Absorption and Factors Affecting Absorption Pharmacology B pharmacy

2. Pharmacokinetics
 Pharmaco-drug
 Kinetics-movement
 It is the branch of pharmacologyconcerned with the
movement of drug in the bodyor study about [ADME]
 Basicallyit is what drug does to the body.
 It involve four process;
a] Absorption
b] Distribution
c] Metabolism
d] Excretion

3. Absorption
❑ It is defined as the movement of drug molecules
from its site of administration to the systematic
circulation .
❑ it is first and important step of pharmacokinetics
❑ When we take any drug through oral route, it goes
into stomach in which it get disintegrate and
dissolution take place then drug reach into intestine.
❑Now , after dissolution drug absorb into blood from
intestine /stomach through membrane.

4. Membrane
❖ It is a biological membrane which is made up with
phospholipids and cholesterol and other groups
❖ It act as a semi permeable membrane..
❑Now, drug reaches into systematic circulation through
membrane transport
Which are following
1] Passive Transport
2] Active Transport
3] Facilitated Transport
4] Endocytosis
 Concentration gradient: when any drug/substance move
from high concentration to lower concentration.

5. 1] passive transport
 Also known as passive diffusion
 In this transport ,drug/substance move across the cocentration
[high to low]
 Most of the drug are absorb by active diffusion

6. 2] facilitated transport
 In this transport drug molecules move across the
concentration gradient ,but with the help of any carrier
bodies.
 Some large molecules or poorly diffusible substance
does not pass through passive transport , so they
required help of any carrier body to cross the
membrane
 Carrier such as SLS[solute carrier transporter]

7. 3] active transport
 In this transport , drug molecules move against the
concentration gradient[low to high]
 It required energy due to movement of drugs against
the concentration gradient
 ATP is used.

8. 4] Endocytosis
 In this transport , drugs of very large size get transport
via engulfment by cell membrane
 Due to large size ,they do not cross membrane and also
not fit in any channel

9. Factors affecting absorption
Physiochemical properties
1] ParticleSize [Drug Molecules]
2] Formulation[dosageForm]
3] ionisation
4] Ph
5] Lipid SolubilityAnd Concentration
biologicalfactor
1]surface Area
2]membrane Transport
3]gastric Emptying Time
4]blood Flow[circulation]
5]food
Routeof administration [ bioavailabilityand first pass metabolism]

10. 1]physiochemical Properties
 1] particle size: it is inverslly proportional tothe absorption.
 particlesize
 Thesmallerthe particlesize ,thegreaterwill be itsabsorptionbecause
small size drug particles dissolveeasily.
 2] formulation: in solid,liquid,parental[injection]
 Parental.>liquiddosageform ……..>solid
 3] ionisation : we all know that ,both form [ionised+unionised]are
importantfor pharmacological responseof drugs ,but for absorption
drug must be in unionizedform.
 4] ph: it tell about natureof drug[acidic/basic]
 Acidic drug must absorbed in stomach EG.ASPIRIN
 Basic drug must absorbed in intestineEG. MORPHINE
 5] lipid solubility : lipophilicnature’sdrug has slightlyhigher
absorptionthan hydrophilic, because in membrane transportlipid
solubledrug cross membraneeasily
 6] concentration : we know thatpassivediffusion follow concentration
gradient,so highertheconcentrationof drugs thegreaterwill its
absorption.

11. 3] Route Of Administration
 This affect drug absorption,because each route has its own
characteristics.
 Route of absorption affect bioavailibility of drug
 Bioavailibility:it is the actual amount of drug ,which
reach into the systematic circulation.
 Parental route has max.bioavaibility [drug absorb maximum]
 In intravenous ,drug directly release into blood ,so their absorption
and bioavalibily is 100 %.
 in subcutaneous /intramuscular ,drug injected near the capillaries
also have great absorption and bioavailibility.
 Enternal [oral] has less bioavailibility and absorption ,because it
follow first past metabolism drug passes through liver which
decrease the absorotion

13. 2] BIOLOGICAL FACTORS
 1] surface area : area of absorbing surface .itsis directlyproportional
to the absorption.so, thelargerthe surface area for absorbing drug,the
greaterwill be itsabsorption.
 2]membrane transport:mostof thedrug absorb throughpassive
diffusion because it does not requireenergyor anything .and also
followconcentrationgradient.
 3]Gastric emtying time : thosedrug whosegastricemptying time is
more[fast] theirrateof absorptionis high .but time is nottoo fast
,otherwisedrug is excrete withoutabsorption . So it isat optimum time.
 4] blood flow circulation: directlyproportional the more blood flow
in body ,thegreaterwill be absorptionof drug.
 5]food : it will also affect theabsorptionof drug . If the food is present
insidethestomach ,then it dilutethedrug and absorption will be
decreases .so, take medicineaftersome timeof meal.