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Bioavailability & bioequivalance

This document discusses bioavailability and bioequivalence. It defines bioavailability as the rate and extent of absorption of a drug in its dosage form. Bioequivalence means that two drug products with the same active ingredient reach systemic circulation at the same rate and to the same extent. The document outlines methods to measure bioavailability including pharmacokinetic studies using plasma concentration over time and urinary excretion studies. It also discusses considerations for bioequivalence studies including objectives, methods used like pharmacokinetic and crossover designs, required documentation and facilities.

Education◦Business◦Health & Medicine◦
BY:- MUKESH JAISWAL BIOAVAILABILITYBIOAVAILABILITY && BIOEQUIVALANCEBIOEQUIVALANCE
BIOAVAILIBILITYBIOAVAILIBILITY ?? Is the rate and extent (amount) of absorption of unchanged drug from its dosage form. Bioavailable fraction: administered dose that enters the systemic circulation f = bioavailable dose administered dose
Objectives:- Development of a suitable dosage form Development of new formulation Control of quality of a drug Influence of recipients , patient related factors , interaction with other drugs
Types Of Bioavailability Are of 2 types:-  Absolute bioavailability systemic availability of a drug administered orally is determined in comparison to its intravenous administration  Relative bioavailability systemic availability of a drug after oral administration is compared with that of the same drug
Methods of enhancing bioavailability Micronization Use of surfactants Use of salt forms Selective adsorption on insoluble carriers Solvent deposition
Above graph shows the comparison of drug concentration in blood due to different dosage forms
BIOAVAILABILITY STUDIES Single dose vs. multiple dose studies Requires collection of fewer blood samples Better evolution of control released drug is possible More accurate Less sensitive analytical method can be used
Healthy human subjects vs. patients Advantages of patient Advantages of healthy subjects 1. Benefit 1.Standard of drugs 2.Therapeutic efficacy 3.Drug absorption Drawbacks of patients 1. Drug absorption modify
Measurement Of Bioavailability Studies 1.> Pharmacokinetic methods  1.plasma level time studies  2. urinary excretion studies 2.>Pharmacodynamic methods  1.acute pharmacologic response  2.therapeutic response 3.>in vitro studies
Pharmacokinetic studies Plasma level time studies  Principle The plama level time profile of a perticular drug will not super impose by the other drug profile thus result in identical therapeutic response. There are three parameters used in plasma time studies:- 1. Cmax, 2. Tmax & 3. AUC Methodology single dose study multiple dose study 1. collection of blood samples 1. collection of blood samples for 2-3 half lives after drug for at least 5 half lives administration 2. analysis of drug concentration 3. plotting of graph b/w conc. Of drugs and time
Urinary excretion studies Principle  urinary excretion of unchanged drug is directly proportional to the plasma concentration of drug  studies is carried for extensively excreted unchanged drugs in the urine methodology  collection of urine samples at regular intervals for 7 biological half lives analysis of unchanged drug in the sample  total emptying of bladder is necessary  parameters used are (dx/dt)max , (tu)max , xu
Pharmacodynamic studies Acute pharmacologic response  This Include ECG readings, pupil diameter is related to time course of a given drug. Pharmacologic effect –time curve is used At least 3 biologic half lives are taken Therapeutic response Observing the clinical response to a drug formulation given to patients
In vitro studies For this dissolution studies is done Rotating paddle apparatus is used Drug is dissolved in 250ml of aqueous media at ph of 1-7.5 Speed of paddle should be 100 rpm Media used having ph-6.8,in 0.1n hcl Temperature 37 degree Celsius.
Bioquivalence Relative term which denotes that the drug substance in 2 or more identical dosage forms ,reaches the systemic circulation at the same relative rate and to the same relative extent
Objectives Should be done for the comparison of the 2 medicinal products having the same active substance In order to ensure clinical performance of such drugs. Cases where bioequivalence studies not required  drug is gas  drug is administered parentally  drug is in form of inhalation
Bioquivalence studies Terms used in bioequivalence studies Bioequivalence Chemical Eqivalence Pharmaceutical equivalents Therapeutic equivalents
Methods used in bioquivalence studies Pharmacokinetic methods Pharmacodynamic methods In –vitro studies Latin square design cross over
Cross over latin design A crossover study (also referred to as a crossover trial) is a study in which subjects receive a sequence of different treatments (or exposures).  crossover studies can be observational studies, many important crossover studies are controlled experiments. crossover designs have "balance", which means that all subjects should receive the same number of treatments and that all subjects participate for the same number of periods
Advantages Minimizes intersubject variability Minimizes the variations due to time effect. Disadvantages Takes a long time Study becomes difficult when there are number of formulations to be tested
Documentation for conduction ofDocumentation for conduction of studistudieses Details of analytical method validation Comments of chief investigator regarding the data Clinical data according to GCP Analytical data of volunteer plasma samples Copy of final report
Study report Table of contents Title of study Name of responsible investigator Site of the study Dates and period in which trials are conducted Name and batch number of products Results of pharmaceutical tests Demographic data of subjects Names and address of subjects Details of dropout and withdrawal of subjects Reports of protocol violations Details of how pharmacokinetic parameters were calculated Documents related to statistical analysis
Facilities for conducting the studies The study site must have the following An investigator Clinical pharmacological unit Qualified and trained personnel to perform the following Data handling and interpretation Documentation and report preparation Laboratory management Quality assurance of all operations in the centre
Maintainance of records Should be maintained by the sponsor for atleast 2 years after the expiration of batch of drug Retention OF BA/BE Samples Should be retained by organization for period of 3 years after the completion of studies or 1 year after the expiration of batch ,whichever is early.
Thank you ....