SlideShare une entreprise Scribd logo
1  sur  32
Télécharger pour lire hors ligne
Biopharmaceutics intro
Core Areas of Pharmacy
1. Drug Design
Involves designing and synthesizing compounds to find a
specific chemical substances that will cure, manage or
prevent diseases: Cancer, AIDS, Ebola
2. Drug Formulation
Mix various chemical compounds with the drug to create
Tablet ,Suspension, Emulsion, Injection.
(These chemicals should not react with drug)
3. Drug Dispensing
Give the right drug to the right patient in right dose and
duration with sufficient counseling
(Biopharmaceutics has application on all three above)
4. Others (manufacturing,marketing and regulatory issues)
Drug?
• Drug is a specific organic compound which has
therapeutic effect (forget inorganic drugs like
MgOH from now on)
Metformin
Diabetis
Imatinib
Cancer
Lidocaine
Local Anesthetic
Paracetamol
Anti-inflamatory
Nelfinavir
AIDS
Omeprazole
Ulcer
Paracetamol
Anti-inflamatory
•How to consume?
•How much to consume?
•What happens if instead of 3 tablets, we take 6 or 9 tablets of
paracetamol on hopes of better or quicker recovery?
•How about we share a single tablet between two person?
•How much is too much or too less?
Understanding “Bio” in biophamaceutics
First of all….Pharmaceutics
• Pharmaceutics is science dealing with drug
formulation
• Drug formulation means process of mixing
drug with other chemicals to prepare a
physical form which facilitates convenient
dosing(intake) for patients
• That physical forms are Tablets, suspension,
emulsion, syrup or solutions. This is also called
oral dosing
Various dosage form
Basic understanding of drug formulation
Formula of Paracetamol tablets
•Drug is never given in pure form but as an intended mixture with other chemicals to
help attain a physical form
•These other chemicals are called excipient
•Excipients don’t react with each other or with the drug
There are many choices for various excipient classes
from which many formulation of same drug in same
strength can be made
Excipient
Fillers/Diluent
(Allows making a
sizable tab if drug
content is very less)
Lactose,lactose anhydrous, lactose spray dried, directly
compressible starch,hydrolyzed starch, MCC, other cellulose
derivatives, dibasic calcium phosphate dihydrate, mannitol,
sorbitol, sucrose, calcium sulfate dehydrate, dextrose.
Binders
(allow drug power to
be compressed into a
solid tablet)
cellulose, methyl cellulose, polyvinyl pyrrolidine, PEG, gelatin,
PVP, HPMC, PEG, sucrose, starch
Disintegrating agent
(breaks hard solid tab
to free the power
drug from tablet)
starch derivatives, clay, cellulose, alginates, PVP, cross linked Na
CMCVeegum HV and Betonite PVP, CMC ,crospovidone, Sodium
bicarbonate
Lubricant Stearic acid, stearic acid salt, stearic acid derivatives, talc, PEG,
surfactants,waxes, Calcium stearate and magnesium stearate
poly ethylene glycol
Glidant talc, colloidal silicone dioxide, corn starch
First thing to do…..
• Understand that ALL drugs must be present in blood/plasma
to show effect (excluding topically (skin, eye, ear) applied
creams, gels etc)
• Depending on drug concentration in plasma either of three
results: no effect, therapeutic effect, side/toxic effect of drug
• This information is the first thing obtained during drug Human trials.
Thus we already know how much drug must be present in blood for
therapeutic effect to occur
• When we take a single dose, our interest is to provide just enough
drug to keep the drug conc within the therapeutic region
No effect Therapeutic effect Toxic effect
Effect of Increasing blood concentration on blood
Secondly, think about the time course of a drug
The drug conc in plasma varies continuously after we take a single dose
We cannot keep on maintaining drug conc in the therapeutic region by
only a single dose. Thus we need to give another dose
But what factors are making drug concentration to decrease and
How to know when to give another dose?????
• To make sense of above graph following
phenomenon have to be considered
– Absorption – drug enters blood circulation by
process of diffusion
– Metabolism – drug structure is enzymatically
altered
– Distribution – drug is distributed from blood to
fat, muscle, organs
– Elimination – Drug is thrown out from body
• Study of these 4 parameters is called
pharmacokinetics
Think about this!!!
• Now that we know what is the range of conc for a
drug to be in body, we could simply calculate the
amount of drug in a single dosage form
• Eg if paracetamol is to be maintainted at 50mg/Lt
plasma volume…considering an avg of 2.7 lt of
plasma in body, we could say that a single PCM
tablet needs to have 50X2.7= 135 mg
• However this type of assuption is wrong.
Determining amount of drug in a single dose is
not that simple because the body does not
behave like a vessel containing 2.7 lt of solvent.
• Body presents a dynamic environment to a drug
where the conc of drug is continuously changing
Understanding Absorption
Absorption occurs when drug dissolved in intestine diffuses through
the epithelium and into the capillaries (which is hepatic portal vein
which takes the drug to the liver)
(Notice the blood capillaries
into where drug diffuses)
Diffusion
• The spontaneous movement of solutes from high to low conc until
equilibrium is diffusion. It occurs in solution only.
• For purposes to study drug diffusion in body we consider diffusion
in the scenario where there are two compartments, left being
stomach and right being blood, and both being separated by the
lipophillic cell membrane epithelium
Let this compartment
represent drug dissolved
in stomach fluid
Let it represent
drug dissolved
in capillary
blood/plasma
Epithelium cell
membrane
Two opposing characteristic for good
absorption
• Diffusion through the epithelium requires crossing the
cell membrane of the epithelium which is lipophilic
barrier. This requires drug to have such structure
which gives it good lipophillicity.
• But since diffusion occurs only in solution, drug must
dissolve into the stomach fluid first. This requires drug
to have such structure which gives it good
hydrophillicity.
• (remember hydrophillicity and lipophillicity depend
are physiochemical properties that solely depend on
drug structure)
But drug is in form of a tablet. So how does a tablet dissolve?
Disintegrating agent!
• A tablet is a relatively hard substance. We
swallow it whole without chewing. That sounds
problematic (coz we always chew our food to
make digestion easy) but there are chemicals
added into the tablets called disintegrating agent
(in above Crosspovidone and Sod bicarbonate)
which swells up when in contact with water and
this causes tablet to break apart spontaneously.
• (Show tablet disintegration in a glass of water)
Show tablet disintregation in water
• Put various brands of 500mg paracetamol
tablets in water and observe that
– Tablet spontaneously breaks apart due to the
disintegrating agent soaks up water and expands,
thus causing tablet to break
– various brands disintegrate at different time and
to different degree
• This diff is due to diff in formulation which be
as we saw there are multiple choice for
particular excipients
Understanding Absorption is
important because….
• Many drugs have failed to be orally active
because they were too soluble and thus cant
permeate through the cell membrane
• Or they were too lipophillic and can’t dissolve in
stomach fluid (remember: diffusion requires drug
to dissolve in aqueous stomach fluid)
• Point is…..just cause we consume a drug doesn’t
mean there is guarantee of being absorbed
(however, for such problematic drugs,
formulation enhancement cab be done which we
will study later in course)
Metabolism
We saw that drug in a tablet
disintregates into smaller particles and
then dissolves to the extent depending on
its solubility which then diffusion through the epithelium into
the capillary. But it hasn’t quiet reached systemic circulation
• This capillary is names hepatic portal vein which goes to
the liver and then to the heart. As it flows through the liver
the drug are acted upon by special enzymes (other than
those involved in biological reactions) dedicated to
destroying endogenous substances.
• This is metabolism and it happens primarily in the liver
• The first time this happens is called 1st pass metabolism
and only applies to oral drugs
Metabolism of paracetamol
• Notice that paracetamol structure
changes- that is metabolism
• These metabolized products generally
lack any therapeutic use
• And are more water soluble for easy
removal by urine
Although it might seem that metabolism is a bad thing in that it destroys our drug,
We can overcome it by simply consuming more dose in compensation. Orally we can take
about 1gm dose. Any more compensation and the tablet would be too big to swallow
Also later on we will incredibly exploit this process in our favor in prodrugs
• Body responds to all endogenous substances, poison or
drugs, as if it were a threat and wants to detoxify them
and clear them out of body
• The enzymes alter the drug structure so that the
product is more water soluble.
• The increased water solubility is important since the
main path to clear the drug is through urine. Thus the
more soluble in urine, more quickly drug can be
cleared.
• Metabolism is another reason that any oral dose does
not fully reach the plasma as they get changed into a
diff compound along the way, even if absorption was
very good
• If liver get diseased causing reduced metabolism of
drugs then more drug are able to enter into the body.
This over exposure can cause toxic conc to build up!
Elimination
• Elimination can be seen as a two stage process
– 1st drug is metabolized by the liver into more water soluble form
– 2nd as blood flows through kidney, the now more water soluble form
is excreted (filtered) into the urine (an aqueous fluid)
• The more quickly elimination occurs, more quickly we need
another dose and vice versa
• Understand that without metabolism, excretion can difficult
cause drugs are mostly lipophilic
• So now we know that a drug action can’t be forever cause it
gets either destroyed by liver or excreted by kidney
• If kidney is damaged resulting in less filtration , than drug stays
in body for longer period of time!
• But what about giving drug to patients with both liver and
kidney damage?
Metabolism worked together with urinary excretion
Elimination also
occurs through bile
Oxidation and conjugation are two
types of metabolism that we will study later
Polar
Metabolite
go to urine
Distribution
Once drug passes through the liver it enter blood
circulation and can go everywhere the blood carries it
Distribution
Distribution takes place once drug has entered blood. As the pic
demonstrates of the given 10mg, only 1 mg is seen in the plasma. Thus
drug does not localized in the blood but can distribute itself out of
circulation into tissues, fat and even be bound to plasma protein.
Distribution is a problematic because, it lowers the conc of drug in
plasma and it is conc of drug and not the amount which determine
Once in blood , drug can go
to all places inside body
Long acting drug!!!
• An important concept is that distribution follows dynamic
equilibrium.
• Once distributed drug does not keep being trapped in fat,
tissues or plasma protein
• As the free drug in the plasma is metabolized and excreted,
the vacancy in plasma causes the distributed drug to again
come back to plasma
• In this way distributed drugs act like a reservoir which
sustains the conc in the plasma
• This can be exploited to make drugs with high distribution
so that they remain the body for a long period of time
compared to drugs that have low distribution (there is still
no way to avoid metabolism and excretion but this way
drug can act for a longer time period)
Conclusion
• We want drug to be within predefined conc range in blood
but we can’t simply treat body as a 5 lt vessel of blood.
• There are barriers for drug to maintain sufficient
concentration in plasma, in that they make sure that not all
the given dose can be reaches plasma (absorption) and
those that do reach plasma have difficult maintaining the
therapeutic concentration as drug is being structurally
altered (metabolism), diluted (distribution), kicked out
from the body (elimination)
• Thus we need to account for all these factors and decide
what should be the dose and frequency for every drug
cause these drugs have variable ADME
• This is the true essence of Biopharmaceutics
D
E
A
M
• Biopharmaceutics is defines as the study of
factors influencing the rate and amount of drug
that reaches the systemic circulation and the use
of this information to optimize the therapeutic
efficacy of drug products
• Biopharmaceutics concerns making such a
formulation of drug and defining its frequency of
dosing, by consideration of the ADME of a
drug,which ensures that the amount of drug in a
single dose (and repeated doses) achieves (and
then is maintained) in therapeutic drug conc in
plasma
• Pharmacokinetics is the study of time course of drug
ADME, and their relationship with it’s therapeutic, toxic
effects of drug
• Eg of Pharmacokinetic manipulation,
Distribution based -Vit k gelatin capsule is dosed at 60000
IU. Normal everyday dose is about 300-500IU. Thus 60 K IU
sounds to much (too much of anything is bad!!!) but won’t
be cause vit k being lipophillic gets stored in fat which is
released slowly in blood thus not only acting like a reservoir
of vit k but also ensuring small conc in blood. It means vit k
can be dosed once weekly but still body gets the needed
amount everyday
At last….
• A challenge in BioPham is to come up with a
method to predict time dependent changes in
drug conc
• They have been able to do that by building some
mathematical models (ie equation) that can
predict what would a drug conc be in any time in
body
(Don’t be afraid of the math portion. It’s the theory
that will be harder to comprehend. You probably
solved many tough problems based on equation of
motion; it is similar. There are some equation and u
just need to understand which one to use where)
Biopharmaceutics intro

Contenu connexe

Tendances

P'kinetic parameters
P'kinetic parametersP'kinetic parameters
P'kinetic parametersAnil Joshi
 
Bioavailability and Bioequivalence Studies
Bioavailability and Bioequivalence StudiesBioavailability and Bioequivalence Studies
Bioavailability and Bioequivalence StudiesDr. Kunal Chitnis
 
Physiologic, pharmacokinetic models, statistic moment,.pptx
Physiologic, pharmacokinetic models, statistic moment,.pptxPhysiologic, pharmacokinetic models, statistic moment,.pptx
Physiologic, pharmacokinetic models, statistic moment,.pptxMdHimelAhmedRidoy1
 
A seminar on one & two compartment open model extra vascular administration
A seminar on one & two compartment open model extra vascular administrationA seminar on one & two compartment open model extra vascular administration
A seminar on one & two compartment open model extra vascular administrationMalla Reddy College of Pharmacy
 
Comparison between conventional and sustained-release drugs
Comparison between conventional and sustained-release drugs Comparison between conventional and sustained-release drugs
Comparison between conventional and sustained-release drugs parthob11
 
Physiological factors of drug absorption
Physiological factors of drug absorptionPhysiological factors of drug absorption
Physiological factors of drug absorptionSirazum Munira
 
P h partition hypothesis
P h partition hypothesisP h partition hypothesis
P h partition hypothesisZahid1392
 
Nonlinear pharmacokinetics.pptx1[1]
Nonlinear pharmacokinetics.pptx1[1]Nonlinear pharmacokinetics.pptx1[1]
Nonlinear pharmacokinetics.pptx1[1]BandariPranay
 
Methods For Assesment Of Bioavailability
Methods For Assesment Of Bioavailability Methods For Assesment Of Bioavailability
Methods For Assesment Of Bioavailability Anindya Jana
 
CONTROLLED DRUG DELIVERY SYSTEMS
CONTROLLED DRUG DELIVERY SYSTEMSCONTROLLED DRUG DELIVERY SYSTEMS
CONTROLLED DRUG DELIVERY SYSTEMSSonam Gandhi
 
Introduction to dosage regimen and Individualization of dosage regimen
Introduction to dosage regimen and Individualization of dosage regimenIntroduction to dosage regimen and Individualization of dosage regimen
Introduction to dosage regimen and Individualization of dosage regimenKLE College of pharmacy
 
Advanced Drug delivery systems
Advanced Drug delivery systemsAdvanced Drug delivery systems
Advanced Drug delivery systemsFarzana Sultana
 
pharmacokinetic drug interactions
 pharmacokinetic drug interactions pharmacokinetic drug interactions
pharmacokinetic drug interactionsSyed Imran
 

Tendances (20)

P'kinetic parameters
P'kinetic parametersP'kinetic parameters
P'kinetic parameters
 
Absorption of drug
Absorption of drugAbsorption of drug
Absorption of drug
 
Multiple Dosage regimen
Multiple Dosage regimenMultiple Dosage regimen
Multiple Dosage regimen
 
Bioavailability and Bioequivalence Studies
Bioavailability and Bioequivalence StudiesBioavailability and Bioequivalence Studies
Bioavailability and Bioequivalence Studies
 
bio-availability
bio-availability bio-availability
bio-availability
 
Physiologic, pharmacokinetic models, statistic moment,.pptx
Physiologic, pharmacokinetic models, statistic moment,.pptxPhysiologic, pharmacokinetic models, statistic moment,.pptx
Physiologic, pharmacokinetic models, statistic moment,.pptx
 
A seminar on one & two compartment open model extra vascular administration
A seminar on one & two compartment open model extra vascular administrationA seminar on one & two compartment open model extra vascular administration
A seminar on one & two compartment open model extra vascular administration
 
Bioavailability and Bioequivalence
Bioavailability and BioequivalenceBioavailability and Bioequivalence
Bioavailability and Bioequivalence
 
Comparison between conventional and sustained-release drugs
Comparison between conventional and sustained-release drugs Comparison between conventional and sustained-release drugs
Comparison between conventional and sustained-release drugs
 
Bioavailability testing protocol
Bioavailability testing protocolBioavailability testing protocol
Bioavailability testing protocol
 
Pharmacokinetics of drug absorption
Pharmacokinetics of drug absorptionPharmacokinetics of drug absorption
Pharmacokinetics of drug absorption
 
Physiological factors of drug absorption
Physiological factors of drug absorptionPhysiological factors of drug absorption
Physiological factors of drug absorption
 
P h partition hypothesis
P h partition hypothesisP h partition hypothesis
P h partition hypothesis
 
Nonlinear pharmacokinetics.pptx1[1]
Nonlinear pharmacokinetics.pptx1[1]Nonlinear pharmacokinetics.pptx1[1]
Nonlinear pharmacokinetics.pptx1[1]
 
Methods For Assesment Of Bioavailability
Methods For Assesment Of Bioavailability Methods For Assesment Of Bioavailability
Methods For Assesment Of Bioavailability
 
CONTROLLED DRUG DELIVERY SYSTEMS
CONTROLLED DRUG DELIVERY SYSTEMSCONTROLLED DRUG DELIVERY SYSTEMS
CONTROLLED DRUG DELIVERY SYSTEMS
 
Introduction to dosage regimen and Individualization of dosage regimen
Introduction to dosage regimen and Individualization of dosage regimenIntroduction to dosage regimen and Individualization of dosage regimen
Introduction to dosage regimen and Individualization of dosage regimen
 
Advanced Drug delivery systems
Advanced Drug delivery systemsAdvanced Drug delivery systems
Advanced Drug delivery systems
 
pharmacokinetic drug interactions
 pharmacokinetic drug interactions pharmacokinetic drug interactions
pharmacokinetic drug interactions
 
Bioequivalence study protocol
Bioequivalence study protocolBioequivalence study protocol
Bioequivalence study protocol
 

En vedette

Sedative Med Chem Lecture
Sedative Med Chem Lecture Sedative Med Chem Lecture
Sedative Med Chem Lecture sagar joshi
 
Antitussive Med chem Lecture
Antitussive Med chem LectureAntitussive Med chem Lecture
Antitussive Med chem Lecturesagar joshi
 
Antiparkinsonics Med chem lecture
Antiparkinsonics Med chem lecture Antiparkinsonics Med chem lecture
Antiparkinsonics Med chem lecture sagar joshi
 
Med chem Lecture on Cholinergics and anticholinesterases
Med chem Lecture on Cholinergics and anticholinesterasesMed chem Lecture on Cholinergics and anticholinesterases
Med chem Lecture on Cholinergics and anticholinesterasessagar joshi
 
Med chem lecture on Anti ulcer drugs
Med chem lecture on Anti ulcer drugsMed chem lecture on Anti ulcer drugs
Med chem lecture on Anti ulcer drugssagar joshi
 
Med chem lecture on Antihistaminicdrugs
Med chem lecture on AntihistaminicdrugsMed chem lecture on Antihistaminicdrugs
Med chem lecture on Antihistaminicdrugssagar joshi
 
Anxiolytics med chem Lecture
Anxiolytics med chem LectureAnxiolytics med chem Lecture
Anxiolytics med chem Lecturesagar joshi
 
Opiod analgesics Med Chem Lecture
Opiod analgesics Med Chem LectureOpiod analgesics Med Chem Lecture
Opiod analgesics Med Chem Lecturesagar joshi
 
Cns depressents
Cns depressents Cns depressents
Cns depressents sagar joshi
 
Anticholinergics Med Chem Lecture
Anticholinergics Med Chem LectureAnticholinergics Med Chem Lecture
Anticholinergics Med Chem Lecturesagar joshi
 
Antipsychotics Med chem lecture
Antipsychotics Med chem lecture Antipsychotics Med chem lecture
Antipsychotics Med chem lecture sagar joshi
 
Bioavailability and bioequivalence lecture
Bioavailability and bioequivalence lectureBioavailability and bioequivalence lecture
Bioavailability and bioequivalence lecturesagar joshi
 
Local anesthetic
Local anestheticLocal anesthetic
Local anestheticsagar joshi
 
Antidepressents Med Chem Lecture
Antidepressents Med Chem LectureAntidepressents Med Chem Lecture
Antidepressents Med Chem Lecturesagar joshi
 
Opiod Structure Activity Relationship
Opiod Structure Activity RelationshipOpiod Structure Activity Relationship
Opiod Structure Activity RelationshipSuji Susanth
 

En vedette (17)

Sedative Med Chem Lecture
Sedative Med Chem Lecture Sedative Med Chem Lecture
Sedative Med Chem Lecture
 
Antitussive Med chem Lecture
Antitussive Med chem LectureAntitussive Med chem Lecture
Antitussive Med chem Lecture
 
Antiparkinsonics Med chem lecture
Antiparkinsonics Med chem lecture Antiparkinsonics Med chem lecture
Antiparkinsonics Med chem lecture
 
Stimulants
Stimulants Stimulants
Stimulants
 
Med chem Lecture on Cholinergics and anticholinesterases
Med chem Lecture on Cholinergics and anticholinesterasesMed chem Lecture on Cholinergics and anticholinesterases
Med chem Lecture on Cholinergics and anticholinesterases
 
Med chem lecture on Anti ulcer drugs
Med chem lecture on Anti ulcer drugsMed chem lecture on Anti ulcer drugs
Med chem lecture on Anti ulcer drugs
 
Med chem lecture on Antihistaminicdrugs
Med chem lecture on AntihistaminicdrugsMed chem lecture on Antihistaminicdrugs
Med chem lecture on Antihistaminicdrugs
 
Anxiolytics med chem Lecture
Anxiolytics med chem LectureAnxiolytics med chem Lecture
Anxiolytics med chem Lecture
 
Opiod analgesics Med Chem Lecture
Opiod analgesics Med Chem LectureOpiod analgesics Med Chem Lecture
Opiod analgesics Med Chem Lecture
 
Cns depressents
Cns depressents Cns depressents
Cns depressents
 
Anticholinergics Med Chem Lecture
Anticholinergics Med Chem LectureAnticholinergics Med Chem Lecture
Anticholinergics Med Chem Lecture
 
Antipsychotics Med chem lecture
Antipsychotics Med chem lecture Antipsychotics Med chem lecture
Antipsychotics Med chem lecture
 
Bioavailability and bioequivalence lecture
Bioavailability and bioequivalence lectureBioavailability and bioequivalence lecture
Bioavailability and bioequivalence lecture
 
Antiarrhythmic drugs - drdhriti
Antiarrhythmic drugs - drdhritiAntiarrhythmic drugs - drdhriti
Antiarrhythmic drugs - drdhriti
 
Local anesthetic
Local anestheticLocal anesthetic
Local anesthetic
 
Antidepressents Med Chem Lecture
Antidepressents Med Chem LectureAntidepressents Med Chem Lecture
Antidepressents Med Chem Lecture
 
Opiod Structure Activity Relationship
Opiod Structure Activity RelationshipOpiod Structure Activity Relationship
Opiod Structure Activity Relationship
 

Similaire à Biopharmaceutics intro

Pharmacokinetics basics
Pharmacokinetics basicsPharmacokinetics basics
Pharmacokinetics basicsmeethy
 
General pharmacology intro
General pharmacology introGeneral pharmacology intro
General pharmacology introJehan Zeb Khan
 
General pharmacology intro
General pharmacology introGeneral pharmacology intro
General pharmacology introJehan Zeb Khan
 
Basic Pharmcology and Pharmacokinetics
Basic Pharmcology and PharmacokineticsBasic Pharmcology and Pharmacokinetics
Basic Pharmcology and PharmacokineticsPeter Branjerdporn
 
ADME in pharmacokinetics_pdf.pdf
ADME in pharmacokinetics_pdf.pdfADME in pharmacokinetics_pdf.pdf
ADME in pharmacokinetics_pdf.pdfSumit Sharma
 
DRUG ACTION- NURSING FOUNDATIONS.pptx
DRUG ACTION- NURSING FOUNDATIONS.pptxDRUG ACTION- NURSING FOUNDATIONS.pptx
DRUG ACTION- NURSING FOUNDATIONS.pptxSandhya C
 
Pharmacokinetics and pharmacodynamics.pptx
Pharmacokinetics and pharmacodynamics.pptxPharmacokinetics and pharmacodynamics.pptx
Pharmacokinetics and pharmacodynamics.pptxShelly Nayyar
 
General pharmacology Diploma in pharmacy second year
General pharmacology Diploma in pharmacy second year General pharmacology Diploma in pharmacy second year
General pharmacology Diploma in pharmacy second year YogeshShelake
 
Chapter 10 basic pharmaceutics
Chapter 10 basic pharmaceuticsChapter 10 basic pharmaceutics
Chapter 10 basic pharmaceuticsAnn Bentley
 
General Pharmacology part 02.pptx
General Pharmacology part 02.pptxGeneral Pharmacology part 02.pptx
General Pharmacology part 02.pptxMAYUR HARAL
 
2 - DRUG METABOLISM 2023.pptx
2 -  DRUG METABOLISM 2023.pptx2 -  DRUG METABOLISM 2023.pptx
2 - DRUG METABOLISM 2023.pptxEmmyKardianasari
 
An introduction to medication administration in english
An introduction to medication administration in englishAn introduction to medication administration in english
An introduction to medication administration in englishMY STUDENT SUPPORT SYSTEM .
 
principle of pharmacology
principle of pharmacologyprinciple of pharmacology
principle of pharmacologybahati_jr
 

Similaire à Biopharmaceutics intro (20)

Pharmacokinetics basics
Pharmacokinetics basicsPharmacokinetics basics
Pharmacokinetics basics
 
1 general pharmacology
1 general pharmacology1 general pharmacology
1 general pharmacology
 
General pharmacology intro
General pharmacology introGeneral pharmacology intro
General pharmacology intro
 
General pharmacology intro
General pharmacology introGeneral pharmacology intro
General pharmacology intro
 
MBBS Year 1 Intro to pharamcology 2016
MBBS Year 1 Intro to pharamcology 2016MBBS Year 1 Intro to pharamcology 2016
MBBS Year 1 Intro to pharamcology 2016
 
Pharmacokinetics and Pharmacodynamics
Pharmacokinetics and Pharmacodynamics Pharmacokinetics and Pharmacodynamics
Pharmacokinetics and Pharmacodynamics
 
Basic pharmco and kinetics
Basic pharmco and kineticsBasic pharmco and kinetics
Basic pharmco and kinetics
 
Basic Pharmcology and Pharmacokinetics
Basic Pharmcology and PharmacokineticsBasic Pharmcology and Pharmacokinetics
Basic Pharmcology and Pharmacokinetics
 
ADME in pharmacokinetics_pdf.pdf
ADME in pharmacokinetics_pdf.pdfADME in pharmacokinetics_pdf.pdf
ADME in pharmacokinetics_pdf.pdf
 
DRUG ACTION- NURSING FOUNDATIONS.pptx
DRUG ACTION- NURSING FOUNDATIONS.pptxDRUG ACTION- NURSING FOUNDATIONS.pptx
DRUG ACTION- NURSING FOUNDATIONS.pptx
 
Pharmacokinetics and pharmacodynamics.pptx
Pharmacokinetics and pharmacodynamics.pptxPharmacokinetics and pharmacodynamics.pptx
Pharmacokinetics and pharmacodynamics.pptx
 
1 Pharmacology Pharmacokinetics
1 Pharmacology   Pharmacokinetics1 Pharmacology   Pharmacokinetics
1 Pharmacology Pharmacokinetics
 
General pharmacology Diploma in pharmacy second year
General pharmacology Diploma in pharmacy second year General pharmacology Diploma in pharmacy second year
General pharmacology Diploma in pharmacy second year
 
chapter 2.pptx
chapter 2.pptxchapter 2.pptx
chapter 2.pptx
 
Chapter 10 basic pharmaceutics
Chapter 10 basic pharmaceuticsChapter 10 basic pharmaceutics
Chapter 10 basic pharmaceutics
 
General Pharmacology part 02.pptx
General Pharmacology part 02.pptxGeneral Pharmacology part 02.pptx
General Pharmacology part 02.pptx
 
2 - DRUG METABOLISM 2023.pptx
2 -  DRUG METABOLISM 2023.pptx2 -  DRUG METABOLISM 2023.pptx
2 - DRUG METABOLISM 2023.pptx
 
An introduction to medication administration in english
An introduction to medication administration in englishAn introduction to medication administration in english
An introduction to medication administration in english
 
Pharmacology
PharmacologyPharmacology
Pharmacology
 
principle of pharmacology
principle of pharmacologyprinciple of pharmacology
principle of pharmacology
 

Dernier

AUDIENCE THEORY -- FANDOM -- JENKINS.pptx
AUDIENCE THEORY -- FANDOM -- JENKINS.pptxAUDIENCE THEORY -- FANDOM -- JENKINS.pptx
AUDIENCE THEORY -- FANDOM -- JENKINS.pptxiammrhaywood
 
Philosophy of Education and Educational Philosophy
Philosophy of Education  and Educational PhilosophyPhilosophy of Education  and Educational Philosophy
Philosophy of Education and Educational PhilosophyShuvankar Madhu
 
Clinical Pharmacy Introduction to Clinical Pharmacy, Concept of clinical pptx
Clinical Pharmacy  Introduction to Clinical Pharmacy, Concept of clinical pptxClinical Pharmacy  Introduction to Clinical Pharmacy, Concept of clinical pptx
Clinical Pharmacy Introduction to Clinical Pharmacy, Concept of clinical pptxraviapr7
 
HED Office Sohayok Exam Question Solution 2023.pdf
HED Office Sohayok Exam Question Solution 2023.pdfHED Office Sohayok Exam Question Solution 2023.pdf
HED Office Sohayok Exam Question Solution 2023.pdfMohonDas
 
Quality Assurance_GOOD LABORATORY PRACTICE
Quality Assurance_GOOD LABORATORY PRACTICEQuality Assurance_GOOD LABORATORY PRACTICE
Quality Assurance_GOOD LABORATORY PRACTICESayali Powar
 
Practical Research 1: Lesson 8 Writing the Thesis Statement.pptx
Practical Research 1: Lesson 8 Writing the Thesis Statement.pptxPractical Research 1: Lesson 8 Writing the Thesis Statement.pptx
Practical Research 1: Lesson 8 Writing the Thesis Statement.pptxKatherine Villaluna
 
CAULIFLOWER BREEDING 1 Parmar pptx
CAULIFLOWER BREEDING 1 Parmar pptxCAULIFLOWER BREEDING 1 Parmar pptx
CAULIFLOWER BREEDING 1 Parmar pptxSaurabhParmar42
 
Presentation on the Basics of Writing. Writing a Paragraph
Presentation on the Basics of Writing. Writing a ParagraphPresentation on the Basics of Writing. Writing a Paragraph
Presentation on the Basics of Writing. Writing a ParagraphNetziValdelomar1
 
Benefits & Challenges of Inclusive Education
Benefits & Challenges of Inclusive EducationBenefits & Challenges of Inclusive Education
Benefits & Challenges of Inclusive EducationMJDuyan
 
Education and training program in the hospital APR.pptx
Education and training program in the hospital APR.pptxEducation and training program in the hospital APR.pptx
Education and training program in the hospital APR.pptxraviapr7
 
CapTechU Doctoral Presentation -March 2024 slides.pptx
CapTechU Doctoral Presentation -March 2024 slides.pptxCapTechU Doctoral Presentation -March 2024 slides.pptx
CapTechU Doctoral Presentation -March 2024 slides.pptxCapitolTechU
 
5 charts on South Africa as a source country for international student recrui...
5 charts on South Africa as a source country for international student recrui...5 charts on South Africa as a source country for international student recrui...
5 charts on South Africa as a source country for international student recrui...CaraSkikne1
 
How to Manage Cross-Selling in Odoo 17 Sales
How to Manage Cross-Selling in Odoo 17 SalesHow to Manage Cross-Selling in Odoo 17 Sales
How to Manage Cross-Selling in Odoo 17 SalesCeline George
 
The Stolen Bacillus by Herbert George Wells
The Stolen Bacillus by Herbert George WellsThe Stolen Bacillus by Herbert George Wells
The Stolen Bacillus by Herbert George WellsEugene Lysak
 
How to Use api.constrains ( ) in Odoo 17
How to Use api.constrains ( ) in Odoo 17How to Use api.constrains ( ) in Odoo 17
How to Use api.constrains ( ) in Odoo 17Celine George
 
Patterns of Written Texts Across Disciplines.pptx
Patterns of Written Texts Across Disciplines.pptxPatterns of Written Texts Across Disciplines.pptx
Patterns of Written Texts Across Disciplines.pptxMYDA ANGELICA SUAN
 
How to Add a many2many Relational Field in Odoo 17
How to Add a many2many Relational Field in Odoo 17How to Add a many2many Relational Field in Odoo 17
How to Add a many2many Relational Field in Odoo 17Celine George
 
The Singapore Teaching Practice document
The Singapore Teaching Practice documentThe Singapore Teaching Practice document
The Singapore Teaching Practice documentXsasf Sfdfasd
 
Diploma in Nursing Admission Test Question Solution 2023.pdf
Diploma in Nursing Admission Test Question Solution 2023.pdfDiploma in Nursing Admission Test Question Solution 2023.pdf
Diploma in Nursing Admission Test Question Solution 2023.pdfMohonDas
 

Dernier (20)

AUDIENCE THEORY -- FANDOM -- JENKINS.pptx
AUDIENCE THEORY -- FANDOM -- JENKINS.pptxAUDIENCE THEORY -- FANDOM -- JENKINS.pptx
AUDIENCE THEORY -- FANDOM -- JENKINS.pptx
 
Philosophy of Education and Educational Philosophy
Philosophy of Education  and Educational PhilosophyPhilosophy of Education  and Educational Philosophy
Philosophy of Education and Educational Philosophy
 
Clinical Pharmacy Introduction to Clinical Pharmacy, Concept of clinical pptx
Clinical Pharmacy  Introduction to Clinical Pharmacy, Concept of clinical pptxClinical Pharmacy  Introduction to Clinical Pharmacy, Concept of clinical pptx
Clinical Pharmacy Introduction to Clinical Pharmacy, Concept of clinical pptx
 
HED Office Sohayok Exam Question Solution 2023.pdf
HED Office Sohayok Exam Question Solution 2023.pdfHED Office Sohayok Exam Question Solution 2023.pdf
HED Office Sohayok Exam Question Solution 2023.pdf
 
Quality Assurance_GOOD LABORATORY PRACTICE
Quality Assurance_GOOD LABORATORY PRACTICEQuality Assurance_GOOD LABORATORY PRACTICE
Quality Assurance_GOOD LABORATORY PRACTICE
 
Practical Research 1: Lesson 8 Writing the Thesis Statement.pptx
Practical Research 1: Lesson 8 Writing the Thesis Statement.pptxPractical Research 1: Lesson 8 Writing the Thesis Statement.pptx
Practical Research 1: Lesson 8 Writing the Thesis Statement.pptx
 
CAULIFLOWER BREEDING 1 Parmar pptx
CAULIFLOWER BREEDING 1 Parmar pptxCAULIFLOWER BREEDING 1 Parmar pptx
CAULIFLOWER BREEDING 1 Parmar pptx
 
Presentation on the Basics of Writing. Writing a Paragraph
Presentation on the Basics of Writing. Writing a ParagraphPresentation on the Basics of Writing. Writing a Paragraph
Presentation on the Basics of Writing. Writing a Paragraph
 
Benefits & Challenges of Inclusive Education
Benefits & Challenges of Inclusive EducationBenefits & Challenges of Inclusive Education
Benefits & Challenges of Inclusive Education
 
Education and training program in the hospital APR.pptx
Education and training program in the hospital APR.pptxEducation and training program in the hospital APR.pptx
Education and training program in the hospital APR.pptx
 
CapTechU Doctoral Presentation -March 2024 slides.pptx
CapTechU Doctoral Presentation -March 2024 slides.pptxCapTechU Doctoral Presentation -March 2024 slides.pptx
CapTechU Doctoral Presentation -March 2024 slides.pptx
 
5 charts on South Africa as a source country for international student recrui...
5 charts on South Africa as a source country for international student recrui...5 charts on South Africa as a source country for international student recrui...
5 charts on South Africa as a source country for international student recrui...
 
How to Manage Cross-Selling in Odoo 17 Sales
How to Manage Cross-Selling in Odoo 17 SalesHow to Manage Cross-Selling in Odoo 17 Sales
How to Manage Cross-Selling in Odoo 17 Sales
 
The Stolen Bacillus by Herbert George Wells
The Stolen Bacillus by Herbert George WellsThe Stolen Bacillus by Herbert George Wells
The Stolen Bacillus by Herbert George Wells
 
How to Use api.constrains ( ) in Odoo 17
How to Use api.constrains ( ) in Odoo 17How to Use api.constrains ( ) in Odoo 17
How to Use api.constrains ( ) in Odoo 17
 
Patterns of Written Texts Across Disciplines.pptx
Patterns of Written Texts Across Disciplines.pptxPatterns of Written Texts Across Disciplines.pptx
Patterns of Written Texts Across Disciplines.pptx
 
How to Add a many2many Relational Field in Odoo 17
How to Add a many2many Relational Field in Odoo 17How to Add a many2many Relational Field in Odoo 17
How to Add a many2many Relational Field in Odoo 17
 
The Singapore Teaching Practice document
The Singapore Teaching Practice documentThe Singapore Teaching Practice document
The Singapore Teaching Practice document
 
Personal Resilience in Project Management 2 - TV Edit 1a.pdf
Personal Resilience in Project Management 2 - TV Edit 1a.pdfPersonal Resilience in Project Management 2 - TV Edit 1a.pdf
Personal Resilience in Project Management 2 - TV Edit 1a.pdf
 
Diploma in Nursing Admission Test Question Solution 2023.pdf
Diploma in Nursing Admission Test Question Solution 2023.pdfDiploma in Nursing Admission Test Question Solution 2023.pdf
Diploma in Nursing Admission Test Question Solution 2023.pdf
 

Biopharmaceutics intro

  • 2. Core Areas of Pharmacy 1. Drug Design Involves designing and synthesizing compounds to find a specific chemical substances that will cure, manage or prevent diseases: Cancer, AIDS, Ebola 2. Drug Formulation Mix various chemical compounds with the drug to create Tablet ,Suspension, Emulsion, Injection. (These chemicals should not react with drug) 3. Drug Dispensing Give the right drug to the right patient in right dose and duration with sufficient counseling (Biopharmaceutics has application on all three above) 4. Others (manufacturing,marketing and regulatory issues)
  • 3. Drug? • Drug is a specific organic compound which has therapeutic effect (forget inorganic drugs like MgOH from now on) Metformin Diabetis Imatinib Cancer Lidocaine Local Anesthetic Paracetamol Anti-inflamatory Nelfinavir AIDS Omeprazole Ulcer
  • 4. Paracetamol Anti-inflamatory •How to consume? •How much to consume? •What happens if instead of 3 tablets, we take 6 or 9 tablets of paracetamol on hopes of better or quicker recovery? •How about we share a single tablet between two person? •How much is too much or too less? Understanding “Bio” in biophamaceutics
  • 5. First of all….Pharmaceutics • Pharmaceutics is science dealing with drug formulation • Drug formulation means process of mixing drug with other chemicals to prepare a physical form which facilitates convenient dosing(intake) for patients • That physical forms are Tablets, suspension, emulsion, syrup or solutions. This is also called oral dosing
  • 7. Basic understanding of drug formulation Formula of Paracetamol tablets •Drug is never given in pure form but as an intended mixture with other chemicals to help attain a physical form •These other chemicals are called excipient •Excipients don’t react with each other or with the drug
  • 8. There are many choices for various excipient classes from which many formulation of same drug in same strength can be made Excipient Fillers/Diluent (Allows making a sizable tab if drug content is very less) Lactose,lactose anhydrous, lactose spray dried, directly compressible starch,hydrolyzed starch, MCC, other cellulose derivatives, dibasic calcium phosphate dihydrate, mannitol, sorbitol, sucrose, calcium sulfate dehydrate, dextrose. Binders (allow drug power to be compressed into a solid tablet) cellulose, methyl cellulose, polyvinyl pyrrolidine, PEG, gelatin, PVP, HPMC, PEG, sucrose, starch Disintegrating agent (breaks hard solid tab to free the power drug from tablet) starch derivatives, clay, cellulose, alginates, PVP, cross linked Na CMCVeegum HV and Betonite PVP, CMC ,crospovidone, Sodium bicarbonate Lubricant Stearic acid, stearic acid salt, stearic acid derivatives, talc, PEG, surfactants,waxes, Calcium stearate and magnesium stearate poly ethylene glycol Glidant talc, colloidal silicone dioxide, corn starch
  • 9. First thing to do….. • Understand that ALL drugs must be present in blood/plasma to show effect (excluding topically (skin, eye, ear) applied creams, gels etc) • Depending on drug concentration in plasma either of three results: no effect, therapeutic effect, side/toxic effect of drug • This information is the first thing obtained during drug Human trials. Thus we already know how much drug must be present in blood for therapeutic effect to occur • When we take a single dose, our interest is to provide just enough drug to keep the drug conc within the therapeutic region No effect Therapeutic effect Toxic effect Effect of Increasing blood concentration on blood
  • 10. Secondly, think about the time course of a drug The drug conc in plasma varies continuously after we take a single dose We cannot keep on maintaining drug conc in the therapeutic region by only a single dose. Thus we need to give another dose But what factors are making drug concentration to decrease and How to know when to give another dose?????
  • 11. • To make sense of above graph following phenomenon have to be considered – Absorption – drug enters blood circulation by process of diffusion – Metabolism – drug structure is enzymatically altered – Distribution – drug is distributed from blood to fat, muscle, organs – Elimination – Drug is thrown out from body • Study of these 4 parameters is called pharmacokinetics
  • 12. Think about this!!! • Now that we know what is the range of conc for a drug to be in body, we could simply calculate the amount of drug in a single dosage form • Eg if paracetamol is to be maintainted at 50mg/Lt plasma volume…considering an avg of 2.7 lt of plasma in body, we could say that a single PCM tablet needs to have 50X2.7= 135 mg • However this type of assuption is wrong. Determining amount of drug in a single dose is not that simple because the body does not behave like a vessel containing 2.7 lt of solvent. • Body presents a dynamic environment to a drug where the conc of drug is continuously changing
  • 13. Understanding Absorption Absorption occurs when drug dissolved in intestine diffuses through the epithelium and into the capillaries (which is hepatic portal vein which takes the drug to the liver) (Notice the blood capillaries into where drug diffuses)
  • 14. Diffusion • The spontaneous movement of solutes from high to low conc until equilibrium is diffusion. It occurs in solution only. • For purposes to study drug diffusion in body we consider diffusion in the scenario where there are two compartments, left being stomach and right being blood, and both being separated by the lipophillic cell membrane epithelium Let this compartment represent drug dissolved in stomach fluid Let it represent drug dissolved in capillary blood/plasma Epithelium cell membrane
  • 15. Two opposing characteristic for good absorption • Diffusion through the epithelium requires crossing the cell membrane of the epithelium which is lipophilic barrier. This requires drug to have such structure which gives it good lipophillicity. • But since diffusion occurs only in solution, drug must dissolve into the stomach fluid first. This requires drug to have such structure which gives it good hydrophillicity. • (remember hydrophillicity and lipophillicity depend are physiochemical properties that solely depend on drug structure) But drug is in form of a tablet. So how does a tablet dissolve?
  • 16. Disintegrating agent! • A tablet is a relatively hard substance. We swallow it whole without chewing. That sounds problematic (coz we always chew our food to make digestion easy) but there are chemicals added into the tablets called disintegrating agent (in above Crosspovidone and Sod bicarbonate) which swells up when in contact with water and this causes tablet to break apart spontaneously. • (Show tablet disintegration in a glass of water)
  • 17. Show tablet disintregation in water • Put various brands of 500mg paracetamol tablets in water and observe that – Tablet spontaneously breaks apart due to the disintegrating agent soaks up water and expands, thus causing tablet to break – various brands disintegrate at different time and to different degree • This diff is due to diff in formulation which be as we saw there are multiple choice for particular excipients
  • 18. Understanding Absorption is important because…. • Many drugs have failed to be orally active because they were too soluble and thus cant permeate through the cell membrane • Or they were too lipophillic and can’t dissolve in stomach fluid (remember: diffusion requires drug to dissolve in aqueous stomach fluid) • Point is…..just cause we consume a drug doesn’t mean there is guarantee of being absorbed (however, for such problematic drugs, formulation enhancement cab be done which we will study later in course)
  • 19. Metabolism We saw that drug in a tablet disintregates into smaller particles and then dissolves to the extent depending on its solubility which then diffusion through the epithelium into the capillary. But it hasn’t quiet reached systemic circulation • This capillary is names hepatic portal vein which goes to the liver and then to the heart. As it flows through the liver the drug are acted upon by special enzymes (other than those involved in biological reactions) dedicated to destroying endogenous substances. • This is metabolism and it happens primarily in the liver • The first time this happens is called 1st pass metabolism and only applies to oral drugs
  • 20. Metabolism of paracetamol • Notice that paracetamol structure changes- that is metabolism • These metabolized products generally lack any therapeutic use • And are more water soluble for easy removal by urine Although it might seem that metabolism is a bad thing in that it destroys our drug, We can overcome it by simply consuming more dose in compensation. Orally we can take about 1gm dose. Any more compensation and the tablet would be too big to swallow Also later on we will incredibly exploit this process in our favor in prodrugs
  • 21. • Body responds to all endogenous substances, poison or drugs, as if it were a threat and wants to detoxify them and clear them out of body • The enzymes alter the drug structure so that the product is more water soluble. • The increased water solubility is important since the main path to clear the drug is through urine. Thus the more soluble in urine, more quickly drug can be cleared. • Metabolism is another reason that any oral dose does not fully reach the plasma as they get changed into a diff compound along the way, even if absorption was very good • If liver get diseased causing reduced metabolism of drugs then more drug are able to enter into the body. This over exposure can cause toxic conc to build up!
  • 22. Elimination • Elimination can be seen as a two stage process – 1st drug is metabolized by the liver into more water soluble form – 2nd as blood flows through kidney, the now more water soluble form is excreted (filtered) into the urine (an aqueous fluid) • The more quickly elimination occurs, more quickly we need another dose and vice versa • Understand that without metabolism, excretion can difficult cause drugs are mostly lipophilic • So now we know that a drug action can’t be forever cause it gets either destroyed by liver or excreted by kidney • If kidney is damaged resulting in less filtration , than drug stays in body for longer period of time! • But what about giving drug to patients with both liver and kidney damage?
  • 23. Metabolism worked together with urinary excretion Elimination also occurs through bile Oxidation and conjugation are two types of metabolism that we will study later Polar Metabolite go to urine
  • 24. Distribution Once drug passes through the liver it enter blood circulation and can go everywhere the blood carries it
  • 25. Distribution Distribution takes place once drug has entered blood. As the pic demonstrates of the given 10mg, only 1 mg is seen in the plasma. Thus drug does not localized in the blood but can distribute itself out of circulation into tissues, fat and even be bound to plasma protein. Distribution is a problematic because, it lowers the conc of drug in plasma and it is conc of drug and not the amount which determine Once in blood , drug can go to all places inside body
  • 26. Long acting drug!!! • An important concept is that distribution follows dynamic equilibrium. • Once distributed drug does not keep being trapped in fat, tissues or plasma protein • As the free drug in the plasma is metabolized and excreted, the vacancy in plasma causes the distributed drug to again come back to plasma • In this way distributed drugs act like a reservoir which sustains the conc in the plasma • This can be exploited to make drugs with high distribution so that they remain the body for a long period of time compared to drugs that have low distribution (there is still no way to avoid metabolism and excretion but this way drug can act for a longer time period)
  • 27. Conclusion • We want drug to be within predefined conc range in blood but we can’t simply treat body as a 5 lt vessel of blood. • There are barriers for drug to maintain sufficient concentration in plasma, in that they make sure that not all the given dose can be reaches plasma (absorption) and those that do reach plasma have difficult maintaining the therapeutic concentration as drug is being structurally altered (metabolism), diluted (distribution), kicked out from the body (elimination) • Thus we need to account for all these factors and decide what should be the dose and frequency for every drug cause these drugs have variable ADME • This is the true essence of Biopharmaceutics
  • 29. • Biopharmaceutics is defines as the study of factors influencing the rate and amount of drug that reaches the systemic circulation and the use of this information to optimize the therapeutic efficacy of drug products • Biopharmaceutics concerns making such a formulation of drug and defining its frequency of dosing, by consideration of the ADME of a drug,which ensures that the amount of drug in a single dose (and repeated doses) achieves (and then is maintained) in therapeutic drug conc in plasma
  • 30. • Pharmacokinetics is the study of time course of drug ADME, and their relationship with it’s therapeutic, toxic effects of drug • Eg of Pharmacokinetic manipulation, Distribution based -Vit k gelatin capsule is dosed at 60000 IU. Normal everyday dose is about 300-500IU. Thus 60 K IU sounds to much (too much of anything is bad!!!) but won’t be cause vit k being lipophillic gets stored in fat which is released slowly in blood thus not only acting like a reservoir of vit k but also ensuring small conc in blood. It means vit k can be dosed once weekly but still body gets the needed amount everyday
  • 31. At last…. • A challenge in BioPham is to come up with a method to predict time dependent changes in drug conc • They have been able to do that by building some mathematical models (ie equation) that can predict what would a drug conc be in any time in body (Don’t be afraid of the math portion. It’s the theory that will be harder to comprehend. You probably solved many tough problems based on equation of motion; it is similar. There are some equation and u just need to understand which one to use where)