reaches in systemic circulation at the
same rate and to the same relative extent.

4. Bioavailability
Drug
Systemic
circulation

5. History
 The study of drug absorption (e.g., sodium iodide) can be
traced back to 1912.
 In 1933 Walker and Nelson [1] observed that vitamin B given
to rats as yeast is absorbed differently if the yeast is fresh or
dried.
 INCIDENTS:
 Chlorpropamide.
 Digoxin.
 Phenytoin.

6. OBJECTIVES
Bioavailability studies are important in the
 Primary stages of development of a suitable dosage form for a
new drug entity to obtain evidence of its therapeutic utility.
 Determination of influence of excipient, -patient related factors,-
possible interaction with other drugs on the efficiency of
absorption.
 Development of new formulations of the existing drugs.
 Control of quality of a drug product during the early stages of
marketing in order to determine the influence of processing
factors, storage, and stability on drug absorption.
 Comparison of availability of a drug substance from different
dosage forms or form the same dosage form produced by
different manufactures

7. SIGNIFICANCE
 Drugs having low therapeutic index e.g. cardiac glycosides ,
quinidine, phenytoin etc.
 Drugs whose peak levels are required for the effect of drugs ,
e.g. phenytoin, phenobarbitone, primidone, sodium valporate,
anti-hypertensive, anti-diabetics, and antibiotics.
 Drugs that are absorbed by an active transport e.g.,
aminoacid analogues, purine analogues etc.
 Drugs which are disintegrated in the alimentary canal, and
liver, e.g. chlorpromazine etc. or those which under go first
pass metabolism.’
 Formulation that give sustained release of drug, formulation
with smaller disintegration time than dissolution rate and drugs
used as replacement therapy also warrant bioavailability
testing.
 In addition, any new formulation has to be tested for its
bioavailability profile.

8. REFERENCES
 Biopharmaceutics and pharmacokinetics A treatise by D.M.
Brahmankar, Sunil B. Jaiswal, second edition, Vallabh
Prakash, pg. no. 315-363.
 Basics of pharmacokinetics, Leon Shargel, fifth edition,
willey publications, pp- 453-490.
 www.google.com