This document discusses the key concepts of pharmacokinetics including absorption, distribution, metabolism, and excretion of drugs in the body. It defines each process and describes mechanisms of absorption such as passive diffusion, carrier-mediated transport, and specialized transport. Metabolism involves phase 1 and phase 2 reactions that make drugs more water soluble for excretion. Drugs are excreted primarily through glomerular filtration, tubular reabsorption, and tubular secretion in the kidneys. Important pharmacokinetic parameters are also outlined that characterize a drug's behavior over time in the body.

1. PHARMACOKINETICS
Mr. Santosh Sopanrao Sarnaik
M.S. Pharmaceutics
CEO Of Only Pharmacy

2. INTRODUCTION
• Study of absorption, distribution, metabolism and excretion
• It refers to time course of drug in through and out of the body
• Absorption is refers to its entry from site of administration to systemic circulation
• Distribution is the reversible transfer of drug between body compartment
• Metabolism is chemical alteration of the drug
• Excretion is the irreversible process of removal of drug from the body
• Pharmacokinetic parameter are very important in dosage regimen

3. ABSORPTION
• Absorption is refers to its entry from site of administration to systemic
circulation
• For hydrophilic drugs drug absorption is the rate limiting step
• For lipophilic drugs dissolution is the rate limiting step
• For control release drug delivery system drug release is rate limiting step
• Decrease in particle size increase in surface area increase in dissolution increase
in absorption and vice versa in case of hydrophobic drugs

4. MECHANISM
Passive
diffusion
Carrier
mediated
transport
Specialise
transport
Filtration

5. PASSIVE DIFFUSION
• From higher concentration to the lower concentration
• Towards concentration gradient
• Does not require energy
• 90% of the drug are absorbed by this mechanism
• Lipid soluble drug are absorbed

6. FILTRATION
Biological membrane is the semipermeable membrane
Small pores are there in membrane
If the drug size is less than the pore of the membrane then drug can pass and the
process called filtration
For hydrophilic drugs

7. CARRIER MEDIATED DIFFUSION
• Carrier are the transporters for drug molecule
• Carrier are the proteins
• They are again of two types :-
Active diffusion Passive diffusion

8. ACTIVE DIFFUSION
• From lower concentration to the higher concentration
• Require energy
• Against concentration gradient
• Carrier take the drug and release them into plasma and returned to its original
position
• Carrier is saturable

9. FACILITATED DIFFUSION
• From lower concentration to the higher concentration
• Does not require energy
• Towards concentration gradient
• Carrier take the drug and release them into plasma and returned to its original
position
• Carrier is saturable

10. SPECIALISED TRANSPORT
Phagocytosis Pinocytosis

11. PHAGOCYTOSIS
• Invagination of the membrane
• Cell eating

12. PINOCYTOSIS
• Invagination of the membrane
• Cell drinking

13. DISTRIBUTION
• Distribution is the reversible transfer of drug between body compartment
• Drug is distributed between tissue and organs
• Higher the lipid solubility higher is the distribution
• Lower the protein binding higher is the distribution
• Distribution depends on the pathological condition of the tissue

14. VOLUME OF DISTRIBUTION
• Vd= dose/plasma conc
• Volume of distribution is the hypothetical volume of plasma where drug is
distributed
• Chloroquine has 13000 litre
• Higher the lipid solubility higher is the distribution
• Lower the protein binding higher is the distribution

15. METABOLISM
• Metabolism is chemical alteration of the drug
• Main aim of metabolism is the to make the drug water soluble
• Metabolism done following :-
Active to
active
Active to
inactive
Inactive to
active
Non polar
to polar
Unionised
to ionised

16. METABOLIC REACTION
Phase
1
Phase
2
Oxidation
Reduction
Hydrolysis
Cyclisation
Decyclisation
Glucoronidation
Glutathione
Acetylation
Methylation
Sulphation

17. DRUGS AFFECTING THE METABOLISM
Inhibitor Inducer
Chloramphenicol
Allopurinal
Cimetidine
MAO inhibitor
Corticosteroids
Erythromycin
Ciprofloxacin
Phenobarbital and other barbiturate
Rifampicin
Phenytoin
Ethanol
Carbamazepine

18. EXCRETION
• Excretion is the irreversible process of removal of drug from the body
• Distribution + Metabolism+ Excretion= Disposition
• Metabolism + Excretion= Elimination
• Polar/water soluble/ionised drug are excreted from body
• Excretion done by the following process
Glomerular filtration
Tubular reabsorption
Tubular secretion

19. GLOMERULAR FILTRATION
• Except protein bound drug all drugs are filtrated
• Nephron is the functional unit of the kidney
• Glomerular filtration rate = 125ml/min
• 180 litre/day
• 99% reabsorbed from the tubular reabsorption
• 1.8 litre urine/day

20. TUBULAR REABSORPTION
• Only lipid soluble can reabsorbed
• Water soluble are filtered
• Poisoning of acid drug require base drug i.e ionised form and vice versa
• 99% reabsorbed

21. TUBULAR SECRETION
• Tubular secretion is the transfer of materials from peritubular capillaries to renal
tubular lumen
• Some pumps are there from drug is secreted
• Ex penicillin

22. PHARMACOKINETIC PARAMETERS
• Cmax
• Tmax
• AUC
• Onset of action
• Duration of action
• Termination of action
• Therapeutic range

23. CONT
• Minimum effective concentration
• Maximum safe concentration
• Bioavailability
• Subtherapeutic level

24. Thank you!