SlideShare a Scribd company logo
Pharmacokinetic
Overview
The intensity of the
drug's effect, and the
duration of the drug
action are controlled by
four fundamental
pathways of drug
movement and
modification in the body.
Figure: Schematic representation of
drug absorption, distribution,
metabolism and elimination.
First, drug absorption from the site of administration
permits entry of the therapeutic agent (either directly or
indirectly) into plasma (input). Absorption is defined as
the passage of a drug from its site of administration
into the plasma.
Second, the drug may then reversibly leave the blood
stream and distribute into the interstitial and
intracellular fluids (distribution).
Third, the drug may be metabolized by the liver,
kidney, or other tissues.
Finally, the drug and its metabolites are eliminated
from the body (output) in urine, bile, or feces.
Routes of drug administration
The route of administration is determined primarily
- by the properties of the drug (such as water or lipid
solubility, ionization, etc.) and
- by the therapeutic objectives (for example, the
desirability of a rapid onset of action or the need for
long-term administration or restriction to a local site).
The route of administration (ROA) that is chosen may
have a profound effect upon the speed and efficiency
with which the drug acts.
Enteral: oral, sublingual,
rectal
Parenteral: intravascular
(intravenous), intramuscular,
subcutaneous
Other: inhalation, intranasal,
intrathecal (in CSF), topical,
transdermal
The main routes of drug administration are:
Figure: Commonly used routes of drug
administration.
PPT_-_Pharmacokinetics.ppt
Enteral routes:
Drug placed directly in the GI tract:
Oral- swallowing
Sublingual- placed under the tongue
Rectum- absorption through the rectum
Oral
Giving a drug by mouth is the most common route of
administration but it is also the most variable, and
requires the most complicated pathway to the tissues.
Little absorption occurs until the drug enters the small
intestine.
Drug absorption from the intestine:
The drug absorbed by passive transport mechanism in
intestine at a rate determined by the ionization and
lipid solubility of the drug molecules.
Strong bases of pKa 10 or higher are poorly absorbed,
as are strong acids of pKa less than 3, because they
are fully ionized.
Figure: Absorption of drugs from the intestine, as a function of pKa,
for acids and bases.
Weak acids and bases are well absorbed; strong acids and bases
are poorly absorbed.
There are a few instances where intestinal absorption
depends on carrier-mediated transport mechanism
rather than simple lipid diffusion.
For example levodopa, iron, calcium.
Advantages:
Convenient- can be self-administered, pain free, easy
to take
Absorption- takes place along the whole length of the
GI tract
Cheap- compared to most other parenteral routes
Disadvantages:
- Unpleasant taste of some drugs
- Irritation to gastric mucosa - nausea and vomiting
- Destruction of drugs by gastric acid and digestive
juices
- Sometimes inefficient- only part of the drug may be
absorbed
- Effect too slow for emergencies
- First-pass effect - drugs absorbed orally are initially
transported to the liver via the portal vein
- Unable to use in unconscious patient or who have
had GI surgery
Most of the drug is absorbed in the small intestine,
Why?
1. Small intestine has a much larger surface area for
absorption (~200 m2) as compared to the stomach
(~1-3 m2).
2. Drug spends more time in the small intestine (~4
hrs) than the stomach (~0.5-1 hrs).
Food in the stomach can decrease absorption
- Food may delays gastric emptying time so that drugs
may destroyed by acid.
- Interactions between drug and food particles.
- Exception: propranolol- due to  blood flow.
First-pass effect
When a drug is absorbed across the GI tract, it enters
the portal circulation before entering the systemic
circulation.
A drug can be metabolized in the gut wall or even in
the portal blood, but most commonly it is the liver that
is responsible for metabolism before the drug reaches
the systemic circulation (plasma). In addition, the liver
can excrete the drug into the bile (fluid secreted by
liver).
Any of these sites can contribute to this reduction in
bioavailability, and the overall process is known as
first-pass effect or first-pass elimination.
Portal circulation
Figure: First-pass effect
The greater the first-pass effect, the less the agent will
reach the systemic circulation when the agent is
administered orally. (imp)
Lidocaine (anesthetic agent) is a drug with a first-pass
effect that is so great that oral administration is not
practical.
In the case of propranolol, a significant portion of the
orally administered dose is metabolized through a first-
pass effect.
More than 90% of nitroglycerin is cleared during a
single passage through the liver.
Therefore, a much larger oral dose is required to
achieve the same therapeutic response as that
obtained from a dose administered intravenously.
Sublingual/Buccal
Placement under the tongue allows the drug to diffuse
into the capillary network and therefore to enter the
systemic circulation directly.
When only small amounts of drugs are required to gain
access to the blood, the sublingual route may be very
satisfactory.
For example, nitroglycerin in angina pectoris.
Because the stomach is bypassed, acid-liability and
gut-permeability is not important.
Drugs are absorbed from the mouth straight into the
systemic circulation without entering the portal system
and so escape first-pass metabolism by the liver.
Advantages
-rapid absorption
-drug stability
-avoid first-pass effect
Disadvantages
-inconvenient
-small doses
-unpleasant taste of some drugs
Rectal
50% of the drainage of the rectal region bypasses the
portal circulation; thus the biotransformation of drugs
by the liver is minimized.
Drug’s property:
- Non-polar
- Lipid soluble
- Devoid of destruction of the drug by intestinal
enzymes or by low pH in the stomach
- Unconscious patients (postoperative) and children
- If patient is nauseous or vomiting
- Absorption may vary
- Good for drugs affecting the bowel such as laxatives
- Irritating drugs contraindicated
- Can be used for both local effects and systemic
effects
Parenteral routes:
Parenteral administration is used for drugs that are
poorly absorbed from the gastrointestinal (GI) tract,
and for agents such as insulin that are unstable in the
GI tract.
Parenteral administration is also used for treatment of
unconscious patients and under circumstances that
require a rapid onset of action.
The three major parenteral routes are
- Intravascular (intravenous or intra-arterial)
- Intramuscular
- Subcutaneous
PPT_-_Pharmacokinetics.ppt
Intravascular:
Intravenous (IV) injection is the most common
parenteral route. For drugs that are not absorbed
orally, there is often no other choice.
- Rapid onset of action because the drug is injected
directly into the bloodstream
- Useful in emergencies and in patients that are
unconscious
- The drug avoids the GI tract and first-pass
metabolism by the liver
- Smaller doses generally are required than the other
routes but cost is high
Greater risk of adverse effects as:
a. High concentration attained rapidly
b. That are injected cannot be recalled by
strategies such as emesis or binding to activated
charcoal
c. Risk of embolism (obstruction of blood vessel)
d. May introduce bacteria through contamination,
induce hemolysis
e. Pain at application site
f. No self administration facility
Capillary: brings the blood into intimate relationship with the tissue cell
Artery Arterioles Capillary VenulesVeins
Intra-artery
Similar properties, advantages and disadvantages of
intravascular route. Intra-artery route is specially used
when high drug concentration in specific tissue is
required than other tissue:
- diagnostic purpose and
- for chemotherapy
Intramuscular
Drugs administered intramuscularly can be aqueous
solutions or specialized depot preparations- often a
suspension of drug in a non-aqueous vehicle, such as
ethylene glycol or peanut oil.
Absorption of drugs in aqueous solution is fast,
whereas that from depot preparations is slow. Drug
passes through capillary walls to enter the blood
stream.
- Pain at injection sites for certain drugs
- This parenteral route may be used when an
immediate effect is not required but a prompt effect is
desirable
- Absorption from an intramuscular depot is more
predictable and uniform than from a subcutaneous site
Subcutaneous
Drug is injected beneath the skin and permeates
capillary walls to enter blood stream.
Absorption from the site of injection is dependent on
local blood flow. Concurrent administration of
vasoconstrictor will slow absorption.
For example, minute amount of epinephrine is
sometime used in combination with a drug to restrict
its area of action. Epinephrine acts as a local
vasoconstrictor and decreases removal of a drug,
such as lidocaine (local anesthetic), from the site of
administration.
Examples of drugs given by this route are insulin and
sodium heparin, neither of which is absorbed orally,
and both of which should be absorbed slowly over
many hours.
Inhalation
Inhalation provides the rapid delivery of a drug across
the large surface area of the mucous membranes of
the respiratory tract and pulmonary epithelium,
producing an effect almost as rapidly as by
intravenous injection.
This route of administration is used for drugs that are
gases and volatile agents (for example, some
anesthetics), or those that can be dispersed in an
aerosol.
The route is particularly effective and convenient for
patients with respiratory complaints (for example,
asthma or chronic obstructive pulmonary disease) as
drug is delivered directly to the site of action and
systemic side effects are minimized.
Topical
Topical application is used when a local effect of the
drug is desired.
Used for most dermatologic and ophthalmologic
preparations.
Clotrimazole is applied as a cream to the skin in the
treatment of dermatophytosis.
Atropine is instilled directly into the eye to dilate the
pupil and permit measurement of refractive errors.
Intra-articular
Injected into bone joints
Intrathecal/lntraventricular
It is sometimes necessary to introduce drugs directly
into the cerebrospinal fluid (CSF): some anesthetics.
Transdermal
This route of administration achieves systemic effects
by application of drugs to the skin, usually via a
transdermal patch.
The rate of absorption can vary markedly depending
upon the physical characteristics of the skin at the site
of application. Small lipid soluble molecule.
This route is most often used for the sustained delivery
of drugs, such as the antianginal drug, nitroglycerin.

More Related Content

Similar to PPT_-_Pharmacokinetics.ppt

Module 2 pharmacokinetics and drug metabolism
Module 2  pharmacokinetics and drug metabolismModule 2  pharmacokinetics and drug metabolism
Module 2 pharmacokinetics and drug metabolism
julialoiko
 
General principles of pharmacology.pptx
General principles of pharmacology.pptxGeneral principles of pharmacology.pptx
General principles of pharmacology.pptx
INSHAURRAHMAN
 
Pharmacokineticsppt 130126012953-phpapp02
Pharmacokineticsppt 130126012953-phpapp02Pharmacokineticsppt 130126012953-phpapp02
Pharmacokineticsppt 130126012953-phpapp02
Linda Amos
 
Routes of drug administration
Routes of drug administrationRoutes of drug administration
Routes of drug administration
amitgajjar85
 
routes of drug administration.pptशहहहहहहहहह
routes of drug administration.pptशहहहहहहहहहroutes of drug administration.pptशहहहहहहहहह
routes of drug administration.pptशहहहहहहहहह
Sanjiv Pandey
 
Pharmacokinetics
PharmacokineticsPharmacokinetics
Pharmacokinetics
Sandeep Killedar
 
Pharma Co Kinetics Filtration by Kidney
 Pharma Co Kinetics Filtration by Kidney Pharma Co Kinetics Filtration by Kidney
Absorption of drugs through non oral routes
Absorption of drugs through non oral routesAbsorption of drugs through non oral routes
Absorption of drugs through non oral routes
Azhar iqbal
 
Basics of Pharmacology general pharmacology.....pptx
Basics of Pharmacology general pharmacology.....pptxBasics of Pharmacology general pharmacology.....pptx
Basics of Pharmacology general pharmacology.....pptx
MosaHasen
 
Routes of Drug Administration
Routes of Drug AdministrationRoutes of Drug Administration
Routes of Drug Administration
Naveen Kumar Sharma
 
Route of drugs administration
Route of drugs administrationRoute of drugs administration
Route of drugs administration
Faryal Javaid
 
pharmacokinetics & pharmacodynamics- seminar- magdum sir.pptx
pharmacokinetics & pharmacodynamics- seminar- magdum sir.pptxpharmacokinetics & pharmacodynamics- seminar- magdum sir.pptx
pharmacokinetics & pharmacodynamics- seminar- magdum sir.pptx
snehapachore2
 
Pharmacokinetics- ABSORPTION, DISTRIBUTION.pptx
Pharmacokinetics- ABSORPTION, DISTRIBUTION.pptxPharmacokinetics- ABSORPTION, DISTRIBUTION.pptx
Pharmacokinetics- ABSORPTION, DISTRIBUTION.pptx
asmitapandey5196
 
ROUTES OF DRUG ADMINISTRATION-Fall 2022.ppt
ROUTES OF DRUG ADMINISTRATION-Fall 2022.pptROUTES OF DRUG ADMINISTRATION-Fall 2022.ppt
ROUTES OF DRUG ADMINISTRATION-Fall 2022.ppt
MuhammadHassan592508
 
pharmacokinetics.pptx
pharmacokinetics.pptxpharmacokinetics.pptx
pharmacokinetics.pptx
AKASHKUMARKAMLESHPRA
 
Introduction to Pharmacology
Introduction to PharmacologyIntroduction to Pharmacology
Introduction to Pharmacology
Mo Kharash
 
Pharmacokinetics lecture i
Pharmacokinetics lecture  iPharmacokinetics lecture  i
Pharmacokinetics lecture i
vineet srivastava
 
DRUG ACTION- NURSING FOUNDATIONS.pptx
DRUG ACTION- NURSING FOUNDATIONS.pptxDRUG ACTION- NURSING FOUNDATIONS.pptx
DRUG ACTION- NURSING FOUNDATIONS.pptx
Sandhya C
 
Routes of drug administration (1)
Routes of drug administration (1)Routes of drug administration (1)
Routes of drug administration (1)
kattamurilakshmi
 
Pharmacokinetics / Biopharmaceutics - physiological factors affecting oral ab...
Pharmacokinetics / Biopharmaceutics - physiological factors affecting oral ab...Pharmacokinetics / Biopharmaceutics - physiological factors affecting oral ab...
Pharmacokinetics / Biopharmaceutics - physiological factors affecting oral ab...
Areej Abu Hanieh
 

Similar to PPT_-_Pharmacokinetics.ppt (20)

Module 2 pharmacokinetics and drug metabolism
Module 2  pharmacokinetics and drug metabolismModule 2  pharmacokinetics and drug metabolism
Module 2 pharmacokinetics and drug metabolism
 
General principles of pharmacology.pptx
General principles of pharmacology.pptxGeneral principles of pharmacology.pptx
General principles of pharmacology.pptx
 
Pharmacokineticsppt 130126012953-phpapp02
Pharmacokineticsppt 130126012953-phpapp02Pharmacokineticsppt 130126012953-phpapp02
Pharmacokineticsppt 130126012953-phpapp02
 
Routes of drug administration
Routes of drug administrationRoutes of drug administration
Routes of drug administration
 
routes of drug administration.pptशहहहहहहहहह
routes of drug administration.pptशहहहहहहहहहroutes of drug administration.pptशहहहहहहहहह
routes of drug administration.pptशहहहहहहहहह
 
Pharmacokinetics
PharmacokineticsPharmacokinetics
Pharmacokinetics
 
Pharma Co Kinetics Filtration by Kidney
 Pharma Co Kinetics Filtration by Kidney Pharma Co Kinetics Filtration by Kidney
Pharma Co Kinetics Filtration by Kidney
 
Absorption of drugs through non oral routes
Absorption of drugs through non oral routesAbsorption of drugs through non oral routes
Absorption of drugs through non oral routes
 
Basics of Pharmacology general pharmacology.....pptx
Basics of Pharmacology general pharmacology.....pptxBasics of Pharmacology general pharmacology.....pptx
Basics of Pharmacology general pharmacology.....pptx
 
Routes of Drug Administration
Routes of Drug AdministrationRoutes of Drug Administration
Routes of Drug Administration
 
Route of drugs administration
Route of drugs administrationRoute of drugs administration
Route of drugs administration
 
pharmacokinetics & pharmacodynamics- seminar- magdum sir.pptx
pharmacokinetics & pharmacodynamics- seminar- magdum sir.pptxpharmacokinetics & pharmacodynamics- seminar- magdum sir.pptx
pharmacokinetics & pharmacodynamics- seminar- magdum sir.pptx
 
Pharmacokinetics- ABSORPTION, DISTRIBUTION.pptx
Pharmacokinetics- ABSORPTION, DISTRIBUTION.pptxPharmacokinetics- ABSORPTION, DISTRIBUTION.pptx
Pharmacokinetics- ABSORPTION, DISTRIBUTION.pptx
 
ROUTES OF DRUG ADMINISTRATION-Fall 2022.ppt
ROUTES OF DRUG ADMINISTRATION-Fall 2022.pptROUTES OF DRUG ADMINISTRATION-Fall 2022.ppt
ROUTES OF DRUG ADMINISTRATION-Fall 2022.ppt
 
pharmacokinetics.pptx
pharmacokinetics.pptxpharmacokinetics.pptx
pharmacokinetics.pptx
 
Introduction to Pharmacology
Introduction to PharmacologyIntroduction to Pharmacology
Introduction to Pharmacology
 
Pharmacokinetics lecture i
Pharmacokinetics lecture  iPharmacokinetics lecture  i
Pharmacokinetics lecture i
 
DRUG ACTION- NURSING FOUNDATIONS.pptx
DRUG ACTION- NURSING FOUNDATIONS.pptxDRUG ACTION- NURSING FOUNDATIONS.pptx
DRUG ACTION- NURSING FOUNDATIONS.pptx
 
Routes of drug administration (1)
Routes of drug administration (1)Routes of drug administration (1)
Routes of drug administration (1)
 
Pharmacokinetics / Biopharmaceutics - physiological factors affecting oral ab...
Pharmacokinetics / Biopharmaceutics - physiological factors affecting oral ab...Pharmacokinetics / Biopharmaceutics - physiological factors affecting oral ab...
Pharmacokinetics / Biopharmaceutics - physiological factors affecting oral ab...
 

Recently uploaded

NUTRICONNECT NEWSLETTER 3RD ISSUE 2ND VOLUME.pdf
NUTRICONNECT NEWSLETTER 3RD ISSUE 2ND VOLUME.pdfNUTRICONNECT NEWSLETTER 3RD ISSUE 2ND VOLUME.pdf
NUTRICONNECT NEWSLETTER 3RD ISSUE 2ND VOLUME.pdf
MatsikoAlex
 
Veterinary Medicines Manufacturers in India
Veterinary Medicines Manufacturers in IndiaVeterinary Medicines Manufacturers in India
Veterinary Medicines Manufacturers in India
Heilsaa Care
 
THE MANAGEMENT OF PROSTATE CANCER . pptx
THE MANAGEMENT OF PROSTATE CANCER . pptxTHE MANAGEMENT OF PROSTATE CANCER . pptx
THE MANAGEMENT OF PROSTATE CANCER . pptx
Bright Chipili
 
Obstructive sleep apnea (OSA) and Obesity hypoventilation syndrome (OHS)
Obstructive sleep apnea (OSA) and Obesity hypoventilation syndrome (OHS)Obstructive sleep apnea (OSA) and Obesity hypoventilation syndrome (OHS)
Obstructive sleep apnea (OSA) and Obesity hypoventilation syndrome (OHS)
HafsaAnwaar1
 
Perforation.pptx
Perforation.pptxPerforation.pptx
Perforation.pptx
Nandish Sannaiah
 
PULMONARY DRUG DELIVERY SYSTEM......pptx
PULMONARY DRUG DELIVERY SYSTEM......pptxPULMONARY DRUG DELIVERY SYSTEM......pptx
PULMONARY DRUG DELIVERY SYSTEM......pptx
PRAMESHPANWAR1
 
How to Relieve Prostate Congestion- Here are some Effective Strategies.pptx
How to Relieve Prostate Congestion- Here are some Effective Strategies.pptxHow to Relieve Prostate Congestion- Here are some Effective Strategies.pptx
How to Relieve Prostate Congestion- Here are some Effective Strategies.pptx
AmandaChou9
 
JULY 2024 Oncology Cartoons by Dr Kanhu Charan Patro
JULY 2024 Oncology Cartoons by Dr Kanhu Charan PatroJULY 2024 Oncology Cartoons by Dr Kanhu Charan Patro
JULY 2024 Oncology Cartoons by Dr Kanhu Charan Patro
Kanhu Charan
 
Operation Theatre Nursing -History of Surgery & Anesthesia.pptx
Operation Theatre Nursing -History of Surgery & Anesthesia.pptxOperation Theatre Nursing -History of Surgery & Anesthesia.pptx
Operation Theatre Nursing -History of Surgery & Anesthesia.pptx
RadhaThapaChhetry
 
2nd week of Human development .embryology
2nd week of Human development .embryology2nd week of Human development .embryology
2nd week of Human development .embryology
Mithilesh Chaurasia
 
Medical oncologic management of Colorectal cancer-1-1.pptx
Medical oncologic management of Colorectal cancer-1-1.pptxMedical oncologic management of Colorectal cancer-1-1.pptx
Medical oncologic management of Colorectal cancer-1-1.pptx
robel26
 
Pharmacological Management of Hypertension: New Drugs and Mechanisms
Pharmacological Management of Hypertension: New Drugs and MechanismsPharmacological Management of Hypertension: New Drugs and Mechanisms
Pharmacological Management of Hypertension: New Drugs and Mechanisms
Medwin Publishers
 
Nosodes in Homeopathy, Understanding the Basis and Applications.pptx
Nosodes in Homeopathy, Understanding the Basis and Applications.pptxNosodes in Homeopathy, Understanding the Basis and Applications.pptx
Nosodes in Homeopathy, Understanding the Basis and Applications.pptx
jeearu
 
PULMONARY EMBOLISM AND ITS MANAGEMENT.pptx
PULMONARY EMBOLISM AND ITS MANAGEMENT.pptxPULMONARY EMBOLISM AND ITS MANAGEMENT.pptx
PULMONARY EMBOLISM AND ITS MANAGEMENT.pptx
neeti70
 
Complete Buying Guide to Modafresh 200mg Tablets: Dosage, Benefits, and More
Complete Buying Guide to Modafresh 200mg Tablets: Dosage, Benefits, and MoreComplete Buying Guide to Modafresh 200mg Tablets: Dosage, Benefits, and More
Complete Buying Guide to Modafresh 200mg Tablets: Dosage, Benefits, and More
Donald Coomer
 
Minimal Residual Disease (MRD)
Minimal Residual Disease           (MRD)Minimal Residual Disease           (MRD)
Minimal Residual Disease (MRD)
Reenaz Shaik
 
Top 10 Habits for Longevity [Biohacker Summit 2024]
Top 10 Habits for Longevity [Biohacker Summit 2024]Top 10 Habits for Longevity [Biohacker Summit 2024]
Top 10 Habits for Longevity [Biohacker Summit 2024]
Olli Sovijärvi
 
Gestational Trophoblastic Disease( GTD)- Molar pregnancy, Gestational Trophob...
Gestational Trophoblastic Disease( GTD)- Molar pregnancy, Gestational Trophob...Gestational Trophoblastic Disease( GTD)- Molar pregnancy, Gestational Trophob...
Gestational Trophoblastic Disease( GTD)- Molar pregnancy, Gestational Trophob...
Dr.Nishant Janu
 
Journal club presentation JC 28.5.24 edit.pptx
Journal club presentation JC 28.5.24 edit.pptxJournal club presentation JC 28.5.24 edit.pptx
Journal club presentation JC 28.5.24 edit.pptx
AdhyaDubey1
 
vaginal thrush presentation by Dr. Rewas Ali
vaginal thrush presentation by Dr. Rewas Alivaginal thrush presentation by Dr. Rewas Ali
vaginal thrush presentation by Dr. Rewas Ali
RewAs ALI
 

Recently uploaded (20)

NUTRICONNECT NEWSLETTER 3RD ISSUE 2ND VOLUME.pdf
NUTRICONNECT NEWSLETTER 3RD ISSUE 2ND VOLUME.pdfNUTRICONNECT NEWSLETTER 3RD ISSUE 2ND VOLUME.pdf
NUTRICONNECT NEWSLETTER 3RD ISSUE 2ND VOLUME.pdf
 
Veterinary Medicines Manufacturers in India
Veterinary Medicines Manufacturers in IndiaVeterinary Medicines Manufacturers in India
Veterinary Medicines Manufacturers in India
 
THE MANAGEMENT OF PROSTATE CANCER . pptx
THE MANAGEMENT OF PROSTATE CANCER . pptxTHE MANAGEMENT OF PROSTATE CANCER . pptx
THE MANAGEMENT OF PROSTATE CANCER . pptx
 
Obstructive sleep apnea (OSA) and Obesity hypoventilation syndrome (OHS)
Obstructive sleep apnea (OSA) and Obesity hypoventilation syndrome (OHS)Obstructive sleep apnea (OSA) and Obesity hypoventilation syndrome (OHS)
Obstructive sleep apnea (OSA) and Obesity hypoventilation syndrome (OHS)
 
Perforation.pptx
Perforation.pptxPerforation.pptx
Perforation.pptx
 
PULMONARY DRUG DELIVERY SYSTEM......pptx
PULMONARY DRUG DELIVERY SYSTEM......pptxPULMONARY DRUG DELIVERY SYSTEM......pptx
PULMONARY DRUG DELIVERY SYSTEM......pptx
 
How to Relieve Prostate Congestion- Here are some Effective Strategies.pptx
How to Relieve Prostate Congestion- Here are some Effective Strategies.pptxHow to Relieve Prostate Congestion- Here are some Effective Strategies.pptx
How to Relieve Prostate Congestion- Here are some Effective Strategies.pptx
 
JULY 2024 Oncology Cartoons by Dr Kanhu Charan Patro
JULY 2024 Oncology Cartoons by Dr Kanhu Charan PatroJULY 2024 Oncology Cartoons by Dr Kanhu Charan Patro
JULY 2024 Oncology Cartoons by Dr Kanhu Charan Patro
 
Operation Theatre Nursing -History of Surgery & Anesthesia.pptx
Operation Theatre Nursing -History of Surgery & Anesthesia.pptxOperation Theatre Nursing -History of Surgery & Anesthesia.pptx
Operation Theatre Nursing -History of Surgery & Anesthesia.pptx
 
2nd week of Human development .embryology
2nd week of Human development .embryology2nd week of Human development .embryology
2nd week of Human development .embryology
 
Medical oncologic management of Colorectal cancer-1-1.pptx
Medical oncologic management of Colorectal cancer-1-1.pptxMedical oncologic management of Colorectal cancer-1-1.pptx
Medical oncologic management of Colorectal cancer-1-1.pptx
 
Pharmacological Management of Hypertension: New Drugs and Mechanisms
Pharmacological Management of Hypertension: New Drugs and MechanismsPharmacological Management of Hypertension: New Drugs and Mechanisms
Pharmacological Management of Hypertension: New Drugs and Mechanisms
 
Nosodes in Homeopathy, Understanding the Basis and Applications.pptx
Nosodes in Homeopathy, Understanding the Basis and Applications.pptxNosodes in Homeopathy, Understanding the Basis and Applications.pptx
Nosodes in Homeopathy, Understanding the Basis and Applications.pptx
 
PULMONARY EMBOLISM AND ITS MANAGEMENT.pptx
PULMONARY EMBOLISM AND ITS MANAGEMENT.pptxPULMONARY EMBOLISM AND ITS MANAGEMENT.pptx
PULMONARY EMBOLISM AND ITS MANAGEMENT.pptx
 
Complete Buying Guide to Modafresh 200mg Tablets: Dosage, Benefits, and More
Complete Buying Guide to Modafresh 200mg Tablets: Dosage, Benefits, and MoreComplete Buying Guide to Modafresh 200mg Tablets: Dosage, Benefits, and More
Complete Buying Guide to Modafresh 200mg Tablets: Dosage, Benefits, and More
 
Minimal Residual Disease (MRD)
Minimal Residual Disease           (MRD)Minimal Residual Disease           (MRD)
Minimal Residual Disease (MRD)
 
Top 10 Habits for Longevity [Biohacker Summit 2024]
Top 10 Habits for Longevity [Biohacker Summit 2024]Top 10 Habits for Longevity [Biohacker Summit 2024]
Top 10 Habits for Longevity [Biohacker Summit 2024]
 
Gestational Trophoblastic Disease( GTD)- Molar pregnancy, Gestational Trophob...
Gestational Trophoblastic Disease( GTD)- Molar pregnancy, Gestational Trophob...Gestational Trophoblastic Disease( GTD)- Molar pregnancy, Gestational Trophob...
Gestational Trophoblastic Disease( GTD)- Molar pregnancy, Gestational Trophob...
 
Journal club presentation JC 28.5.24 edit.pptx
Journal club presentation JC 28.5.24 edit.pptxJournal club presentation JC 28.5.24 edit.pptx
Journal club presentation JC 28.5.24 edit.pptx
 
vaginal thrush presentation by Dr. Rewas Ali
vaginal thrush presentation by Dr. Rewas Alivaginal thrush presentation by Dr. Rewas Ali
vaginal thrush presentation by Dr. Rewas Ali
 

PPT_-_Pharmacokinetics.ppt

  • 1. Pharmacokinetic Overview The intensity of the drug's effect, and the duration of the drug action are controlled by four fundamental pathways of drug movement and modification in the body. Figure: Schematic representation of drug absorption, distribution, metabolism and elimination.
  • 2. First, drug absorption from the site of administration permits entry of the therapeutic agent (either directly or indirectly) into plasma (input). Absorption is defined as the passage of a drug from its site of administration into the plasma. Second, the drug may then reversibly leave the blood stream and distribute into the interstitial and intracellular fluids (distribution). Third, the drug may be metabolized by the liver, kidney, or other tissues. Finally, the drug and its metabolites are eliminated from the body (output) in urine, bile, or feces.
  • 3. Routes of drug administration The route of administration is determined primarily - by the properties of the drug (such as water or lipid solubility, ionization, etc.) and - by the therapeutic objectives (for example, the desirability of a rapid onset of action or the need for long-term administration or restriction to a local site). The route of administration (ROA) that is chosen may have a profound effect upon the speed and efficiency with which the drug acts.
  • 4. Enteral: oral, sublingual, rectal Parenteral: intravascular (intravenous), intramuscular, subcutaneous Other: inhalation, intranasal, intrathecal (in CSF), topical, transdermal The main routes of drug administration are: Figure: Commonly used routes of drug administration.
  • 6. Enteral routes: Drug placed directly in the GI tract: Oral- swallowing Sublingual- placed under the tongue Rectum- absorption through the rectum
  • 7. Oral Giving a drug by mouth is the most common route of administration but it is also the most variable, and requires the most complicated pathway to the tissues. Little absorption occurs until the drug enters the small intestine. Drug absorption from the intestine: The drug absorbed by passive transport mechanism in intestine at a rate determined by the ionization and lipid solubility of the drug molecules. Strong bases of pKa 10 or higher are poorly absorbed, as are strong acids of pKa less than 3, because they are fully ionized.
  • 8. Figure: Absorption of drugs from the intestine, as a function of pKa, for acids and bases. Weak acids and bases are well absorbed; strong acids and bases are poorly absorbed.
  • 9. There are a few instances where intestinal absorption depends on carrier-mediated transport mechanism rather than simple lipid diffusion. For example levodopa, iron, calcium. Advantages: Convenient- can be self-administered, pain free, easy to take Absorption- takes place along the whole length of the GI tract Cheap- compared to most other parenteral routes
  • 10. Disadvantages: - Unpleasant taste of some drugs - Irritation to gastric mucosa - nausea and vomiting - Destruction of drugs by gastric acid and digestive juices - Sometimes inefficient- only part of the drug may be absorbed - Effect too slow for emergencies - First-pass effect - drugs absorbed orally are initially transported to the liver via the portal vein - Unable to use in unconscious patient or who have had GI surgery
  • 11. Most of the drug is absorbed in the small intestine, Why? 1. Small intestine has a much larger surface area for absorption (~200 m2) as compared to the stomach (~1-3 m2). 2. Drug spends more time in the small intestine (~4 hrs) than the stomach (~0.5-1 hrs). Food in the stomach can decrease absorption - Food may delays gastric emptying time so that drugs may destroyed by acid. - Interactions between drug and food particles. - Exception: propranolol- due to  blood flow.
  • 12. First-pass effect When a drug is absorbed across the GI tract, it enters the portal circulation before entering the systemic circulation. A drug can be metabolized in the gut wall or even in the portal blood, but most commonly it is the liver that is responsible for metabolism before the drug reaches the systemic circulation (plasma). In addition, the liver can excrete the drug into the bile (fluid secreted by liver). Any of these sites can contribute to this reduction in bioavailability, and the overall process is known as first-pass effect or first-pass elimination.
  • 14. The greater the first-pass effect, the less the agent will reach the systemic circulation when the agent is administered orally. (imp) Lidocaine (anesthetic agent) is a drug with a first-pass effect that is so great that oral administration is not practical. In the case of propranolol, a significant portion of the orally administered dose is metabolized through a first- pass effect. More than 90% of nitroglycerin is cleared during a single passage through the liver. Therefore, a much larger oral dose is required to achieve the same therapeutic response as that obtained from a dose administered intravenously.
  • 15. Sublingual/Buccal Placement under the tongue allows the drug to diffuse into the capillary network and therefore to enter the systemic circulation directly. When only small amounts of drugs are required to gain access to the blood, the sublingual route may be very satisfactory. For example, nitroglycerin in angina pectoris. Because the stomach is bypassed, acid-liability and gut-permeability is not important. Drugs are absorbed from the mouth straight into the systemic circulation without entering the portal system and so escape first-pass metabolism by the liver.
  • 16. Advantages -rapid absorption -drug stability -avoid first-pass effect Disadvantages -inconvenient -small doses -unpleasant taste of some drugs Rectal 50% of the drainage of the rectal region bypasses the portal circulation; thus the biotransformation of drugs by the liver is minimized. Drug’s property: - Non-polar - Lipid soluble
  • 17. - Devoid of destruction of the drug by intestinal enzymes or by low pH in the stomach - Unconscious patients (postoperative) and children - If patient is nauseous or vomiting - Absorption may vary - Good for drugs affecting the bowel such as laxatives - Irritating drugs contraindicated - Can be used for both local effects and systemic effects
  • 18. Parenteral routes: Parenteral administration is used for drugs that are poorly absorbed from the gastrointestinal (GI) tract, and for agents such as insulin that are unstable in the GI tract. Parenteral administration is also used for treatment of unconscious patients and under circumstances that require a rapid onset of action. The three major parenteral routes are - Intravascular (intravenous or intra-arterial) - Intramuscular - Subcutaneous
  • 20. Intravascular: Intravenous (IV) injection is the most common parenteral route. For drugs that are not absorbed orally, there is often no other choice. - Rapid onset of action because the drug is injected directly into the bloodstream - Useful in emergencies and in patients that are unconscious - The drug avoids the GI tract and first-pass metabolism by the liver - Smaller doses generally are required than the other routes but cost is high
  • 21. Greater risk of adverse effects as: a. High concentration attained rapidly b. That are injected cannot be recalled by strategies such as emesis or binding to activated charcoal c. Risk of embolism (obstruction of blood vessel) d. May introduce bacteria through contamination, induce hemolysis e. Pain at application site f. No self administration facility Capillary: brings the blood into intimate relationship with the tissue cell Artery Arterioles Capillary VenulesVeins
  • 22. Intra-artery Similar properties, advantages and disadvantages of intravascular route. Intra-artery route is specially used when high drug concentration in specific tissue is required than other tissue: - diagnostic purpose and - for chemotherapy Intramuscular Drugs administered intramuscularly can be aqueous solutions or specialized depot preparations- often a suspension of drug in a non-aqueous vehicle, such as ethylene glycol or peanut oil.
  • 23. Absorption of drugs in aqueous solution is fast, whereas that from depot preparations is slow. Drug passes through capillary walls to enter the blood stream. - Pain at injection sites for certain drugs - This parenteral route may be used when an immediate effect is not required but a prompt effect is desirable - Absorption from an intramuscular depot is more predictable and uniform than from a subcutaneous site
  • 24. Subcutaneous Drug is injected beneath the skin and permeates capillary walls to enter blood stream. Absorption from the site of injection is dependent on local blood flow. Concurrent administration of vasoconstrictor will slow absorption. For example, minute amount of epinephrine is sometime used in combination with a drug to restrict its area of action. Epinephrine acts as a local vasoconstrictor and decreases removal of a drug, such as lidocaine (local anesthetic), from the site of administration.
  • 25. Examples of drugs given by this route are insulin and sodium heparin, neither of which is absorbed orally, and both of which should be absorbed slowly over many hours. Inhalation Inhalation provides the rapid delivery of a drug across the large surface area of the mucous membranes of the respiratory tract and pulmonary epithelium, producing an effect almost as rapidly as by intravenous injection.
  • 26. This route of administration is used for drugs that are gases and volatile agents (for example, some anesthetics), or those that can be dispersed in an aerosol. The route is particularly effective and convenient for patients with respiratory complaints (for example, asthma or chronic obstructive pulmonary disease) as drug is delivered directly to the site of action and systemic side effects are minimized.
  • 27. Topical Topical application is used when a local effect of the drug is desired. Used for most dermatologic and ophthalmologic preparations. Clotrimazole is applied as a cream to the skin in the treatment of dermatophytosis. Atropine is instilled directly into the eye to dilate the pupil and permit measurement of refractive errors. Intra-articular Injected into bone joints
  • 28. Intrathecal/lntraventricular It is sometimes necessary to introduce drugs directly into the cerebrospinal fluid (CSF): some anesthetics. Transdermal This route of administration achieves systemic effects by application of drugs to the skin, usually via a transdermal patch. The rate of absorption can vary markedly depending upon the physical characteristics of the skin at the site of application. Small lipid soluble molecule. This route is most often used for the sustained delivery of drugs, such as the antianginal drug, nitroglycerin.

Editor's Notes

  1. 1